Chapter 1 Basic of well drilling process.pptx

WELCOME TO THE STUDENTS
7th Semester (Mining)
Bogura Polytechnic Institute, Bogura.
Md. Majedur Rahman
B. Sc (Hon’s), M. Sc in Geology & Mining, RU
Instructor (Tech)
Mining and Mine Survey Technology
Bogura Polytechnic Institute, BOGURA.
Presented By
Prepared by Md. Majedur Rahman, E-mail: majedu1r_ru6871@yahoo.com
August 3, 2022 1

Petroleum Well Design & Completion
Course Code No. 69372
Course Curriculum T C P
2 3 3
Prepared by Md. Majedur Rahman, E-mail:
majedu1r_ru6871@yahoo.com
August 3, 2022 2

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Why we study Petroleum Well Design & Completion?

Aim of Petroleum Well Design & Completion
To be able to develop knowledge, skill and attitude in the area of
petroleum well design & completion with special emphasis on:
 Well planning
 Well design
 Well completion
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Short description of the course
• Well drilling process;
• Well planning;
• Well drilling design;
• Casing deign;
• Drilling bit design;
• Drilling fluid;
• Cementing; Coring;
• Well control and Blowout prevention;
• Well completion and testing.
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Chapter-01
Understand the basic of well drilling process
1.1 Define well drilling.
1.2 Purpose of well drilling.
1.3 Classify different types of drilling.
1.4 Define Horizontal and Directional drilling.
1.5 Describe cable tool drilling process.
1.6 Describe Rotary drilling process.
1.7 Describe drilling rigs.
1.8 Drilling hazards and controlling process.
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Well drilling is the process of drilling a hole in the ground for the
extraction of a natural resource such as ground water, brine, natural
gas, or petroleum, for the injection of a fluid from surface to a
subsurface reservoir or for subsurface formations evaluation or
monitoring.
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1.1 Define well drilling.

Drilling is an important method of prospecting subsurface rocks and ore
deposits. In drilling data are collected by direct penetration of subsurface
rocks by drill holes. The samples of rocks are obtained in the form of
cylindrical cores or rock fragments. The drilling holes provide the following
information’s.
• Size, shape and morphology of the ore body.
• Geological structures and number of lodes present.
• Nature of the host rocks.
• Composition and grade of the ore body.
• To produces oil and gas.
• To collect the sample for exploration well.
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1.2 Purpose of well drilling.

