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Shenglai Yang

Fundamentalsof PetrophysicsSecond Edition

123

Shenglai YangDepartment of Petroleum EngineeringChina University of PetroleumBeijingChina

Springer GeophysicsISBN 978-3-662-55028-1 ISBN 978-3-662-55029-8 (eBook)DOI 10.1007/978-3-662-55029-8

Jointly published with Petroleum Industry Press, Beijing, China.

The print edition is not for sale in China Mainland. Customers from China Mainland please order theprint book from Petroleum Industry Press.

Library of Congress Control Number: 2016953633

© Petroleum Industry Press and Springer-Verlag GmbH Germany 2016, 2017This work is subject to copyright. All rights are reserved by the Publishers, whether the whole or partof the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations,recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmissionor information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilarmethodology now known or hereafter developed.The use of general descriptive names, registered names, trademarks, service marks, etc. in thispublication does not imply, even in the absence of a specific statement, that such names are exempt fromthe relevant protective laws and regulations and therefore free for general use.The publishers, the authors and the editors are safe to assume that the advice and information in thisbook are believed to be true and accurate at the date of publication. Neither the publishers nor theauthors or the editors give a warranty, express or implied, with respect to the material contained herein orfor any errors or omissions that may have been made. The publishers remains neutral with regard tojurisdictional claims in published maps and institutional affiliations.

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Preface

This book presents fundamental physical and physicochemical knowledge involvedin oil and gas development engineering, such as physical and chemical phenomena,physical process. It is arranged to provide the knowledge of porous rock propertiesof reservoir rocks, and properties of fluids, i.e., gases, hydrocarbon liquids, andaqueous solutions, and the mechanism of multiphase fluid flow in porous media.The book also brings together the application of the above theories and knowledge.

This textbook is written to serve the undergraduate teaching of the petroleumengineering major. It focuses on the introduction of basic conceptions, terms,definitions, and theories, placing more emphasis on the width of knowledge ratherthan the depth. What should be learned through the course includes the definitionsof some essential physical parameters, the physical process, important physicalphenomena, influencing factors, and engineering applications. In addition, themeasuring methods and experimental procedures for the key parameters are alsoincluded.

Through the study of this book, good foundation of knowledge frame for pet-roleum engineering should be established for students, which is benefit for boththeir further studying and their work in the future when they are engaged in job.

The book is originally arranged to match a 48-class-hour course, but flexibility ispermitted during teaching and studying process.

The editing work of this book began from year 2002. In 2004, It is translated toEnglish from the textbook PetroPhysics (Yang 2004, in Chinese) published by thePetroleum Industry Press, Beijing, China, and was used in teaching in ChinaUniversity of Petroleum, Beijing. It is Mr. Dong Hua, Lü Wenfeng, Li Baoquan,Yang Sisong, Guo Xiudong, Sheng Zhichao, Sun Xiaojuan, Sun Rong, HangDazhen, and Wu Ming, who made contribution during the translation andcompiling.

In 2008, Ms. Ma Kai helped to recheck and recompile the textbook again. In2010, Ms. Li Min and Mr. Cao Jie helped and made some corrections.

I would like to express my sincere thanks and appreciations to all people whohave helped in the preparation of this book and given any helps in anyways.

v

Due to limitations of my knowledge and ability, this book may contain mistakes,wrong sentences, and so on. Therefore, it is welcomed for the interested readers tomake a correction and let me known, if any mistake is found.

Beijing, China Shenglai Yang

vi Preface

Contents

Part I Physico-Chemical Properties of Reservoir Fluids

1 Chemical Composition and Properties of Reservoir Fluids . . . . . . . 31.1 Chemical Properties of Crude Oil . . . . . . . . . . . . . . . . . . . . . . . . 3

1.1.1 The Elemental Composition of Oil . . . . . . . . . . . . . . . . 31.1.2 The Hydrocarbon Compounds in Crude Oil . . . . . . . . . 51.1.3 The Non-hydrocarbon Compounds in Crude Oil . . . . . . 61.1.4 Molecular Weight, Wax Content, and Colloid

and Asphaltene Content in Crude Oil . . . . . . . . . . . . . . 71.2 Physical Properties and Classification of Crude Oil . . . . . . . . . . 8

