This paper discusses site selection, air directional drilling, stimulations, and economic evaluation for a 72 degree slant well drilled in the Devonian shale, Roane County, West Virginia. The well was drilled to evaluate the concept of using directional drilling and multiple hydraulic fracturing to improve the gas production from a 450-foot naturally fractured Devonian shale section. The well trajectory remained in target for more than 1,500 feet at a preferred azimuthal direction perpendicular to preferred azimuthal direction perpendicular to the regional fracture trend and also the known production fairway.
The well was conventionally drilled to the kickoff point of 2,150 feet. Afterwards, positive displacement downhole motors were positive displacement downhole motors were used to build hole angle up to a 72 deg. hole angle at the top of the target zone. Once the target zone was reached at 67 deg., conventional rotary assemblies were used to rotate the well across a 1,500-foot target section in which inclination varied from 67 deg. to 72 deg. of hole angle. After reaching total depth of 4,833 feet, the well was logged using wireline and drill pipe conveyed methods. Then 5 1/2-inch casing was run and cemented with 60 rigid centralizers to improve zonal isolation.
Four stimulations were designed and completed. All stimulations will be discussed in the paper. Economic analysis was conducted to show expected improvements from the application of this technology to fractured Devonian shale. Post-stimulation well testing has been identified for each zone to show initial results.
The U.S. Department of Energy, Morgantown Energy Technology Center has been investigating the development of marginal gas resources using high-angle and horizontal drilling for more than 20 years. Mobil Oil Corporation first tested the concept in the Austin Chalk in the early 1970's. DOE also experimented in the early 70's by drilling two high-angle wells in the Devonian shale but poor well siting and mechanical problems plagued early production results. In 1986, DOE sponsored a production results. In 1986, DOE sponsored a 2,000-foot horizontal well in Devonian shales in which multiple hydraulic fracturing experiments were performed. These marginal gas resources are contained in tight gas formations like Devonian shale, tight sands, and coalbeds where non-damaging drilling fluids like air will be used to allow for maximum production from an undamaged formation.
The U.S. Department of Energy developed a cost-sharing contract with Sterling Drilling and Production Company (SD and P) to drill, log, test, and stimulate a high-angle directional well in Roane County, West Virginia. In addition, SD and P developed an R and D agreement with the Gas Research Institute to conduct supporting research in well siting, well logging, testing, and stimulation. SD and P had Columbia Gas and Pennzoil Company as working interest Pennzoil Company as working interest partners in this slant well project. partners in this slant well project. P. 45
