Procedure for calculating estimated ultimate recoveries of wells in the Wolfcamp shale of the Midland Basin, Permian Basin Province, Texas

In 2016, the U.S. Geological Survey published an assessment of technically recoverable continuous oil and gas resources of the Wolfcamp shale in the Midland Basin, Permian Basin Province, Texas. Estimated ultimate recoveries (EURs) were calculated with production data from IHS Markit^TM using DeclinePlus software in the Harmony interface. These EURs were a major component of the quantitative resource assessment. For five of the six assessment units in the study, an industry operator in the Midland Basin provided information that was used to differentiate the Wolfcamp horizontal well landing zones. The IHS Markit^TM production database does not distinguish between the Wolfcamp A, B, C, and D well landing zones. These different units of the Wolfcamp have different production patterns that are important for calculation of EURs. The calculated mean EURs for each assessment unit ranged from 99,000 barrels of oil in the Wolfcamp C to 142,000 barrels of oil in the Wolfcamp A.