Geological Characterization and Reserve Growth Potential of Spraberry Reservoirs in the Midland Basin, West Texas

Major reservoirs in the Spraberry-Dean play of the Midland Basin, West Texas, initially contained approximately 10.6 billion barrels of oil at discovery. However, current projections indicate that only around 7 percent of this vast resource will be recovered. Despite the significant remaining reserves, a large amount of mobile oil remains trapped in place due to reservoir heterogeneities at abandonment. Consequently, these reservoirs present excellent opportunities for reserve growth through extended conventional recovery methods.

Given the substantial volume of movable, nonresidual oil estimated to be present (more than 4 billion barrels), the Spraberry reservoirs were selected for detailed reinvestigation aimed at extended conventional recovery through strategic infield exploration. It was recognized that these reservoirs exhibit significant heterogeneity. Therefore, the primary objective of the project was to determine how an understanding of the genetic stratigraphy of these reservoirs could be leveraged to maximize recovery.

Traditionally, Spraberry reservoirs have been perceived as homogeneous "layer cake" oil pools, with development strategies focusing on natural fractures while overlooking the depositional sedimentary architecture of the productive sandstones and siltstones. This reinvestigation seeks to rectify this oversight and explore new approaches to optimize recovery from these complex reservoirs.