Abstract: Principles of Hydrocarbon Generation and Application to Oil and Gas Exploration

Geoffrey S. Bayliss

Petroleum generation in the subsurface involves primarily the geothermal (time-temperature) conversion of organic matter into hydrocarbons. The type of organic matter, its abundance, and the geothermal history of the sediments largely determine the quantity and the type of petroleum hydrocarbons generated in a specific source facies.

Many physical methods have been used to measure the geothermal history of a sedimentary sequence but by far the most informative, with respect to oil-gas generation, are the geochemical changes in hydrocarbon type and composition concomitant with increasing diagenesis. The chemical parameters reflecting diagenesis are well documented and, when applied to the exploration process, commonly are used to evaluate the hydrocarbon potential of sedimentary sections in frontier areas prior to extensive exploration drilling.

In a complete basin assessment, a comprehensive geochemical program provides pertinent, basic information necessary to delineate organic facies, hydrocarbon-source facies, and the types of oil and/or gas which can be expected within prospective-reservoir facies.

AAPG Search and Discovery Article #90973©1976-1977 AAPG Distinguished Lectures