Core plugging test

KOYA UNIVERSITY
FACULTY OF ENGINEERING
SCHOOL OF PETROLEUM AND
CHEMICAL
FLUID MECHANIC LAB
NAME OF EXPEREMENT:
Core Plugging Test
NAME OF STUDENT:
Kamal Abdurahman
Group: B
SUPERVISED BY: Mr.Ali Kamal

Aim of Experiment:
In this test we will try to prepare core plugs from 4`` cores. Different
core sizes can be obtain during the drilling operation process, the
main object behind this is to get more information about some
targets in which we may get or find hydrocarbon or for many other
objects.

Introduction
Knowledge of the physical properties of the rock and interaction
between hydrocarbon system and the formation rock is crucial in
understanding and evaluating the performance of a given reservoir.
These data are usually obtained from two main sources: core
analysis and well logging. In this test we describe the analysis of
cores. A core which is a solid cylinder of rock about 3 inches in
diameter and would usually be about 30 feet long is taken by
replacing the drill bit by a “core bit” which is capable of grinding out
and retrieving the heavy cylinder rock. Once the cores are retrieved
it is crucial to properly handle (avoid damaging) and preserve them
by avoiding exposure to air. When the core arrives in the laboratory
plugs are usually drilled 20-30 cm apart throughout the reservoir
interval. Then the plugs are analyzed with respect to porosity,
permeability, saturation, grain density and lithology.

This analysis, which is performed at high sampling frequency and
low cost, is called routine core analysis. The results from routine
core analysis are used in interpretation and evaluation of the
reservoir. Examples are prediction of gas, oil and water production,
definition of fluid contacts and volume in place, definition of
completion intervals. There are other important measurements with
the aim of obtaining the detailed information about the multiphase
flow behavior. This analysis, which is performed at low sampling
frequency due to high cost and more time due to gathering the data,
is called special core analysis. Special core analysis gives
information about the rock wettability, the distribution of oil, gas,
and water in the reservoir (capillary pressure data).

Theory
A coring program is similar to many engineering projects. It begins
with the idea that an investment will reap a reward. It progresses
through a phase of exploring alternate sources of information; well
tests, logs, previous cores, and cuttings or sidewall cores.
Planning begins by listing the objectives of the coring program. This
is best done by a team of petro physical, reservoir, geological,
drilling, and production personnel. When discussing objectives,
every expenditure must ultimately lead to producing more oil or gas
at a lower unit cost. Constraints in budget, location, and timing will
be placed on the program.
Hole size, hole angle, temperature, pressure, and rock type will
inﬂuence the selection of the coring tools. Planning becomes an
interactive process where consensus is built and a detailed
program formulated.

The keys to a successful coring operation are planning and
communication.
Objective
The objective of every coring operation is to gather information that
leads to more efficient oil or gas production. Some specific tasks
might include the:
a. Geologic objectives:
1. Lithologic information:
(a) Rock type.
(b) Depositional environment.
(c) Pore type.
(d) Mineralogy/geochemistry.
2. Geologic maps.
3. Fracture orientation.
b. Petrophysical and reservoir engineering:

1. Permeability information:
(a) Permeability/porosity correlation. (b) Relative permeability.
2. Capillary pressure data.
3. Data for reﬁning log calculations:
(a) Electrical properties.
(b) Grain density.
(c) Core gamma log.
(d) Mineralogy and cation exchange capacity.
4. Enhanced oil recovery studies.
5. Reserves estimate:
(a) Porosity.
(b) Fluid saturations.

Coring Fluids The selection of a coring fluid should be based
on four points:
a. Safety.
b. The primary objective of the coring program.
c. Environmental concerns.
d. Cost.

Apparatus of experiment
1-Conventional Core Barrel.
2- Heavy-Duty Conventional Core Barrels.
The core cutting machine is designed to cut cores of between 3 to
6 inches, or from blocks of a similar size. The produced plugs are
in two different size of 1 and 1.5 inches.

