Potential Hydrocarbon Reservoirs and Source Rocks in Cambrian and Ordovician Strata and Their Thermal Maturity, Eastern Kentucky and Adjoining West Virginia
RYDER, R. T., REPETSKI, J. E., and HARRIS, A. G., U. S. Geological Survey, Reston, VA
Recent commercial gas discoveries in Cambrian rocks in eastern Kentucky's
Elliott County have renewed exploration activity in the Rome trough. Regional
cross sections by the U. S. Geological Survey based on drill holes through
the Cambrian and Ordovician sequence in the Rome trough of eastern Kentucky
and adjoining West Virginia show potential reservoir and source rocks.
Moreover, conodont color alteration indices along or near these cross sections
indicate that the thermal maturity of the sequence is favorable for oil
and gas.
Possible reservoir units in the sequence are quartzose sandstones in
the 1) Middle and Upper Cambrian Maryville Limestone of the Conasauga Group,
2) upper sandstone member of the Upper Cambrian Copper Ridge Dolomite (equivalent
to the Rose Run Sandstone), and 3) Middle Ordovician St. Peter Sandstone.
The apparent absence of good source rocks (TOC ³ 1) in the Rome trough
has diminished its prospects for having large hydrocarbon accumulations.
However, the recent commercial gas discoveries are encouraging and suggest
that organic-rich strata must exist in the trough. No source for this gas
outside the trough is conceivable. Thick Middle Ordovician black shale
that is the source for oil and gas in Cambrian and Ordovician rocks in
Ohio is absent from this area. Argillaceous carbonate units with black
shale interbeds in the Maryville Limestone, shown on the cross sections,
may be the source of the gas. Conodont color alteration indices of CAI
= 11/2-2 in the Middle Ordovician Black River Limestone and CAI = 2-3 in
the Upper Cambrian and Lower Ordovician Knox Group suggest that the thermal
maturity is favorable for natural gas and local oil in the Rome trough
of eastern Kentucky and adjoining West Virginia.
Back
to the EAAPG/TSOP 1997 Meeting Home Page