Splitting and lumping schemes of the plus-fraction 1137 Splitting schemes 1138 Lumping schemes 1148 Problems 1155 References 1159 APPENDIX 1165 INDEX 1177 Second Edition Reservoir Eng FOB 2001-10-29 16:18 Page i Reservoir Eng FOB 2001-10-29 16:18 Page ii Gulf Professional Publishing Boston • London • Auckland • Johannesbourg • Melbourne • New Delhi Second Edition Reservoir Eng FOB 2001-10-29 16:18 Page iii Gulf Professional Publishing is an imprint of Butterworth-Heinemann. Copyright © 2001 by Butterworth-Heinemann A member of the Reed Elsevier group Previously copyrighted © 2000 by Gulf Publishing Company, Houston, Texas All rights reserved. No part of this publication may be reproduced, stored in a retrival system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher. Recognizing the importance of preserving what has been written, Butterworth-Heinemann prints its books on acid-free paper whenever possible. Library of Congress Cataloging-in-Publication Data Ahmed, Tared H., 1946- Reservoir engineering handbook / Tarek Ahmed. p.cm. Includes bibliographical references and index. ISBN 0-88415-770-9 (alk. paper) 1. Oil reservoir engineering. 2. Oil fields. 3. Gas reservoirs. I. Title. TN871 .A337 2000 622’.3382 dc21 99-005377 British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library. The publisher offers special discounts on bulk orders of this book. For information, please contact: Manager of Special Sales Butterworth-Heinemann 225 Wildwood Avenue Woburn, MA 01801–2041 Tel: 781-904-2500 Fax: 781-904-2620 For information on all Butterworth-Heinemann publications available, contact our World Wide Web home page at: http://www.bh.com 10 9 8 7 6 5 4 3 2 1 Printed in the United States Reservoir Eng FOB 2001-10-29 16:18 Page iv To my gorgeous wife Shanna, And my beautiful children Jennifer Justin Brittany Carsen Reservoir Eng FOB 2001-10-29 16:18 Page v ACKNOWLEDGMENTS xiii PREFACE TO THE SECOND EDITION xiv PREFACE TO THE FIRST EDITION xv 1 FUNDAMENTALS OF RESERVOIR FLUID BEHAVIOR 1 Classification of reservoirs and reservoir fluids 1 Pressure-temperature diagram 2 Oil reservoirs 4 Gas reservoirs 10 Undefined petroleum fractions 24 Problems 27 References 28 2 RESERVOIR-FLUID PROPERTIES 29 Properties of natural gases 29 Behavior of ideal gases 30 Behavior of real gases 36 Effect of nonhydrocarbon components of the Z-factor 44 Nonhydrocarbon adjustment methods 45 The Wichert-Aziz correction method 45 Correction for high-molecular weight gases 49 Direct calculation of compressibility factors 54 Compressibility of natural gases 59 Gas formation volume factor 65 Gas viscosity 67 Methods of calculating the viscosity of natural gases 68 Properties of crude oil systems 74 Crude oil gravity 75 Specific gravity of the solution gas 76 Gas solubility 77 Bubble-point pressure 86 Oil formation volume factor 92 Isothermal compressibility coefficient of crude oil 98 Oil formation volume factor for undersaturated oils 103 Crude oil density 106 Crude oil viscosity 108 Methods of calculating viscosity of the dead oil 109 Methods of calculating the saturated oil viscosity 111 Methods of calculating the viscosity of the undersaturated oil 112 Surface/interfacial tension 115 Properties of reservoir water 118 Water formation volume factor 118 Water viscosity 119 Gas solubility in water 119 Water isothermal compressibility 120 Problems 120 References 126 3 LABORATORY ANALYSIS OF RESERVOIR FLUIDS 130 Composition of the resevoir fluid 131 Constant-composition expansion tests 131 Differential liberation (vaporization) test 143 Separator tests 146 Adjustment of differential liberation data to separator conditions 151 Extrapolation of resevoir fluid data 158 Correcting constant-composition expansion data 158 Correcting differential liberation data 160 Correcting oil viscosity data 161 Correcting the separator tests data 163 Laboratory analysis of gas condensate systems 165 Recombination of separator samples 165 Constant-composition test 168 Constant-volume depletion (CVD) test 170 Problems 178 References 182 4 FUNDAMENTALS OF ROCK PROPERTIES 183 Porosity 184 Absolute porosity 184 Effective porosity 185 Saturation 189 Average saturation 191 Wettability 193 Surface and interfacial tension 194 Capillary pressure 197 Capillary pressure of reservoir rocks 200 Capillary hysteresis 203 Initial saturation distribution in a reservoir 206 Leverett J-function 218 Converting laboratory capillary pressure data 221 Permeability 221 The Klinkenberg effect 228 Averaging absolute permeabilities 235 Weighted-average permeability 236 Harmonic-average permeability 239 Geometric-average permeability 243 Absolute permeability correlations 244 Rock compressibility 248 Net pay thickness 254 Resevoir heterogeneity 255 Vertical Heterogeneity 256 Areal heterogeneity 268 Problems 273 References 278 5 RELATIVE PERMEABILITY CONCEPTS 280 Two-phase relative permeability 281 Drainage process 285 Imbibition process 286 Two-phase relatie permeability correlations 286 1 Wyllie and Gardner correlation 288 2 Torcaso and Wyllie correlation 289 3 Pirson’s correlation 289 [...]