The general characteristics of the producing oil and gas fields in that portion of the Rocky Mountain region, comprising Wyoming, Colorado, and northwestern New Mexico, are briefly discussed. This area is naturally divisible into three distinct provinces: an intensely folded, broken, and overthrust area in the west; a central area prominently folded into large and small anticlines and synclines; and an eastern area in which the folding is much less pronounced and the structure approaches the Mid-Continent type. Rules for determining productive versus non-productive structural features in advance of drilling are formulated. In actual practice it is not always possible to abide by all of these rules, as some of the conditions are not everywhere determinable in advance of drilling. An otherwise favorable structural feature is not lightly passed even if all the conditions prescribed in these rules are not inherent to it, because ideally favorable structural features are becoming scarce.
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.