Abstract

The Barnett Shale in southeastern New Mexico and West Texas was deposited during Mississippian Osagean Chesterian time (Hamitlon and Asquith, 2000; Broadhead, 2006; Osterlund, 2012) in the deeper-water area of the Tobosa Basin. Siliciclastic muds were the predominant sediment type deposited in the basin, except for several sections of mixed silt- to very fine sand–sized siliciclastic–carbonate units that are composed of relatively thin 0.5 mm to 1 m hybrid/cogenetic event beds that amalgamate to form a deep-water submarine fan system in the Mis-sissippian Tobosa Basin. Based on their wireline-log expression, these units are referred to as the Two Finger Sand. Specific objectives include: (1) Construct the regional paleogeographic setting and associated stratigraphic architecture of the upper Barnett interval. (2) Describe the reservoir characteristics of the Two Finger Sand bodies.

The Two Finger Sand has a long history of oil production (Candelaria, 1990; Osterlund, 2012; Entzminger, 2015). The Moonlight Field has produced 1,300,676 barrels (bbl) of oil, 3.32 billion cubic feet (Bcf) of gas. Only 1 yr after discovery, the Moonlight Field had already produced 729,000 bbl of oil (Pausé et al., 1985). The produced oil is high-API-gravity oil (60 to 70°). All the wells in the Moonlight Field are overpressured, with high-pressure gradients of 0.7 psi/ft and initial reservoir pressures of 7,500 to 10,000 psi (Candelaria, 1990). The Two Finger Sand units form oil and gas reservoirs that produce from natural fractures and low-permeability intra-particle-matrix nano- to micropores (Candelaria, 1990; Osterlund, 2012; Entzminger, 2015; this study).