Characteristics of palynofacies and its hydrocarbon generation potential of member 4 of Shahejie formation in Dongying depression

Key words:  petroleum geology  organic matter  core analysis  Dongying depression  member4 of Shahejie formation(Es4 )  source rocks  palynofacies  hydrocarbon generation potential

Abstract:

The source rock samples which were drilling cores from member 4 of Shahejie formation ( Es4 ) of Dongying depression underwent sporopollen processing in totally enclosed conditions. Based on this, the vertical sedimentary organics changes, the deep sedimentary environment evolution and the hydrocarbon generation potential were researched. The results show that the hydrocarbon source rocks of Es4 in Dongying depression are identified as three palynofacies and two sub-palyno-facies from bottom to up. Spores powder facies are charactered by woody tissue，particle amorphous and cavernous amorphous dominant position respectively, and sub-facies are distinguished by spores type and woody tissue abundance. The sedimentary environment of palynofacies includes edge turbidite, the occlusion salt lake developed in fan delta, the super occlusion salt lake of lasting layered，occlusion season layered half salt water deep lake and closed-open layered-half salt water mixed with deep lake, which indicates the sedimentary process of gradually deepen of ancient lake in Dongying. With the increase of water injection, water salinity gradually reduces and the productivity of lake increases. And the organic matter input varies from mainly by terrigenous supply to its own production in dominance. The organic matter abundance increases gradually and the hydrocarbon generation potential of source rocks varies from poor to the best.