Abstract: Tectonic and Palaeoenvironmental Controls on the Distribution of Source Rocks and Reserves: Global Models

J. P. Harris, P. C. Barnard, A. C. Barnwell, A. C. Ellis

It has been established that hydrocarbon source rocks exhibit a distinct stratigraphic distribution pattern. This has been related to both climatic and oceanographic processes. The reserves attributable to these source rocks also exhibit distinct patterns which can be related to a combination of both tectonic and palaeoenvironmental processes. To substantiate these observations, SPT has compiled a global source-rocks database using a series of palaeotectonic reconstructions and a global basins and reserves database. Both these data sets are dependant on GIS techniques and are analyzed using process based stratigraphic models for each basin.

Analysis of these data demonstrate that over 80% of reserves are attributable to source rocks deposited during seven distinct phases of earth history. These correspond with the previously described black shale events. However, it can be shown that both upwelling and restricted circulation in silled basins also contribute. Both processes seem to be most effective in producing prolific source rocks during black shale events. The global distribution pattern of hydrocarbon reserves also indicates a tortuous relationship with contemporary subsidence regime such that a league table of basin types can be constructed. Foreland basin/thrust belt couplets in continent-continent collisional environments head this table. Investigation of the reasons for this reveals that the products of precursor rift and passive margin subsidence regimes (megasequences) are critical to the development of optimal petroleum systems in these basins.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994