Abstract: Study on Hydrocarbon Potential of Salt of Fatty Acid in Carbonate Rocks

ZHOU SHIXIN, Lanzhou Institute of Geology, Chinese Academy of Sciences, Lanzhou, Gansu, Peoples Republic of China

Studies on hydrocarbon generation mechanism of carbonate rocks are widely paid attention to in geological field. Geological study indicates that carbonate rocks are important source rocks as well as important reservoirs for oil and gas. However, carbonate rocks widely developed in Palaeozoic and pre-palaeozoic strata of China contain lower residual organic abundance and fewer quantity of kerogens, it is very difficult to explain the hydrocarbon formation with traditional thermal evolution of kerogens. According to my previous research, applicant proposes that there is a kind of unknown potential hydrocarbon generation material (Salt of fatty acid) in carbonate rocks. It is often thought that n-alkanes present in crude oil are formed from straight- chain fatty acid, but in alkalinity sedimentary condition, fatty acids will decompose and form negative ion of fatty acid, which can continually react with Ca{2+} and Mg{2+} and form stable sediment of salt of fatty acid. This kind of salt is neither soluble in water nor in organic solvents. Along with temperature and pressure increasing, they will yield hydrocarbons. For instance, applicant prepared magnesium stearate by chemical synthesis, and used magnesium stearate as simulation samples at 300 degrees C and 350 degrees C, the results of the simulation indicated that hydrocarbon conversion ratio of magnesium stearate is higher than that of stearic acid. In this investigation, we will search the abundance of salt of fatty acid in various maturity carbonate rocks, and carry out simulation to inquire for hydrocarbon generation mechanism of salt of fatty acid. The results of this research will be of great theoretical and practical significance to evaluate carbonate rocks.

AAPG Search and Discovery Article #90931©1998 AAPG Foundation Grants-in-Aid