Exploitation of Source Rock Hydrocarbons through Propane Stimulation

CONFIDENTIAL TRANSLATION – DO NOT CIRCULATE
Technical Note on the Exploitation of Source Rock Hydrocarbons through Propane Stimulation – page 1
TECHNICAL NOTE
Exploitation of Source Rock Hydrocarbons
through Propane Stimulation
FEBRUARY 2013

CONTENTS
1 Introduction
1.1 Summary – Recommendations
1.2 Context and objectives of the mission
2 Organization of the field study mission
2.1 Preliminary assessment of available data
2.2 On-site observation and assessment of an operation
2.3 Reviewing supplementary data requested during or after the field study
mission
3 Principles of propane stimulation
3.1 Why propane stimulation?
3.2 Analysis and very simplified description of the main phases of operations on
the field
3.3 Principles for the implementation of stimulation and recovery operations.
3.4 Pure propane stimulation trial observed December 2012: description /
observations
4 Simplified evaluation of the sector’s main phases
4.1 Method of analysis used: simplified mapping of risks, impact and harmful
effects
4.2 Elements of risk analysis
4.3 Analysis of environmental impacts and harmful effects
4.4 Summary of mapping for all of the scenarios under review
5 Conclusion: Pure propane injection technology, risk analysis,
readiness and evolution of the process
5.1 Pure propane injection
5.2 Risk analysis
5.3 Technological readiness of the technologies and evolution of the process

1 Introduction
1.1 Summary – Recommendations
The exploration and production of hydrocarbons from source rock has raised
serious apprehension in France.
This is linked to:
 General concerns about the exploration and production of hydrocarbons, and
about the place of this production in the transition to a carbon-free economy.
This aspect is not within the scope of the technical expertise on the methods
of exploration and productions that are the subject of this report.
 More specific concerns related to hydraulic fracturing and especially to the
risks in terms of water cycle effects and chemicals introduced into the
environment.
Over the past five years in North America (USA and Canada), a method has been
developed that does not need water for fracturing – propane gel stimulation,
implemented more than one thousand times on a few hundred sites – and this
technology has further evolved into a method that requires neither water nor
chemical additives – pure propane stimulation –, which seems to offer a response to
the specific fears raised by hydraulic fracturing. The information collected on this
method led us to carry out an expert mission on the kinds of perspectives at hand,
in order to determine if and to what extent this could be a positive alternative. The
mission also fulfills the need to acquire knowledge so that the government is not
dependent only on declarations made by interested parties and can provide
information to the public that might otherwise be lacking.
For these purposes, a delegation travelled to the USA in December 2012 (Pearsall).
There we were able to study the whole line of a propane stimulation operation as it
was implemented (method of managing propane tanks, of connecting these tanks to
the medium-pressure circuit, organization of the high-pressure networks from the
compressors to the wellhead, organization of the flows emerging from the well, …)
and its monitoring, in particular through an observation well located nearby, carried
out on a site near the town of Pearsall (south Texas, USA), under the supervision of
the eCORP company, who contracted the GASFRAC company to carry out
operational details.
In the course of this mission, an injection of non-gel propane (that is, no chemicals
had been added to thicken the propane) under high pressure was carried out on the
site. The injection was made at 5,000 psi, i.e. 350 bar, a "medium" pressure that
was appropriate for the moderate depth of the field (1,500 m). For deeper fields,
pressures of 500 or even 1000 bar may be required.
This injection was a world first for non-gel propane. The microseismic monitoring
showed that it did crack the horizon of the targeted source rock.

The mission was an opportunity for many discussions with company managers from
eCORP, in particular from the technical division; we saw presentations and there
were question and answer sessions. We were also able to visit nearby sites with
different ways of organizing operations and monitoring wells.
Observations carried out on the site and discussions with GASFRAC and eCORP
personnel enabled us to undertake an analysis of risks, impacts and harmful effects,
and to identify specific advantages of the process. Several main points emerge:
Implementation of the technology
 The technology has proved efficient during fracturing trials,
 The test did not include proppants. The capability of this technique to
eliminate any injection of chemical additives should be confirmed (technical
efficiency and environmental gains are largely dependent on this),
 The technologies suggested for reducing the diameter of the wellbore should
be evaluated in regard to compatibility with extraction flow rates of the
hydrocarbons produced,
 The amount of propane used is significant. The amounts used on American
sites would qualify a site as "top-tier SEVESO". Changes involving, in
particular, an adapted management of flows and recycling of propane should
be made to restrict the number of propane tankers on the site, bringing the
site below the threshold, as far as possible, and reducing the associated
truck traffic.
Controlling risks, impacts and harmful effects
 The security of surface installations (taking into account French regulatory
obligations, security distances around the site) is one area where technical
improvements are indispensable for transposition to Europe;
 Selection of appropriate sites (the order of magnitude of the security distance
to be established would be about 300 m);
 Doubts on the short and long term impact on water and air quality must be
resolved.
"Pure propane stimulation" is in the early stages of industrial application, which
means there are many possibilities for improvement, in particular at the time of
transposition to Europe. The technical means assessed during the mission were
those used for "propane gel stimulation"; "pure propane stimulation" is an
improvement on this technology. The assessment covered a technology that is
evolving, so it is a simple estimation based on the principles. In the context of this
evaluation, we did not detect any point or item that seemed to be an obstacle of
such significance that it would be impossible to overcome; potential improvements
within reach could solve these problems. The mapping exercise gives a first view of
the risks, advantages, and/or drawbacks of the technique, and identifies the items
that already seem to be acceptable – in terms of the environment and security –, as
well as items that require attention and items that call for improvement.
* *
*

The technique of pure propane stimulation eliminates the injection of water and
chemical additives into the ground. Associated with wellbores of small diameter,
which also reduce the environmental impact, it seems especially well adapted to
exploration of the subsoil in order to determine the extent of the resources.
Furthermore, the technique is still in development and has not yet been brought to
Europe.
The use of pure propane stimulation could be included in a research program
coupling work on the technology (tests and validation of the new procedures,
techno-economic performance analysis) with a better knowledge of the underground
resources. Such a program could include, as appropriate, actions (drilling,
stimulation) that are part of an experimental implementation under the control of
public authorities, as provided under the terms of French law 2011-835, Article 4,
dated 13 July 2011, concerning the prohibition on exploration and operation of liquid
or gas hydrocarbon mines by means of hydraulic fracturing.

1.2 Context and objectives of the mission
1.2.1 Context of the mission: hydraulic fracturing has raised serious
apprehension in France, in particular concerning its effects on the
water cycle
Shale gas and oil are today extracted mainly by means of hydraulic fracturing.
Several tens of thousands of hydraulic fracturing operations have taken place in the
Unites States (one million is the estimate usually given). The accumulation of
experience enables us to identify exactly what precautions must be taken to control
the impact of this technology. The most recent report by the IEA estimates that the
United States' oil production could exceed that of Saudi Arabia around 2020 thanks
to the growing extraction of shale oil, relying on the implementation of this
technology. We can therefore consider that the technical efficiency of hydraulic
fracturing has been proven and that the measures that need to be implemented for
controlling its effects are known.
However, and despite the long French experience in the exploration and production
of hydrocarbons (more than two thousand wells in the Paris area in the last forty
years, without a single environmental incident, nearly two hundred hydraulic
fracturing in the same Paris area in the past twenty years in the context of enhanced
hydrocarbon recovery, also without environmental incident), the exploration and
production of hydrocarbons from source rock has given rise to very negative
reactions from the public and the political spheres. Opposition has focused, in
particular, on hydraulic fracturing techniques (injection of chemically enhanced water
at high pressures).
Beyond the unfortunate way that the permit process was handled (government
decisions, dating back fifteen years, not to hold public hearings when applications
were made, which led certain parties to believe that information had been hidden
from them; poor communication on the local level by the companies seeking
permits), opposition centered on questions linked to water and associated chemical
additives: water consumption, treatment of wastewater aboveground, chemical
additives that remain in the subsoil, release of heavy metal brought from
underground to the surface.
In response to these potential risks, a law was passed on 13 July 2011 prohibiting
the use of hydraulic fracturing.
In a press conference on last 13 November, the President of the Republic declared,
on the subject of shale gas exploration in France: “Research on techniques other
than hydraulic fracturing is possible. For the time being, that research has not yielded
all of its results, I cannot prohibit it, it is not forbidden under law. As long as there is
no new technique, I have said that during my term of office there will be no
authorizations for shale gas exploration.”
Given the potential resources in France for both shale gas (2500G m3
) and shale oil
(16G bbl), the Ministère du Redressement Productif began to investigate the possible
recourse to alternative technologies that would minimize potential risks associated
with hydraulic fracturing, in the follow-up to the report drafted by the CGEIET
(Conseil général de l'économie, de l'industrie, de l'énergie et des technologies) and
the CGEDD (Conseil général de l'environnement et du développement durable) in
February 2012.

1.2.2 The objective of the mission: a first preliminary evaluation of the
principle of propane stimulation
ANCRE (Alliance Nationale de Coordination de la Recherche pour l'Energie –
National Coordinating Alliance for Energy Research) published a report1
in July 2012
in which several alternative options were discussed. Among these alternatives was
stimulation using propane gel, which seems to be an advantageous technology
because it solves the water use problem, reduces or eliminates the number of
chemical additives required, minimizes chemical interactions between the fracturing
fluid and the rock and thereby reduces the freeing-up of other, undesirable minerals,
simplifying the treatment of production water.
Whilst hydraulic fracturing is a proven technique (the first operations date from 1948),
its massive use associated with horizontal drilling has only been implemented for
extracting shale gas since 2003-2004 in the United States, with an sharp increase
since 20082
. Furthermore, in the early years in the United States, there were some
negligent practices3
before State regulators and the EPA stepped in with better
regulations. Stimulation using propane gel is an even more recent technique. It is
1
title of the report, internet link – not supplied in original NDT
2
Marcellus Shale wells drilled in Pennsylvania per calendar year
The extraction of shale gas in the USA started on the Barnett Shale, in Texas, and then was
developed on the Fayetteville Shale in north Arkansas and the Haynesville Shale in north-west
Louisiana; operations in Pennsylvania are more recent.
3
Negligent practices resulted in part from exemptions accorded by US lawmakers. The report made to
the French National Assembly by members François-Michel Gonnot and Philippe Martin presented the
situation in the following terms:
The past twenty years have witnessed many new policies targeting the oil industry, whether tax
incentives to encourage the development of new extraction technology or regulatory exemptions
aimed at increasing the profitability of production at the price of lowered environmental standards.
Investigations carried out by your rapporteurs have revealed that this trend seems to be over today.
We travelled to a site in Pennsylvania and observed conditions on-site, where strict control
procedures are in place, established by major operators.

