“Lateral migration” is defined as movement of oil (or other fluids), essentially parallel with the bedding, and “vertical migration” as movement of oil essentially across the bedding, in a series of strata. These two methods of migration are discussed as they are related (1) to lenses, structural terraces, and anticlinal noses; (2) to domes and closed anticlines; and (3) to fault structures. Strong arguments are presented for both phenomena, but the preponderance of evidence is in favor of lateral migration; for even if vertical migration be granted in certain cases, the oil must almost certainly have reached the channel of “vertical movement” by a process of lateral migration through porous media at unknown depths. Vertical migration has undoubtedly assisted or even effected the accumulation of oil in some reservoirs (and perhaps the depletion of oil in others), but all pools have been served, directly or indirectly, by lateral migration.
Figures & Tables
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.