Fracturing in Spraberry Reservoir, West Texas

TLDR: The Spraberry formation of West Texas is developed in the lower Leonard of middle Permian, restricted in most part to the Midland basin this article, and the main producing structure is a fractured permeability trap on a homoclinal fold.

Abstract: The Spraberry formation of West Texas is developed in the lower Leonard of middle Permian, restricted in most part to the Midland basin. The main producing structure is a fractured permeability trap on a homoclinal fold. This homogeneous mass is undifferentiated except as to alternate layers of sands, siltstones, shales, and limestones, deposited in a deep basin under stagnant conditions with hydrocarbons formed throughout the 1,000 feet of sedimentary rocks. Fractures were created by tensional forces after induration, probably during post-Leonard time. With storage of the oil reservoir in the sandstone matrix, the fractures serve as "feeder lines" to conduct the oil to the bore hole. Without these fractures commercial production would be from a seemingly "too-tight" reservoir rock. The producing area of the Spraberry formation is a "fairway" 150 miles long and 50 miles wide at an average depth of 6,800 feet. The main area, however, is 50 miles long, with width ranging from a few miles to 48 miles, thus creating a triangle of 488,000 proved and semi-proved productive acres.