1.3 Classify different types of drilling.
There are a variety of drilling mechanisms which can be used to sink a
borehole into the ground. Each has its advantages and disadvantages, in
terms of depth to which it can drill, type of sample returned, the costs
involved and penetration rates achieved. There are two basic types of drills:
drills which produce rock chips, and drills which produce core samples.
• Auger drilling
• Percussion rotary air blast drilling (RAB)
• Air core drilling
• Cable tool drilling
• Reverse circulation (RC) drilling
• Diamond core drilling
• Hydraulic Rotary drilling
• Sonic (Vibratory) drilling
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1.4 Define Horizontal and Directional drilling.
Define Horizontal: Natural gas,
crude oil and geothermal drilling is
frequently performed using the
rotary drilling process. In the rotary
drilling process, a rotating drilling
head on a drill pipe bores into the
earth’s crust down to the crude oil,
natural gas or geothermal deposit.
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The application of horizontal drilling
• Directly following vertical drilling, the direction of the drilling head
can be changed to continue drilling “horizontally”. The exploration
and extraction of crude oil and natural gas deposits is increasingly
being realised by means of horizontal drilling, also in Germany.
• Horizontal drilling within the deposit allows oil and gas fields to be
developed with fewer bore holes. In combination with the fracking
technique (see hydraulic fracturing), additional crude oil or natural
gas can be extracted even from harder layers of rock.
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Directional drilling:
Most wells drilled for water, oil, natural gas,
information or other subsurface objectives are
vertical wells - drilled straight down into the
earth. However, drilling at an angle other than
vertical can obtain information, hit targets, and
stimulate reservoirs in ways that cannot be
achieved with a vertical well. In these cases, an
ability to accurately steer the well in directions
and angles that depart from the vertical is a
valuable ability.
When directional drilling is combined with
hydraulic fracturing, some rock units which were
unproductive when drilled vertically can
become fantastic producers of oil or natural gas.
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Why Drill Wells That Are Non-Vertical?
Directional and horizontal drilling have been used to reach targets beneath
adjacent lands, reduce the footprint of gas field development, increase the
length of the "pay zone" in a well, deliberately intersect fractures, construct
relief wells, and install utility service beneath lands where excavation is
impossible or extremely expensive.
Below is a list of six reasons for drilling non-vertical wells. They are
graphically illustrated by the six drawings on this page.
A) Hit targets that cannot be reached by vertical drilling.
B) Drain a broad area from a single drilling pad.
C) Increase the length of the "pay zone" within the target rock unit.
D) Improve the productivity of wells in a fractured reservoir.
E) Seal or relieve pressure in an "out-of-control" well.
F) Install underground utilities where excavation is not possible.
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1.5 Describe cable tool drilling process.
• A Drilling method in which a hole is drilled by dropping a sharply pointed
bit on the bottom of the hole. The bit is attached to a cable, and the cable
is repeatedly picked up and dropped as the hole is drilled.
• Cable-tool was the first method used to drill a bore hole and is still in use,
particularly for shallow oil or gas wells in the Appalachian Basin. The cable
refers to the manila hemp rope used to suspend the wooden rods and the
drilling tools in the earliest operations. The manila line and wooden rods
were eventually replaced by multiple-strand steel rope often called wire
line or wire rope.
• The cable (manila rope or wire line) pulls the string of tools up and down as
brought about by a spring pole or a walking beam at the surface. The
heavy bit has a blunt chisel end which cracks, chips and smashes the rock
by the repeated blows delivered in a measured or regular cadence.
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• Percussion drilling is another name for
cable-tool drilling. It refers to the
blows delivered to the rock by the bit.
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1.6 Describe Rotary drilling process.
A Drilling method in which a
hole is drilled by a rotating bit to
which a downward force is
applied. The bit is fastened to
and rotated by drill stem, which
also provides a passage way
through which the drilling fluid
is circulated. Additional joints of
drill pipe are added as drilling
progresses.
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ROTARY DRILLING RIG
• The main function of rotary drilling rig is to make hole.
• The moving of the rig from site to site depends on weight and size of
each rig component.
• Each unit assembly is limited in weight because of truck and highway
limitations on gross weight.
• Rotary drilling rigs must be disassembled into many components so
that weight limits are not exceeded.
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1.7 Describe drilling rigs.

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ROTARY DRILLING RIG
• Rotary rig design should:
Allow for rapid erection and take-down, and consist of
few pieces as possible.
Not require special cranes for assembly (rig-up) or
disassembly (tear-down).
Enable drill pipe to be run into the hole or pulled out
with minimum time wasted.
Provide the maximum amount of available power for
the circulating fluid to the bit.
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ROTARY DRILLING RIG
• Many factors determine a rig’s portability:
Wheel-mounted rigs can be used for drilling to depths of
10,000 feet or more and for completion/workover service on
15,000-foot wells.
These rigs have self-erecting, telescoping masts; and the
mast, drawworks and engines are built on a trailer or self-
propelled unit.
Equipment such as mud pumps must be handled as
packages.
Therefore, efficient planning and design are necessary.
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• The drilling rig
consists of six major
systems:
• Hoisting System
• Rotating System
• Fluid Circulating
System
• Power System
• Well Control
System
• Well Monitoring
System
ROTARY DRILLING RIG
Rotary Drilling Rig.
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• RC Cyclone
• Gear Type Rotation Head
• Diverter System
• Hydraulic Wet Rotary Splitter, for
Reverse Circulation drilling
• Universal Hydraulic Tilt Splitter, for
Reverse Circulation drilling
• Blow Back System
• Hydraulic Hoses
• Hydraulic Mud Mixer
• Air-Operated Double Diaphragm Pumps
• Mud Tank
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Drill Rig Accessories
 Mud Mixer Spare Parts: Parker motor and impeller
 Left Hand and Right Hand Angle indicators
 Bit Basket
 Bit Sharpening System
 Automatic lubricator for the down the hole
hammer
 Whip Checks
 Thread locking compound Bakerlok
 Handled Oiler
 Rigging Hardware
 Fishing Tools
 Compressor air hoses