mainly used by the GASFRAC4
, who was contracted by the eCORP company for the
mission. Today there have been more than 1500 propane stimulation operations.
And yet the only represents a small share of the market, as 500 hydraulic fracturing
operations take place in the United States every week.
The upshot of the relative newness of propane stimulation is, in particular:
 Feedback is relatively limited: just over one thousand wells have been drilled
 At the same time, this technology has potential for evolution.
We can consider these possibilities for technological evolution as significant. It is also
clear that handling large amounts of propane under high pressure requires a great
deal of caution; precautionary measures should be further reinforced in European
operations, because the population density is higher than in the America, where sites
may be surrounded by vast empty space. The objective of the preliminary study was
therefore not to determine if the method of propane stimulation used in the United
States could be transposed, as is, to Europe, but rather to see if advances in this
technique were likely to bring it up to acceptable European standards, and therefore
if it would be appropriate to encourage industrial concerns to anticipate this new
technology, which, once any advancements have been made, should be subject to
the process of authorization within the framework of French regulations.
It was from this standpoint that we participated in a field study in south Texas
organized with the help of the eCORP company5
, to observe a stimulation trial using
pure liquid propane. The test was designed to determine if fracturing did occur and to
measure it, but did not make use of proppant (an additional trial will be required to
observe how the proppant behaves in the flow and consolidates the cracks).
The field study mission to the United States, 17-20 December 2012, gave us the
opportunity to see the different components making up a propane stimulation
operation as well as observe an actual pure propane stimulation.
During the mission, we were free to ask questions to personnel from both of the
companies. We were thus able to understand the details of the different phases of
the operation, to understand their purpose, to assess the risks and the procedures in
place to limit those risks.
This led us make some comments and recommendations in regard to implanting this
technology in France.
That is the subject of this report, which is organized as follows:
 Organization of the field study mission to Texas: this covers the different
stages of the mission: preparatory technical presentations, on-site visits
(organization and purpose);
 Principles of propane stimulation: first of all, we present the operational plan
for stimulation using propane gel as it is practiced in the United States by
GASFRAC; then we present the trial stimulation using pure propane (no
additives) carried out by GASFRAC and eCORP, which was a first;
4
GASFRAC Web site information not included on the original NDT
5
Web site ? information not included on the original NDT

 Simplified evaluation of the main phases of the procedure: this section is risk,
impact and harmful effects mapping, and indications of how these could be better
controlled;
 Pure propane injection technology, risk analysis, readiness and evolution of
the process: this section develops the information reported in the previous
sections to draw up a summary of certain knowledge and uncertainties
concerning pure propane injection technology, a summary of major risk items as
mapped out – this reveals that the technology is especially relevant for
exploration purposes – and concludes with an assessment of readiness and
avenues for improvement and evolution.

2 Organization of the field study mission
Given the significance of the challenge in terms of human safety (control of the
technology), the environment (advantages and drawbacks of the new technology)
and economic interests (impact of new gas resources on the national economy), the
mission had three phases, designed to ensure the maximum benefit from the on-site
visit: a preparatory phase (documentation in particular), a field visit, and a phase for
reviewing supplementary data.
2.1 Preliminary assessment of available data
A first phase of information exchange took place in the last quarter of 2012. A
questionnaire was sent out to the eCORP company which has been promoting,
notably in France, pure propane stimulation technology. The questionnaire examined
, in particular: a) description of training, well completion practices, operational
parameters of fracturing in general (preparing the fluid, injecting, monitoring
fracturing, production); b) general safety parameters linked to transporting, storing
and using propane and the monitoring techniques employed.
In reply to the questionnaire, a preparatory meeting was held in Paris with eCORP;
prior to and following the meeting, documents were exchanged.
2.2 On-site observation and assessment of an operation
The operation we observed on site was a "pure" propane stimulation (no other
components added, in particular no "gelling" agents). This stimulation was made
using equipment that is standard in North America for propane gel stimulation, and
the wellbore dimensions were also standard for the industry.
The technique that could be used in France would not be a simple transposition of
the technique observed on the site. To name a few of the main differences, upstream
and downstream in the process: the operator plans to use a reduced-diameter drilling
technique ("slim hole drilling"), which, in particular, diminishes the amount of propane
required and reduces the impact and duration of the drilling phase; in addition,
measures for greater security and environmental protection are planned for the
improved method of operation; furthermore, the operator is studying optimized
methods for site recovery.
The two techniques (one that we observed and one that might be used in France) are
closely linked: the second technique is an improvement of the first. Our observations
enabled us to have a first look at the risks, advantages and/or drawbacks of the
technique, and to identify items for which the state of the art is satisfactory, items for
attention, and items that require improvement. We did not detect any items for which
the impediments were so great that a significant improvement would not be likely to
solve the issue.
2.2.1 Technical presentations
Technical presentations focused first of all the nature of the source rock in the Eagle
Ford formation, in terms of petrophysics, geology and geochemistry. The main area
of exploration targeted by eCORP is the volatile oil zone.

A presentation on monitoring via micro-seismicity was given by Mr. Dane Wright, an
expert in the technique, from the Pinnacle company.
In the same vein, there was a presentation on the SPL chain and its monitoring.
In addition, we took a training course on H2S risks in order to receive authorization to
observe the SPNA trials on site. Indeed, below the source rock there is a stratum of
oil that is rich in H2S. Because the fissures could connect with this H2S during
stimulation, it was decided to inform us of the risks at hand and the behavior to adopt
in the event of a safety incident.
General organization of the presentations made on site
Subject Presented by: From:
Introduction, general presentation John Thrash, CEO
eCORP
Geological characteristics of the
Eagle Ford field
Tom Harris, COO
Well preparation Johnny Kopecky, GM
Productivity of the field (reserves) Steve Schubarth CEO Schubarth Inc
Stimulation operations Audis Byrd ACB Energy
"Flow back" management Chris Bruegger Republic
Blake Maywald
Monitoring via micro-seismicity Dave Wright Pinnacle
Environmental monitoring Patty Riley AK Env
Doug Carter Titan Eng
Safety procedures David Dobbs
Total Safety
H2S training and certification Johnny Reed
2.2.2 On-site technical visits
The mission was organized over the period of 17-20 December 2012 and focused
mainly on the preparation and undertaking of a stimulation of a source rock horizon,
using non-gel propane, in the Eagle Ford formation (south Texas, USA).
Three field trips were arranged during the mission:
 The first, on Monday 17 December, involved preparation of the stimulation
operation and we visited the monitoring well located nearby, operated by the
Pinnacle company;
 The second, on Tuesday 18 December, concerned a stimulation operation using
liquid propane with no chemical additives;
 The third and last on-site visit, Wednesday 19 December was an opportunity to
observe the dismantling of the injection modules and the preparation of the flow
back operation (injected stimulation fluid recovered).

2.3 Reviewing supplementary data requested during or after the
field study mission
During the mission, and after a review of the documents provided, supplementary
questions were submitted to eCORP, which provided new data and information.

3 Principles of propane stimulation
3.1 Why propane stimulation?
Propane stimulation was first used mostly in Canada, where winter temperatures can
make it difficult to handle large quantities of water.
Several advantages became apparent with use of this technology, and it has been
emerging from this "niche". eCORP has indicated, specifically, that the injection of
propane results in a better rate of recovery of hydrocarbons and that the impact on
the environment is less severe when propane is used rather than water (the risks of
carbon leach and the upflow of heavy metals that may be present in the field is
eliminated; the recovery of the injected propane is easily incorporated in the
management of the hydrocarbons extracted from the field). Added to these
advantages that exist for the injection of propane "gel", the use of pure liquid propane
is equally effective but requires none of the chemical additives that have been used
up until now. eCORP also promotes the use of slim hole drilling, which should tend to
reduce the environmental impact of the operation.
In general, in as much as France is interested in technologies that present an
alternative to hydraulic fracturing, propane stimulation has two features: it is the only
technique that has been used a significant number of times, making it quickly
transposable; we are aware of the major areas where it can be improved.
It is therefore appropriate to give priority to this preliminary study.
Nonetheless, it is clear that handling large amounts of propane under high pressure
involves certain risks that are not at stake when using water.
The preliminary analysis undertaken during our field study did not have the objective
of producing a "GO / NO GO" assessment for immediate use of this technology in
France; the objective was to determine whether, for use in France, evolutions in the
technique make it worth considering – and in that case, which items or areas require
special attention – or whether, on the contrary, the dangers inherent in handling
propane in the context of shale hydrocarbon stimulation make it unrealistic to
envision the use of this technique.
3.2 Analysis and very simplified description of the main phases of
operations on the field
Bringing a gas or oil field into production typically involves three phases: exploration,
operation, and closure. This is also true for shale oil or gas, with a few specific
considerations that are described here below.
3.2.1 Exploration phase
The exploration phase begins with reconnaissance of the resource network and the
modeling of the field using 3D seismic data. The modeling is both stratigraphic
(different geological strata) and structural (tectonic deformations and geological

formations), in order to define the target areas where hydrocarbon accumulation is
most likely.
The exploration phase is then followed by the drilling of one or several wells seeking
to determine if hydrocarbons are present, to quantify them by a well test and qualify
them by taking a sample. Finally, the reservoir or reservoirs are delineated, an
operation plan drafted, and a techno-economic assessment is made of the
production of the resources.
Specific case of source rock
The case of source rock is specific because the reservoir for production is the
accumulation of original organic matter. Modeling of the resource area is simplified in
that it is not necessary to include the movement of hydrocarbons from the source
rock to the well sites.
However, it is important to be able to evaluate:
 The spatial distribution of the extension of source rock, the petrographic
properties (in particular the silica, carbonate and clay content which indicate
the fracturability of the rock); the petrophysical properties (porosity,
permeability); the organic materials and their levels, which may vary within the
area. These values are determined using digital models of the area;
stratigraphic and structural models; core samples of the surrounding rock and
the source rock; geochemical, petrographic and petrophysical laboratory
analyses;
 The "compartmentalization" of the source rock: reconnaissance of the
spatial distribution of conventional reserves in distinct compartments is a
typical aspect of exploration. The qualification of faults separating these
compartments from each other, their capacity or incapacity to permit hydraulic
communication between the compartments is a determining factor in the
complexity of the development plan. Initially, production of shale hydrocarbons
(gas or oil) will be limited to zones farthest from the natural faults, in order to
avoid any reactions that could lead to seismic activity. Measures taken in
Great Britain to authorize and monitor shale gas exploration could serve as an
example. After this initial period, it is necessary to evaluate the mechanical
behavior of these faults to better assess the risk of induced seismicity.
 Drilling exploration wells: the exploration phase winds up with the drilling of
one or several exploration wells enabling the verification of, on the one hand,
of the spatial variability of the source rock and, on the other, of the possibility
of achieving production by the method selected.
o In regard to the spatial variability of the source rock, in the event that
the petroleum resources in a given source rock area are well known
because many wells have been drilled and analyzed, one would expect
that a limited number of wells would suffice for exploration to qualify
source rock. In the event that the resources are not well known, as
would be the case for the area in southeast France, an appropriate
method must be developed. One approach could be use a seismic map
to identify clusters of variable seismic response (impedance). Using this
source rock "zoning", a drilling plan could be drawn up for
characterizing and qualifying the different zones. Depending on the

case and the prior knowledge of the resource area, the reconnaissance
will be more or less complex.
o In regard to the possibility for production from the source rock, small
scale tests (in reference to both production and injection), carried out
on exploration wells as described here above, should be made using
the selected production technique.
o The number of exploration wells that would enable the precise
identification of the production potential is determined by available data
for the field (the Paris area is well covered, the south-east less so) as
well as feedback from previous explorations. Technology for
hydrocarbon exploration in source rock has improved progressively: ten
thousand wells were required over a fifteen-year period for the Barnett
Shale, whereas the Marcellus Shale, explored later, required a few
hundred wells over five years, and it would appear that just a few dozen
wells and two years have made it possible to identify the Eagle Ford
resources.
These tests will inform the techno-economic assessment of the field, leading to the
decision on whether or not to develop the resources.
3.2.2 Operation phase
A limited number of wellheads6
for exploration purposes
The hydrocarbons present in source rock are immobile. This is why it is necessary to
stimulate the rock to produce hydrocarbons. This stimulation is achieved through the
use of a production well with a casing perforated over a dozen cm2
. The drainage
zone is restricted to the zone that it stimulated. To maximize the productivity of a
layer of source rock, it is necessary to maximize the drainage zone around the well.
If a typical, vertical well is drilled in this sort of rock, only the hydrocarbons contained
in a very limited area will be recovered, from a cylindrical zone around the wellbore
(small diameter), at a height at best equal to that of the resource layer. The amount
of hydrocarbons produced would be so small that the costs of the operation would
not even be covered.
Therefore, the goal is, on the one hand, to increase the area of contact between the
well and the rock (along the cylinder) and, on the other, to create a migration path for
the gas or oil towards in the direction of the walls of the bore hole (increase the
radius of the cylinder). To increase the contact surface well/rock, horizontal wells are
drilled from a limited number of vertical bores; they cross the source rock over great
distances (see figure below):
6
The wellhead is the assemblage drilling and production equipment on the surface

