Completion Influence on Production Decline in the Bakken/Three Forks Play

Abstract

Recent developments in completion techniques and stimulation efficiency have allowed many unconventional resource plays to reach economically viable levels. The Bakken/Three Forks play of the Williston basin has rapidly evolved during recent years, and its predominantly successful completion techniques continue to emerge as programs are tailored to geographic areas. As completion intensity increases to facilitate higher early time production returns, so does the need for the critical analysis of production decline rates to meet economic targets.The application of decline curve analysis in unconventional reservoirs, such as the Bakken/Three Forks play in North Dakota, is often problematic because of very long periods of transient flow. This has caused the development of various decline curve relations outside the conventional Arp's equations in an attempt to better explain the transient flow period. Additionally, it has sparked interest in quantifying the uncertainty associated with production and the estimated ultimate recovery (EUR) from these various techniques.The Bakken/Three Forks system is exploited using a large variation of publically reported completion techniques throughout a significant geographic area. Because of the uncertainty in assessing the performance of unconventional wells and the multitude of variables that could affect their production, it is often difficult to determine dominant influencing parameters of completion design. Efficiently implementing optimal completion techniques, provided there is high variability within a continuous horizontal target lithology, is critical because of the large geographic extent of the Williston basin.The focus of this study is to evaluate the completion efficiency of individual wells using decline curve analysis and to quantify uncertainty using this performance metric. A comprehensive completions database of the Bakken/Three Forks play is used to evaluate the expected costs and benefits of various completion designs used throughout the basin. This paper provides examples of stimulation methods optimized to specific regions of the Bakken/Three Forks system using this methodology. Overview of DatabaseTo document the variability in completion design and production throughout the Williston basin Bakken/Three Forks system, a comprehensive database of publically reported completion and production data has been compiled using the North Dakota Industrial Commissions (NDIC) website. In addition to legal information (well name and number, completion date, etc.), the latitude and longitude, target formation, maximum rate, stimulation zones, total treatment fluid, total proppant, completion system, annular isolation, stimulation fluid, primary proppant, and initial production (IP) test choke were recorded. For each well reported, production data was also recorded at various time steps. Because the NDIC reports the number of production days each month, down days were removed from the production data, and linear interpolation was used to obtain production values at 30-da...

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