Characteristics Of Source Rocks And Gas-source Correlation In Dehui Fault Depression,Songliao Basin

This thesis attempts to analyze the distribution and geochemical characteristics of source rocks,and types and sources of the natural gases in the Dehui fault depression.This will lay the foundation for further study of accumulation model,selecting favorable exploration targets and expanding exploration achievements in the fault depression.The geological distribution,organic abundance,organic matter type and organic matter maturity of the three sets of deep source rocks in the Dehui fault depression were studied systematically using our data,combining with previous studies.The results show that the source rocks of the Dehui fault depression are widely distributed,with high organic matter abundance,moderate hydrocarbon generation potential,type II and Type III kerogens,and at mature to highly mature stages.The three sets of source rocks mainly generated natural gas.The source rocks of the Huoshiling formation are the best in quality,followed by those of the Shahezi formation.According to the analyses of the characteristics of natural gas composition,carbon isotope and biomarker compounds in the Dehui fault depression,we can know that the geochemical characteristics of natural gas in the various strata of the fault depression are similar,and all of gases are mainly coal-derived gas,with only a small amount of oil-derived gas and mixture gas.The natural gases from the Denglouku formation and Yingcheng formation are derived from the mixed sources of the three sets of source rocks.The natural gas from the Shahezi formation is mainly derived from the source rocks of Shahezi formation itself and is slightly mixed by gas from the Huoshiling formation source rock.The gas from Huoshiling formation is from the source rock of Huoshiling formation itself.