An Investigation of Ancient Geological Events and Localized Fracturing on Current Bakken Trends

Abstract To date the most prolifically producing geologic structure in Montana's Bakken formation is the Elm Coulee Field. While the first wells drilled into this structure 35 years ago had some success, significant production did not occur until horizontal wells were drilled starting in 2000. The Bakken Petroleum System consists of three members, the Upper Bakken, shale, the Middle Bakken, silty dolostone, and the lower Bakken, siltstone. Production of the Bakken Petroleum System is extremely difficult to predict with standard reservoir models. Thus, the decision to understand initial production through geologic drivers was made. An investigation of the implications of ancient geology on what is believed to be specific areas of micro-flexures in and around the major geologic structures in Montana's Bakken three-member formation will form the basis for a Bakken production model. The challenge in modeling the Bakken's production, both initial and subsequent, stems from the unusual history matching problem of either extremely high initial production with an unpredictably low subsequent production or surprisingly low production to begin with. The authors believe this phenomenon is due to broaching a series of micro-flexures and draining them, resulting in high initial production and unsustained subsequent production, or missing these structural flexures all together resulting in low production. This paper will investigate the genesis of Montana's Bakken micro and macro fractures with the ultimate goal of simulating and thus predicting production for wells currently producing in the area.