1.2.1 Physical Properties of Crude Oil . . . . . . . . . . . . . . . . . . 81.2.2 Classification of Tank-Oil . . . . . . . . . . . . . . . . . . . . . . . 131.2.3 The Classification of Reservoir Oil . . . . . . . . . . . . . . . . 17

1.3 Chemical Composition of Natural Gas . . . . . . . . . . . . . . . . . . . . 181.4 Classification of Oil and Gas Reservoirs. . . . . . . . . . . . . . . . . . . 18

1.4.1 Classification 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191.4.2 Classification 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191.4.3 Classification 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201.4.4 Other Classifications . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

1.5 The Chemical Composition and Classificationof Formation Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211.5.1 The Chemical Composition of Formation Water . . . . . . 211.5.2 The Classification of Formation Water . . . . . . . . . . . . . 23

2 Natural Gas Physical Properties Under High Pressure . . . . . . . . . . 272.1 Apparent Molecular Weight and Density of Natural Gas . . . . . . 27

2.1.1 Composition of Natural Gas . . . . . . . . . . . . . . . . . . . . . 272.1.2 The Molecular Weight of Natural Gas. . . . . . . . . . . . . . 302.1.3 The Density and Specific Gravity of Natural Gas . . . . . 31

2.2 Equation of State for Natural Gas and Principle ofCorresponding State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

vii

2.2.1 Equation of State (EOS) for Ideal Gas . . . . . . . . . . . . . 322.2.2 Equation of State (EOS) for Real Gas . . . . . . . . . . . . . . 332.2.3 Principle of Corresponding State . . . . . . . . . . . . . . . . . . 342.2.4 Other Equations of State for Natural Gas . . . . . . . . . . . 472.2.5 The Calculation of Z-Factor Using State Equation

Correlations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 522.3 Physical Properties of Natural Gas Under High Pressure . . . . . . 55

2.3.1 Natural Gas Formation Volume Factor (FVF) . . . . . . . . 552.3.2 Isothermal Compressibility of Natural Gas . . . . . . . . . . 572.3.3 Viscosity of Natural Gas . . . . . . . . . . . . . . . . . . . . . . . . 61

2.4 Natural Gas with Water Vapor and the Gas Hydrate . . . . . . . . . 672.4.1 Water Vapor Content in Natural Gas. . . . . . . . . . . . . . . 672.4.2 Natural Gas Hydrate . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

3 Phase State of Reservoir Hydrocarbons and Gas–LiquidEquilibrium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 753.1 Phase Behavior of Reservoir Hydrocarbon Fluids. . . . . . . . . . . . 76

3.1.1 Phase and the Descriptive Approaches of Phase . . . . . . 763.1.2 Phase Behavior of Single/Two–Component System . . . 803.1.3 Phase Behavior of Multicomponent System . . . . . . . . . 843.1.4 Phase Behaviors of Typical Reservoirs . . . . . . . . . . . . . 90

3.2 Gas–Liquid Equilibrium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 943.2.1 Ideal Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 943.2.2 Phase-State Equations for Real Gas–Liquid System . . . 1013.2.3 Evaluation of the Equilibrium Ratio K—By Charts . . . . 1063.2.4 Evaluation of the Equilibrium Ratio K—By

Calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1103.3 Solution and Separation of the Gas in an Oil–Gas System . . . . . 113

3.3.1 The Separation of Natural Gas from Cruel Oil . . . . . . . 1133.3.2 The Solution of Natural Gas in Crude Oil. . . . . . . . . . . 120

3.4 Calculation of Oil–Gas Separation ProblemsUsing Phase-State Equations. . . . . . . . . . . . . . . . . . . . . . . . . . . . 1253.4.1 Trial Calculation of Bubble-Point Pressure on Basis

of Given Composition . . . . . . . . . . . . . . . . . . . . . . . . . . 1253.4.2 Comparison Between Single-Stage Degasification

and Multistage Degasification . . . . . . . . . . . . . . . . . . . . 1263.4.3 Differential Liberation Calculation. . . . . . . . . . . . . . . . . 130

4 Physical Properties of Reservoir Fluids Under ReservoirConditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1354.1 High-Pressure Physical Properties of Reservoir Oil . . . . . . . . . . 135

