Well Logging for Earth Scientists, Notas de estudo de Engenharia de Petróleo

Baixe Well Logging for Earth Scientists e outras Notas de estudo em PDF para Engenharia de Petróleo, somente na Docsity!

Well Logging for Earth Scientists

Published by Springer,

www.springer.com

Printed on acid-free paper

ISBN 978-1-4020-4602-5 (e-book)

This is a second revised and enlarged edition of the first edition published by Elsevier NY, 1987.

A Manual of Solutions for the end-of-chapter problems can be found at the book’s homepage

of Schlumberger.

P.O. Box 17, 3300 AA Dordrecht, The Netherlands.

ISBN 978-1-4020-3738-2 (HB)

First published 2007 Reprinted with corrections 2008

Cover illustration: First recorded electric log, Pechelbronn field, Sept. 5, 1927, reproduced courtesy

No part of this work may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recordingor otherwise, without wri tten permission from the Publisher, with the exception of any material supplied specifically for the purpose of being entered and executed on a computer system,for exclusive use by the purchaser of the work.

at www.springer.com

© 2007, 2008 Springer Science+Business Media B.V.

Library of Congress Control Number: 2008921855

Dedication

To a place where much of this was invented, elaborated, or pondered and where a friendship developed that even the writing of a book could not spoil.

Preface

Twenty years ago, the objectives of the first edition of this book were numerous and ambitious: to demystify the process of well log analysis; to examine the physical basis of the multitude of geophysical measurements known collectively as well logging; to clearly lay out the assumptions and approximations routinely used to extract petro- physical information from these geophysical measurements; to expose the vast range of well logging instrumentation and techniques to the larger geophysical community. Finally, there was the important goal of providing a textbook for university and gradu- ate students in Geophysics and Petroleum Engineering, where none suitable had been available before. What’s different twenty years later? First of all, Well Logging for Earth Scientists is long out of print. The petroleum industry, the major consumer of the geophysical information known as well logging, has changed enormously: technical staffs have been slashed, and hydrocarbons have become increasingly harder to locate, quantify, and produce. In addition, new techniques of drilling high deviation or horizontal wells have engendered a whole new family of measurement devices incorporated into the drilling string that may be used routinely or in situations where access by traditional “wireline” instruments is difficult or impossible. Petroleum deposits are becoming scarce and demand is steadily increasing. Massive corporate restructuring and the “graying” of the workforce have caused the technical competence involved in the search and exploitation of petroleum to become scarce. Although we are only attempting to address this latter scarcity with our textbook, the objectives are still ambitious. In this thorough updating of the text, we have attempted to include all of the new logging measurement technology developed in the last twenty years and to expand the petrophysical applications of the measurements. As in the first edition, we are primarily concerned with logging techniques that lead to formation evaluation, but mention a few other applications where appropriate. We also trace the historical development of the technology as a means of better understanding it. Throughout, large sections of the text have been set in italics, which may be skipped by the casual reader. These detailed sections may be of more interest to researchers. The goals of providing a graduate level textbook as well as a useful handbook for any practicing earth scientist (geophysicist, geologist, petroleum engineer, petrophysicist) remain.

Darwin Ellis Julian Singer

xvii

Acknowledgments

The authors would like to acknowledge the special help received from a number of individuals, without which this tome could not have been achieved. Therefore we owe our thanks to: Chuck Fulton, Charlie Flaum, Richard Woodhouse, and Austin Boyd for log ex- amples; Tom Plona, Lalitha Venkataramanan, Drew Pomerantz, Tancredi Botto, Alan Sib- bit, Jacques Tabanou, Jack LaVigne, Barbara Anderson, Nikita Seleznev, and Nick Bennett for critically reviewing early versions of various chapters; John Hsu, David Johnson, Tarek Habashy, Chris Straley, and Pabitra Sen for helpful discussions; Charlie Case, Joe Chiaramonte, Laurent Moss´e and especially to Mehdi Hizem for substantial contributions to the form and content of several chapters; George Stewart for the drafting of the figures; and Frank Shray, Tarek Habashy, Mark Andersen, Martin Issacs and Vicki King for help in innumerable ways with the multitude of figures. For the deficiencies, errors, and omissions, both in the text and in these acknowl- edgements, the blame rests with us.

Darwin Ellis & Julian Singer

The authors also are grateful for the use of a number of figures, in this new edition, drawn from Schlumberger’s Oilfield Review. The following figures are copyright Schlumberger Ltd. Used with permission.

