Rotary Drilling System:Introduction

Drilling Engineering 1 Course
3rd Ed. , 3rd Experience

1.
Introduction
2.
Types of rigs
3.
Personnel at Rig Site
4.
How to drill a well

2 drilling goals

to build the well according to its purpose and in a safe manner

(i.e, avoiding personal injuries

and avoiding technical problems)

to complete it with minimum cost

Thereto the overall costs of the well during its lifetime in conjunction with the field development aspects shall be minimized. Fall 14 H. AlamiNia Drilling Engineering 1 Course (3rd Ed.) 4

Parameters

The overall cost minimization, or optimization, may influence

the location from where the well is drilled,

(e.g., an extended reach onshore or above reservoir offshore),

the drilling technology applied,

(e.g., conventional or slim–hole drilling, overbalanced or underbalanced, vertical or horizontal, etc),

and which evaluation procedures are run to gather subsurface information to optimize future wells.
Fall 14 H. AlamiNia Drilling Engineering 1 Course (3rd Ed.) 5

drilling technologies

To build a hole, different drilling technologies have been invented:

Percussion drilling

Cable drilling “Pennsylvanian drilling”

Drillstring
•
With mud Quick percussion drilling
•
Without mud “Canadian drilling”

Rotating drilling (Will be discussed exclusively)

Full cross-section drilling
•
Surface driven
o
Rotary bit
o
Rotary nozzle
•
Subsurface driven
o
Turbine drilling
o
Positive displacement motor drilling
o
Electro motor drilling

Annular drilling
•
Diamond coring
•
Shot drilling

drilling technologies (Cont.)

Special techniques

Abrasive jet drilling

Cavitating jet drilling

Electric arc and plasma drilling

Electric beam drilling

Electric disintegration drilling

Explosive drilling

Flame jet drilling

Implosion drilling

Laser drilling

REAM drilling

Replaceable cutterhead drilling

Rocket exhaust drilling

Spark drilling

Subterrene drilling

Terra drilling

Thermal-mechanical drilling

Thermocorer drilling

drilling rig

A drilling rig is a device used to drill, case and cement oil and gas wells.

The correct procedure for selecting and sizing a drilling rig is as follows:

Design the well

Establish the various loads to be expected during drilling and testing operations and use the highest loads. This point establishes the DEPTH RATING OF THE RIG.

Compare the rating of existing rigs with the design loads

Select the appropriate rig and its components.

Rig Classification
Rotary Drilling Rigs
Land
Mobile
Jackknife
Portable Mast
Conventional
Marine
Bottom Supported
Platform
Self Contained
Tendered
Barge
Jack-Up
Submersible
Floating
Drill Ship
Semi Submersible
Caisson Vessel
Tension Leg

Land: Mobile Rigs
Jackknife rig
Portable mast

Marine: Bottom Supported Platform rigs
Self Contained
Tendered

Marine: Other Bottom Supported rigs
A Jack–Up rig A submersible platform
A cantilever rig on a barge

Marine: Floating rigs
Caisson vessel
(also called
sparbuoy) and
Diagram of a
spar–buoy
A tension–
leg platform
A drill–ship
Semi– submersible vessel

comparison of drilling rigs

Well Classifications

According to a wells final depth, it can be classified into:

Shallow well: < 2000m

Conventional well: 2 000m –3500m

Deep well: 3500m –5000m

Ultra deep well: > 5 000m

With the help of advanced technologies in MWD/LWD and extended reach drilling techniques, horizontal departures of more than10000m are possible today.

Personnel

People directly involved in drilling a well are employed either by

the operating company,

the drilling contractor,

or one of the service and supply companies

The operating company is the owner of the lease/block and principal user of the services provided by the drilling contractor and the different service companies.

Tasks

Since drilling contractors are companies that perform the actual drilling of the well, their main job is to drill a hole to the depth/location and specifications set by the operator.

Along with hiring a drilling contractor, the operator usually employs various service and supply companies to perform

logging,

cementing,

or any other special operations, including maintaining the drilling fluid in its planed condition.

drilling crews

Most drilling crews consist of

a tool pusher,

a driller,

a derrickman,

a mud logger,

and two or three rotary helpers

(also called floormen or roughnecks).

Along with this basic crew configuration the operator sends usually a representative, called

company man to the rig.

For offshore operations the crews usually consist of many more employees.

crew requirements

Tool Pusher:

supervises all drilling operations and is the leading man of the drilling contractor on location.