4.1.1 Density and Specific Gravity of Reservoir Oil. . . . . . . . 1354.1.2 Solution Gas–Oil Ratio of Reservoir Oil . . . . . . . . . . . . 1374.1.3 Formation Volume Factor of Oil . . . . . . . . . . . . . . . . . . 1394.1.4 Compressibility Coefficient of Reservoir Oil . . . . . . . . . 142

viii Contents

4.1.5 Viscosity of Reservoir Oil . . . . . . . . . . . . . . . . . . . . . . . 1434.1.6 Freezing Point of Oil . . . . . . . . . . . . . . . . . . . . . . . . . . . 147

4.2 Physical Properties of Formation Water Under HighPressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1474.2.1 Composition and Chemical Classification of

Formation Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1484.2.2 High-Pressure Physical Properties of Formation

Water. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1484.3 Measurement and Calculation of High-Pressure Physical

Parameters of Reservoir Oil and Gas . . . . . . . . . . . . . . . . . . . . . 1534.3.1 Method to Measure the High-Pressure Properties

of Oil and Gas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1534.3.2 To Obtain the High-Pressure Physical-Property

Parameters of Reservoir Oil by Charts . . . . . . . . . . . . . 1674.3.3 To Obtain the High-Pressure Physical-Property

Parameters of Reservoir Oil by Empirical RelationEquations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170

4.4 Application of the Fluid High-Pressure Property Parameters:Material Balance Equation of Hydrocarbons in Reservoirs . . . . . 1734.4.1 Derivation of Material Balance Equation. . . . . . . . . . . . 1734.4.2 Analysis of the Parameters Used in Material

Balance Equation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176

Part II Physical Properties of Reservoir Rocks

5 Porosity of Reservoir Porous Medium . . . . . . . . . . . . . . . . . . . . . . . . 1815.1 Constitution of Sandstone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181

5.1.1 Granulometric Composition of Sandstone . . . . . . . . . . . 1815.1.2 Specific Surface of Rock . . . . . . . . . . . . . . . . . . . . . . . . 1885.1.3 Cementing Material and Type of Cementation . . . . . . . 192

5.2 Pores in Reservoir Rocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1985.2.1 Types and Classification of Pores Within

Reservoir Rock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1985.2.2 Size and Sorting of Pores . . . . . . . . . . . . . . . . . . . . . . . 2035.2.3 Pore Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205

5.3 Porosity of Reservoir Rocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2095.3.1 Definition of Porosity . . . . . . . . . . . . . . . . . . . . . . . . . . 2095.3.2 Grade Reservoir Rocks According to Porosity . . . . . . . 2105.3.3 Porosity of Dual-Porosity Medium Rock. . . . . . . . . . . . 2105.3.4 Measurement of Porosity . . . . . . . . . . . . . . . . . . . . . . . . 2125.3.5 Factors Influencing Porosity of Rock. . . . . . . . . . . . . . . 216

Contents ix

5.4 Compressibility of Reservoir Rocks . . . . . . . . . . . . . . . . . . . . . . 2215.4.1 Rock-Bulk Compressibility (Rock Compressibility). . . . 2215.4.2 Total Compressibility . . . . . . . . . . . . . . . . . . . . . . . . . . 223

5.5 Fluid Saturation in Reservoir Rocks . . . . . . . . . . . . . . . . . . . . . . 2255.5.1 Definition of Fluid Saturation . . . . . . . . . . . . . . . . . . . . 2255.5.2 Methods of Determining Fluid Saturation . . . . . . . . . . . 228

6 Permeability of Reservoir Rocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2336.1 Darcy’s Law and Absolute Permeability of Rock . . . . . . . . . . . . 233

6.1.1 Darcy’s Law . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2336.1.2 Measurement of Absolute Permeability of Rock . . . . . . 2366.1.3 Applying Conditions of Darcy’s Law . . . . . . . . . . . . . . 237

6.2 Gas Permeability and Slippage Effect . . . . . . . . . . . . . . . . . . . . . 2396.2.1 Calculation Equations for Perm-Plug Method . . . . . . . . 2396.2.2 Slippage Effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241

