Evaluation of hydrocarbon generating conditions of Palaeogene source rocks from Xidalinzi Sag in Sanjiang Basin

The Palaeogene source rocks from the Xidalinzi Sag of the Qianjin Depression of the Sanjiang Basin were evaluated systematically and were compared with those from the Yishu Graben.In the Xidalinzi Sag,mudstones developed well in Palaeogene,especially in the Baoquanling Formation.From the 2nd member of the Baoquanling Formation to the Dalianhe Formation,the organic abundance of mudstones increased and the organic type gradually improved;however,the maturity of organic matters was lower,generally during the immature and low mature stages.The mudstones in the Dalianhe Formation and the lower part of the 1st member of the Baoquanling Formation served as the effective source rocks for the Xidalinzi Sag which has good exploration prospect.