AAPG Annual Convention and Exhibition

Datapages, Inc.Print this page

Geometry, Trap Configuration and Production Characteristics of Mississippian Porous Chert Reservoirs in Ice Cream Cone Structures of Foraker Field, Osage County, Oklahoma


Deep basement-involved structures govern the architecture of production in Mississippian reservoirs of northeastern Oklahoma. Linear buttresses such as the Nemaha Ridge and White Tail system frame a trend of NNE/SSW and NW/SE intersecting faults. Conventional traps align along these features and are genetically related to reverse faulting and associated pop-up structures. Sandwiched between two such faults, the overall geometry of the Foraker Field resembles nothing so much as a sugar cone, with the porous chert reservoirs of the Mississippian draped over the top and dripping off the sides. Reservoir development is also genetically related to these features, as it is apparently associated with granite-derived fluids moving laterally and vertically through the brittle siliceous carbonate section from source kitchens to oil fields to ore deposits to surface oil deposits. As these fluids moved vertically along the basement related faults, they intersected porous lenses of the Osagean section, including but not limited to the meteorically altered layers at the top of the section commonly referred to as the Mississippian Chat. These layers were further altered to porous and brittle chert fabrics. Subordinate faulting acts to either compartmentalize or breach traps. Dense drilling in the field allows for reservoir quality and thickness to be roughly correlated to seismic expression. While single well production data from Foraker Field are limited, available test information has been used to calibrate this seismic expression. Current drilling in the field will test the hypothesis that seismic attribute analysis convolved with structural position provides a tool that can be used to maximize infill drilling opportunities and to explore for un-drilled analogs in adjacent areas.