Preface
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Published:2021
"Preface", Production Logging: Theoretical and Interpretive Elements, A. Daniel Hill
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In May 1990, the Society of Petroleum Engineers published my first book, SPE Monograph, Vol. 14: Production Logging—Theoretical and Interpretive Elements. Now, 31 years later, this second edition is intended to bring the monograph up to date on the subject of production logging. The changes in technology over this long period are so substantial and dramatic that approximately half of this book is new material not at all covered in the first edition.
In 1990, there were only four primary production logging tools: temperature, spinner flowmeter, fluid density, and fluid capacitance tools. These had been developed for logging vertical wells, and all interpretation methods tacitly assumed the flow would be like that observed in perfectly vertical pipes. At that time, the number of horizontal wells being drilled was in the hundreds annually, primarily being drilled in the Austin chalk trend in Texas. Of course, now a large majority of all oil and gas wells being drilled are nominally horizontal wells. The advent of horizontal wells exposed the inadequacy of traditional production logging measurements in wells in measuring multiphase flows in which significant phase separation occurs. Tools that deploy arrays of sensors to sample multiple locations in the pipe cross section are now routinely run in these challenging logging environments. This new edition contains a chapter completely devoted to production logging in nominally horizontal wells.
Of course, the other technological development that has enabled dramatically more capable production logging instruments is the evolution of electronics and computer technology. Today’s data-acquisition capabilities and the modern display of output of all production logging tools was not possible 30 years ago.
Besides the production logging tools and methodologies aimed at measuring the flow distribution in wells, I also include in this monograph logs run to directly evaluate the well completion—cement-quality logs, noise logs, and downhole video. These logs, like the more traditional production logging tools, have evolved greatly since the first edition of this book was published.
This book is intended to help the engineer or geoscientist select the best log or combination of logs to satisfy the desired well or reservoir diagnosis objectives and to be able to interpret these logs. I have also endeavored to make clear the uncertainties that exist in some of these measurements. The production logging practitioner should always understand that running a production log in a well does nothing in itself to enhance well or reservoir performance. The production log only provides information about the well and/or the reservoir, so the acquired information should have value in guiding future activities with that well or similar wells.
Dan Hill
Regents Professor and Noble Chair
Harold Vance Department of Petroleum Engineering
Texas A&M University
College Station, Texas