Circular 130—Hydrocarbon potential of pre-Pennsylvanian rocks in Roosevelt County, New Mexico

By W. D. Pitt, 1973, 7 pp., 3 tables, 8 sheets.

Briefly describes geologic structures, Precambrian terranes, stratigraphy of sedimentary units, and possible areas of hydrocarbon accumulation. The hydrocarbon potential of pre-Pennsylvanian rocks in Roosevelt County was appraised from data available in published reports, scout tickets, lithology logs, and other well data at the log libraries in Roswell and Socorro, New Mexico, and Midland, Texas. Elevations from lithology logs were used when differing from scout tickets or other sources. Thickness and data other than lithology logs were assumed to be sufficiently accurate if they fitted the control obtained by contouring. The author hopes this summary study will stimulate interest in prospecting for pre-Pennsylvanian hydrocarbons in southern Roosevelt County.

Roosevelt County is located on the northwestern shelf of the Delaware Basin of southeastern New Mexico. Most of the drilling and oil production is found in southern Roosevelt County, part of a 100-mi-long production trend, extending from Hockley County in west Texas, across Roosevelt County to eastern Chaves County. Splitting this 20-mi wide production trend is a major fault, herein called the Roosevelt County fault having a maximum throw of 4,500 ft, and upthrown on the north. The Roosevelt County fault extends northwestward from a point near the southeast corner of the county. It cuts the Precambrian and all formations through the Permian; movement may be occurring imminently today. The straightness of the fault trend on maps suggest that its northern end might involve strike-slip motion. Complex subcrop patterns of Paleozoic rocks strongly suggest that there were two or more intervals of fault movement. The fault was an active controller of deposition, erosion, oil and gas migration; it also probably localized southeastward movement of ground water.