The petroliferous basins in California are intermontane valleys whose formation antedates the sediments causing the occurrence of oil. For this reason the sections vary greatly in basins only a few miles apart. In order of importance the types of traps are: (1) closed anticlines; (2) homoclines on which the producing sand has been overlapped by younger formations; (3) homoclines truncated by a fault or faults; (4) brea traps; (5) plunging anticlines; and (6) lenses. California fields are characterized by their small areal extent, remarkably thick and rich source rocks, and thick sand reservoirs.
Figures & Tables
Problems of Petroleum Geology
The AAPG volumes of Structure of Typical American Oil Fields preceed this book, which was written as a sequel to those, and at first conceived as a third volume of the earlier work. This book is designed to review, modify and, if possible, clarify ideas with regard to the fundamental concepts of oil geology, utilizing, for this purpose, the material presented in the two earlier data-based volumes. To conform to the original standard set for it, this book has been kept relatively free from factual data and has been compiled rather as a summation, based upon the best available evidence, of present knowledge of the science. This volume does not include a discussion of the technique of field or laboratory geology, but does include papers divided into 7 parts: History; Origin and evolution of petroleum; Migration and accumulation of petroleum; Relations of petroleum accumulation to structure; Porosity, permeability, compaction; Oil-field waters; and Subsurface temperature gradients.