Fundamentals of the Petrophysics of Oil and Gas Reservoirs

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Petrophysics Fundamentals of the Petrophysics

of Oil and Gas Reservoirs

Leonid Buryakovsky, Ph.D. Russian Academy of Natural Sciences, U.S.A. Section

George V. Chilingar, Ph.D. Emeritus Professor of Civil, Environmental and Petroleum

Engineering, University of Southern California, Los Angeles, CA

Herman H. Rieke, Ph.D. Professor of Petroleum Engineering, University of Louisiana

at Lafayette, Lafayette, LA

and

Sanghee Shin, Ph.D. Research Associate, Rudolf W. Gunnerman, Energy and

Environmental Laboratory, University of Southern California, Los Angeles, CA

Scrivener

WILEY

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Library of Congress Cataloging-in-Publication Data:

ISBN 978-1-118-34447-7

Printed in the United States of America

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77ns volume is dedicated to Dr. Chengyu Fu for his important contributions to World Petroleum Industry

and World Economy

Contents

Preface xi List of Contributors xvii Acknowledgement xix

1. Introduction 1 1.1 Characterization of Hydrocarbon Reservoirs 1

1.1.1 Geographical and Geological Background of the South Caspian Basin 5

1.1.2 Sedimentary Features of Productive Horizons in the South Caspian Basin 9

1.1.3 Depositional Environment of Productive Series, Azerbaijan 13

1.2 Reservoir Lithologies 16 1.2.1 Clastic Rocks 16 1.2.2 Pore Throat Distribution in Carbonate Rocks 24 1.2.3 Carbonate Rocks 35 1.2.4 Carbonate versus Sandstone Reservoirs 47 1.2.5 Volcanic/Igneous Rocks 47 1.2.6 Classification of Hydrocarbon Accumulations

Based on the Type of Traps 52

2. Characterization of Hydrocarbon Reservoirs 57 2.1 Petrophysical Parameters 57 2.2 Porosity, Void Ratio, and Density 57

2.2.1 Quantitative Evaluation of Porosity in Argillaceous Sediments 63

2.3 Permeability 66 2.3.1 Porosity /Permeability Relationship 73

2.4 Specific Surface Area 79 2.4.1 Derivation of Theoretical Equation Relating

Porosity, Permeability, and Surface Area 79

viii CONTENTS

2.4.2 Relationship Between Specific Surface Area (Area Per Unit of Pore Volume) and Permeability of Carbonate Rocks 85

2.4.3 Relationship Between Specific Surface Area and Residual Water Saturation of Carbonate Rocks 85

2.5 Interrelationship Among Prorosity, Permeability, and Specific Surface Area 86 2.5.1 Vuktyl'skiy Gas-Condensate Field, Russia 88 2.5.2 Central Asia 88 2.5.3 Kuybyshev, Along-Volga Region, Russia 89 2.5.4 Orenburg Field, Russia 90

2.6 Wettability - Capillarity 98 2.6.1 Interfacial Tension and Contact Angle 98 2.6.2 Capillary Pressure Curves 107 2.6.3 Compressibility 108

2.7 Elastic Properties 118 2.7.1 Classification of Stresses 119

2.8 Acoustic Properties 123 2.8.1 Borehole Seismic and Well Logging Methods 125 2.8.2 Practical Use of Acoustic Properties of Rocks 126

2.9 Electrical Resistivity 128 2.9.1 Spontaneous Potential 131

2.10 Radioactivity 137 2.10.1 Atomic Structure 138 2.10.2 Radioactivity Logging Applications 145

2.11 Chemistry of Waters in Shales versus those in Sandstones 149

3. Seismic Parameters 151 3.1 Introduction 151 3.2 Elastic Properties 152 3.3 Velocity and Rock Properties 154 3.4 Pore Pressure 159 3.5 Seismic Anisotropy 164

