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Well Engineering & Construction

24 Kilometers

Hussain Rabia

Index

Well Engineering &
TOC Previous Next

Table of Contents

Construction

Chapter 1 : Pore Pressure

1

Chapter 2 : Formation Integrity Tests

49

Chapter 3 : Kick Tolerance

71

Chapter 4 : Casing Functions & Types

89

Chapter 5 : Casing Design Principles

95

Chapter 6 : Cementing

131Chapter 7 : Drilling Fluids

197

Chapter 8 : Practical Rig Hydraulics

235

Chapter 9 : Drill Bits

269

Chapter 10 : Drillstring Design

313

Chapter 11 : Directional Drilling

373

Chapter 12 : Hole Problems

461

Chapter 13 : Horizontal & Multilateral Wells

517

Chapter 14 : Rig Components

569

Chapter 15 : Well Costing

601

Well Engineering &Constructioni

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P ORE P RESSURE

.....

...................................

1

Contents
1
2
3
4
5
6
7
8
9

Introduction
Definitions
Pore Pressure
Causes Of Abnormal Pore Pressure
Abnormal Pore Pressure Evaluation
Measurement While Drilling (MWD) & Logging while drilling (LWD) Data
Repeat Formation Tester (RFT) Data
Drill Stem Test (DST) Data
LearningMilestones

1.0

. . . . . . INTRODUCTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
...............

This chapter will present the origins of pore pressure and principles its determination. It
should be emphasized here that this subject alone requires more than one book to cover in
detail.
Hence the emphasis will be placedon the practical utilisation of pore pressure in the well
planning process. It is hoped that the ideas presented here will help the engineer to better
understand lithological columns and deduce potential hole problems before producing a final
well plan.
Knowledge of formation pressures is vital to the safe planning of a well. Accurate values of
formation pressures are used to design safe mudweights to overcome fracturing the
formation and prevent well kicks. The process of designing and selection of casing
weights/grades is predominately dependent on the utilisation of accurate values of formation
pressure. Cementing design, kick control, selection of wellhead and Xmas trees and even the
rig rating are dependent on the formation pressures encountered in the well.

WellEngineering &Construction

1

1

PORE PRESSURE

Definitions

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2.0

. . . . . . D. EFINITIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. ...........

All formations penetrated during the drilling of a well contain pressure which may vary in
magnitude depending on depth, location and proximity toother structures. In order to
understand the nature, extent and origin of formation pressures, it is necessary to define and
explain basic wellbore pressure concepts.
2.1

HYDROSTATIC PRESSURE

Hydrostatic pressure is defined as the pressure exerted by a column of fluid. The pressure is
a function of the average fluid density and the vertical height or depth of the fluid column.Mathematically, hydrostatic pressure is expressed as:
HP = g x ρf x D

(1.1)

where:
HP = hydrostatic pressure
g = gravitational acceleration
ρf = average fluid density
D = true vertical depth or height of the column
In field operations, the fluid density is usually expressed in pounds per gallon (ppg), psi per
foot, pounds per cubic foot (ppf) or as specific gravity (SG).
In the Imperial systemof units, when fluid density is expressed in ppg (pounds/gallon) and
depth in feet, the hydrostatic pressure is expressed in psi (lb/in2):
HP (psi) = 0.052 x ρf (ppg) x D (ft)

(1.2)

For the purposes of interpretation, all wellbore pressures, such as formation pressure,
fracture pressure, fluid density and overburden pressure, are measured in terms of
hydrostatic pressure.
When...
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