The advantages are, on the one hand, the optimization of the productivity of the
source rock and thus the maximization of recoverable reserves, and on the other
hand the minimization of the surface area of the production installation. Typically, it is
possible to set out boundaries (largely flexible) for the production zone, which is
made up of pads a few kilometers apart, each of which controls 15 to 30 horizontal
wells. These pads only take up one or two hectares above ground, whilst the
drainage zone covers 500 hectares.
The location of these pads of course is decided with regard to the source rock
reconnaissance carried out during the exploration phase.
Principles of liquid propane stimulation
Propane stimulation consists of injecting liquid propane under high pressure (several
hundred bars) in order to crack rock to increase its apparent permeability7
. Typically,
for source rock located 2000 m below the surface, the required pressure at the
bottom hole is at least 350 bar. The pressure will however be above this threshold in
order to force the fracture zone and thus optimize the drainage area, all the while
ensuring that the cracks remain confined (generally a crack will extend for just a
dozen meters to each side of the wellbore) and do not cross into protected strata, for
example drinking water aquifers.
During the stimulation operation, monitoring wells with micro-seismic detectors are
used to record seismic events generated and thus verify the final extension of the
cracks. Other monitoring techniques are also used, such as real-time monitoring of
the bottom hole pressure and the quantity of fluid injected.
Once the stimulation has been achieved, the cracks created must be kept open after
the pressure drops. To this end, proppants (solid particles) are injected along with the
liquid propane. If the particles are of a density close to that of the fluid injected, then
no chemical additives are needed (chemicals are added to liquid propane to make it
"gel").
7
Permeability is expressed in m2
and indicates the capacity of a rock to carry fluid at a given flow rate
when the fluid is subject to a pressure difference.

Simplified explanation of "flow back" treatment
After the stimulation has been achieved, it is necessary to recover the injected
propane. To this end, the well is put into production and the fluids are collected
aboveground in closed separators that use pressure and temperature regulators to
separate propane, water produced, and shale gas.
After this separation, most almost all of the initial propane is collected and stored in a
tank for potential reuse.
Operation monitoring
All during the operation phase (which usually lasts about a dozen years for a well),
pressures at the well bottom hole are recorded. Monitoring of the seismic activity that
may be generated is also undertaken on the surface, in order to compare this activity
with activity existing in the area under survey before production began.
It is also necessary to take regular measurements of the composition of deep
aquifers located above the production zone to ensure that the operation is confined.
3.2.3 Closure phase and "restoration"
When production is no longer profitable, the operation site is closed. Well completion
and abandonment are regulated by API (American Petroleum Institute) standards.
Before closure, it is necessary to have carried out an assessment of the site's future
and to have taken steps necessary for site restoration.
Closure begins with a thorough evaluation of the state of the well in order to identify
any defects in the equipment, such as corrosion on the tanks, for example. This
evaluation is indispensable because the sustainability of the barriers (primary
cementing of the annular space, bridge plugs) put into place to ensure resistance to
leaking must be guaranteed.
Because the well is regularly subject to mechanical stress during production
(pressure peaks), the primary cementing can weaken (for example, it may crack or
dissolve); this means the integrity of the well must be verified. Once an inspection
has been made, corrective measures can be taken as necessary (for example, the
partial recompletion of a well), and then the well can be plugged by the injection of
several cubic meters of cement material inside the well casing. Plugging does not
consist of filling the hole length of the bore with cement: 50 to 100 meters are
considered sufficient for protecting against leaks. The material used are generally
Portland cement with some additives (making up just 0.1% to 5% of the total weight).
These cement materials and the additives present no risk of toxicity and in the case
of use on Europe, would have to comply with regulations in effect (for example, the
REACH Directive).
After closure, the site is returned to its original state and use.

3.3 Principles for the implementation of stimulation and recovery
operations.
The first impression of a liquid propane stimulation wellhead may be one of
complexity and congestion. A lot of equipment, much of it very large, coexists in a
relatively small area, all linked together by different kinds of piping and tubing (photo
a).
Photo a: general view of fracturing operation using liquid propane gas
However, once the different part of the line have been identified in more detail (photo
b), the operating principles for the installation as a whole are in fact fairly simple and
sturdy.

Photo b: main equipment on the operation site
To facilitate the reader's overall comprehension of the operation of the injection and
recovery process, and without getting bogged down by technical details that are often
secondary, we shall divide the installation into three distinct modules, based on their
main principles (figure c):
 Module 1: liquid propane feed and injection line at medium pressure,
 Module 2: liquid propane injection line at high pressure,
 Module 3: "Flow back" (or recovery) line.

Figure c: simplified plan of injection and flow back lines.
The simplified operation of the different modules is very summarily explained in the
following section. The basic characteristics of the main features are given in detail in
the appendix (in respect of intellectual property rights, and because of its confidential
nature, the information that was shared with us in this regard is only for those to
whom this memorandum is specifically addressed).
3.3.1 Module 1: liquid propane feed and injection line at medium
pressure
The module for liquid propane injection at medium pressure is the upstream part of
the production line. It is made of four main parts:
 Liquid propane tankers which are central and key to the module
 A low pressure pump (LP)
 A silo under pressure used to mix proppant into the LPG
 A nitrogen gas feed.
3.3.2 Module 2: liquid propane injection line at high pressure
Module 2, which is the high pressure injection of propane, covers a larger surface
area than module 1, but has only two main elements:
 A series of high pressure compressors (HP)
 A high pressure injection line that directs flows to either the well or the flare
line

3.3.3 Module 3: "Flow back" (or recovery) line
The flow back line processes all of the fluids coming up out of the well after fracturing
and separates the different components (water, oil, gas) and manages each as most
appropriate. This line can also serve as a blowdown system, in which case, the fluid
does not go through the different lines described here, but is sent directly to the flare.
The flow back module can be divided into a series of units that make up the
processing line:
 Valves and manifold for upstream flow management,
 Phase separation modules (heating, decanting, cooling),
 Storage tanks.
3.3.4 General safety procedures linked to managing the operation
To best manage the dangers associated with propane used for fracturing, the
operator has perfected and constantly applies different procedures to reduce the risk
of accident on the site. The most important are summarily described here below.
Material aspects
 Many propane detection devices are spread around the site, in general there
is one next to any piece of equipment that is in direct contact with the propane
(tankers, pumps, compressors, …). Readings are transmitted by radio wave to
the general control post and appear on security screens.
 The worksite has three 360° surveillance cameras, one of them thermal.
These cameras enable the detection of leaks (evaporation cloud forms) or any
fire ignition. They are monitored continuously by a dedicated employee.
Organizational and human aspects
 There is a "hot zone" where no one may enter during the high pressure
injection phase. The boundaries are set out using the following principles: any
area located less than 15 meters from the wellbore is included and that area is
extended to include zones where human presence is not indispensable. The
totality of the "blue line" (high pressure) is included in the "hot zone".
 Beyond the dismantling and the daily inspection of high pressure lines every
evening, each morning a pressure mounting trial carried out before actual
fracturing begins. This procedure leads to a first phase of pressurizing
nitrogen on all of the line, up to 20 bars, to ensure there are no leaks. Then
the circuit is blown down with propane before pressure in the circuit is
increased to 550 bars in order to further assure that there are no leaks in the
system. In this case, the pressure is brought back down to 20 bars and an
operator is allowed into the hot zone to open the well valves. Pressurizing can
then begin and fracturing undertaken.
 The personnel we encountered has solid experience of this process and know
the equipment and the procedures perfectly well. Employees are trained by

"tutors". Tutors must have at least one year of experience. However,
responsibilities on the job vary greatly and depend on the capacities and
aptitudes of the individual worker.
3.4 Pure propane stimulation trial observed December 2012:
description / observations
The pure propane stimulation trial was carried out on the "Oppenheimer A#3" well. It
did not make use of proppants. The objective was to verify the capacity to stimulate
the source rock, to create cracks, but not to keep them open in order to carry out
production tests.
The formation targeted was shale in the Eagle Ford field (see figure 4.4a below). The
stratigraphic interval (in increasing depths) includes Austin chalk, Buda and
Georgetown limestone, and two shale intercalations: Eagle Ford shale between the
Austin and Buda strata and the Del Rio shale between the Buda and Georgetown
strata.
The stimulation targeted the Eagle Ford shale (subdivided in two equal parts – Upper
Eagle Ford and Eagle Ford). These layers of about 50 m each are at a depth of
between -1770 m and -1820 m. Well A#3 was perforated at -1816 m.
In addition to monitoring the pressure at the bottom hole, the stimulation was also
monitored from an observation well with micro-seismic detectors set at -1650 m. The
observation well (Oppenheimer Calvert #1) was 800 m from the Oppenheimer A#3
well.

The trial consisted of an injection of pure propane at two flow rates: 2.38m3
/min (15
bbl/min) and 4.76m3
/min (30bbl/min) creating pressure at the well bottom of 315 bar
(4500 psi) then 364 bar (5200 psi). In all, a little over 70m3
was injected.
The creation of cracks monitored by the fall in observed pressure (see figure below)
was also recorded at the observation well by micro-seismic measurements. Micro-
seismic events of a magnitude of between -2.9 and -2.3 were recorded on the Del
Rio formation and on a wall of the Eagle Ford layer.
It may seem surprising that cracking occurred at this level. Yet the relative precision
of the localisation of event should be noted, given their low amplitude.

Conclusion
This first test shows that it is possible to stimulate formations by the injection of pure
propane.
Without the use of proppants, it was not possible to test the efficiency of stimulation
with regard to production of the shale.

4 Simplified evaluation of the sector’s main phases
4.1 Method of analysis used: simplified mapping of risks, impact
and harmful effects
The objective of the mission was to carry out a preliminary analysis of risks, mapping
out the major issues in regard to the safety and security of persons and property as
well as the environment. This analysis in no way enables us to determine if a given
risk is acceptable or not, but only to better define and establish a hierarchy of further,
more detailed studies to be carried out.
The preliminary analysis focused on a procedure and its phases of implementation.
For this purpose, we adopted an “integrated vision” of the main impacts, whether
positive or negative, that are likely to result from the implementation of the
technology under consideration.
4.1.1 Field of the study
Because this was a preliminary analysis, the approach was applied to the three
temporal phases described in paragraph 4.2 (exploration, operation and long term). It
integrates the long-term evolution of the site (after closure8
), taking into account
measures for site recovery implemented at the time of closing and the analysis of any
possible ground contamination.
From the "geographic" point of view, i.e. concerning localization, we evaluated all of
the activities around the site(s) operated for drilling/exploration/extraction,
transportation of materials including hydrocarbons to and from the site. We did not
include phases of production or transport of LPG to the storage site where tank
trucks are filled. Nor did we include the production of materials (equipment, piping,
fuels …) used for operations in the sector.
4.1.2 Issues and types of risks covered by the overall field of study
The points we assessed are those covered by French regulations on "classified
installations", and additionally certain specific points relevant to the extraction of
hydrocarbons (wellbore breakdown). The points fall into three categories9
.
Accidental risks: risk of gas leaks, wellbore breakdown, fire, explosion. Workers'
risk of accidental injury has not been formally evaluated in this study. However, it is
clear that wherever there a critical item mark (orange or red), the safety of individuals
near the installations under review is at stake.
Environmental impact: waste into water and air, emission of greenhouse gasses,
risk of soil pollution, refuse, health concerns.
Harmful effects: traffic, noise, land use, induced seismicity, and consequences on
landscape.
8
French law (code minier) requires that the site remain the liability of the operator until closure has
been made official. This takes place after a joint assessment has been made of the steps taken to
ensure the good condition of the site at the time of closure and in the future over the long term.
9
NB: the method of analysis used does not consider risk related to “malicious” acts.