HOISTING SYSTEM
DERRICK
The function of a derrick is
to provide vertical
clearance to the raising
and lowering of drill string
into and out of borehole
Two type of Derricks
Standard Derricks - it is of
bolted construction and
assembled part by part
Mast – a portable derrick,
one capable of being
erected as a unit
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CROWN BLOCK
The fixed set of pulleys
(called sheaves) located at
the top of the derrick or
mast over which the drilling
line is threaded.
TRAVELLING BLOCK
A pulley (sheave)
assembly that connects the
drilling line to the hook and
swivel
HOISTING SYSTEM
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DRAWWORKS
 It is the control center
from which the driller
operates the rig. It
contains clutches,
chains and other
controls
 It houses the drum
which spools drilling line
during hoisting and
allows feed off during
drilling
HOISTING SYSTEM
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• The hoisting system is used to raise and lower the drill
stem.
• It is also used to support and lower pipe that is used for
casing and tubing.
• A mast or derrick supports the hook by means of the
travelling block, wire rope, crown block and drawworks.
• The drawworks is powered by two or three engines
(called prime movers) to raise or lower the drill stem so
that the bit can drill.
HOISTING SYSTEM
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• The drill stem is the
whole assembly from
the swivel to the bit,
including the kelly, drill
pipe, drill collars and bit
sub.
HOISTING SYSTEM
Hoisting System
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• Standard drilling rig derricks are tall steel structures with four
supporting legs standing on a square base.
• The derrick and substructure plays an important role in drilling
operations.
• The derrick provides the vertical height necessary for the
hoisting system to raise and lower the pipe.
• The derrick is assembled piece by piece at the drilling site.
• A drilling mast, which is partially assembled when it is
manufactured, usually has a smaller floor area.
DERRICK, MAST & SUBSTRUCTURE
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• It can be raised from a horizontal to a vertical position in
as shown below.
• The standard derrick has become rare today except for
extremely deep wells and offshore drilling.
Raising a Mast Prepared by Md. Majedur Rahman, E-mail:
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August 3, 2022

