Splitting and lumping schemes of the plus-fraction................................................. 1137 Splitting schemes......................................... 1138 Lumping schemes........................................ 1148 Problems ..................................................... 1155 References.................................................. 1159 APPENDIX.................................................. 1165 INDEX ......................................................... 1177 Reservoir Eng FOB 2001-10-29 16:18 Page i Second Edition Reservoir Eng FOB 2001-10-29 16:18 Page ii Reservoir Eng FOB 2001-10-29 16:18 Page iii Second Edition Gulf Professional Publishing Boston • London • Auckland • Johannesbourg • Melbourne • New Delhi Reservoir Eng FOB 2001-10-29 16:18 Page iv 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. 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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 v To my gorgeous wife Shanna, And my beautiful children Jennifer Justin Brittany Carsen 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