Company Man:

The company man is in direct charge of all company’s activities on the rig site.

He is responsible for the drilling strategy as well as the supplies and services in need. His decisions directly effect the progress of the well.

crew requirements (Cont.)

Driller:

The driller operates the drilling machinery on the rig floor and is the overall supervisor of all floormen.

He reports directly to the tool pusher and is the person who is most closely involved in the drilling process.

He operates, from his position at the control console, the rig floor brakes, switches, levers, and all other related controls that influence the drilling parameters.

In case of a kick he is the first person to take action by moving the bit off bottom and closing the BOP.

Inside a control console


Derrick Man:

The derrickman works on the so– called monkeyboard, a small platform up in the derrick, usually about 90 ft above the rotary table.

When a connection is made or during tripping operations he is handling and guiding the upper end of the pipe.

During drilling operations the derrickman is responsible for maintaining and repairing the pumps and other equipment as well as keeping tabs on the drilling fluid.


Floormen:

During tripping, the rotary helpers are responsible for handling the lower end of the drill pipe as well as operating tongs and wrenches to make or break up a connection.

During other times, they also maintain equipment, keep it clean, do painting and in general help where ever help is needed.

Mud Engineer, Mud Logger:

The service company who provides the mud almost always sends a mud engineer and a mud logger to the rig site. They are constantly responsible for logging what is happening in the hole as well as maintaining the proper mud conditions.

drilling process

In rotary drilling, the rock is destroyed by the action of rotation and axial force applied to a drilling bit.

The drilling bit is located at the end of a drill string which is composed of drill pipes (also called joints or singles), drill collars, and other specialized drilling tools.

Drill collars are thick walled tubes responsible for applying the axial force at the bit.

Rotation at the bit is usually obtained by rotating the whole drill string from the surface.

A simplified drillstring

The components of the drillstring are:

Drillpipe

Drillcollars

Other Accessories called bottom hole assembly (BHA) including:

Heavy-walled drillpipe (HWDP)

Stabilisers

Reamers

Directional control equipment

Etc. Fall 14 H. AlamiNia Drilling Engineering 1 Course (3rd Ed.) 28

Functions of the drillstring

The drill string is the mechanical linkage connecting the drillbit at the bottom of the hole to the rotary drive system on the surface.

The drillstring serves the following functions:

transmits rotation to the drillbit

exerts weight on the bit;

the compressive force necessary to break the rock

guides and controls the trajectory of the bit; and

allows fluid circulation

which is required for cooling the bit and for cleaning the hole. Fall 14 H. AlamiNia Drilling Engineering 1 Course (3rd Ed.) 29

drilling process (Cont.)

A large variety of bit models and designs are available in industry.

The choice of the right bit, based on the characteristics of the formations to be drilled, and the right parameters (weight on bit and rotary speed)

are the two most basic problems the drilling engineer faces during drilling planning and drilling operation.

The cuttings are lifted to the surface by the drilling fluid.

At the surface, the cuttings are separated from the drilling fluid by several solid removal equipment.

Drilling mud is picked up by the system of pumps and pumped again down the hole.

connection

As drilling progresses, new joints are added to the top of the drill string increasing its length, in an operation called connection.

A pipe slips is used to transfer the weight of the drillstring from the hook to the master bushing. Fall 14 H. AlamiNia Drilling Engineering 1 Course (3rd Ed.) 31

round trip

As the bit gets dull, a round trip is performed to bring the dull bit to the surface and replace it by a new one.

A round trip is performed also to change the BHA.

The drillstring is also removed to run a casing string. The operation is done by removing stands of two (“doubles”), three (“thribbles”) or even four (“fourbles”) joints connected, and stacking them upright in the rig.

Removing one stand of drillstring

wiper trip

Sometimes the drillstring is not completely run out of the hole.

It is just lifted up to the top of the open-hole section and then lowered back again while continuously circulating with drilling mud.

Such a trip, called wiper trip,

is carried out to clean the hole from remaining cuttings that may have settled along the open–hole section.

1.(CDF) Jorge H.B. Sampaio Jr. “Drilling Engineering Fundamentals.” Master of Petroleum Engineering. Curtin University of Technology, 2007.
Chapter 1 and 2
2.(WEC) Rabia, Hussain. Well Engineering & Construction. Entrac Consulting Limited, 2002.
Chapter 16

Rotary Drilling System:Introduction

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