Investigation of the Davis Sandstone (Ft. Worth Basin, Texas) as a Suitable Formation for the GRI Hydraulic Fracture Test Site


The concept of the GRI Hydraulic Fracture Test Site (HFTS) was to provide a field laboratory to (1) validate three-dimensional hydraulic fracture models in tight gas sandstone and (2) develop technology in fracture diagnostics and stimulation. The Davis sandstone in the Fort Worth Basin, north-central Texas, was initially selected as a viable candidate formation for HFTS research based on the results of a cooperative well program initiated with Dallas Production. To gather comprehensive data on a specific site for HFTS research, the S.A. Holditch & Associates Data Well No. 1 was drilled in June 1991. The results of geological, petrophysical, and engineering analyses of the co-ops and data well are the basis of this report. These analyses indicate that in northern Parker and southern Wise Counties, Texas, the Davis sediments range from 250 to 350 feet thick. A broadly continuous, 100-foot thick interval in the upper part of the gross interval comprises the Davis Reservoir. The average permeability of the Davis Reservoir was found to be 0.08 millidarcies with an average closure stress of 0.45 pounds per square inch per foot. The shale barriers above and below the Davis had average closure stress of 0.63 to 0.73 pounds per square inch per foot and 0.88 to 0.98 pounds per square inch per foot, respectively. Hydraulic fracture azimuth was found to range from N10°E to N20°E. Drainage area from production analyses was calculated to be 48.7 acres in northwest Parker County. Natural fractures were encountered in the Davis, causing severe drilling problems in Data Well No. 1. Davis was therefore suspended.


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