We did not take into account certain issues that are necessarily related to local
analyses: impact on the natural environment/biodiversity (proximity of
environmentally sensitive areas such as those in the "Natura 2000 program), light
pollution…
4.1.3 Mapping scenarios and challenges
As in the approach used in France for ICPE (installation classée pour la protection de
l'environnement – installations classified for environmental protection), the analysis of
the risk of accident is based on the identification of possible events and an estimation
of their consequences (on people, property and the environment).
These scenarios are listed from RS1 to RS6 for risk, from SI1 to SI5 for impact and
from SN1 to SN5 for harmful effects. The list was drawn up in consideration of all of
the potential events identified in the report (except for those linked to the injection of
chemical additives, as these are not present in the procedure under review in this
report); available literature (EPA, 201110
; BAPE, 201111
; French arrêté dated 10 May
200012
; French circulaire dated 10 May 200013
); and lastly the scenarios that are
typically used in cases similar to those found during our tour of sites ("analogy"
approach).
We use the term "scenario" very broadly. It does not refer to an exhaustive list of
detailed situations that could lead to predictable consequences (case of risk
analysis), but enables us to identify accident situations, which are analyzed in terms
of their consequences on safety or the environment, and not in terms of their
causes14
. An analysis of causes is much more complicated and could be envisioned
at a later date, based on the precise and consolidated definition of the technology to
be implemented.
In regard to environmental impact, to ensure that our approach is coherent with the
joint BRGM, IFPEN, INERIS report, we studied the consequences of the normal
operating conditions of the procedure under review (circulation of fluids over the long
term in the heart of the massif), and also the consequences of failures in the
processes (failure of bore seals).
All of the issued are studied and evaluated in the following sections of this report.
4.1.4 Evaluating scenarios and challenges
Each of the scenarios or issues is systematically analyzed on the basis of available
information. In some cases, data is sufficiently precise that we can make an estimate,
10
EPA (2010) Draft Plan to Study the Potential Impacts of Hydraulic Fracturing on Drinking Water
Resources. 126 p. February 7, 2011. EPA/600-D-11/001
11
BAPE (2011) Sustainable development of the shale gas industry in Quebec. Report on the public
hearings. February 2011. Report 273.
12
Decree concerning the prevention of major accidents involving dangerous substances or mixtures
found in some installations classified for environmental protection or subject to special authorisation.
13
Memorandum on the rules of methodology to be used in evaluating dangers, in light of the approach
of risk reduction at the source and the "PPRT" (plan for the reduction of technological risks), regarding
classified installations and in application of French law dated 30 July 2003
14
For example, a scenario could be a "leak in tubing", but not a "falling object" or "collision with a
motor vehicle" which might be the cause of said leak

albeit simplified, of the possible consequences or impacts; in other cases, the
analysis is an "expert opinion" made on the basis of current acquired data. In all
cases, the analysis is carried out in terms of:
 Seriousness (criticality),
 Probability of occurrence in the case of accident scenarios,
 Difficulty of adapting the technology or its implementation to make it safer or
cleaner,
 Needs for developing data acquisition and/or getting feedback in order to
progress in terms of evaluating the reliability or efficiency of technologies.
The objective being to map out the issues, i.e. undertake a preliminary study of the
risks, the results of the estimations are expressed by color codes. The color code
applied (green, orange or red) is determined on the basis of three fundamental
concepts:
o The criticality of the scenario in terms of possible consequences on the
safety of people and the environment,
o The existence of tested technologies to ensure satisfactory control of
consequences,
o The research and development needs associated with a given issue.
Special attention will be paid to the association of items under a single color code
(logical "and" / "or" combined on principle). Thus, the two corresponding items must
be verified before the green code is attributed. On the opposite end, if only one of
three items is validated red, the scenario is given the red code. For attribution of the
orange code, the first item must be associated with at least one of the two others.
Another essential point should be specified: "Orange" or "red" attributions do not
indicate by any means the impossibility of implementation of the process. They
reveal the critical nature of the scenario and call for necessary measures to control
the risk, or for more extensive information and data acquisition that would answer
any persistent doubts that remain in regard to current capacity to control risk,
impacts, and harmful effects.

 Risks, impacts or harmful effects very limited, a priori
And
 Technologies for the control of risk, impacts and
harmful effects already implemented and tested.
Transposition into French regulatory and technical
context can be envisioned as is. A priori, research and
development needs and needs for further data
acquisition are low.
 Risks, impacts or potentially harmful effects are not
negligible, but not "restrictive" for the design and
implementation of the operational chain.
And
 Technologies for the control of risk, impacts and
harmful effects are not immediately available and/or
need to be adapted significantly before transposition to
France. However, no major impediments identified.
or
 Scenarios for which evaluations create some doubt,
requiring extended data acquisition or feedback that it
not yet available.
 Risks, impacts or harmful effects may be high and, a
priori, "restrictive" for the design and implementation of
the operational chain.
or
 Significant technical developments are necessary for
controlling risks, impacts and harmful effects and/or
transposition into the French context.
Or
 Scenarios lead to assessments that portray situations
of doubt requiring significant development of data
acquisition or feedback that is not yet available in
order to determine the level of risk or impact.

4.2 Elements of risk analysis
4.2.1 French regulations on LPG use
a Classification under the "Installation Classées" regulation
This paragraph does not seek to analyze the regulatory framework that would be
applied to such an installation. The amount of propane that would be present on the
site is the factor that determines the dimensions of the risk of fire, explosion, and
projection of debris in the event of an explosion.
Using the analogous approach, comparing to equivalent fixed, long-standing
installations, operations in review herein would be subject to authorization and would
be at the threshold of SEVESO regulations if the amount of propane was between 50
and 200 tons; they would be at the top tier of SEVESO regulations if the amount of
propane was greater than 200 tons.
Among the main obligations associated with this classification, in particular, the
operator must file a "DDAE" (Dossier de Demande d'Autorisation d'Exploiter –
Application for Authorization to Operate). This application must include a study on
dangers and an impact study; it is processed by the administrative services having
authority and subject to a public hearing. Once the application has been processed
and reviewed, the Prefect delivers, or refuses to deliver, an authorization to operate.
There are substantial differences between the lower and upper tiers of the SEVESO
regulations. Specifically, for top-tier sites, the operator must establish a Safety
Management System (SMS) integrated in the overall management system of the
company; an internal operations plan (IOP); and must provide the Prefect with the
information necessary to draw up an Emergency Response Plan (ERP). Special
attention must also be paid to the areas around the site of operations.
b Principles for the selection and analysis of risk scenarios used
The objective of this simplified mapping of risks is not to identify all potential
accidents that might occur due to the arrival of the installation, and it is certainly not
to identify the causes that might be behind such accidents (HAZOP approach). In the
context of this preliminary analysis, we mainly sought to establish an order of
magnitude for the effects expected from severe scenarios.
As a general rule, accidents involving LPG (liquid under pressure) are most serious
when a storage vessel ruptures (BLEVE phenomenon), especially in the event of fire;
or when pipes or hoses burst. On the basis of feedback and in order to cover the
main types of accidents that might occur on a site like the one we reviewed (cf.
paragraph 4.3), six generic risk scenarios were used.
Ignition resulting from a propane leak on the injection or flowback circuit
 RS1: ignition following a leak in the "medium pressure" zone
 RS2: ignition following a leak in the "high pressure" zone
Indirect consequences of a propane leak
 RS3: BLEVE in a propane tank
 RS4 : Explosion in a densely occupied area

Others
 RS5: breakdown at the wellbores
 RS6 Transport of hazardous materials, especially outside of the site of
operation
In the context of this preliminary analysis, the selection of risk scenarios was limited
to specific aspects concerning the implementation of the technology under review
(injection and recovery of propane under high pressure).
The estimation of the criticality of a scenario was based on the scope of potential
effects on persons and property in the event of an accident. Potential effects and
their range of impact are those found in French regulations:
Reference values for the threshold of excess pressure effects15
:
 20 mbar, threshold defining the zone of indirect effects (glass shatters);
 50 mbar, threshold defining irreversible effects in a "zone presenting
significant peril to human life";
 140 mbar, threshold defining lethal effects (>1% lethality) in a "zone
presenting grave peril for human life";
 200 mbar, threshold defining significant lethal effects (>5% lethality) in a "zone
presenting very grave peril for human life".
Reference values for thresholds of thermal effects8
:
 3 kW/m2 (average over a significant period) or (cumulative over a very brief
period) 600 [(kW/m2) 4/3].s, the level at which irreversible effects define the
"zone presenting significant peril to human life";
 5 kW/m2 or 1000 [(kW/m2) 4/3].s, threshold defining lethal effects in a "zone
presenting grave peril for human life";
 8 kW/m2 or 1,800 [(kW/m2) 4/3].s, threshold defining significant lethal effects
(>5% lethality) in a "zone presenting very grave peril for human life".
The analogy is extended in the section of the report following, specifying for each
scenario the type of use of neighboring areas, generally planned16
to limit the
presence of people in the in the zone associated with the threshold of irreversibility
and, if possible, the presence of people in buildings with glass surfaces in the zone of
indirect effects (shattering glass). However, a zone subject to only indirect effects can
be used for temporary activities (agriculture, secondary road, for example).
The analysis of certain risk scenarios makes use of the establishment of security
distances. The values presented must be considered, as they stand now, as degrees
of magnitude. Only a detailed analysis carried out on the basis of the precise
characteristics of the installation in question would enable the modeling of more
precise security distances.
15
French arête (decree) dated 29 September 2005, on the evaluation and consideration of the
probability of occurrence, the kinetics, the intensity of effects and the seriousness of the
consequences of a potential accident in studies on the dangers of classified installations subject to
authorization
16
French circulaire (memorandum) DPPR/SEI2/A-07-0066 dated 4 May 2007 concerning making data
on "technological risks" available and urban planning around classified sites

Simplified mapping of risks in the current state of technology
Risk scenario no. 1: Ignition in a free field following a leak in module 1
(medium pressure)
This scenario describes the consequences of a leak that could occur in the flow from
the tank trucks. Considering that there are flow rate controls on each outflow valve on
the tankers (3.7 m3
/min), the hypothesis is that six valves would contribute to
leakage, for a flow rate of 20 m3
/min (or 200 kg/s). The results of the calculation
reveal the following orders of magnitude in terms of security distance from the leak17
:
Indirect
effects (glass)
Irreversible
effects
First lethal
effects (<1%)
Lethal effects
(>5%)
Excess
pressure
450 m 300 m NA NA
Thermal NA 330 m
The prospect of being able to eliminate, a priori, all risk of leaks in an operation that
uses many hoses, flanges, ducts, nozzles etc. is daunting. In the situation today, the
simplified evaluation of the technology under review on the site gives this result:
Exploration Operation Long term
RS1
Ignition in a free field
following leak on
module 1
NA
As indicated in the introduction to this chapter, the "orange" and "red" indicators do
not mean that it would be impossible to implement the procedure. They illustrate the
criticality of the scenario in the current state of the art and the need to take
appropriate measures to control risks. As is, the principles of limiting use (SEVESO
analogy) of the surrounding area meets the following objectives:
Distance from the
edge of the operation
site
<300 m
300 m < < 450
m
>450 m
RS1
following leak on
module 1
Workers only
Temporary
activities
Residential
In terms of optimizing the process, the approach using French regulatory
requirements should contribute to reducing the probability of such a scenario. The
reinforcement of casings and the application of more systematic inspection
procedures, added to optimization of gas leak and fire detection systems could help
in obtaining this objective. No major technological developments have been identified
as necessary. The addition of protective measures for workers (cf. scenario RS3)
could enable the revision of the degree of sensitivity of the scenario during the
fracturing phase and lead to the re-evaluation of the operational phase as an
item for attention and not a critical item.
Regarding the reduction of the effects measured at horizontal distances, we could
suggest reducing the tanker outflow rates to the overall injection flow rate required
17
There is no observed diminishment of thermal effects because of the "flash fire" effect: possible
ignition of a cloud of gas up the Lower Explosive Limit.

