It is not very satisfactory to explain hydrocarbon formation in carbonate rocks with conventional thermal evolution of kerogens. A tentative viewpoint has been proposed that there are kinds of potential hydrocarbon generation matters (fatty acid salts) in carbonate rocks.
Metal salts of carboxylic acids had been reported to present in Green River oil shale. As they are of special physical and chemical properties, it is very difficult to obtain pure fatty acid salts from sedimentary formation. Thus, we had prepared magnesium stearate with the method of chemical synthesis. Magnesium stearate, stearic acid and magnesium stearate plus CaCO3, were used as simulation samples at 300°C and 350°C.
The results of simulation indicate that hydrocarbon conversion ratio of magnesium stearate is higher than that of stearic acid. The distribution patterns of n-alkane from magnesium stearate suggest that alpha cleavage is predominant process. In the meantime, b and r cracking have also obviously preponderance, and longer chain n-alkanes are also produced by heating.
From salts of fatty acids experiments, the new enlightenment will be gained about hydrocarbon generation in carbonate rocks.
AAPG Search and Discovery Article #90925©1999 AAPG Foundation Grants-in-Aid