Deep-Water Turbidite Fan Deposits and Relation to Hybrocarbon of the Upper Sha-4 of Shahejie Formation at Yong-55 Block in Dongying Sag

Deep-water turbidite fans are widely developed in the upper part of the fourth member of Shahejie Formation at Yong-55 block in the north steep slope of Dongying sag.They are among the best reservoirs in the area.The characteristics of sedimentary sequence are studied on the conglomerate body in Yong-55 block with drilling core discription,thin-section and grain size analysis,seismogram and logging.It is showed that the conglomerate body had low compositional maturity and textural maturity.Results of grain size analysis showed that graded suspending was the main transportation way of the clasts.Most of the sedimentary structures were generated by gravity flow.Bouma sequence is recognized from the core observing.The turbidite fan's depositional models are summarized.According to the characteristics of sandstone and conglomerate bodies,the turbidite fan can be subdived into three subfacies,including inner fan,middle fan and outer fan.The sandy conglomerate bodies of brained channel in middle fan are the good reservoirs.Dark mudstone of lake facies containes hybrocarbon source rocks and good cover rock.It was proved that the deep-water turbidite fan deposits have good potentials for oil and gas accumulation.