Fig. 6.6 Fig. 16. Fig. 12.20 Fig. 16. Fig. 12.21 Fig. 16. Fig. 15.9 Fig. 16. Fig. 15.10 Fig. 16. Fig. 15.12 Fig. 16. Fig. 15.13 Fig 18. Fig. 15.14 Fig. 18. Fig. 15.15 Fig. 18. Fig. 15.17 Fig.19. Fig 15.18 Fig. 19. Fig. 15.19 Fig. 19. Fig. 16.9 Fig. 19. Fig. 16.22 Fig. 19.

4 Dec. 2006

xix

An Overview

of Well Logging

1.1 INTRODUCTION

The French translation of the term well logging is carottage electrique,´ ∗^ literally “electrical coring,” a fairly exact description of this geophysical prospecting technique when it was invented in 1927 [1, 2]. A less literal translation might be “a record of characteristics of rock formations traversed by a measurement device in the well bore.” However, well logging means different things to different people. For a geologist, it is primarily a mapping technique for exploring the subsurface. For a petrophysicist, it is a means to evaluate the hydrocarbon production potential of a reservoir. For a geophysicist, it is a source of complementary data for surface seismic analysis. For a reservoir engineer, it may simply supply values for use in a simulator. The initial uses of well logging were for correlating similar patterns of electrical conductivity from one well to another, sometimes over large distances. As the mea- suring techniques improved and multiplied, applications began to be directed to the quantitative evaluation of hydrocarbon-bearing formations. Much of the following text is directed toward the understanding of the measurement devices and interpreta- tion techniques developed for this type of formation evaluation. Although well logging grew from the specific need of the petroleum industry to evaluate hydrocarbon accumulations, it is relevant to a number of other areas of interest to earth scientists. New measurements useful for subsurface mapping have evolved which have applications for structural mapping, reservoir description, and

∗The French definition is mentioned for two reasons: as an acknowledgment of the national origin of well logging and as one of the rare cases in which Anglo-Saxon compactness is outdone by the French.

1

2 1 AN OVERVIEW OF WELL LOGGING

sedimentological identification. The measurements can be used to identify fractures or provide the formation mineralogy. A detailed analysis of the measurement principles precedes the discussion of these applications. In this process, well logging is seen to require the synthesis of a number of diverse physical sciences: physics, chemistry, electrochemistry, geochemistry, acoustics, and geology. The goal of this first chapter is to discuss well logging in terms of its traditional application to formation hydrocarbon evaluation and to describe the wide variety of physical measurements which address the relevant petrophysical parameters. We begin with a description of the logging process, to provide an idea of the experimental environment in which the measurements must be made.

1.2 WHAT IS LOGGING?

The birth of logging can be dated to the first recorded event [1] at Pechelbronn on September 5, 1927 where H. Doll and the Schlumberger brothers (and a few others) made a semicontinuous resistivity measurement in that tired old field in Alsace. The operation was performed with a rudimentary device (a sonde) consisting of a bakelite cylinder with a couple of metallic electrodes on its exterior. Connecting the device to the surface was a cable/wire, thus providing us with the term wireline logging. Wireline refers to the armored cable by which the measuring devices are lowered and retrieved from the well and, by a number of shielded insulated wires in the interior of the cable, provide for the electrical power of the device and a means for the transmission of data to the surface. More recently, the devices have been encapsulated in a drill collar, and the transmission effected through the mud column. This procedure is known as logging while drilling (LWD).

1.2.1 What is Wireline Logging?

The process of logging involves a number of elements, which are schematically illus- trated in Fig. 1.1. Our primary interest is the measurement device, or sonde. Currently, over fifty different types of these logging tools exist in order to meet various informa- tion needs and functions. Some of them are passive measurement devices; others exert some influence on the formation being traversed. Their measurements are transmitted to the surface by means of the wire line. Much of what follows in succeeding chapters is devoted to the basic principles exploited by the measurement sondes, without much regard to details of the actual devices. It is worthwhile to mention a few general points regarding the construction of the measurement sondes. Superficially, they all resemble one another. They are generally cylindrical devices with an outside diameter on the order of 4 in. or less; this is to accommodate operation in boreholes as small as 6 in. in diameter. Their length varies depending on the sensor array used and the complexity of associated electronics required. It is possible to connect a number of devices concurrently, forming tool strings as long as 100 ft.