Print this pageRenewed Interest in Heavy Oils and Rock Asphalt in South Central Kentucky
Heavy oils and rock asphalt (bitumen-bearing sandstone) occur in strata of Mississippian and Pennsylvanian age along the southern and southeastern margins of the Central Interior (Illinois) Basin in Kentucky. Documented subsurface and outcrop investigations have been numerous in the area and renewed interest in development of these resources began a few years prior to the 2008 spike in oil prices. Studies of these heavy-end hydrocarbons have ranged from the basic geologic sketches and short essays produced by early state geological surveys in the 1850s to detailed sedimentological studies of the 1970s to petrophysical and original oil-in-place studies over the past 25 years.
Oil-bearing or bitumen-bearing units that have been exploited in the Mississippian (Chester Series) include the Big Clifty (Golconda Fm), Hardinsburg and Tar Springs (Leitchfield Fm) sandstones as well as the basal Pennsylvanian Caseyville Sandstone. The latter unit in particular is well known for its historical production of a commercial asphalt material (Kyrock) that was used nationally and internationally for paving roads during the first half of the 20th century. Although the regional Mississippian-Pennsylvanian unconformity mainly controlled hydrocarbon migration and emplacement in the region, there are numerous cases where heavy oils and asphaltic sands occur in underlying Chester sections that are not physically associated with the sequence boundary.
Future challenges in the area include the design, operation and maintenance of a steam flood or similar recovery system to generate significant long-term production from the three billion barrels of oil equivalent (BOE) estimated to remain in place in this region of Kentucky.
AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009