• The mast has almost completely replaced the
conventional derrick for drilling on land because:
• It can be quickly dismantled and erected on another location by
the regular rig crew
• The mast can be moved in large units without complete
disassembly.
• Masts 135 to 145 feet in height are the most common size.
• The rig floor, rotary table, casing and drill pipes rest on a
substructure.
• The rig floor provides an area for handling the drill stem
and related equipment.
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• Blowout preventers and wellhead fittings are located
under the substructure.
• Drill pipe is suspended from the rotary table, which is
supported by the beams of the substructure.
• Heavy-duty masts and substructures can stand a load of
1,200,000 pounds.
• The normal capacity is in excess of 500,000 pounds.
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• The derrick and the substructure must have
enough strength to withstand:
• Load suspended from a hook.
• Pipes set in the derrick.
• Wind loads.
• The API has developed size classifications for
the derrick as shown on the next slide.
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Derrick Size Classifications (Courtesy API)
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General Dimensions of Derrick Sizes
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• The derrick and substructure must be able to support the
force imposed by pipe weight on the block by a portion of
the drillstring standing in the derrick.
• Due to the manner in which the hook load is distributed
over the derrick, the effective load may exceed the actual.
• When heavy casing strings are run, it may be necessary
to lay down some drill pipe initially so the derrick loading
capacity is not exceeded.
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Free Body Diagram of the Block, Fast and Dead Lines
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• The derrick load resulting from a hook load can be
evaluated with the free body diagram (FBD) on the
previous slide.
• The force on the derrick (FD) includes the hook load (L),
the tension in the fast line (TF) and the tension in the
dead line (TD).
• The tension in the fast line in a non-ideal friction is given
by:
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• where:
• EB = efficiency factor of block system
• L = hook load, lb
• N = number of lines strung over the block system
• TF = fast-line tension, lb
• Since the dead line does not move, the tension is
in the dead line is given by:
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• FD can now be written as:
• The total force on the derrick (FD) is not evenly distributed
over each of the four legs.
• The fast-line tension is distributed evenly between legs C
& D, since the drawworks is commonly positioned
between the legs.
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• The dead-line tension is near a leg.
• The force on each leg can be summarized as follows:
Load
Source
Total Load
Load on each Derrick Leg
A B C D
Hook
Load
L L/4 L/4 L/4 L/4
Fast
Line
L/NEB - - L/2NEB L/2NEB
Dead
Line
L/N L/N - - -
Total L + L/NEB + L/N L((N+4)/4N) L/4 L((NEB+2)/4NEB) L((NEB+2)/4NEB)
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C
A
D
B
Lines to Block Fast line
Dead line
Derrick Leg
Typical Rig Floor for Distribution of Forces
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• The load on leg A is greater than any other leg if EB >
0.5.
• Therefore, the maximum derrick load can be defined
as four times the strength of the weakest leg:
• where:
• FDE = effective derrick load.
• The derrick will be exposed to loads created by wind
acting horizontally on pipe set back in the derrick.
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• The Wind Load (Lw) is calculated from:
• where:
• Lw = wind load, lb/ft, and
• V = wind velocity, mph.
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• The hoisting system is a vital component of the rig
equipment.
• It provides a means for vertical movement of pipe in the
well, i.e., to lower and raise the drillstring and casing.
• The principal items in the hoisting system are as follows:
• drawworks.
• crown and travelling blocks.
• wireline.
• ancillary equipment such as elevators, hooks and bails.
DRAWWORKS
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• The hoisting system, in conjunction with the circulating
equipment, consumes a portion of the rig’s power.
• A drawworks on a rig is known in other industries as a
hoist.
• The main purpose of the drawworks is to lift and lower
pipe in and out of the hole.
DRAWWORKS
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• The hoisting drum either reels in wire rope to pull the pipe
from the hole or lets out wire rope to lower the travelling
block and attached drill stem, casing or tubing.
• The drawworks includes a transmission, which uses
chains, sprockets and gears to allow speed changes of
the hoisting drum.
• Often, the drawworks has a drive sprocket to power the
rotary table.
• This arrangement is common, even on diesel-electric rigs.
DRAWWORKS
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A Rotary Rig Hoisting System
DRAWWORKS
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The Drawworks consists of a revolving drum around which the wire rope is
spooled
DRAWWORKS
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• The drawworks brake system makes it possible for
the driller to control a load a several hundred tons of
drill pipe or casing.
• Most rigs are equipped with two brake systems for
the drawworks hoisting drum: one that is mechanical
and one that is hydraulic or electric.
• The mechanical system consists of compounded
levers to tighten brake bands to bring the drum to full
stop.
DRAWWORKS
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August 3, 2022

• The hydraulic or electric brake can control the speed
of descent of a loaded travelling block, although it is
not capable of stopping the drum completely.
• Another of component of the drawworks is the
catheads.
• The makeup, or spinning, cathead is located on the
driller’s side of the drawworks and is used to tighten
the drill pipe joints.
DRAWWORKS
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• The other cathead, located opposite the driller’s
position, is the breakout cathead.
• It is used to loosen the drill pipe when it is pulled
from the hole.
• Air hoists are provided on many rigs for handling
light loads.
DRAWWORKS
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The Friction Cathead
DRAWWORKS
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August 3, 2022

• The travelling block, crown block and drilling line
within the derrick raise and lower loads of pipe out
of and into the hole.
• During drilling operations, these loads usually
consist of drill pipe and drill collars.
• The blocks and drilling line must also support
casing while it is being run in the hole.
BLOCKS AND DRILLING LINE
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• This casing is often heavier than the drill stem.
• Drilling line is reeved around sheaves (pulleys) in the
crown block at the top of the derrick or mast and in
the travelling block.
• The blocks and drilling line assembly must have
great strength to support the heavy loads.
• The number of sheaves is determined by the weight
to be supported.
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August 3, 2022