6.3 Factors Affecting the Magnititude of Rock Permeability. . . . . . . 2456.3.1 Deposition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2456.3.2 Diagenesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2486.3.3 Tectogenesis and Others . . . . . . . . . . . . . . . . . . . . . . . . 250

6.4 Measurement and Calculation of Permeability . . . . . . . . . . . . . . 2506.4.1 Laboratory Measurement of Permeability . . . . . . . . . . . 2506.4.2 Evaluation of Permeability Based on Well-Logging

Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2566.4.3 Calculation of Permeability Based on Mean Pore

Radius (r) and Porosity (φ) . . . . . . . . . . . . . . . . . . . . . . 2576.4.4 Methods for the Calculation of Average

Permeability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2576.5 Permeability of Naturally Fractured and Vuggy Rocks . . . . . . . . 262

6.5.1 Permeability of pure-fractured rocks . . . . . . . . . . . . . . . 2636.5.2 Permeability of fracture-pore double-medium rocks. . . . 2656.5.3 Permeability of vuggy rocks . . . . . . . . . . . . . . . . . . . . . 266

6.6 Ideal Models of Rock Structure . . . . . . . . . . . . . . . . . . . . . . . . . 2676.6.1 Model of Bundles of Capillary Tubes . . . . . . . . . . . . . . 2676.6.2 Network Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273

6.7 Sensibility of Sandstone Reservoir Rocks. . . . . . . . . . . . . . . . . . 2756.7.1 Sensitive Minerals Present in Sandstone

Cementing Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . 2766.7.2 Evaluation for Formation Sensibility . . . . . . . . . . . . . . . 289

7 Other Physical Properties of Reservoir Rocks. . . . . . . . . . . . . . . . . . 2977.1 Electrical Conductivity of Fluids-Bearing Rocks . . . . . . . . . . . . 297

7.1.1 Electrical Conductivity and Resistivity of Material . . . . 2977.1.2 Relationship Between Electric Resistivity

of Rock and Formation Water Properties. . . . . . . . . . . . 299

x Contents

7.1.3 Relationship Between Electric Resistivityof Water-Bearing Rocks and Porosity . . . . . . . . . . . . . . 302

7.1.4 Relationship Between Electrical Resistivityof Oil-Bearing Rocks and Saturations . . . . . . . . . . . . . . 306

7.1.5 Measurement of Electrical Resistivity of Rocks. . . . . . . 3097.2 Thermal Properties of Reservoir Rocks. . . . . . . . . . . . . . . . . . . . 310

7.2.1 Heat Capacity of Oil-Bearing Formations . . . . . . . . . . . 3107.2.2 Specific Heat Capacity of Rock. . . . . . . . . . . . . . . . . . . 3107.2.3 Heat Conductivity Coefficient . . . . . . . . . . . . . . . . . . . . 3117.2.4 Thermal Diffusion Coefficient . . . . . . . . . . . . . . . . . . . . 312

7.3 Acoustic Characteristics of Reservoir Rocks. . . . . . . . . . . . . . . . 312

Part III Mechanics of Multi-Phase Flow in Reservoir Rocks

8 Interfacial Phenomena and Wettability of Reservoir Rocks . . . . . . . 3178.1 Interfacial Tension Between Reservoir Fluids . . . . . . . . . . . . . . . 317

8.1.1 Free Surface Energy of the Interface BetweenTwo Phases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317

8.1.2 Specific Surface Energy and Surface Tension . . . . . . . . 3198.1.3 Influencing Factors on Surface Tension. . . . . . . . . . . . . 3228.1.4 Interfacial Tension Between Reservoir Fluids . . . . . . . . 3238.1.5 Measurement of Surface Tension. . . . . . . . . . . . . . . . . . 327

8.2 Interfacial Adsorption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3318.2.1 Concept of Adsorption . . . . . . . . . . . . . . . . . . . . . . . . . 3318.2.2 Adsorption at the Gas–Liquid Interface

(Surface Adsorption) . . . . . . . . . . . . . . . . . . . . . . . . . . . 3318.2.3 Adsorption at the Gas–Solid Interface . . . . . . . . . . . . . . 3358.2.4 Adsorption at the Liquid–Solid Interface . . . . . . . . . . . . 3368.2.5 Wetting Phenomena and Capillary Force. . . . . . . . . . . . 3378.2.6 Interfacial Viscosity. . . . . . . . . . . . . . . . . . . . . . . . . . . . 338

