This paper discusses the rationale for selection of a well site where geologic and reservoir conditions are favorable for a horizontal well to increase gas recovery efficiency over that of vertical wells. In this effort, an area of favorable geology was selected and a multi-site reservoir evaluation study was conducted to determine an appropriate location for a long horizontal wellbore in the Devonian shale in southwestern West Virginia. Within a candidate reservoir, existing wells and their suspected directional properties were analyzed to develop the best candidates for location of the horizontal well. Reservoir data from over 38 wells in the area were used to establish areas of high flow capacity. A 3-dimensional gas flow simulator capable of modeling both fracture and matrix porosity and permeability and desorption were used to investigate both the adjacent well interference and production performance of a 2,000-foot horizontal wellbore. Final well location selection was based on minimum interference, high expected recovery efficiency, and reasonable access in rugged terrain.

Once site selection was completed, a well-planned drilling approach was developed based on a complete review of horizontal well drilling technology with particular emphasis on methods to directionally drill on air or air/mist to intersect the inherent fracture system (based on regional mapping trends), horizontal coring for natural fracture spacing, and multiple hydraulic fracturing horizontal boreholes through cemented casing. The lessons learned in this effort are that horizontal wells can be achieved in naturally fractured formations, but good reservoir studies are required to increase the probability of success in achieving noteworthy production.

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