Machine Description:
Figure 3: Core plugging machine
The speed can be adjusted by repositioning the belt (1800 rpm –
2500 rpm – 3500 rpm)
The machine comprises of:
• clamping stand
• column
• « Spindle-Motor » unit
• adjustable tilting table
• protective housing
• clamping unit
• recycling tank

Procedure
1- Slab bedding; the cores need to be slab bed with the aim of
making the rock structure visible. This can simply be done by
sawing down the middle of the core and cutting it at desired length.
2- Plugging: one can drill the plugs at every one foot of the core.
3- Trimming: both end of the plugs and core samples can be
trimmed in order to produce high quality without disturbing the
structure of the sample.
1- Core Slabbing :
Core slabbing is the first step in the preparation of samples for core
laboratory experiments, with the use of saw machine for cutting

rocks into the smaller parts. Figure below shows the core slabbing
machine (Fig. 1).
The machine has a motor which supplies the rotational motion for
sawing. The main machine parts are:
• Radial saw
• Electro motor
• Shaft and pulleys
• Adjustable tilting table
• Cooling system, including pumps, water supply, flexible pipes.

Experiment Operation
The procedure for cutting a given sample is as follows:
• If the rock is big then it should first be cut by another method
• Put the sample on the table
• Check the tension on the pulleys
• Adjust the direction of water line on both saw and sample
• Check water tanks and fill them if they are empty
• Start the water pump and check the direction of water and check
the flow
• Start the saw by pressing the start bottom
• Cut the sample by screwing up and down of the saw and pushing
the sample table of machine
• Press the stop button
• Unclamp the core sample
However, in working with the machine consider the following safety
issues:

(1) Prevent touching of saw with the machine sample table,
because of damaging of saw.
(2) Protect yourself from any splash and water drops by wearing
overall and safety glasses.
2- Plugging using plug drill Press machine :
The core cutting machine is designed to cut cores of between 3 to
6 inches, or from blocks of a similar size. The produced plugs are
in two different size of 1 and 1.5 inches.

Discussion
Q: Why we take the core plugging?
-We take the core plug to determined the physical properties of the
rock like (porosity ,permeability ,saturation ,capillary pressure
,surface & interfacial tension &…..so on).
Q: What is the target of this experiment?
The target of this experiment is to prepared a core plugging sample
underground in laboratory (rock sample)to know information of
these beds(for ex: porosity ,permeability ,saturation).
Q: What are the types of core?

Q: What are the objectives of coring?

Result of Experiment
The results from routine core analysis are used in interpretation
and evaluation of the reservoir. Examples are prediction of gas, oil
and water production, definition of fluid contacts and volume in
place, definition of completion intervals. There are other important
measurements with the aim of obtaining the detailed information
about the multiphase flow behavior. This analysis, which is
performed at low sampling frequency due to high cost and more
time due to gathering the data, is called special core analysis.
Special core analysis gives information about the rock wettability,
the distribution of oil, gas, and water in the reservoir (capillary
pressure data).

Reference
1.Andersen, G., 1975, Coring and Core Analysis Handbook:
Tulsa, OK, PennWell Books, 200 p.
2. Park, A., 1985, Coring, Part 2—core barrel types and uses:
World Oil, v. 200, p. 83–90.
3. Bradburn, F. R., Cheatham, C. A., 1988, Improved core
recovery in laminated sand shale sequences: Journal of
Petroleum Technology, v. 40, p. 1544–1546., 10.,
2118/18570-PA
4.Toney, J. B., Speiglets, S. L., 1985, Coring, Part 6—sidewall
operations: World Oil, v. 201, p. 29–36.
5.Craft, M., Keelan, D. K., 1985, Coring, Part 7—analytical
aspects of sidewall coring: World Oil, v. 201, p. 77–90.

6.American Petroleum Institute, 1960, RP-40 recommended
practices for core analysis procedures: Dallas, API, 55 p.

Core plugging test

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Core plugging test