Wolfberry Play Overview

The Wolfberry play, originally named because of the commingling of production from the Wolfcamp and Spraberry Formations, is a major low-permeability oil play in the Permian Basin. Located mostly in western Texas, the Permian Basin is one of the most prolific oil-producing basins in North America. The largest accumulation of oil and gas reserves in the Permian Basin is found in the Spraberry trend, which cover large parts of six counties and has a total area of approximately 2,500 square miles. The Spraberry trend is ranked third in the United States by total proved reserves, and seventh in total production.

Completions in the Wolfberry are generally anticipated from a 2,500 to 3,000 foot gross interval, and located between 7,000 and 10,500 feet, drilling depth. Completions begin at the bottommost formation, and can include up to 8 to 12 fracture stimulations.

The term "Wolfberry trend" is used to characterize the completion method of perforating, fracture stimulating and commingling for production. The various Spraberry and Wolfcamp intervals, and more recently, deeper intervals, including the Strawn and Mississippian

Geology

The Wolfberry Play is a resource play characterized by heterogeneous lithologies, low permeabilities, and reservoirs and source rocks in close proximity. The paleogeographic setting was a deep ocean basin surrounded by shallow carbonate platforms. Basin-floor stratigraphy comprises alternating layers of calcareous and siliciclastic lithofacies with widespread continuity.

In siliciclastic intervals, such as the Spraberry and Dean, turbidite sandstones and laminated siltstones are interbedded with organic-rich mudrocks. In calcareous intervals, such as the lower Leonard and the Wolfcamp, carbonate debris flows are interbedded with carbonate turbidites and organic-rich calcareous mudrocks (Figs. 3c, d). Although coarser-grained turbidites and debris flows are the obvious reservoirs, finer-grained calcareous facies are also productive after fracture stimulation.

Source : University of Texas