... Oil reservoirs—If the reservoir temperature T is less than the critical temperature Tc of the reservoir fluid, the reservoir is classified as an oil reservoir • Gas reservoirs—If the reservoir temperature is greater than the critical temperature of the hydrocarbon fluid, the reservoir is considered a gas reservoir Oil Reservoirs Depending upon initial reservoir pressure pi, oil reservoirs can be subclassified... general, reservoirs are conveniently classified on the basis of the location of the point representing the initial reservoir pressure pi and temperature T with respect to the pressure-temperature diagram of the reservoir fluid Accordingly, reservoirs can be classified into basically two types These are: Reservoir Eng Hndbk Ch 01 2001-10-24 09:04 Page 4 4 Reservoir Engineering Handbook • Oil reservoirs—If... principles of reservoir fluid phase behavior and illustrate the use of phase diagrams in classifying types of reservoirs and the native hydrocarbon systems CLASSIFICATION OF RESERVOIRS AND RESERVOIR FLUIDS Petroleum reservoirs are broadly classified as oil or gas reservoirs These broad classifications are further subdivided depending on: 1 Reservoir Eng Hndbk Ch 01 2001-10-24 09:04 Page 2 2 Reservoir Engineering. .. Undersaturated oil reservoir If the initial reservoir pressure pi (as represented by point 1 on Figure 1-1), is greater than the bubble-point pressure pb of the reservoir fluid, the reservoir is labeled an undersaturated oil reservoir 2 Saturated oil reservoir When the initial reservoir pressure is equal to the bubble-point pressure of the reservoir fluid, as shown on Figure 1-1 by point 2, the reservoir is... the near-critical crude oil Reservoir Eng Hndbk Ch 01 2001-10-24 09:04 Page 10 10 Reservoir Engineering Handbook Figure 1-10 compares the characteristic shape of the liquid-shrinkage curve for each crude oil type Gas Reservoirs In general, if the reservoir temperature is above the critical temperature of the hydrocarbon system, the reservoir is classified as a natural gas reservoir On the basis of their... is called a saturated oil reservoir 3 Gas-cap reservoir If the initial reservoir pressure is below the bubblepoint pressure of the reservoir fluid, as indicated by point 3 on Figure 1-1, the reservoir is termed a gas-cap or two-phase reservoir, in which the gas or vapor phase is underlain by an oil phase The appropriate quality line gives the ratio of the gas-cap volume to reservoir oil volume Crude... equation of state xiv Reservoir Eng FOB 2001-10-29 16:18 Page xv PREFACE TO THE FIRST EDITION This book explains the fundamentals of reservoir engineering and their practical application in conducting a comprehensive field study Chapter 1 reviews fundamentals of reservoir fluid behavior with an emphasis on the classification of reservoir and reservoir fluids Chapter 2 documents reservoir- fluid properties,... reservoir conditions, natural gases can be classified into four categories: • Retrograde gas-condensate • Near-critical gas-condensate • Wet gas • Dry gas Retrograde gas-condensate reservoir If the reservoir temperature T lies between the critical temperature Tc and cricondentherm Tct of the reservoir fluid, the reservoir is classified as a retrograde gas-condensate reservoir This category of gas reservoir. .. saturated-oil reservoirs Case 3 Gas-cap-drive reservoirs Case 4 Water-drive reservoirs 751 753 The pot-aquifer model in the MBE The steady-state model in the MBE The unsteady-state model in the MBE 755 755 760 762 766 768 769 770 Tracy’s form of the material balance equation 774 Problems 778 References 781 12 PREDICTING OIL RESERVOIR PERFORMANCE 782 Phase 1 Reservoir. .. illustrating the practical applications of the material balance equation in oil and gas reservoirs xv Reservoir Eng FOB 2001-10-29 16:18 Page xvi xvi Reservoir Eng Hndbk Ch 01 2001-10-24 09:04 Page 1 C H A P T E R 1 FUNDAMENTALS OF RESERVOIR FLUID BEHAVIOR Naturally occurring hydrocarbon systems found in petroleum reservoirs are mixtures of organic compounds which exhibit multiphase behavior over wide . 1946- Reservoir engineering handbook / Tarek Ahmed. p.cm. Includes bibliographical references and index. ISBN 0-88415-770-9 (alk. paper) 1. Oil reservoir engineering. 2. Oil fields. 3. Gas reservoirs EDITION xv 1 FUNDAMENTALS OF RESERVOIR FLUID BEHAVIOR 1 Classification of reservoirs and reservoir fluids 1 Pressure-temperature diagram 2 Oil reservoirs 4 Gas reservoirs 10 Undefined petroleum. waterflooding 858 Reservoir geometry 859 Fluid properties 859 Reservoir depth 859 Lithology and rock properties 860 Fluid saturations 861 Reservoir uniformity and pay continuity 861 Primary reservoir