(<10m3/min). The existence of barriers on the boundaries of the site could also help
limit the lateral horizontal extension of the explosive cloud, the value of which has a
negative effect as is.
Risk scenario no. 2: Ignition in a free field following a leak in modules 2 or 3
(high pressure)
This scenario describes the consequences of a leak in the "high pressure" zone. We
chose to simulate a leak on the flowback line, considering that the maximum flow had
temporary periods when it was less constrained than the flow through the injection
line18
(limited by the BP pump). Modelling simulated a leak in the 2" pipe connected
to the wellbore at 800 bars pressure, capable of supplying 35m3
/min, or about
300kg/s (safety hypothesis). The results of the calculation reveal the following orders
of magnitude in terms of security distance, from the site of origin of the leak:
Indirect
effects (glass)
Irreversible
effects
First lethal
effects (<1%)
Lethal effects
(>5%)
Excess
pressure
390 m 260 m NA NA
Thermal NA 300 m 270 m
It seems that it would be difficult to eliminate any risk of leakage in this section that
gets a lot of use, has many connections and is subject to the abrasive effects of the
proppant19
. The scenario continues on through the entire operation phase of the
flowback line. As is, the evaluation of the technology under review gives this result:
RS2
following leak on
modules 2 & 3
NA
As in the previous scenario, the "orange" and "red" indicators show that the scenario
is a critical item in the current state of the art and it is necessary to take steps to
control the associated risks. As is, the principles of limiting use (SEVESO analogy) of
the surrounding area meets the following objectives:
Distance from the
site
<300 m
300 m < < 400
m
>400 m
RS2
following leak on
modules 2 & 3
Workers only
Temporary
activities
Residential
In terms of optimizing the process, the approach using French regulatory
requirements do not specifically cover these conditions of operation. To limit the risks
of leaks occurring, however, there are several types of action that might be taken. A
casing of larger diameter surrounding the high pressure line could contain the leak.
But the feasibility and modularity of such a measure remain to be evaluated. The
18
For lack of data and in with the idea that check valves would be in place, we did not study the case
of well blowdown using the injection line, a very safe scenario which could be a significant point for
evaluation
19
We should underline that regular, thorough inspections are the usual practice at Gasfrac; using this
method, after 1500 operations of this type, there have been no incidents reported linked to this effect.
It would appear that the preventive methods adopted should enable us to requalify this risk as an item
for attention.

addition of protective measures for workers (cf. scenario RS3) could enable the
revision of the degree of sensitivity of the scenario during the fracturing phase.
Regarding the reduction of the effects measured at distances, installation of system
restricting the flow rate and barriers on the boundaries of the site could also help limit
the lateral horizontal extension of the explosive cloud.
Risk scenario no. 3: BLEVE of a propane tanker20
Simulations carried out concerned BLEVE of a 75 m3
propane tanker, filled to 85%
(maximum thermal effects) or to 10% (maximum excess pressure effects). This is in
line with the characteristics described in paragraph 4.3. The results of the calculation
reveal the following orders of magnitude in terms of security distance:
Indirect
effects (glass)
Irreversible
effects
First lethal
effects (<1%)
Lethal effects
(>5%)
Excess
pressure
300 m 150 m 70 m 50 m
Thermal NA 260 m 200 m 150 m
"Missile"
effect
85% of debris in a radius of 300 m
It seems that it would be difficult, a priori, to eliminate any risk of BLEVE. It should be
noted that tanker trucks supplying the installation are also subject to BLEVE. Past
experience with these vehicles shows that, in the event of BLEVE, 85% of the debris
are projected within a radius of 300 m. Analysis of the literature reveals that are
some cases, these distances may be greater (several hundred meters in the case of
Mexico in 1984, or more recently in Bellville Canada, 2002). Special attention should
be paid to this subject once a specific technology has been adapted to French
regulations and established, so that a more detailed assessment can be made. The
simplified evaluation of the technology under review gives this result:
RS3 Tanker BLEVE NA
As in the previous scenarios, the "orange" and "red" indicators show that the scenario
is a critical item in the current state of the art and it is absolutely necessary to take
steps to control the associated risks. Two significant measures should be considered
in this regard. The first, given the current state of the art, is the principles of
regulating use (SEVESO analogy) of the surrounding area on the following basis:
Distance from the
site
<260 m
260 m < < 300
m
>300 m
RS3
Tanker BLEVE
(supply/collection)
Workers only
Temporary
activities
Residential
The second measure aims to optimize implementation of the procedure. In this
regard, the requirements of French regulations should contribute to the reduction of
20
Even it "cold BLEVE" is possible, the result of a mechanical breakdown in the tank (collision,
corrosion), most often BLEVE follows a fire that leads to an increase in the pressure of the liquid
inside the tank (indirect consequence of scenario 1, in particular). This is the typical "hot BLEVE"
scenario that we used for evaluating security distances

BLEVE risk. Modification of tanker design would seem to be necessary (separate
tank level automated individual sprinklers, respect for rules of isolation, optimization
of installation and set-up on site to limit missile effect …). No major technological
developments have been identified as necessary. If, in addition, measures are taken
to enhance the security of workers on site (personnel restricted to a control center
that is resistant to fire and blast debris, adequately protected and set up on the site of
operations during the critical phases of fracturing), we could see a revision of the
degree of sensitivity of the scenario during the fracturing phase.
Prospects for limiting the effects measured at horizontal distances seem rather
narrow. BLEVE events develop vertically, so building a protective embankment on
the boundary would have little (or no) effect. Limits on the volume (or operating
pressure) of the tankers could be brought into play, but the direct consequence would
be an increase in the number of vehicles, thus increasing the likelihood of an
accident.
Risk scenario no. 4: explosion in a densely occupied area
Another possible consequence of scenario 1, this scenario describes the ignition of a
propane cloud in a densely occupied area, which adds to the seriousness of the
effects. The presence of materials (in particular vehicles and equipment) in this area
is counters the increase in the volume of gas linked to ignition, and can provoke to a
powerful explosion. Modeling has simulated an open volume of 2500m3
of gas in the
stoichiometric conditions of propane (about 4%, or 240kg), in a densely occupied
area (multi-energy index ≥6). The orders of magnitude are limited to the effects of
excess pressure:
Indirect
effects (glass)
Irreversible
effects
First lethal
effects (<1%)
Lethal effects
(>5%)
Excess
pressure
460 m 230 m 100 m 80 m
The small quantity of propane required makes it tricky, a priori, to eliminate any risk
of this phenomenon. In the current state of the technology under review, here is the
mapping result:
RS4
Explosion in the
densely occupied area
NA
As in the previous scenarios, the "orange" and "red" indicators show that the scenario
is a critical item in the current state of the art and it is necessary to take steps to
control the associated risks. As is, the principles of regulating use of the surrounding
area meet the following objectives:
Distance from the edge
of the operation site
<230 m
230 m < < 450
m
>450 m
RS4
Explosion in the
densely occupied area
Workers only
Temporary
activities
Residential
In regard to optimizing the procedure, the requirements of French regulations should
contribute to reducing the probability of such an event occurring, in particular by the
use of optimized gas leak and fire detection systems that automatically set off alarms
or cut-off switches. The addition of protective measures for workers (cf. scenario

RS3) could enable the revision of the degree of sensitivity of the scenario during
the fracturing phase.
Regarding the reduction of the effects measured at horizontal distances, a reduction
in the density of site occupation (limiting the size of the vehicles and equipment on
the site), added to protective fencing at the boundaries could help reduce the
distances, in particular for glass shattering, which has a negative effect as is.
Risk scenario no. 5: Failure or leak at the wellbore
This scenario is not specific to the technology of pure propane fracturing; it concerns
all oil drilling operations as well as underground storage of hydrocarbons. However,
because the technology under review consists of injecting highly pressurized liquid
propane and recovering that same propane (in addition to the hydrocarbons
extracted) through a flowback line, we determined that it was legitimate to study
wellbore breakdown as a separate scenario (the most significant incident associated
with a site where Gasfrac operated, in Robb, Alberta, in 2011, does not appear to be
directly related to fracturing but rather resulted from gas escaping upwards from the
wellbore.
In this way, the most critical situation could be the result of such an event at the
beginning of the flowback phase (significant quantities of propane under high
pressure flowing back up; valves to cut off the flow). There are two consequences
that might be expected: the potential blow out of the wellbore under pressure from
flowback and the formation of an explosive cloud of gas.
Regarding the first consequence, because of the heavy weight of the wellhead and
the essentially vertical thrust of the flow upward through the bore, the distance of
horizontal projection should, in all likelihood, be contained with the radius of 300 m
beyond the operation site as defined in the other scenarios (a simulation could be run
if a more detailed phase of the analysis were to be implemented).
Regarding the formation of a gas cloud, there are few references on vertical
discharge. Because the effects are less serious in terms of effective distance in
comparison to horizontal leaks, they are rarely studied in detail. In a set of guidelines
on studies on the dangers of underground gas storage, some simulations carried out
by the INERIS do indicate some comparative orders of magnitude, despite the fact
that the hypotheses for calculation used quite a different basis (non-liquid gas under
lower pressure). Thus, in the case of vertical discharge of 50 mm diameter (about 2")
of gas under pressure just above 100 bars, thermal effects cover a horizontal
distance of less than 50 m in case of the ignition of a gas cloud.
Even if there is a maximum propane flowback during the first minutes, the volume of
the cloud that could be expected would be significantly smaller than the modeling in
the study cited previously predicts, as the verticality of the flow would increase the
vertical distances much more than the horizontal ones. In addition, such a phase of
very high pressure discharge could only be temporary. Once the injected propane
has been discharged, the flow of hydrocarbons in extraction will continue at much
lower pressures.
If the cloud doesn't ignite during its formation, it will mix in with the surrounding air in
dilution (the time span and distances involved mainly depend on the prevailing winds)
until it reaches the Lower Explosive Limit. Once the injected propane has been mixed
in with the atmosphere, in no case can there be a credible risk that great quantities of
it would fall back to the ground.