3.5.1 Effective Medium Theories 168 3.5.2 The Effect of Pore Space and Pore

Geometry on Moduli 174 3.5.3 Gassmann's Equations 176 3.5.4 Bounding Average Method 178 3.5.5 Kster and Toksz Theory 179

CONTENTS

Historical Review 183 A.l Introduction 183 A.2 Initial Phases of Development 183 A.3 Gus Archie's Equations and the Dawn

of Quantitative Petrophysics 195 A.4 Air-Filled Boreholes, Oil-Based Muds,

and Induction Logs 197 A.5 World War II Technology Legacy 198 A.6 Cased-Hole Correlation and Natural Gamma

Ray Logs 198 A.7 Seismic Velocities, Acoustic Logs, and

Jessie Wylie's Time Average Equation 199 A.8 The Manhattan Project and Nuclear Logging 201 A.9 Space Program Technology Legacy 201 A.10 SANDIA Geothermal Log Program and

Hardened Microcircuits 202 A.ll Extended-Reach Directional Drilling,

Horizontal Wells, Deep Water, Ultra Deep Wells and Measurements While Drilling 203

A.12 Data Acquisition, Data Recording, and Data Transmission Developments 203

A. 13 Log Analysis Developments 206 A.14 Formation True Resistivity, Rt, Flushed Zone

Resistivity, Rxo, Water Saturation, S , and Flushed Zone Saturation, S 210

A. 15 Rat Holes, Bed Resolution, Depth of Investigation, and Laterolog Developments 212

A.16 Air, Mist and Oil-Based Muds: Induction Log Developments 220

A.l7 Departure Curves, Tornado Charts and Inversion 225

A. 18 Acoustic Log - The Accidental Porosity Tool 228 A.19 Neutron Log - The First True Porosity Tool 233 A.20 Density Log - The Porosity Tool that

almost did not Make It 237 A.21 Pulsed Neutron Capture Logs -

The All Purpose Tool 242 A.22 Through Casing Resistivity Measurements -

Well Logging's Holy Grail 245 A.23 Nuclear Magnetic Resonance Log - Patience

and Persistence 248

x CONTENTS

A.24 S Tool Developments 252 A.25 Dielectric Tool Developments 253 A.26 Dipmeters to Borehole Imaging 256 A.27 Wireline Formation Testers 264 A.28 Shaly Sands 266 A.29 Golden Era and Black Period of Petrophysics 267 A.30 The Future 269 Bibliography 271 Web Pages 278

B. Mechanics of Fluid Flow 279 . Fundamental Equation of Fluid Statics 279 B.2 Buoyancy 280 B.3 General Energy Equation 281 B.4 Derivation of Formula for Flow

Through Orifice Meter 282 B.5 Compressible Flow Formula 284 B.6 Farshad's Surface Roughness Values and

Relative-Roughness Equations 290 B.7 Flow Through Fractures 293 B.8 Permeability of a Fracture-Matrix System 294 B.9 Fluid Flow in Deformable Rock Fractures 294 B.10 Electrokinetic Flow 299 References 301

C. Glossary 303 References 347

Bibliography Subject Index

349 369

Preface

Petrophysics (rock physics) is a branch of applied geology relating to the study of reservoir and caprock properties and their interactions with fluids (gases, hydrocarbons, and aqueous solutions) based on fundamental methods of physics, chemistry, and mathematics. The geologic material forming a reservoir for the accumulation of fluids (oil, gas and water) in the subsurface must contain a three-dimensional network of interconnected voids (pores, vugs and/or fractures) to store the formation fluids and allow their movement within the reservoir during hydrocarbon recovery. Petrophysical applications are widely used in petroleum geology, economic geol-ogy, seismic interpretations, hydrocarbon reserve estimation, reser-voir description and simulation, field development planning, and reservoir production management.

The goal of petroleum geology is to perform the exploration and to provide, if a discovery is made of a commercial oil and gas accu-mulation, a geological/geophysical descr