AAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
USGS Assessment of Undiscovered Natural Gas Resources of the Lower Cretaceous Knowles-Calvin Gas Assessment Unit, Northern Gulf Coastal Plain, USA
(1) Department of Interior, U. S. Geological Survey, Reston, VA.
(2) Department of Interior, U. S. Geological Survey, Denver, CO.
The U. S. Geological Survey (USGS) has recently completed an assessment of the undiscovered, technically recoverable gas resources of the Lower Cretaceous Knowles [Limestone]-Calvin [Sandstone] Gas Assessment Unit (AU) in the Gulf Coastal Plain of Texas, Louisiana, and Mississippi. These resources were all attributed to the Upper Jurassic-Cretaceous-Tertiary Composite Total Petroleum System (TPS) and are most likely reservoired in conventional gas accumulations. The Knowles-Calvin Gas AU encompasses that volume of rock extending approximately from the Knowles limestone reef crest (or its paleogeomorphic equivalent), west to the national border between the United States and Mexico and east and south to the State - Federal waters boundary, and includes the stratigraphic interval between the top of the Jurassic as regionally represented by the base of the Knowles Limestone and the base of the Hosston-Travis Peak Formations (and their downdip equivalents).
Potential reservoir intervals in the Knowles-Calvin Gas AU are composed primarily of shallow-water to upper slope sandstone and carbonate shelf margin to distal bank/fore-reef limestone. These intervals are likely sourced by the underlying Jurassic Bossier-Haynesville shale and possibly the underlying Jurassic Smackover limestone. Ten fields producing from within the AU have been identified, including the trend discovery at Calvin Field, in Winn Parish, LA, in 1976. These fields range in depth between 11,300 ft and 16,500 ft. They are developed in combination stratigraphic-structural traps on faulted salt-cored anticlines. The AU has been classified as a frontier area, with new field wildcat discovery potential and some remaining field growth potential.