Pollastro, Richard M.1, Timothy S. Klett1, Ronald R.
Christopher J. Schenk1, Troy A. Cook1, Ronald J. Hill1
(1) U.S. Geological Survey, Denver, CO
ABSTRACT: 2003 Assessment of Undiscovered Technically Recoverable Oil and Gas Resources of USGS Province 045, Fort Worth and Hardeman Basins, Texas and Oklahoma
Three total petroleum systems (TPS) are identified for the 2003 U.S. Geological Survey assessment of undiscovered, technically recoverable oil and gas resources of the Bend Arch–Fort Worth Basin Province: 1) Barnett-Paleozoic TPS, Fort Worth Basin and Bend arch; 2) Barnett-Hardeman Basin TPS, Hardeman Basin; and 3) Pennsylvanian Bend-Broken Bone Graben TPS that partly separates the Barnett-Paleozoic and Barnett-Hardeman TPS systems in the northwest part of the province. The Barnett Shale (Mississippian-Pennsylvanian) is the primary source rock for hydrocarbons in the Barnett-Paleozoic and Barnett-Hardeman TPS, whereas organic-rich shale of the Pennsylvanian-age Bend Group generated mainly gas from the Broken Bone graben.
Geologically defined units for assessment of mature conventional accumulations include the Mississippian Chappel Limestone pinnacle reefs and Waulsortian mounds, and the Pennsylvanian Bend Group conglomerates and Strawn Group sandstones. Assessment of the Bend Arch-Fort Worth Basin Province focuses on the continuous (unconventional) Barnett Shale accumulation where gas and some oil are sourced and reservoired in tight, organic-rich siliceous shale.
The Barnett continuous accumulation is expected to add the greatest volume of undiscovered, technically recoverable gas to reserves. Barnett gas will be assessed after determining areas of gas potential, and by estimating distributions of drainage areas of wells (cell size) and estimating ultimate recoverable gas volumes. The Greater Newark East area is considered a “sweet spot” within the Barnett where thick, organic-rich siliceous shale is within the gas window and overlain and underlain by impermeable limestone that confine induced fractures during completion and allow maximum gas recovery.
AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.