In any event, the wellbore breakdown scenario, which should be carefully considered
for reasons of worker safety, is not of sizable importance for the definition of the
effects measured horizontally beyond the operation site (compared with scenarios of
horizontal leaks).
As is, the simplified evaluation of the technology under review on site gives this
result:
RS5 Wellbore failure NA
Risk scenario no. 6: Road transport of hazardous materials
This scenario concerns the risk of accidents linked to LPG supply tanker trucks
travelling outside the site and to truck used to evacuate LPG collected at the end of
the fracturing operations. It also includes, where relevant, truck used to carry oil
produced in the event that there is no dedicated network of pipes to carry it away
from the site.
Most vehicle traffic will be concentrated over a very limited period of time (site supply
then evacuation of remaining LPG), for a total of just a few days. Meanwhile, the rate
of recovery of the liquid propane is very high (over 90% on average according to
figures supplied by the operator), so there is no need for regular re-supply to the site.
If we start from the hypothesis of about 180 tons of propane required on the site, and
tank trucks can carry 20 tons at a time, a dozen trucks would be needed over one or
two days at the outside and the same would be true at the end of the fracturing
operation. If, for reason of accessibility, smaller tankers were used (nine or even six
tons), the number of vehicles would be multiplied by two or three. In regard to
intermediate needs (replenishing supply or removing production), it is difficult to
make a precise estimate at this time, but we believe that traffic would be limited to
one or two vehicles per day on average.
The transport of LPG by the road is very common in France. Specific regulations
cover this practice. The likelihood of an accident involving the substance is very low.
Daily traffic density on the site would be at typical SEVESO levels for LPG storage
for only a few days out of its lifespan (about 20 trucks per day). Outside of the two
peak periods (supply and removal), the activity as planned would not significantly
increase traffic of vehicles dedicated to the transport of hydrocarbons on the regional
scale. However, plans should be made to distribute the supply and removal activities
over the different operation sites in a single region to avoid any congestion peaks.
Because vehicles move, it is difficult to use the "effects at a distance" approach. We
can keep in mind the case of tanker truck BLEVE, for twenty or nine ton vehicles,
which results in irreversible effects at 210 m or 150 m. This does not modify the
security distances established in regard to potential BLEVE events involving a tanker
on site. As The simplified evaluation of the technology under review on site gives this
result for potential danger:
RS6
Ignition after leak or
tanker truck BLEVE
NA

Summary of risk scenarios
In light of the different risk scenarios analysed here above, we can sum up the
simplified risk mapping, in the current state of the art, through the following table:
RS1 to RS5: Scenarios linked
to the risk of propane ignition on
site
NA
RS6: Hazmat transport risk NA
Applying the requirements of French regulations to the technology under review and
the integration of new equipment and procedures should contribute to improving
safety levels for workers and environmental protection as well as to reducing the
likelihood of accidents occurring on the site and therefore potentially lead to the
attenuation of the degree of sensitivity of the corresponding scenarios during
the fracturing phase.
However, it is indispensable that security distances be established to guarantee the
safety of people in the general area (off the site of operations), even if the probability
of occurrence remains slight. As is, based on simplified calculation and integrated
available provisional data (references taken on the Gasfrac site reviewed), the
following orders of magnitude were determined for security distances. These may
change depending on any modifications to the operational chain as seen on the
Gasfrac site.
Distance from the
site
<300 m 300 m < < 450
m
>450 m
RS1 to RS4:
Scenarios linked to the
risk of propane ignition
on site
Workers only Temporary
activities
Residential
4.3 Analysis of environmental impacts and harmful effects
The approach for selecting the scenarios on impacts and harmful effects to be taken
in consideration in the context of this simplified analysis is directed based on the
conclusions of the summary report established in 2011, collectively, by INERIS,
IFPEN and BRGM, for the Ministère de l'Ecologie, du Déveoppement Durable et de
l'Energie (ministry of environment, sustainable development and energy). This
document, Maîtrise des impacts et risques lies à l'exploitation des hydrocarbures en
roche-mère: enjeux, verrous et pistes de recherche (Controlling the impacts and risks
associated with bedrock hydrocarbons: stakes, impediments, and research topics)21
identifies the essential points to take into account (paragraphs 4.2 to 4.7), which we
have separated into two categories: impacts and harmful effects.
The report explicitly refers to:
21
http://www.developpement-durable.gouv.fr/IG/pdf/Note_GHRM_Maitrise_des_risques_et_impacts.pdf

 Impact on water, air and soil quality and health impacts,
 Vehicle traffic, noise, induced seismicity, land use and consequences on the
landscape.
Restricted to a generic, preliminary analytical approach, we have not taken specific
legal mechanisms into account ("Natura 2000", for example).
4.3.1 Environmental and health impacts
Impact scenario no. 1: Potential impacts on water resources
Fracturing with propane has several main advantages in regard to the preservation of
water resources:
 It does not require water for breaking the rock. For this reason, very little
groundwater is removed (enough for sprinkling the work site),
 It does not require chemical additives. For this reason, the effects of
accidental spills on the surface are limited; even in the event of underground
leaks, no additive could leak into the water table. The use of innovative
techniques for drilling and casing the bore should also reduce the risk of leaks,
 Unlike water, propane does not disrupt the geochemical balance of the natural
source rock and does not dissolve any mineral or organic elements that are
normally found in solid form. The only water extracted is water that was in the
ground prior to fracturing. Because the volume is small, this water can be
stored in closed tanks (sent for treatment when they are full) rather than piped
to large holding pond (with a risk of seepage and leaks).
The main item for attention concerning the preservation of water resources is the
possibility of uncontrolled hydrocarbon contamination underground (discontinuity
underground due to faults or leaks). Whilst propane is not toxic in and of itself, it can
transport hydrocarbons (liquid or gas) and other substances (oil, H2S, metals, VOCs
…), often in small amounts, but that may have toxic/ecotoxic potential specific to
each site; this should analyzed beforehand (exploration phase). The risk of a failure
of tanks holding polluted water or oil should also be taken into account, although
probability is low if the materials comply with regulations.
The "orange" indicator in the exploitation phase mainly concerns the need to fully
identify the nature of the rock (oil or gas, nature of substances that may be released
…) and a more detailed evaluation of the technologies to be used for sealing the well,
especially over the long term. Special attention should be paid to the detection and
identification of sizable faults in the area of the planned operation. The item for
attention on the closure phase results from a lack of experience and feedback and
the need to develop more knowledge of the long or very long term effects of the
circulation22
of fluids within the source rock modified by the process of intensive
fracturing over a limited area. It is also necessary to designate an authority to monitor
the different phases of the operation (drilling, completion, closure and long-term
security). The idea of the "ability to monitor and control" technologies implemented
will then take on its full significance.
22
When there is no more pressure gradient, there is no driving force other than gravity in zones of
very low permeability (nanodarcy). Because of this low permeability runoff is not darcean but diffuse;
this concerns a very low time constant

If the data required proves to be favorable in terms of site context and technological
efficiency, the "items for attention" (orange indicators) could be re-evaluated as "very
limited effects, a priori" (green indicator).
IS1
Potential impacts on
water resources
Impact scenario no. 2: Potential impacts on air quality
The issue of gaseous hydrocarbon leaks, and their contribution to global warming is
a critical question in regard to extraction from hydrocarbon source rocks. Although
we do not have precise feedback data at this time on the "liquefied propane"
technology, we nonetheless believe that this technology would limit the impact on air
quality significantly.
Unlike other technologies that require great quantities of waste water to be stored in
open-air holding ponds that release dissolved hydrocarbons as gas in considerable
quantity, fracturing by liquefied propane does not produce any contact between the
recovered fluid and the atmosphere. The flowback line, as described in paragraph
4.3, ensures that there is a thorough separation of the different fluid and gaseous
phases in order that the substances be recovered for appropriate treatment. In
addition to the program for recycling liquefied propane, the approach also permits the
capture, a priori quite efficiently, of methane. In the same way, the water extracted
(after passing through several phase separators) is stored in an airtight tank. Any
gasses residually desorbed are sent to the flare and burned off (rather than being
emitted into the atmosphere, thus considerably reducing the warming effects of the
gasses).
The main items for attention concern the kind of hydrocarbons involved; the
technology itself is only slightly involved:
 The possibility of propane leaks or environmental release (pressure relief
valves) from the flowback or injection line (propane itself is not a greenhouse
gas, but it can react with other components in the atmosphere and contribute
in a secondary manner to GHG);
 The presence of potentially toxic gas associated with propane when the large
tank is emptied (H2S, benzene …).
 The flare contributes to C02 production (many purging phases for
pressurization). Specific data on this can only result from a life-cycle analysis
of the operation in whole, using data and precise measurements that are not
available at this time.
The "orange" indicators associated with the phases of exploration and operation
reveal, despite the positive initial perception of the advantages offered by the
technology in regard to air quality, there is the need for quantitative data, today
unavailable, to answer any questions pertaining to the existence of potentially toxic
gases that can be associated with hydrocarbons (H2S23
, benzene, …) and the
"carbon contribution of this operational sector overall.
23
In France, legislation is especially strict in regard to the presence of H2S and forbids, in particular,
marketing gas with an elevated H2S level – 100 ppm – : when present, this gas must be captured and
processed

If the data acquired are favorable in terms of context and technological efficiency, the
"for attention" could be re-evaluated as "very limited effects, a priori".
IS2 Potential impacts on air
quality
Impact scenario no. 3: Impacts on soil quality
The advantages of liquefied propane fracturing compared to other technologies in
regard to the preservation of water resources also fully apply to the preservation of
soil quality (surface).
The absence of chemical additives limits the risk of accidental spills on the surface,
and the fact that wastewater holding ponds are not used is also a favorable point.
Liquid propane is not a pollutant in itself and it vaporizes in contact with the
atmosphere.
The main items for attention are those intrinsic to all types of oil exploration:
 Risks linked to the use of oils or fuels to operate machines on the site,
 Risk of breakdown and accidental spills of the tanks of wastewater and oil
produced.
The choice of appropriate materials and procedures should contribute to controlling
the risk of soil pollution.
IS3 Potential impacts on
soil quality
Impact scenario no. 4: Impacts on health
The fact that chemicals are not used considerably limits any health impacts that
might result from the implementation of the operational sector. In line with analyses
carried out for IS1 and IS2, the following items for attention result, which are related
to the nature of extracted hydrocarbons and not to the specific technology under
review:
 The possible uncontrolled migration of toxic substances present in the deep
rock (H2S, metals) associated with hydrocarbons and the degradation of the
toxicological and ecotoxicological quality of the water tables that might be
affected;
 The release of potentially toxic gases that are present in the large tank and
drained by propane associated with propane when the large tank is emptied
(H2S, benzene…).
The "green and orange" indicators for the operation and long-term phases show the
positive initial perception of the advantages offered by the technology under review in
regard to health impacts. However, there is a need for more precise data, to be
collected for each location, on the nature and possible release of potentially toxic
substances already found in the reservoir (H2S, benzene, metals, …).

