The morphology and composition of minerals are known to be of great importance in determining the suitability of rocks as hydrocarbon reservoirs. However, their role in the generation and release of hydrocarbons from kerogen is still poorly understood. Recent studies suggest that the interaction of some clay minerals with the organic matter in source rocks results in a series of processes which can be characterized as follows: (1) catalytic increase in the rate of organic carbon decomposition, (2) control of the chemical nature of the hydrocarbon products, (3) retention of bitumens and asphaltenes that may be carried to depths where the geothermal gradient causes them to be cracked to light hydrocarbons, (4) transform nonporous carbonate rocks to porous reservoir rocks as a result of early catagenic CO₂ and organic acids' release, (5) recrystallize minerals involving release of water, mineral dissolution, and release of trapped bitumen, and (6) influence the formation of mature sweet light oil or immature sour heavy oil.

This evaluation suggests that the character of hydrocarbons produced, which is generally thought to be facies controlled, is a result of both mineral as well as kerogen type within the source rock. Recognition of the above could have important implications in the strategy of geochemical exploration for oil and gas.

End_of_Article - Last_Page 271------------