• Five is the most common, but deeper wells often
require six or seven.
• Friction is minimized in the blocks by heavy duty
bearings.
• Large-diameter sheaves are provided to lessen wear
on the drilling line, which is usually a multistrand
steel cable, 1 ¼ to 1 ½ inches in diameter.
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• The block system is not a frictionless system, i.e., its
efficiency factor is less than 1.0.
• It is often assumed that the efficiency factor is
computed from:
• where n is the number of sheave pairs.
• The following Table indicates EB for various pulley
systems.
Number of Lines EB
6 0.886
8 0.85
10 0.817
12 0.785
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• Drilling rigs have many applications for wire
ropes.
• The more common uses for wire ropes are as
drilling lines and guideline tensioners.
• The drilling line connects to the drawworks and
the dead-line anchor.
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• It is pulled through the crown and travelling block sheaves
so that the travelling block can be raised or lowered as
necessary.
• Wire rope is made from cold drawn carbon steel of
various grades, depending on the strength required.
• The API classifies the various grades as follows:
• extra improved plow steel (EIPS).
• improved plow steel (IPS).
• plow steel (PS).
• mild plow steel (MPS).
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• Generally, the first two higher-strength grades,
EIPS and IPS, are used currently for drilling lines
due to the rugged service encountered.
• The primary element of wire rope is the individual
wires.
• Wires are carefully selected, sized, and layered
into strands. After stranding, the strands are
layered together around a core to form wire rope.
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• The core may be a fiber rope (either natural grown fibers
or man-made fibers), a plastic core, a spring steel core, a
multiple-wire strand, or an independent wire rope (IWRC).
• The independent wire rope is the most widely used
because it resists crushing and distortion.
• The wire rope is usually described by type of core, the
number of strands wrapped around the core, and the
number of individual wires per strand.
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August 3, 2022

• For example, a 6 x 19 with an independent IWRC
is a typical type of rope used as drilling line.
• It contains one independent wire rope core, six
strands, with nineteen separate wires per strand.
• Wire rope is usually furnished preformed but can
be furnished non-preformed upon special request.
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August 3, 2022

• A preformed rope has the strands shaped to the
helical form they assume in the finished rope
before the strands have been fabricated in to the
rope.
• The strands of the preformed rope will not spring
from the normal position when the sizing bands are
removed.
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Typical wire-rope construction with correct ordering
descriptions Prepared by Md. Majedur Rahman, E-mail:
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• The lay of the rope describes the direction of the strand
wrap around the core and the direction of the wire rope
around within the strands.
• The strands may be right or left lay.
• The individual wires can be regular or lang lay.
• The length of the lay is usually 7.25-8 times the nominal
diameter.
Lay of the Rope Prepared by Md. Majedur Rahman, E-mail:
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• The nominal strength of the wire rope depends on
the material used in construction, the number of
strands and wires, and the size of the rope.
• The API has published Tables for breaking
strengths of various wire ropes.
• As an example, the nominal strength of 13/8”, 6 x 37
drawn galvanized IWRC rope is 192,000 lb.
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• The API has established minimum design factors
for wire ropes operating under oilfield conditions.
• These design factors are specified in API
Recommended Practice 9B.
• When working near the minimum design factor,
consideration should be given to the efficiencies of
wire rope bent around sheaves, fittings or drums.
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• The minimum design factors are as follows:
• The primary function of the wire rope in conjunction with
other components of the hoisting system is to provide a
mechanical advantage (M) for raising or lowering the
drillstring or casing.
• If the tension line in the fast line attached to the
drawworks is defined as TF, then the mechanical
advantage is as follows:
Type of Service Minimum Design Factor
Cable tool line 3
Sand line 3
Hoisting service other than rotary drilling 3
Mast hoisting and lowering 2.5
Rotary drilling line when setting casing 2
Pulling on stuck pipe and similar infrequent
operations 2
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• where:
• L = hook load, lb
• TF = fast-line tension, lb
• M = mechanical advantage
• The fast-line tension can be computed, if an ideal
system is considered:
• where N = number of lines strung over the block
system.
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• Since block efficiency (EB) must be considered in a non-
ideal case, the fast-line tension is as follows:
• The horsepower (HP) required to lift a load, L, at some
velocity is given by:
• where :
• V = velocity in ft/min, and
• 33,000 = ft-lb/min/hp
• This equation is very useful in determining the amount of
input horsepower requirements from the prime movers.
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Breaking Strengths of various Wire Ropes
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KELLY
 A Kelly is a square or
hexagonal length of pipe
that fits into a bushing in
the rig's rotary table. As
the rotary table turns to
the right, the Kelly turns
with it.
 The main function of a
Kelly is to transfer energy
from the rotary table to
the rest of the drill string.
SWIVEL
 It suspends the drill string
and allows rotation at the
same time. KELLY
ROTARY TABLE
RAT HOLE
ROTATING SYSTEM
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DRILL PIPES
Drill pipes furnish the
necessary length for the
drill string and serves as
a conduit for the drilling
fluid
DRILL COLLARS
Provides weight and
stability to the drill bit,
maintain tension on the
drill pipe and help keep
the hole on a straight
course
ROTATING SYSTEM
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• HEAVY WALL DRILL PIPES
provides additional hole stability
and aids in directional control
• STABILIZERS
centralize the drill collars, help
maintain the hole at full-gauge
diameter
• JARS
provide sharp upward or
downward impact to free stuck
pipe
• REAMERS
helps to maintain a full-gauge
hole diameter
• CROSSOVER SUBS
which join components having
different types of connections.
ROTATING SYSTEM
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BITS:
•Most critical component in rotary
drilling operations. Different types of
bits.
•Two main type of bits:
•Rolling cutter bits - consist of
cutting elements arranged on cones
(usually three cones, but sometimes
two) that rotate on bearings about
their own axis as the drill string turns
the body of the bit. These bits can
have teeth or buttons
ROTATING SYSTEM
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• Fixed cutter bits - also
known as drag bits,
consist of stationary
cutting elements that are
integral with the body of
the bit and are rotated
directly by the turning of
the drill string.
• The principal types of
fixed cutter bits are:
• natural diamond
• polycrystalline diamond
compact (PDC)
ROTATING SYSTEM
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• The rotating system includes all the equipment used
to achieve bit rotation.
• A principal feature of the rotating system is the
rotary table, or rotary.
• The rotary table is powered by the prime movers to
rotate the kelly, which is raised or lowered through
the kelly drive bushing.
ROTATING SYSTEM
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August 3, 2022

