三江盆地西大林子凹陷古近系烃源岩特征及勘探潜力

Evaluation of Palaeogane Source Rock Characteristics and Potential of Exploration in Xidalinzi Depression of Sanjiang Basin

三江盆地西大林子凹陷勘探程度较低,其主要目的层一直被认为是上白垩统,前参1井钻探揭示其为上白垩统之上沉积的一套新近系-古近系湖相地层,新近系富锦组不发育泥岩,古近系宝泉岭组、达连河组、新安村组和乌云组泥岩发育。对古近系烃源岩的研究结果表明,烃源岩有机碳含量较高,烃源岩有机质类型主要为Ⅱ2,少量Ⅱ1型和Ⅲ型,烃源岩热演化程度较低。宝泉岭组和达连河组上部（〈2000m）处于未成熟阶段,达连河组下部、新安村组和乌云组烃源岩处于低成熟阶段。与具有相同背景的依舒地堑对比,西大林子凹陷的未成熟-低成熟烃源岩具有一定的生物气和石油勘探潜力。

The exploration degree was low in Xidalinzi Depression of Sanjiang Basin,it was considered that the key target zones were in Cretaceous system.Drilling of Well Qiancan 1 indicated that there were a set of lake facies strata of Neogene and Palaeogane Systems above it,and mudstones were not grown in Fujin Formation and not grown in Baoquanling Formation,Dalianhe Formation and Xinan Formation of Eogene System.The results of study show that the content of organic carbon is higher and organic matteris mainly of type Ⅱ2 and less of types Ⅱ1 and III with low level of thermal evolution.The source rocks from Baoquanling Formation and the upper part of Dalianhe Formation(less than 2000m) are non-matured,however,the source rocks form the upper part of Dalianhe Formation,Xinancun and Wuyun Formations are at low mature stage.Generally speaking,non-mature and lower matured source rocks in Xidalinzi Depression have certain potential for future exploration of biogenic gas and oils.