--> --> Abstract: Tectonic Influence on the Deposition and Reservoir Development in Bull Creek Field (Newman Limestone), Eastern Kentucky--A Model for Future Exploration, by M. Conrad, J. Tebo, T. Heinecke, and S. Moshier; #90984 (1994).

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Abstract: Tectonic Influence on the Deposition and Reservoir Development in Bull Creek Field (Newman Limestone), Eastern Kentucky--A Model for Future Exploration

Matthew Conrad, Jerry Tebo, Tom Heinecke, Stephen Moshier

Bull Creek is the largest "Big Lime" (Middle to Upper Mississippian) oil reservoir in eastern Kentucky, with an original oil-in-place estimate approaching 100 million bbl. An integrated study employing aeromagnetic and seismic analyses, geophysical logs, and petrography was conducted to determine factors controlling paleovalley evolution, depositional facies, porosity development, and reservoir morphology. The resulting reservoir model could apply to future discoveries in the region.

Structural and isopach analysis of the field reveals a strong north-south linear orientation, suggesting the influence of tectonic control. Geophysically delineated basement normal faults directly underlie and influenced reservoir geometry. Subsequent to Borden deposition and marine regression, remobilization of the basement faults created linear trends of fractured (brecciated) strata. These rocks were subject to accelerated erosion, and a deeply incised paleovalley was created. Marine transgression from the southeast established carbonate deposition and the accumulation of crinoidal grainstones, initially restricted to the inundated paleotopographic lows. Further sea level rise resulted in the development of a vast carbonate shelf across the entire central Appalachian foreland basin

Reservoir porosity is attributed to fractured dolomites, which are restricted to the basal Big Lime within the narrow paleovalley fill. Initial dolomitization probably occurred prior to deep burial of the Big Lime. After significant burial, reactivation of basement faults resulted in reservoir fracturing. The faults provided vertical migration paths for diagenetic fluids, resulting in a second phase of dolomitization that further enhanced porosity and permeability. Hydrocarbon migration succeeded late dolomitization and was also aided by fracturing.

AAPG Search and Discovery Article #90984©1994 AAPG Annual Convention, East Lansing, Michigan, September 18-20, 1994