IS4 Impacts on health
to to
4.3.2 Harmful effects on the environment
Harmful effects scenario no.1: Road traffic
The combination of the compressibility of propane (transported in liquid form) and the
possibility of recovering LPG from the flowback to use as in a new injection mean
that the number of vehicles required to bring LPG to the site should be limited, at first
assessment, to a dozen trucks in the installation phase, and about as many in the
closure phase; during the operation, the number should be quite low on a daily basis
(cf. scenario RS6).
In the same way, harmful effects linked to heavy vehicle traffic to and from the site,
carrying the equipment and material needed for operation will mostly be felt during
the few weeks of installation and then the dismantlement of the site.
The rest of the time, the flow of traffic expected is quite similar to that of a typical
industrial site (personnel transport, maintenance activity, …).
HES1 Road traffic NA
Harmful effects scenario no.2: Noise
The harmful effect of "noise" is the result of a vibration in the air, the intensity of
which is measured in decibels (dB) with a sound meter. The threshold of pain is
considered to be 120 dB (race car, rock crusher) and the level at which hearing can
be damaged in 85 dB (garbage truck, horn).
As is, we do not have precise data on the noise level to be expected from the
potential operation under review. On the basis of on-site observations made for a
reduced chain of operations, the noise could be compared to a jackhammer or rock
crusher (100 to 110 dB). Without any devices to actively muffle the sound (silencing
systems on motors, sound barrier walls, for example), noise diminishes over distance
according to the following calculation: Xn = X – 20 log(n). On this basis, we can
calculate the order of magnitude would be 60 dB at 300 m and 55 dB at 500 m.
To protect people in the surrounding area from accidents, security distances are
established for residential uses (RS1 and RS4); a priori, these distances should be
sufficient to limit noise pollution to the edges of adjacent property (regulatory limits 70
dB in the daytime and 60 dB at night). However, sound levels at the source, which
were hypothetical for these purposes, should be verified.
HES2 Noise NA

Harmful effects scenario no.3: Consequences on land use
The effect of this type of operation on land use can be a central point in regard to the
transposition to France. The French and North American situations are radically
different. In the case of Texas, the very low population density, regulations of the
ownership of resources and security distances required have contributed to a kind of
"sprawl", with many operation sites as each owner seeks to exploit the resources
"under his feet".
In France, such an approach would not be possible. Thus eCORP suggests an
approach of bringing several wellbore onto one operational site, with horizontal drill
extending outward in all directions to a length of several kilometers. This significantly
reduces any constraints on land use because the "footprint" of the operation site can
be estimated at first assessment within ten or twelve kilometers. In addition, the
optimal planning of site installation can include sharing of infrastructures required to
support the operation (roadways, pipelines, …) and streamline traffic patterns.
On the other hand, the need to respect security distances with regard to
environmental protection places a direct constraint on land use adjacent to the
operational site, to a somewhat lesser degree for fixed property (building and
houses) or temporary activates (agriculture, secondary roads).
We should keep in mind that easements change over time. During the exploration
phase, the number of sites to investigate is relatively small and most likely the
security distances are too because of the limited extent of the fracturing that may be
undertaken (in regard to the volume of propane and the duration of the tests).
In the exploration phase, the nature of the land use in the region where the potential
underground resources lie may mean that this is an item for attention or even a
critical point because it can severely limit deployment of an operation if the land is
densely occupied. Only a region-be-region analysis, beyond the scope of this
preliminary analysis, can give us the detailed information required on this point. The
dismantlement of operational structures (in particular wellbores) and the restoration
plans set forth in the documents we were given lead us to believe that the process
would have a limited impact after the land has been through the recovery program.
The mapping result is:
HES3 Land use
to
Harmful effects scenario no.4: Induced seismicity
Because of the fracturing of the rock, extracting hydrocarbons from source rock
provokes a multitude of microseisms that are absolutely non-detectable by people on
the ground above (negative magnitude). In certain particular circumstances, this
activity has also generated phenomena that are known as "induced seismicity" near
extractive sites (magnitude generally below three).

This type of phenomenon results, a priori, from a change in the stress to which the
source rock is normally subject, to which the repeated injected of liquid under high
pressure, associated with the extraction of hydrocarbons contributes. In the case of
"sensitive" regional faults, close to the point of an event, the operation can contribute
to the fault play that may produce "a small natural seismic event of anthropogenic
origin."
Such phenomena do not endanger the security of people or property but, if they are
repeated and of a magnitude greater than three (highly improbable24
), they can have
harmful effects and raise concern among the nearby population. It is very difficult to
predict these phenomena and requires an excellent knowledge of the subsoil and
regional tectonics (faults, stresses).
The technique using propane fracturing limits, a priori, the risk of induced seismicity.
The amount of fluid injected is reduced and is almost totally desorbed after injection
(90% of the propane injected comes back up). The fact that large quantities of water
are not coming back up to the surface also means that the practice of re-injecting this
water in less deep, permeable horizons is totally avoided.
Nonetheless, even though the probability of such an event is especially low, the
complexity of the phenomenon and of its prediction as well as the need for very
detailed level of knowledge of the characteristics of the subsoil make it impossible to
exclude all possibility of such an event occurring for reasons related to the tectonic
environment more than the technology itself.
The "orange" indicator attributed only to the operation phase, does not express the
criticality of this disturbing phenomenon, it is meant to underscore the importance of
geophysical surveys to determine the tectonic environment of the site and in
particular to ensure that there are no major faults near the injection zone.
HES4 Induced Seismicity NA NA
Harmful effects scenario no.5: Consequences on the landscape
The concept of a limited site of operations with many wellbores would help reduce
the sprawl effect on the landscape that can be seen in certain parts of North America.
The use of the best available technologies (limiting the diameter of the well and
therefore the height of the derricks, optimize flare designs, …) can also contribute to
reducing the impact on the landscape, even if some impact will be felt, especially in
the well boring phase. Major steps can also be taken for better landscape integration.
The operation site can be sunken and hidden from view by green embankments (as
is done for landfills). In this case, the areas adjacent to the operation, as defined by
the security distances, can be used to advantage.
In the absence of precise data on the precise procedure the operator plans to
implement, the operations phase has an indicator for item for attention.
HES5
Consequences on
landscape
24
The event observed in Great Britain that led to a moratorium on shale gas exploration (moratorium
since lifted) registered 2.3 on seismographs, but was imperceptible to humans

4.4 Summary of mapping for all of the scenarios under review
Risk
Scenarios
RS 1 to RS 5:
Risk of propane
ignition on the
site
NA
RS6: Risks
linked to
HAZMAT road
transport
NA
Impact
Scenarios
IS1: Potential
impact on water
resources
IS2: potential
impact on air
quality
IS3: Potential
impact on soil
quality
IS4: Impact on
health
to to
Harmful
Effects
Scenarios
HES1: Road
traffic
HES2: Noise NA
HES3: Land
use
to
HES4: Induced
seismicity
NA NA
HES5:
Consequences
on landscape

5 Conclusion: Pure propane injection technology,
risk analysis, readiness and evolution of the
process
The purpose of this report is to analyze the transposition of the production of shale oil
or gas through a process of pure propane injection into the French context.
Analyses developed in the previous sections have enabled us to map out the
advantages and risks of this technology regarding effects on the surface and
underground.
5.1 Pure propane injection
Documents provided by eCORP, discussion held with eCORP personnel and the
observation of a pure propane stimulation trial held in our presence have allowed us
to list the points of interest and the items for attention regarding the implementation
of this technology, in regard to the subsurface.
Compared to other techniques frequently used in North America to produce shale oil
and gas, eCORP technology differs by the use of:
 Lighter proppants that can be dispersed in and carried by the pure propane,
 Slim hole bores, at least in the exploration phase.
a Proppants
We were not able to observe the total implementation process because the trial
carried out in our presence was mainly designed to show that it is possible to
stimulate source rock with an injection of pure propane. The extension of the cracks
was monitored by observing the change in pressure (increase then drop) at the
bottom of the well, and also by the use of a dedicated well nearby where
microseismic events created by the fracturing were recorded. The propane was
injected at two flow rates (15 bbl/min and 30 bbl/ min) at pressures of around 4500 to
5000 psi (i.e. 300 to 350 bar).
During this trial, there was no injection of proppants that would have served to
maintain the cracks open after the drop in pressure and therefore to follow up with a
production trial. This point is of crucial importance because in the context of pure
propane injection, the proppants must have a "similar density" to the pure liquid
propane, which is about 0.5, or half that of water. There are questions about the
composition of the material used as a proppant because, although very light-weight,
the proppant must also be able to resist the pressure from the rock.
Because of the conditions under which the eCORP trial was held, we are not able to
respond to this question at this time.
b Slim hole bores
Another point that remains to be validated is the use of slim hole drilling and in
particular the use of coiled tubing technology. In this report, we must make the
distinction between the implementation of these technologies during the exploration
and operation phases.

In the exploration phase, the use of a slim hole well25
(half as large as the diameter at
the end of a typical well) is an advantage because the volume of propane to be
injected is significantly reduced.
The use of coiled tubing presents several advantages:
 It saves a considerable amount of time inasmuch as it is not necessary to pull
up the drill rods when multiple stimulations are carried out,
 It can be put in place with great precision,
 The amount of fluid to be injected to provoke the fracturing of the rock is
supposed to be reduced by half.
Nonetheless, it remains to be seen whether the complexity of this type of tubing
doesn't affect its reliability, although the many operations that have already taken
place are reassuring in this regard; and also whether this technology can be applied
to a large variety of source rock types inasmuch as the injection flows will certainly be
restricted.
Along with the possibility of greatly reducing the number of exploratory wells to drill in
order to have a fairly reliable estimation of the resources and reserves in a given
field26
, this technology also shrinks the surface footprint of the necessary installations
in the exploration phase as well as the length of time that the equipment is in use,
thus diminishing the environmental impact of the exploration phase.
Questions may be raised about the possibility of using this technology in the
operation phase. Indeed, during the exploration phase the volumes managed are low
and there is a genuine interest in miniaturizing the well to reduce the overall impact;
but the same might not be true for the operation phase. The use of coiled tubing
leads to lower injection capacities and it must be determined whether or not these
capacities enable an acceptable level of production for the field.
c In conclusion with regard to the subsurface implementation of the
technology
On the condition that it is possible to use low-density proppants with adequate
mechanical properties on the one hand and, on the other, that we can shed more
light on the use of slim hole bores, pure propane stimulation technology could
reasonably be foreseen in France.
The trials were held under very good conditions, which shows that experienced
eCORP personnel have mastered the technology. This indicates the technical
excellence that is available and should make it possible to answer the remaining
questions listed here above.
5.2 Risk analysis
The analysis expounded in section 5, having led to the simplified mapping of risks,
impacts and harmful effects on the surface linked to deployment of the operations
under review, brings several items to the fore, which are summarized here.
25
The well is a coiled tubing of a single diameter from the surface on, about 3" to 4", including casing;
fracturing is achieved by injecting propane between the tubing and the casing.
26
It took 15 years and nearly 10,000 wells to evaluate the reserves in the Barnett shale field; for
Marcellus only about 100 wells, and just over 5 years were needed; to estimate the Eagle Ford
reserves, it is expected that 2 year and a dozen wells will suffice.

