DISTRIBUTION OF METHYL PHENANTHRENE IN SEDIMENTS AND ITS IMPACTING ON MATURITY PARAMETERS

In this paper,the distribution features of methyl phenanthrene from some coals in Jiyang Depression and some hydrocarbon source rocks in Bonan Sag were analyzed.The results show that the sedimentary environment and the biologic source have a great influence on the distribution of methyl phenanthrene.In Bonan Sag,the 9-methyl phenanthrene is more abundant than 1-methyl phenanthrene in the lake facies sediments with lower hydrobios being the dominant species.The relative abundances of 3-methyl phenanthrene and 2-methyl phenanthrene increase in the hydrocarbon source rock under the salt lagoon environment and the methyl phenanthrene index is on the high side.But the index is on the low side in the fresh-brackish lake facies sediments.In the coals in Jiyang Depression,the 9-methyl phenanthrene is liable to form in the salty reducing environment with aboundant bacteria and alga,while 1-methyl phenanthrene is more abundant than 9-methyl phenanthrene in the weak oxidizing environment with higher plants being dominant species.The difference causing by biologic source should be considered in utilizing methyl phenanthrene index for evaluating maturity of organics.