There have been over 14,000 wells drilled and completed in the Cotton Valley sand of east Texas and north Louisiana, with more than 7,900 drilled and completed since 2003. (IHS 2010) All of these wells require multistage hydraulic fractures to economically produce. Well over 180 operators have an actively producing Cotton Valley sand well. With so many operators, there are numerous completion approaches used to optimize Cotton Valley sand production, and these strategies are ever evolving over time.
The ultimate question from anyone who owns a Cotton Valley sand well is how to best complete it. By looking in-depth at more than 400 vertical Cotton Valley sand wells completed since 2003, we determined the impact of various completion parameters on production. For comparison purposes, we obtained production data on all wells and their offsets from publicly available. Well production was compared in various ways including: (1) offset wells within a 1-mi radius of the subject well; (2) normalized to the perforated interval; (3) decline trends of various completion types; and (4) delineating well groups based on production maps.
Injection rate, fluid type (i.e., slickwater versus crosslinked gel), fluid volume, proppant type, proppant amount, number of stages, etc. were objectively compared with resultant production data ranging from 1- to 5-year spans. Those completion parameters that have a significant impact on production are identified and examined, along with those factors that do not correlate to production. Completion practices that sustain a flatter decline trend are also analyzed.
Trends in the data were examined to steer the key design parameters that impact production in the Cotton Valley sand. A brief section discussing applicability of the results to other formations, including shale, is also discussed. General recommendations for a Cotton Valley sand completion are made based on the correlative production results.