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INTRODUCTION TO CPH 3.10
This book is about the art and science of petrophysics as practiced today, using quantitative methods, computers, and high quality graphic displays. It wasn't always like this - petrophysics is more than 80 years old! In the earliest days, we used visual analysis methods exclusively, and called it log interpretation. Later we used charts and nomographs, pencil and paper, tables of logarithms, or slide rules to attempt quantitative analysis, guided by our visual interpretation. Still later, scientific calculators replaced the charts and slide rules. Strangely enough, the actual quantitative methods didn't change much; they just got a little more efficient. Mainframe and time-share computers overlapped the chart and calculator era, but were horribly slow and cumbersome.

The desktop workstation for quantitative petrophysical analysis, developed by the author, arrived in 1976. It was later supplanted by the ubiquitous Personal Computer, commonly known as the IBM-PC, although IBM had little to do with its success. Today, every petrophysicist has a PC, connected to huge databases on servers, with access to the Internet, email, and sophisticated analytical software.

LOG/MATE, the first desktop computer aided log analysis system, was developed by the
author in 1976, 5 years before the IBM-PC debut.

Much of the training material for the study of petrophysics has its origins in the chartbook era, revised over time with new editions, with the same chapter organization as the first edition. The mathematical notation style dates back 2500 years to Pythagaras (500 BC), Euclid (300 BCE) and updated by Descartes (1650 CE). The symbols used were often Greek letters and there was little consistency among authors. Computer programs don't understand Greek nor can they handle conventional math notation, as found in most textbooks. Such texts leave the user to decode the ancient symbols, not unlike deciphering the hieroglyphics on ancient tombs.

In 1984, I decided to change this. I wrote "The Log Analysis Handbook", later published by Pennwell Publishing in 1986, with "computer-ready" math and a chapter order that followed the workflow rather than  the conventional logging-tool sequence of previous textbooks. There were no Greek symbols, no integral signs, no divisor bars. The publisher resisted but it finally saw print. It was eagerly accepted by working petrophysicists and chastised by the academics. If you insist on the academic snobbery and arcane rules of equation typography, you are welcome to it, but you'll get a lot more work done by converting to modern "computer-ready" math.

For an example of how difficult it is to use Greek symbols and conventional math notation in text and equations, see the Section on Maxwell's Equations. All equations were set up in a specialized software package, converted to image format, then manually inserted in the correct location in the text. Surely it is time to give up this antiquated system for a more modern approach. It is not difficult to use the word "Curl" to mean , dB/dt for , or "Sum" if you mean .

Ten years later, I migrated the textbook to the Internet (www.spec2000.net) and added the rest of the chapters that had been scheduled to become Volume Two. The result became "Crain's Petrophysical Handbook", also available on CD-ROM for portability. Chapters could be updated and expanded at will, instead of waiting 10 years for a new paper edition. The site is free, with a hint that the shareware fee would be appreciated. The site is also free of advertising, pop-ups, spam, and sponsors. Hundreds of students and practitioners worldwide use the site daily.

The current version offers a complete reorganization to make searches and maintenance easier. Although no one has complained about it, some chapters were pretty large and you had to scroll through a long page to find what you wanted. So this web version has peeled the chapters into smaller chunks that load faster and are easier to browse. Some obsolete material has been dropped and the non-quantitative (theory and practice) sections have been further reorganized to combine similar topics into a central location. More case histories have been added to help the "interpretation and understanding" part of the petrophysicists' function.

As usual, if you find errors or omissions, please email me. Contributions from other petrophysicists are welcome - think of this site as your Petrophysics Wikipedia. I hope the changes are helpful.
 

DEDICATION
This book is dedicated to Mr. H. A. (Al) Gorrell who was instrumental in guiding my early attempts to find truth in log data. He was successful in instilling a sense of excitement and wonder about all things scientific, especially the infant science of quantitative log analysis. He gave unstintingly of his time, experience, and knowledge to all who asked. He traveled the world over on oil, gas, water, and mineral exploration projects, as well as social and humanitarian endeavours.

Al Gorrel was killed in a terrorist attack on a hotel in Manila, Philippines, on 12 February 1985 while on a mission for the United Nations. He will be missed by his friends and family, and his business associates. The world will be less rich because of his untimely passage.

ACKNOWLEDGEMENTS
Many people were acknowledged in the 1986 textbook and in the Foreword of the 1st website version. Even more deserve credit for their assistance during my long career - too many to list without the possibility of leaving out one or two by mistake. You know who you are. Thank you.
 

ABOUT THE AUTHOR
E. R. (Ross) Crain, P.Eng. is a Consulting Petrophysicist and a Professional Engineer with over 45 years of experience in reservoir description, petrophysical analysis, and management. He has been a specialist in the integration of well log analysis and petrophysics with geophysical, geological, engineering, and simulation phases of oil and gas exploration and exploitation, with widespread Canadian and Overseas experience.

His textbook, "Crain's Petrophysical Handbook on CD-ROM" is widely used as a reference to practical log analysis. Mr. Crain is an Honourary Member and Past President of the Canadian Well Logging Society (CWLS), a Member of Society of Petrophysicists and Well Log Analysts (SPWLA), and a Registered Professional Engineer with Alberta Professional Engineers, Geologists and Geophysicists.