Changing Concepts in Petroleum Source Rocks
Bhattacharya, Swapan K.*1
(1) Faculty of Geoscience, University Technology Petronas, Tronoh, Malaysia.
Source rock in petroleum geology is still a concept because it has not been possible to experimentally simulate generation and expulsion of petroleum from a rock. The concept of source rock changed from time to time following the advances of analytical techniques as well as the need to explain the difficult hydrocarbon occurrences. The first concept of source rock was proposed in 1860 by John Newberry to describe marine Late Devonian Ohio Shale as the source of Pennsylvanian oil occurrence. The next major concept was introduced in 1968 when Hedberg proposed terrestrial organic matter as the source of petroleum. A third concept of lacustrine source rock as intermediate between two earlier extreme environments was introduced in late eighties. Thus, there was a complete sequence of environments where source rock could be deposited - marine anoxic, terrestrial anoxic and terrestrial oxic.
Although the changes in the source rock concept have been evolved with development of technology, it is known that each and every technology has its own limitation. Attempt has been made here to review the justifications of the corresponding changes in the light of the technology limitations and it has been observed that a change was necessary but the way it has been changed is not justified. A new concept is proposed here suggesting organic lipids as the dominant source of petroleum source rock. This will resolve the hydrogen deficiency problem in the organic source and will end up the biogenic and abiogenic source rock debate for ever.
AAPG Search and Discovery Article #90141©2012, GEO-2012, 10th Middle East Geosciences Conference and Exhibition, 4-7 March 2012, Manama, Bahrain