8.3 Wettability of Reservoir Rocks . . . . . . . . . . . . . . . . . . . . . . . . . . 3388.3.1 Basic Concepts About Wettability of Reservoir

Rocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3398.3.2 Wetting Hysteresis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3438.3.3 Influencing Factors for the Wettability of Reservoir

Rocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3468.3.4 Distribution of Oil and Water in Rock Pore Space . . . . 3508.3.5 Measurement of Wettability of Reservoir Rocks . . . . . . 356

9 Capillary Pressure and Capillary Pressure Curve . . . . . . . . . . . . . . 3659.1 Concept of Capillary Pressure. . . . . . . . . . . . . . . . . . . . . . . . . . . 365

9.1.1 Rise of Fluids in Capillary Tube . . . . . . . . . . . . . . . . . . 3659.1.2 Additional Force Across Differently Shaped

Curved Interfaces. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 370

Contents xi

9.1.3 Resistances Caused by Capillary Force . . . . . . . . . . . . . 3769.1.4 Capillary Hysteresis. . . . . . . . . . . . . . . . . . . . . . . . . . . . 379

9.2 Measurement and Calculation of Capillary Pressure Curvesof Rock. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3839.2.1 Porous Diaphragm Plate Method . . . . . . . . . . . . . . . . . . 3849.2.2 Mercury Injection Method . . . . . . . . . . . . . . . . . . . . . . . 3889.2.3 Centrifuge Method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3919.2.4 Conversion Between the Capillary Forces Obtained

Through Different Methods of Measurement . . . . . . . . . 3939.3 Essential Features of Capillary Pressure Curve . . . . . . . . . . . . . . 398

9.3.1 Qualitative Features of Capillary Pressure Curve. . . . . . 3989.3.2 Quantitative Features of Capillary Pressure Curve. . . . . 3999.3.3 Factors Affecting Capillary Pressure Curve . . . . . . . . . . 400

9.4 Application of Capillary Pressure Curve. . . . . . . . . . . . . . . . . . . 4059.4.1 Determine the Wettability of Reservoir Rocks. . . . . . . . 4059.4.2 Averaging Capillary Pressure Data: J(Sw) Function . . . . 4069.4.3 Determination of the Fluid Saturation in the

Oil–Water Transition Zone . . . . . . . . . . . . . . . . . . . . . . 4099.4.4 Calculation of Recovery by Using Capillary Loop . . . . 4109.4.5 Calculation of Absolute Permeability of Rock. . . . . . . . 4119.4.6 Estimation of the Degree of Damage on Formation. . . . 412

10 Multiphase Flow Through Porous Medium and RelativePermeability Curve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41310.1 Characteristics of Multiphase Flow Through Porous

Medium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41310.1.1 Non-piston-Like Displacement. . . . . . . . . . . . . . . . . . . . 41410.1.2 Unconnected Capillary Pore-Channels,

Single-Phase Fluid Flowing. . . . . . . . . . . . . . . . . . . . . . 41610.1.3 Unconnected Capillary Pore-Channels,

Two-Phase Fluid Flowing . . . . . . . . . . . . . . . . . . . . . . . 41710.1.4 Unequal-Diameter Pore-Channels Connected

in Parallel, Two-Phase Fluid . . . . . . . . . . . . . . . . . . . . . 42010.1.5 Flow of Mixed Liquids Through Capillary

Pore-Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42210.2 Two-Phase Relative Permeability . . . . . . . . . . . . . . . . . . . . . . . . 424

10.2.1 Effective and Relative Permeability . . . . . . . . . . . . . . . . 42410.2.2 Characterizing Features of Relative Permeability

Curve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42610.2.3 Factors Affecting Relative Permeability . . . . . . . . . . . . . 431

10.3 Three-Phase Relative Permeability . . . . . . . . . . . . . . . . . . . . . . . 44110.3.1 Relative Permeabilities for Pseudo-Three-Phase

Flow System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44110.3.2 Relative Permeabilities for Real Three-Phase

