Well drilling design

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.comMay 29, 2020 1

Petroleum Well Design & Completion
Course Code No. 69372
Prepared by Md. Majedur Rahman, E-mail:
majedu1r_ru6871@yahoo.com
May 29, 2020 2

Chapter-04
Understand the well drilling design
4.1 Define drilling design.
4.2 Well design characteristics.
4.3 Selection of optimum mud weight.
4.4 Define hydraulic optimization.
4.5 Define drilling string, Drill bit, Drill pipe and Drill collar.
4.6 Mention the main components of hoisting system.
4.7 State test string design.
May 29, 2020 3

Detail engineering of the selected well model for a Basis of Design. Planned
hole and casing sizes, and setting depths, Required drilling mud properties
(weight, viscosity, etc.), Planned well trajectory and directional drilling
requirements, Cement recipes and job specifications (rate, volume, etc.)
Well design proceeds in two stages: the functional requirements of the well
being first specified, following which the well construction details to deliver
those functional requirements can be defined. Many aspects of well design
are dictated by regulatory requirements.
Drilling engineers design and implement procedures to drill wells as safely
and economically as possible. They work closely with the drilling contractor,
service contractors, and compliance personnel, as well as with geologists and
other technical specialists.
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4.1 Define drilling design.

4.2 Well design characteristics.
Well design characteristics
• Well Design Process
• Underbalanced Drilling Design
Well Design Process:
• Prior to the commencement of the well design process, the following considerations shall be established:
• Type of well (exploration, appraisal, production)
• Location and installation (integrated platforms, wellhead platforms, subsea)
• Main and secondary targets
• Data collection demands
• Well evaluation methods to be applied (coring, logging, sampling, testing, stimulation)
• Application of the well (exploration, appraisal, production, injection, monitoring, relief/killing)
• Characteristic inclinations and depths (vertical, deviated, horizontal, side-track, HPHT, deepwater)
• Type of drilling-, production-, and workover system (fixed-, floating-, subsea installation, jack-up)
• Life time prognosis (permanent-, temporary abandonment, production-, injection completion, partial
completion and later tie-back, expected time between work over’s, down hole pressure and temperature
profile)
• Environmental and safety constraints
May 29, 2020
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Underbalanced Drilling Design:
• To succeed in proper well design, the issues below shall be considered:
• Wellbore stability and consolidation
• Safety and well control
• Inability to use conventional MWD technology for through-string injection
techniques
• Gravity drainage effects in high permeability zones
• Condensate drop-out or gas liberation effects
• Near wellbore damage
• Probability for corrosion problems
• Discontinuity of the underbalanced situation
May 29, 2020
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• Recognized barrier elements are:
• BOP arrangements
• Christmas tree arrangement
• Properly cemented casing
• Production tubing
• Cement plugs
• Production packer elements
• Mechanically/hydraulically operated plugs/packers
• Well safety valve (SCSSV)
• Lubricators
• BOP system of coil tubing/snubbing unit
• Seal assembly of casing/production tubing
• Wellhead systems
• ASV (Annulus Safety Valve)
May 29, 2020 7
Barrier Elements of well drilling design

4.3 Selection of optimum mud weight.
Mud weight must be carefully selected based on parameters, hydraulics
must be utilized to control the equivalent circulating density of the fluid, and
the type of drilling mud should be compatible with the borehole and
formation being drilled.
Drilling mud plays important role in the successful completion of the drilling
process. Mud serves various functions including exerting sufficient
hydrostatic pressure against subsurface formations and preventing wellbore
instability. Selection of an appropriate mud weight is one way to prevent
borehole failure. Mud pressure is the only parameter analysed routinely in a
quantitative fashion, resulting in a recommendation for the mud weight
margin (also referred to as drilling window). The mud-weight margin is the
density range between pore and fracturing pressures.
May 29, 2020
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Effects of high mud weight
May 29, 2020
9
Element Advantage Debatable Disadvantage
Reduce borehole collapse √
Reduce fill √ √
Reduce pressure variations √
Reduce washout √ √
Reduce tight hole √ √
Reduce clay swelling √ √
Increase differential
sticking
√ √
Increase lost circulation √
Reduced drilling rate √ √
Expensive mud √
Poor pore pressure
estimation
√ √

4.4 Define hydraulic optimization.
May 29, 2020
10
The goal of the optimization is to make the maximum usage of the
pump's power to help the bit to drill at maximum efficiency. These
criteria include the maximum bit hydraulic horsepower, the maximum
bit hydraulic impact force, and the maximum bit jet velocity.
For drilling hydraulics optimization, there are two ways which is the
maximum jet impact force and the maximum hydraulic
horsepower used to indicate good hole cleaning.

What are the criteria to select the drilling hydraulics
optimization methods?
• In shallow, large diameter sections where the rate of penetration and
cutting volume is high, you need higher flow rate to clean the wellbore.
With these criteria, the maximum impact force method is
recommended because it gives you 19.5% higher flow rate than the
maximum hydraulic horsepower.
• In deeper, smaller diameter sections where the ROP is lower than the
shallow section and cuttings affecting down force become a drilling
hydraulic issue. Hence, you need higher jet velocity and pressure at the
bottom hole. To match the requirement, the best optimization way for this
case is the maximum hydraulic horsepower because it gives 14.3% higher
jet velocity and 34.7% higher pressure than the maximum impact force.
May 29, 2020
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4.5 Define drilling string, Drill bit, Drill pipe and Drill
collar.
Drill string: the string of drill pipe with tool joints which transmits
rotation and circulation to the drill bit. Sometimes used to include both
drill collars and drill pipe.
Drill bits are cutting tools used to remove material to create holes, almost
always of circular cross-section. Drill bits come in many sizes and shapes and
can create different kinds of holes in many different materials. In order to
create holes drill bits are usually attached to a drill, which powers them to
cut through the workpiece, typically by rotation. The drill will grasp the
upper end of a bit called the shank in the chuck.
May 29, 2020
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Drill pipe: a heavy seamless pipe which is used to rotate the bit and
circulate the drilling fluid. Lengths of drill pipe 30ft long are coupled
together with tool joints to make the drill string.
Drill collar: a heavy, thick-walled steel tube which provides weight on the bit
to achieve penetration. A number of drill collars may be used between the
bit and the drill pipe.
May 29, 2020
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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
14
4.6 Mention the main components of hoisting system.
May 29, 2020

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
15May 29, 2020

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
16May 29, 2020

• 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
17May 29, 2020

• 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
18May 29, 2020

• 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
19May 29, 2020

• 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:
20May 29, 2020

• 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.
21May 29, 2020

• 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.
22May 29, 2020

4.7 State test string design.
The combination of the drill pipe, the bottom hole assembly and any
other tools used to make the drill bit turn at the bottom of the
wellbore.
The goal of String Testing is to ensure the successful integration of all
region and non-region specific programs and objects that make up
process. All steps should be accomplished without manual
intervention, since the objective is to test the end-to-end automated
process that will ultimately be used within the production
environments.
May 29, 2020
23

Recent advances in solids control include the creation of a closed loop system
which allows for increased environmental control and reduction in the
potential for spills of drilling fluids. Several US states have either passed or are
considering the implementation of closed loop systems, particularly for hydro-
fracturing operations.
May 29, 2020
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Any Questions
May 29, 2020 25

THANKS TO ALL
May 29, 2020 26

Well drilling design

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