The Wind River Basin ranks third in cumulative oil production in Wyoming, and is also third in size. The stratigraphy and structure are fairly well known although much remains to be learned about the deeply filled Tertiary portions which account for 75 per cent of the area and over half the volume of the basin. Nineteen oil fields, six of which produce gas, plus three additional gas fields have been discovered along the well-exposed west and south margins of the basin. These fields have produced over 86 million barrels of oil plus about 100 billion cubic feet of gas. Oil reserves are known to approximate 163 million barrels. With 75 per cent of the basin virtually unexplored it is reasonable to assume that many good oil fields remain to be found.
The great volume of Tertiary rocks, almost unexplored, contains oil-saturated sands on many outcrops and in several wells that have penetrated the section. Gas has also been found, but not produced, in some of these sands. Major unconformities exist within the Tertiary and below it, and may have trapped oil and gas in commercial quantities. These rocks offer great future potential in both stratigraphic and structural traps. Beneath the Tertiary several thousand feet of Upper Cretaceous rocks, mainly Mesaverde, upper Cody, and Frontier, have barely been explored. Thick porous sands within these formations lens out in short distances. Some of the Paleozoic formations also offer a challenge, such as the Madison limestone, untested on many known structures. One reward for deeper drilling to evaluate older rocks is the expected increase of gravity. Most of the younger rocks carry high-gravity oils regardless of depth.
Entrapment of oil in the basin under hydrodynamic conditions may become an important part of future exploration. Also of future importance is the conservation of reservoir energies and secondary recovery.
Figures & Tables
The history of oil exploration in a large basin is very much like the history of research in most fields of investigation. In the history of research into the subject of oil occurrence, however, the rate of increase of knowledge has fluctuated greatly. Sourced from the 1955 AAPG Annual Meeting, this publication contains many of the papers presented at that meeting, which discuss the habitat of most of the oil found in the world prior to 1955.