Flow System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 442

xii Contents

10.4 Measurements and Calculations of Relative PermeabilityCurves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44410.4.1 Steady-State Method . . . . . . . . . . . . . . . . . . . . . . . . . . . 44410.4.2 Unsteady-State Method . . . . . . . . . . . . . . . . . . . . . . . . . 44710.4.3 Relevant Problems in the Measurement

of Relative Permeability . . . . . . . . . . . . . . . . . . . . . . . . 44910.4.4 Calculation of Relative Permeability Curves from

Capillary Pressure Data . . . . . . . . . . . . . . . . . . . . . . . . . 45310.4.5 Calculation of Relative Permeability

from Empirical Equations . . . . . . . . . . . . . . . . . . . . . . . 45610.4.6 Calculation of Relative Permeability

from Field Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45710.5 Use of Relative Permeability Curves . . . . . . . . . . . . . . . . . . . . . 460

10.5.1 Calculation of Production, Water–Oil Ratio,and Fluidity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 460

10.5.2 Analysis of the Water Production Regularity of OilWells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 461

10.5.3 Determination of Vertical Distribution of Oiland Water in Reservoir . . . . . . . . . . . . . . . . . . . . . . . . . 464

10.5.4 Determination of Free Water Surface . . . . . . . . . . . . . . 46510.5.5 Calculation of Displacement Efficiency

and Water Drive Recovery . . . . . . . . . . . . . . . . . . . . . . 46710.5.6 Other Usage of Relative Permeability Data . . . . . . . . . . 471

Appendix A: Unit Conversation Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . 473

Appendix B: Vocabulary of Technical Terms in Chapters . . . . . . . . . . . 477

Appendix C: Charts of Equilibrium Ratio . . . . . . . . . . . . . . . . . . . . . . . . 487

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 501

Contents xiii

Introduction

Why to Exploit Oil and Gas

Energy is the power to push the industrialization and modernization forwards. Thedevelopment and utilization of energy is what a country’s competitive strength andcomprehensive national power hinge on.

Oil and Gas is an important kind of energy, high-quality material for chemicalindustry, and an important warfare material. Therefore, petroleum industry and oiland gas trade has been attached great attention by the super great power countriesbecause it is important to both the energy safety and national defense of a country.Today, it is impossible to imagine what the society should be without the oil andgas. It can be say that petroleum is standing on an essential and indispensable pointin the economic development of the world.

To meet increasing demands for oil and gas and maintain steadily growth in thenational economy, the following policy should be taken:

(1) Explore and discover new oil and gas fields to enlarge the figure of petroleumreserves;

(2) Adopt advanced technology to develop the oil & gas reservoirs effectively;(3) Apply EOR method to improve the oil & gas recovery and increase the

production rate in the developing reservoirs;(4) Develop energy-saving techniques and find alternative or new energy to reduce

the amount of consumption for oil and gas;(5) Cooperate internationally to engage in the development of world petroleum

resources.

For every student who will work in the petroleum industry, related knowledgeand techniques are required to study and hold reliably, in order to take on the abovework successfully.

xv

What is Petrophysics

Petrophysics is a science about the physical property of oil & gas, its formations,and physicochemical phenomena involved in an oil & gas reservoirs and during theexploiting of an oil & gas reservoirs. It primarily includes 3 parts:

(1) The physical properties of the reservoir fluids, including physical properties ofoil, water, and gas at high pressure and high temperature, and the law thatgoverns their phase-changing.

(2) The physical properties of the reservoir rocks, including porosity, permeability,saturation, and sensibility of the formation rocks.

(3) The physical properties of multiphase fluids in porous media and their seepagemechanisms.

A petroleum reservoir is geological structure which consists with formation rock,which is a porous medium, and the oil and gas is contained in the porous medium.

The reservoir, which is the objectives what we study, is buried thousands ofmeters below the earth surface, the reservoir fluids are under states of high pressureand high temperature. At this state, the crude oil dissolves large volume of gas;therefore, the physical properties of the underground reservoir fluids are vastlydifferent from those of the subaerial ones.

This textbook is aimed to introduce the fundamental physical properties of thereservoir fluids and rocks, involving terms, concepts, and related knowledge, tohelp the students to build foundations for their professional studying in the future.

