东营凹陷永55区块沙四上亚段深水浊积扇沉积与油气

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

深水浊积扇是东营凹陷北部陡坡带永55区块沙四上亚段最发育的沉积相,也是最有利的砂砾岩储层。在岩心观察基础上,通过薄片鉴定、粒度分析等测试手段,综合地质、物探和测井资料,对永55区块砂砾岩体储层的沉积特征进行了研究。结果表明,本区深水浊积扇沉积具有如下特征:(1)岩石成分成熟度和结构成熟度均较低;(2)碎屑物质以递变悬浮搬运为主;(3)沉积构造具有典型的重力流成因特征;(4)岩心中见典型鲍马沉积序列。建立了深水浊积扇退积型沉积模式,并进一步细分为内扇、中扇和外扇3个亚相及4个微相。位于中扇的辫状沟道砂体物性好,可以构成优质储层,较深湖暗色泥岩为主要的烃源岩和盖层,本区生、储、盖发育齐全,有着良好的勘探开发前景。

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 chan- nel 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.