Geochemical Characteristics and Hydrocarbon Generation Potentials of Chang 10 Source Rock in Wuqi-Zhidan Area,Ordos Basin

There is a set of dark lacustrine mudstones in the upper part of Chang 10beds in Wuqi-Zhidan area,Ordos Basin.Evaluation of the geological and geochemical characteristics and hydrocarbon generation potential of this set of source rocks is very important for the oil/gas exploration in Wuqi-Zhidan area.The authors studied the distribution of Chang 10bed dark mudstones through core and well log data and evaluated the hydrocarbon generation potential of Chang 10source rock based on the analyses of rock pyrolysis,micro-composition of kerogen,vitrinite reflectance,group composition of solvable organic matter,GC-MS of saturated hydrocarbon,and so on.The study illustrates that the dark mudstones of Chang 10bed spread widely and its thickness vary from 5mto 20m.Organic matter abundance and hydrocarbon generation conversion of source rock are high.The terrigenous plants which mainly attribute to type II and type III kerogen contribute enormously in source organic matter.Organic matter reached mature oil generation stage.In conclusion,they were determined to be relatively good-good source rocks.The biomarker compound of Chang 10source rock bed has high Pr/Ph ratio,oppositeLtype distribution ofααα20Rconfiguration C27、 C28and C29regular steranes,which differs distinctly from source rocks of Chang 7and Chang 9beds.The source rock of Chang 10bed,whose hydrocarbon generation quantity is large,is another important efficient source rock of Mesozoic Group in Ordos Basin and its discovery provides scientific evidence for further exploration of the bottom layer of Yanchang Formation in midland of Ordos Basin.