Book excerpt: The first edition of this book demystified the process of well log analysis for students, researchers and practitioners. In the two decades since, the industry has changed enormously: technical staffs are smaller, and hydrocarbons are harder to locate, quantify, and produce. New drilling techniques have engendered new measurement devices incorporated into the drilling string. Corporate restructuring and the "graying" of the workforce have caused a scarcity in technical competence involved in the search and exploitation of petroleum. The updated 2nd Edition reviews logging measurement technology developed in the last twenty years, and expands the petrophysical applications of the measurements.