Well Engineering

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Well Engineering & Construction

24 Kilometers

Hussain Rabia

Index

Well Engineering &
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Table of Contents
Chapter 1 : Pore Pressure Chapter 2 : Formation Integrity Tests Chapter 3 : Kick Tolerance Chapter 4 : Casing Functions & Types Chapter 5 : Casing Design Principles Chapter 6 : Cementing Chapter 7 : Drilling Fluids Chapter 8 : Practical Rig Hydraulics Chapter 9 : Drill Bits Chapter 10 : Drillstring Design Chapter 11 : Directional Drilling Chapter 12 : Hole Problems Chapter 13 : Horizontal & Multilateral Wells Chapter 14 : Rig Components Chapter 15 : Well Costing

Construction

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Well Engineering &Construction

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Contents
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P ORE P RESSURE

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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 Learning Milestones

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. . . . . . 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 placed on 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 mud weights 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.

Well Engineering &Construction

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PORE PRESSURE

Definitions

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

All formations penetrated during the drilling of a well contain pressure which may vary in magnitude depending on depth, location and proximity to other 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 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 system of 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) 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 planning or drilling a well it is often more convenient to refer to hydrostatic pressures in terms of a pressure gradient. A pressure gradient is the rate of increase in...
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