Summary
This paper describes a systematic approach to exploration, appraisal and completion optimization in the Wolfcamp Formation in the Southern Midland Basin. In 2011, ConocoPhillips acquired ~70,000 gross contiguous acres in the Midland Basin, West Texas. Geological uncertainty and limited production from the horizontal Wolfcamp Play in the southern portion of the basin required an appraisal effort of this acreage prior to making a development decision. Initially, from 2011-12, ConocoPhillips appraised the upper Wolfcamp potential with 7 horizontal wells with a fixed well length (5000'), completion style (hybrid X-link), and lateral placement. The appraisal program focused on 3 areas in the acreage to understand the lateral geologic heterogeneity of the reservoir, and its impact on productivity. First production began in July 2012 and indicated a working petroleum system with sub-optimal well rates.
Given the limited production from this new play in 2012, detailed reservoir characterization across the acreage was required for accurate appraisal. Our significant data collection program included microseismic, whole core, advanced logging, PVT, geochemistry and Diagnostic Fracture Injection Tests (DFIT). Concurrently, a 3D-seismic dataset was acquired and used to characterize the reservoir and to identify geo-hazards. Interpretation of the acquired data indicated that reservoir properties in the Wolfcamp varied laterally across the acreage, and resulted in development of a new completion strategy.
Based on results from the initial drilling, a confined spacing pilot was implemented on the eastern side of the acreage in 2013. The program entailed a vertical monitor well and 4 horizontal wells (7500-10000' lateral length) at 880' spacing, with an optimized completion design relative to 2011-12. The 2013 data collection program was focused on understanding wellbore connectivity and the optimized completion design. We collected image logs, chemical tracers, and microseismic through which, we observed connectivity between the wells during the initial flowback. The microseismic compared to the 2011-2012 results revealed improved stimulated rock volume. In accordance, the first production in early 2014 indicated enhanced well rates. From our results in the south Midland Basin, we observed that a data-rich appraisal program is necessary to characterize the reservoir in a large acreage position. Additionally, completions optimization is an iterative process that is best achieved through an integrated team approach.
