Permo-Carboniferous and older plays, their historical development and future potential

Abstract

The plays reviewed in this paper are those developed where Permian and older organic-rich rocks have been preserved. These have sourced approximately 60 × 109 barrels of oil equivalent in the area under consideration, in oil, gas and oil shale developments, and range in age from the Cambrian to Permian. They were deposited in marine to terrestrial environments, and their development was controlled by the evolution of life forms, changes of relative sea-level and the plate tectonic configuration of the depocentres. Clastic and carbonate reservoir distribution was controlled by tectonic phases and relative sea-level variations. Trapping is by both structural and stratigraphic mechanisms. Preservation of source and reservoir potential is dependent on a lack of intense orogenic activity and should, therefore, be sought away from zones of intense tectonism that post-date potential source rocks. Proven play types are extrapolated to under-explored areas where similar potential may exist, and the potential of methane extraction from coal beds is suggested.