Rowan, E. L.1, R. T. Ryder1, C. S. Swezey1, J. E.
Repetski1, R.D. Crangle1, M. H. Trippi1, L. F.
(1) U.S. Geological Survey, Reston, VA
ABSTRACT: Burial and Thermal History Model of a Cross-Section through the Central Appalachian Basin, Ohio and West Virginia
A Phanerozoic burial and thermal history model was developed from well data along a 230-mile, northwest trending cross-section oriented approximately perpendicular to the axis of the central Appalachian basin. The cross-section extends from the Allegheny structural front in central West Virginia across the deep Dunkard basin (~20,000 ft) and continues onto the Findlay arch in northwestern Ohio. The Dunkard, a ‘sub-basin’ within the larger Appalachian basin and a Paleozoic depocenter, was probably controlled by reactivation of faults bounding the Cambrian Rome trough.
The burial/thermal history model incorporates the low thermal conductivities of Pennsylvanian coal beds (0.2-0.6 W/mK) and Devonian kerogen-rich shales (0.9-1.2 W/mK). The model is constrained by limited fluid inclusion data, and by vitrinite reflectance and conodont CAI measurements from Ordovician, Devonian, and Pennsylvanian rocks. Preliminary results from the model indicate that ~6000 ft of Permian-Mesozoic sediment were eroded at the southeast end of the cross-section, thinning northwestward to ~1100 ft. Thermal maturities are calculated for hydrocarbon source rocks vertically and laterally over the cross-section, and through time. For example, the Ordovician Utica Shale entered the oil window (0.6<Ro<1.2%) near the end of the Early Devonian in the Rome trough. To the northwest, where the stratigraphic section thins over the Findlay arch, the Utica Shale is, at most, marginally mature and did not enter the oil window until deposition of Permian sediments. This model is a preliminary step toward a comprehensive, regional-scale burial history model integrating thermal and geologic data to aid in understanding and quantifying hydrocarbon resources.
AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.