Abstract

With the success of the Barnett shale play, there has been an industry focus on identifying unconventional reservoirs capable of sustaining commercial resource plays. This emphasis has spilled over into the Permian Basin over the last six years. This paper examines MPI’s successful application of geological, geophysical, and engineering practices in producing hydrocarbons from the “Wolfberry play” in the Eastern Midland Basin. The Wolfberry play as defined by MPI includes the interval of rocks bounded at the top by the upper Spraberry formation down to the top of the “Penn Lime” formation. The Wolfberry was evaluated from large scale regional mapping to the small scale microscopic analysis of the rock samples. Well logs from 175 wells were processed using commercial logging software to identify “pay zones” within the Wolfberry play. The “pay zone” results were then mapped to further refine the geological model. Prospective wells were identified as re-entry candidates or new drill areas. In addition to a complete logging suite, full core or rotary sidewall cores were extracted and analyzed to enhance the evaluation of the rocks. Through the identification of pay zones using log and core data, several unconventional zones became candidates for perforating. Rock properties logs were generated to define the mechanical stresses that affect the hydraulic stimulation of the “pay zones”. A geophysical model in conjunction with image logs and cores was designed to identify areas that were most likely to have the presence of natural fractures. The presumption was that the presence of naturally fractured rocks correlated with better hydrocarbon production. The properties that were leased by MPI were then analyzed with respect to this geophysical model. A typical engineering approach was to block perforate and hydraulically fracture the lime zones with high rates and low sand concentrations throughout the Wolfberry. In the Eastern Midland Basin, this approach has been met with mixed results thus creating a need to better understand how to identify and complete the pay zones. The coordination of the geological, petrophysical, geophysical, and engineering models has increased the value of the leased properties beyond the original investments.