THE ORGANIC-RICH HYDROCARBON SOURCE ROCKS AND THEIR RESOURCE POTENTIALS IN JIYANG DEPRESSION

The organic-rich hydrocarbon source rocks in Jiyang Depression are analyzed for their main sedimentary and geochemistry characteristics and resource potentials. The E (2-3)s~l 3 organic-rich hydrocarbon source rocks was found first during the seventh five year plan in the well Niu38, then followed by E (2-3)s~u 4 and E (2-3)s~l 1. The three sedimentary unit all belong to the lacustrine transgression system tracts of different third-order sequence formed during the basin intense rift stage. The lithology assemblages consist mainly of deep-lacustrine shale, oil shale and laminated mudstone with strong sedimentary rhythm, which indicate that the sedimentary environments bear some characteristics of closed lake and favor the formation and preservation of organic matter. The hydrocarbon source rocks all have high abundance of organic matter, high hydrocarbon potential and show great heterogeneity. The resource evaluation history analysis and oil and source correlations show that the giant oil fields in Jiyang depression are mainly associated with the organic-rich hydrocarbon source rocks.