ORGANIC PETROLOGY OF SOURCE ROCKS FROM THE UPPER PERMIAN LINXI FORMATION IN LINXI AREA, INNER MONGOLIA

Linxi area in eastern Inner Mongolia is one of the important potential areas for Carboniferous-Permian oil-gas exploration in the periphery of Erlian Basin. The total organic carbon (TOC), organic macerals, vitrinite reflectance and rock pyrolysis of the source rocks from Upper Permian Linxi Formation in field section are tested and analyzed to study the organic petrological characteristics of the source rocks. The results show that the TOC content of source rocks is 0.63%-1.30%, averagely 0.87%. The content of organic macerals ranges from 0.27% to 3.66%, averagely 2.08%, with 95.24% of the samples above 1.0%, indicating that the organic matter abundance is at relatively good-good level. The vitrinite reflectance(R_o) is 1.26%-2.58%, averagely 1.88%, with that of 90.47% of the samples more than 1.3%, showing the organic matter is in high mature-overmature stage. The hydrogen index of rock pyrolysis is 8×10^-3-89×10^-3, averagely 27.52×10^-3, reflecting that the organic matter belongs to III-type. It is concluded from the comprehensive evaluation that the source rocks of Upper Permian Linxi Formation are relatively good-good, with great hydrocarbon potential and good prospect of oil-gas resources.