History of the Petrophysics

Petrophysics is a young science with history about 80 years. In the 1930s, some oilfield engineers in America and Russia noticed the influence of the reservoir fluidson the production rate of oil wells and then gave some preliminary test and mea-surement on the fluid property. During the 1930s, a monograph about reservoirfluids was compiled in Russia already. In 1949, M. Mosket, an American, wrote abook named ‘Physical Principles of Oil Production,’ in which the related researchand practical information present in the first half of the twentieth century werecollected and gathered. It illustrated reservoir fluids information from a physicsperspective and guided oil field development technically for various drive-typedreservoirs. In 1956, Ф.И. Koтяxoв, Russian, wrote a book named ‘Fundamental ofPetrophysics.’ This was the first book especially for the petrophysics, and it foundthe base for this subject.

In China, professional team in researching and teaching on petrophysics was setup during 1950s. The first Petroleum University in China, Beijing PetroleumCollege, was founded in 1953. IN BPC, Russian expert Ш.К.Гимaтyдинoв was

xvi Introduction

invited to teach the course petrophysics, and postgraduates researching on petro-physics were firstly trained.

From 1950s and on, with the discovery and development of large oil fields, suchas Daqing oil field, Liaohe oil field, Dagang oil field, the science on petrophysics inChina was vigorously promoted. Research institutes and laboratories were estab-lished in every oil field, as well in the capital city, Beijing. A large number ofresearches on the petrophysical and EOR study were made and achievements hadyielded.

During the 1960s, several books that recorded the research achievements inChina were published in succession, and large numbers of articles and papers werepublished on magazines and journals.

Nowadays, the science of petrophysics has already become an indispensable partof the knowledge system in the development of oil fields, and it is sure that it willplay more important roles in the coming days, to conquer more complicatedproblems we will face during the oil field development.

In the world, some monographs were published in the 1970s, and the physicalproperties of carbonate reservoirs were systematically illustrated in these booksfrom an exploiting perspective. In those books, fractured reservoirs were alsostudied for its deposits, forming mechanisms, and recovery calculation, etc.

In 1977, two books wrote by Russian were published. The mechanism of thereservoir oil’s seepage in the formation was probed in the books from a physico-chemical standpoint. The books stressed that only by strengthening the study on thephysicochemical mechanisms of the formations, the recovery ratio could beenhanced.

At the end of the twentieth century, the researches were focused on the followingstudy, such as carbonate formations, clasolites, induced porosity, thenon-Newtonianism of the reservoir fluids, and the application of the phase-stateequations. At the same time, the modern experimental and measuring techniquesand the application of computing technology had also made new progress, too.

Up to now, the petrophysics science has been developed preliminarily.A comparative theory-integrated system is framed. And the experimental andmeasuring techniques are also standardized, for example, standards for conven-tional core analysis, special core analysis, EOR experiments, flow test for theformation sensibility, and physical analysis of the reservoir fluids have alreadydeveloped.

However, it should be noted that, due to the heterogeneity of the reservoir rocksand fluids and the complexity of some physical process in oil formations, lack ofmature cognition for some phenomena still exists here and there. As researchprogressing, the science of petrophysics will certainly continue to develop.

Looking forward to the twenty-first century and further, the science of petro-physics will continue to develop and step onto a new stage in both breadth anddepth. Its developments will have the following characteristics:

(1) Synthesis: By the infiltration and mutual coordination with other near disci-plines, new borderline theories may be formed.

Introduction xvii

(2) Innovation: New theories may have to be applied to solve new problems.(3) Practicality: Developing process will be simulated truly and really reservoir

conditions by using new experiment technology.

The Aim and Learning Methods for Petrophysics

Petrophysics is a core course for students majoring in petroleum engineering, or oilfield chemistry and geology. It is the aim of this course for students to have a firmgrasp of the fundamentals and professional knowledge and skills about petroleumengineering.

As a science branch, petrophysics is based upon the experiments, so both the-ories and experiments are important. Therefore, students have to pay enoughattention on the laboratory experiment and finish some exercise as homeworkinvolved in this book.

The SI unit system is adopted in this book, while some English engineering unitsare also briefly introduced. For example, when citing some particular equations likeDarcy’s law, the original Darcy units are reserved. It is necessary for the readers tomaster the unit system that are used in concerned equations.

xviii Introduction