• The rotation of the kelly causes the drill stem and bit
to turn and thus “make hole” as the bit grinds away
the rock formation.
• The kelly is supported by the hoisting system.
• Drilling fluid is pumped down the drill pipe to the bit
and then up the annulus.
ROTATING SYSTEM
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ROTATING SYSTEM
The Rotating
System
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• The rotary is the piece of equipment that gives
the rotary drilling rig its name.
• It is the machine that turns the drill stem and the
bit in order to make hole.
• A rotary table is fitted with a drive bushing.
ROTARY, KELLY AND SWIVEL
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• The three-, four-, six-, or eight-sided kelly fits
through the bushing and is thus turned by the
rotary.
• The rotary is a basic yet extremely rugged
machine that is distinguished by its ability to
withstand hard service.
• The drive bushing may fit in a square opening in
the rotary tale, or four pins that fit in the openings
of the table may drive it.
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• The drive bushing permits vertical movement of
the kelly as the hole is deepened, at the same
time rotating the drill stem.
• The rotary serves two main functions:
• to rotate the drills stem; and
• to hold friction-grip devices called slips to support the
drill stem or casing.
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• A sprocket and chain may mechanically drive the
rotary from the drawworks.
• However, many drilling rigs provide power to an
electric motor that drives the rotary directly.
• In some cases, an independent engine is used to
drive the rotary.
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• The kelly is the top member of the drill stem.
• It is about 40 feet long and may be either
triangular-, square-, hexagon- or octagon-shaped
to fit its drive bushing.
• The kelly can move freely up and down through
the drive bushing while the rotary is turning it.
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• The swivel hangs from a hook under the
travelling bloc, and serves several vital functions.
• It supports the weight of the drill stem.
• It allows rotation of the drill stem.
• It provides a passageway for drilling fluid to enter
the drill stem.
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• The rotary hose is connected to a gooseneck-
fitting on the swivel.
• Drilling fluid is pumped into the gooseneck,
through the swivel, and down the kelly.
• This fluid may be under pressure exceeding
3,000 psi.
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The following are some of the most common hazards in drilling and can be
overcome by proper control of the mud properties.
• Salt section hole enlargement
Salt section can be eroded by the drilling fluid and causes hole enlargement. These
enlargements will require larger mud volume to fill the system and in case of casing
the hole, larger cement volume is required. To avoid these problems a salt
saturated mud system is prepared prior to drilling the salt bed
• Heaving shale problems
Areas with shale sections containing bentonite or other hydratable clays will
continually absorb water, swell and slough into the hole.
Such beds are referred to as heaving shales and constitute a severe drilling hazard
when encountered. Pipe sticking, excessive solid buildup in the mud and hole
bridging are typical problems.
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86
1.8 Drilling hazards and controlling process.

