Evaluation Of Neogene Source Rock In Yiliping Area,Qaidam Basin

As a potential oil and gas exploration area in the Qaidam Basin,the Yiliping area has a favorable regional structural position with large thick Neogene strata deposited,and thick saline lacustrine source rocks.The study of organic matter characteristics in this area is the key to evaluate the source rocks and provides guidance for the next exploration.Based on the data of chloride ion content in the study area,the longitudinal and planar distribution characteristics of formation salinity were analyzed;then,the TOC,chloroform asphalt "A",the hydrocarbon generation potential,the asphalt group component,the kerogen microstructure,vitrinite reflectance,kerogen elements analysis,maximum pyrolysis temperature and gas chromatographic parameters were used to evaluate the abundance,type and maturity of organic matter.The relationship between salinity and organic matter abundance was also studied.The results show that: with the increase of salinity,organic matter abundance increases firstly and then decreases;on the whole,the abundance of organic matter in the study area is low,but there are high organic matter abundance in some formations;organic matter is generally in immature to low mature stage;the lower limit of organic matter abundance is TOC=0.3%;in Neogene strata,Shizigou Formation are the main source rock formations.Based on the above analysis,the favorable hydrocarbon generation area is mainly distributed in the Hongsanhan-Jianshishan structure and Yikeyawuru-Taijinaier structure.