Total petroleum system assessment of undiscovered resources in the giant Barnett Shale continuous (unconventional) gas accumulation,Fort Worth Basin,Texas

摘要

Undiscovered natural gas having potential for additions to reserves in the Mississippian Barnett Shale of the Fort Worth Basin,north-central Texas,was assessed using the total petroleum system assessment unit concept and a cell-based methodology for continuous-type (unconventional) resources.The Barnett-Paleozoic total petroleum system is defined in the Bend arch-Fort Worth Basin as encompassing the area in which the organic-rich Barnett is the primary source rock for oil and gas produced from Paleozoic carbonate and clastic reservoirs.Exploration,technology,and drilling in the Barnett Shale play have rapidly evolved in recent years,with about 3500 vertical and 1000 horizontal wells completed in the Barnett through 2005 and more than 85% of the them completed since 1999.Using framework geology and historical production data,assessment of the Barnett Shale was performed by the U.S.Geological Survey using vertical wells at the peak of vertical well completions and before a transition to completions with horizontal wells.The assessment was performed after (1] mapping critical geological and geochemi-cal parameters to define assessment unit areas with future potential,(2) defining distributions of drainage area (cell size) and estimating ultimate recovery per cell,and (3) estimating future success rates.