Various treatments of the mud are sometimes successful, such as
• Changing mud system to high calcium content by adding lime, gypsum etc
which reduces the tendency of the mud to hydrate water sensitive clays.
• Increasing circulation rate for more rapid removal of particles.
• Increasing mud density for greater wall support
• Decreasing water loss mud
• Changing to oil emulsion mud
• Changing to oil-based mud.
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• Blowouts
Blowout is the most spectacular, expensive and highly feared hazard of
drilling. This occurs when encountered formation pressure exceed the mud
column pressure which allows the formation fluids to blow out of the hole.
Mud density or the mud weight is the principal factor in controlling this
hazard.
In drilling a blow out preventer (BOP) stack is always attached at the top of
the conductor pipe. In case of a gas kick (a sign that may lead to a blow out)
the BOP stack can close the annular space between the drilling pipe and the
conductor pipe or casing or shut the whole hole (with a blind ram of the
BOP).
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• Lost Circulation
Lost circulation means the loss of substantial amount of drilling mud to an
encountered formation. Lost circulation materials are commonly circulated
in the mud system both as a cure and a continuous preventive. These
materials are the fibrous materials such as the hay, sawdust or padi husk and
lamellated (flat and platy) materials such as mica, cellophane.
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A drilling hazard is defined as any event off of the critical path of drilling
operations. Using a DHM approach early in the well planning process is
essential to its effectiveness and success. DHM focuses on wellbore
stability and consequential hazards such as stuck pipe, fluids loss, and
equivalent circulating density (ECD) management. These events lead to
non-productive drilling time in the least case or catastrophic wellbore
failure and jeopardize well control in the worst cases. DHM requires
understanding the uncertainty of the drilling margin—the safe applied
ECD between the in-situ pore pressure and/or stress equivalence and
the fracture gradient as a result of the overburden at true vertical
depth(TVD). Because all drilling operations have risk, mitigating these
risks is fundamental to DHM.
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Drilling hazards and controlling process.

The initial phase of the process is where the well is formulated and
objectives are determined. SMART well objectives consider and define
the following:
• Specific
• Measurable
• Achievable
• Relevant
• Timely
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Often the root cause of failure lies with objectives that are not initially
aligned and understood by the disciplines or stakeholders. Well planners
must guard against developing objectives that are not measurable, often
conflict, and together are not achievable. The following objectives for a
12,000 ft TVD, 15,000 ft MD directional well do not follow the SMART
criteria:
• Right size initial flow capabilities
• Adequate hole size for evaluation, coring, completion
• Completions free of formation damage
• High―rig-less intervention capabilities
• Minimal complexity
• Directional well with a target on-bottom radius of 200’
• Multiple targets
• Well availability, design life
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• Good reservoir surveillance
• Provide for a future sidetrack
• Case the well with a minimize number of casing strings
• Mono-bore small wellbore with minimum costs
• Optimize costs Ability to stimulate the well by fracturing
• ESP artificial lift system
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Oil well control is one of the most important aspects of drilling
operations. Improper handling of kicks in oil well control can result in
blowouts with very grave consequences, including the loss of valuable
resources and also lives of field personnel. Even though the cost of a
blowout (as a result of improper/no oil well control) can easily reach
several millions of US dollars, the monetary loss is not as serious as the
other damages that can occur: irreparable damage to the environment,
waste of valuable resources, ruined equipment, and most importantly,
the safety and lives of personnel on the drilling rig.
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Importance of oil well control

Any Questions
August 3, 2022 95

THANKS TO ALL
August 3, 2022 96

Chapter 1 Basic of well drilling process.pptx

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