Fracture Height Development and Control in the Mississippian Sandstones of Central West Virginia

摘要

Natural gas production in central West Virginia isrnprimarily from the shales of Devonian age upward to thernsandstones of Pennsylvanian age. These productivernintervals are typically low permeability, under pressuredrnand adjacent pay zones can have similar closurernpressures with only a minimally competent barrierrnseparating them.rnSuch a scenario exists in the Weir and Injun sandstonesrnof Nicholas, Fayette and Kanawha Counties, WestrnVirginia. At a depth of 2000 to 2500 ft, both thernunderlying Weir and overlying Injun exhibit only a fewrnhundred psi reservoir pressure, frac gradients in the 0.4rnto 0.6 psi/ft range and are separated by 10 to 20 ft ofrnsandy shale. To make either of these zonesrncommercially productive, both must bernhydraulically fractured.rnInitially it was felt that historical treatment data and therncomparison of conventional electric logs to offset wellsrnwould provide sufficient data to effectively fracture modelrnstimulation treatments. This technique providedrninteresting computer simulations, but treatment andrnproduction results did not substantiate the modeling.rnIn an effort to better model and stimulate both zones,rnmechanical properties were obtained from a sonic log.rnTreatment parameters such as pressure, fluidrnefficiency/formation permeability and near wellborernconnectivity characteristics were obtained from stepdownrnand mini-frac tests. Real-time job monitoring,rnpost-frac RA tracer survey and production testing werernperformed to verify the design simulation.rnTreatment design history and current philosophy will berndiscussed in this paper. In addition, the results of therndata gathering, treatment design and execution and RArntracer survey will be presented.