5.2.1 Security of aboveground installations
Simplified mapping of risks, impacts and harmful effects shows that pure propane
stimulation can contribute to radically modifying the nature of the critical items
inherent in its exploitation. Whereas hydraulic fracturing raises questions in terms of
environmental impact (mainly on water and air) over the short and long term, pure
propane fracturing, in the current state of the art, raises a very different critical item:
the safety of workers on the site and environmental challenges during the phase of
operation.
Whatever the nature of accident scenarios (leaks, BLEVE, …), simplified modeling
reveals that the orders of magnitude for security distances are all quite similar in
terms of the distance at which potential effects would be felt (irreversible effects at
less than 300 m, no further effects beyond 450 m).
If the technology currently in use in North America seems to be well designed in
general, robust and proven efficient (several thousand wells in operation with very
rare reports of accidents), the dangerous nature of the product used (propane is
flammable) means that it is difficult to eliminate all risk of accident, especially in the
operational phase.
Two major avenues could lead to the reduction of the criticality of accident scenarios.
The first is the optimization of operation sites to limit the presence of people and
property within the zones defined by the calculation of effects measured at distances.
Thus it is necessary to:
 Exclude all public occupation within the zone defined by a 300-meter-wide
strip adjacent to the operation site;
 Exclude the presence of any building with glass surfaces (residences, offices,
businesses) within 450 meters of the operation site;
 Limit, thereby, occupation of the intermediate zone (from 300 m to 400 m) to
temporary activities that do not require the use of buildings with glass windows
(agriculture, secondary roads, …).
The second is the optimization of the operation procedure in such a way as to
further reduce the likelihood of an accident on the operation site and/or to protect the
operational personnel in case such an event were to occur. The technologies under
review must therefore be adapted to the French regulatory environment (gas and fire
detectors, automatic sprinkling of tankers, …), and improvements planned by eCORP
for greater security along the line (confinement pipes to control any leaks, automation
of all valves, …) should be adopted, making the whole system more secure.
Specific measures regarding the safety of workers must also be defined, validated
and implemented (a secure control center where workers remain during the high-
pressure injections, fire-safe, explosion-resistant and located at a safe distance from
the main sources of danger, for example).
Once these two avenues for improvement have been carefully studied and
implemented concomitantly, the criticality of the accident scenarios listed as
"critical items" could be revised downward (item for attention, or under control, a
priori).
In regard to the possible reduction of security distances, although there are different
means for achieving this (reduce tanker size, embankments, optimize organization of
the operation site, …), the perspectives are limited for two main reasons:

 The four scenarios used result in effects measured at distances that were
equivalent. Therefore, in order to reduce the overall distances, it would not be
enough to reduce the distances for a single scenario, but necessary to reduce
the distances inherent to each scenario;
 The limitation of the line capacities (tanker volume, diameter of hoses, for
example) often has only a very slight effect on the effects measured at
distances.
5.2.2 Land use
The global approach for planning and sharing infrastructures (setting up several
wellbores on a single operation site, careful distribution of operational sites) and the
nature of the technologies proposed (smaller diameter wellbore, optimization of site
recovery after closure), could contribute to a considerable reduction of impacts on
land use in comparison to the "sprawl" effect that can be observed in some parts of
North America.
Nonetheless, it is necessary to maintain buffer zones adjacent to the operation site
and to control access to sites in exploration or operation in order to meet
requirements, and this can be an important factor to consider in regard to deployment
of this technology (especially if densely inhabited areas are concerned). Depending
on the type of urbanization of the geographic zones where resources may be present
underground, the possibility of setting up operations in due respect of security
distances from sensitive surrounding areas and facilities shall be the subject of
careful study.
Only a systematic analysis, carried out on each geographic sector, will enable us to
assess the "criticality" of this item or to lower the indicator to an "item for attention".
5.2.3 The necessity of assessing the natural milieu in order to answer
questions pertaining to environmental and health impacts
The technique of pure propane fracturing offers, a priori, significant improvements in
terms of the reduction of environmental impacts in the short and long term, compared
to hydraulic fracturing.
The fact that demands on the water resources are limited, that no chemicals are
added, and the systematic isolation of recovered fluids from the atmosphere are so
many positive factors in favor of the preservation of the water, air and soil quality.
The "orange" indicators that remain attributed to these impacts (and to induced
seismicity) in the simplified mapping are essentially related to the need to better
assess the environmental milieu (geochemistry of the hydrocarbons and the field,
presence of faults or aquifers nearby, …), in particular to determine if there are any
mineral or organic elements that might be freed up during fracturing of the rock and
conveyed by flowback of fluids used in the operation (mainly a concern when shale
oil is present).
If this assessment of the milieu (undertaken during the exploration phase) and a
careful examination of the efficiency of the drilling technologies planned is positive,
the "items for attention" on these points (air and water quality, health impacts,
induced seismicity) could be, on a case-by-case basis (depending on the
assessment of each site) re-evaluated as "Effects very limited, a priori".

5.2.4 If an exploration phase is to take place, the technology under
review appears to be well adapted to its implementation
The simplified mapping of risks, impacts and harmful effects shows that, except for
the issue of the security of surface installations (and the associated security
distances), the technological implementation of pure propane fracturing does not
seem to raise any particular problems ("green" indicators) in regard to assessing the
available underground resources (exploration phase).
During the exploration phase, the number of sites that must be assessed to obtain
the information is fairly limited (from one to several dozen for a geographical field
where data is already available, such as the Paris area), and the amounts of propane
(as well as the duration of work) are limited as well during the potential phase testing
for the "fracturability of the rock". The probability of identification, on a regional scale,
of several sites that could be put into operation with due respect of the requirements
and constraints (security distances) seems to be a reasonable assumption at this
time.
An assessment campaign would yield a reasonably quick, non-binding report on the
potential underground resources and also supply information needed to better
examine prospective impacts or harmful effects that might result during the operation
phase or in the long term (in particular with regard to water resources). It would thus
be possible to make an objective decision on the advantages and drawbacks of the
process (resources, profitability, impacts, …) and to evaluate the prospect of moving
into an operational phase for certain sectors that have been previously assessed.
5.3 Technological readiness of the technologies and evolution of
the process
The table hereafter reviews, for each of the three phases under consideration
(exploration, operation, closure), the actions to be taken, their readiness, their
environmental impact and their capacity to reduce risk underground.
5.3.1 Technological readiness

Phase Nature of the
activity
* Specific to
context
Description
of the activity
Contribution of
knowledge
Readiness
-: More knowledge
needed
0: knowledge at
R&D level or not
commercialized
+: Commercialized
knowledge
Environmental
impact
-: Impact
0:low impact
+: No impact
Risk
Reductio
n
-: No
reduction
0: slight
reduction
+: Big
reduction
Exploration Geophysical
reconnaissance
Reprocessing
of existing
data:
underground
imaging
Characterization of
stratigraphic layers
and major
discordances
+ + 0
Geophysical
reconnaissance
Seismic 3D
acquisition
Location of faults,
compartmentalization
of reserves
+ 0 +
Field modeling Digital
modeling of
the phases of
sediment
deposits and
deformations
Representation of the
structure of the
underground and its
stratigraphy, use of
geophysical data for
modeling,
heterogeneity and
distribution of
sediments
+ + +
* Field
modeling
Digital
modeling of
organic matter
Heterogeneity of
distribution of organic
matter, identification of
productive zones,
localization of
exploration wells to
drill
-/0 + +
Drilling
exploration and
observation
wells, sampling,
borehole logs
Coiled tubing
drilling
Improved precision of
the geological model,
acquisition of samples
from zones and
organic matter for
assessment
+ 0 +
* Well tests Perforation,
stimulation,
production
tests
Identification of the
extension of the
drainage zone created
by stimulation
+ 0 +
Exploration Evaluation of
reserves
Elaboration of
an initial
model of the
reserves
From the stratigraphic
modeling on the scale
of the field,
comprehension of the
variability of the
source rock
composition estimate
of the recoverable
reserves by an initial
digital modeling of the
reserves, techno-
economic plan for
development
+ + NA
Operation Drilling the
production well
From the initial
model of the
reserved,
drilling of first
operation well,
acquisition of
borehole logs
Update of the
geographic model,
confirmation of
reserves
+ -/0 0/+
Stimulation of
production well
Perforation
and injection
of pure
propane
Confirmation of
reserves
Update of
geomechanical
properties
0 - -

Phase Nature of the
activity
* Specific to
context
Description
of the activity
Contribution of
knowledge
Readiness
-: More knowledge
needed
0: knowledge at R&D
level or not
commercialized
+: Commercialized
knowledge
Environmental
impact
-: Impact
0:low impact
+: No impact
Risk
Reductio
n
-: No
reduction
0: slight
reduction
+: Big
reduction
Operation Monitoring
stimulations
Aboveground
and at the
observation
well (micro-
seismic)
Monitoring the
extension of the
cracks and the
drainage zones,
adjustment of the
stimulation program
+ + +
Production Observation of
flows and
pressure
Update of geological
model and reserves
model, optimization of
development plan
+ 0 +
Recovery and
restoration
Depressurizati
on, cementing
Adjustment of the
recovery method
+
0 +
Closure * Long-term
modeling of the
reserves
Simulation of
the long-term
behavior of the
reserves
Verification of
confinement,
modeling the effects
of fluid-rock
interaction and
geomechanical
properties
-/0 NA +
* Monitoring the
control aquifer
Measurements
of pressure,
composition
and
comparison
with base line
Confirmation of
reserves
Updating of
geomechanical
properties
0 + +
Monitoring
aboveground
and at the
observation well
Recording of
micro-seismic
events,
methane
emission
detection
Verification of
confinement
0/+ + +
Plugging the
well
Cement
plugging
according to
regulations in
effect
After verification of the
stability of the site, it
is sealed off + 0 +

5.3.2 Considerations for the future evolution of the process
Issues Considerations
Minimize road traffic and
the size of drilling and
production equipment to be
transported in populated
areas on existing roads
Encourage the recycling of propane and use a more
sequential development plan
Minimize, as much as possible, the size of bores, while
maintaining sufficient injection and production flows
Plan the deployment of activities on a regional scale to
optimize transport infrastructures (fluids, traffic)
Minimize the number of
wells to drill
Better characterization of the spatial distribution of the
properties of the source rock in order to identify production
zones on a small scale
Ensure appropriate
monitoring during the
exploration phase
Define the base line for seismic activity for the sector under
consideration
Drill observation wells and fit them with micro-seismic
detectors
Equip aquifers in contact with the works with gages for leak
detection
Define a base line in terms of air quality and natural gas
emissions aboveground
Ensure appropriate
monitoring during the
operation phase
Measure seismic activity aboveground
Record the bottom hole pressure and seismic events
generated
Ensure the monitoring of "water and air" control networks in
order to detect any problems and immediately take corrective
measures
Match French standards
with the available feedback
The technologies developed do not necessarily have an
equivalent in France. The specificities that led to their
development (flexibility, mobility) should be taken into account
so that there is no opposition based merely on the principle of
new solutions, when they offer advantages in terms of
efficiency and security (using high-resistance tubing, for
example)

Issues Considerations
Capitalize on the
expertise of
experienced teams
Know-how in the area of fracturing deep layers exists today in
North America. If such techniques were to be used in France, it
seems imperative that we benefit from this experience, at least in
the short term before implementation of transfer of skills. The
experience acquired by specialized teams, in particular in regard to
management and prevention and management of risk is of primary
importance.
Adapt organizational
procedures to the
French context
The regulatory environment on work conditions is quite different
between France and some states of the United States. It is
necessary to confirm that the real added-value, in terms of safety
measures surrounding the practices of pressurizing and inspecting
the production line, are not jeopardized due to constraints on
effective working hours of teams (avoid sacrificing time allotted for
security and safety in favor of time spent on production if the need
to make a choice arises).
Carry out a detailed
analysis of the
operation line as soon
as it is running
The simplified analysis in this report called for a "hybrid" approach
integrating the audit of an operation line that is different from the
one ultimately envisioned, and the consideration of certain
concepts for improvement submitted by eCORP. The "upstream"
nature of the approach did not allow us to exchange views with
scientific or government authorities that could benefit from the
feedback on the implementation of some of the techniques
mentioned by the operator. A consideration for the improvement of
this analysis in the near future could be a more detailed update
based on the actual technology, and its actual operating line, as
eCORP plans.

Exploitation of Source Rock Hydrocarbons through Propane Stimulation

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Exploitation of Source Rock Hydrocarbons through Propane Stimulation