近岸水下扇砂砾岩沉积特征及扇体分布规律

近岸水下扇是在陆相湖盆陡坡带发育的一种重要油气储层类型,沉积特征复杂,扇体多期叠置.在系统观察岩心和精细地层对比的基础上,结合地震、测井等资料,详细分析了东营凹陷北部陡坡带胜坨地区坨123断块沙四段近岸水下扇砂砾岩体的沉积特征和扇体分布规律.研究表明,近岸水下扇岩性以砂砾岩、含砾砂岩为主,粒度特征、电性特征、沉积构造、...

Depositional characteristics of glutenite and distribution pattern of fan on nearshore subaqueous fan

The nearshore subaqueous fan is a type of important hydrocarbon reservoir,which developed in the steep slope zone of continental faulted basin.The fan bodies were formed by multiphase fans,and the depositional characteristics are very complicated.Based on core observation and stratigraphic correlation and combined with seismic data and well logging data,the depositional characteristics of glutenite and fan distribution laws in nearshore subaqueous fan are analyzed for the fourth member of Shahejie Formation of Tuo 123 block in Shengtuo Area of northern steep slope zone of Dongying Depression.The study shows that the lithology of nearshore subaqueous fan is mainly the glutenite and pebbled sandstone.The grain size characteristics,logging responses,sedimentary structure and seismic reflections indicated the depositional environment with density current feature.The single-stage fan can be divided into six kinds of depositional microfacies,including main body of middle fan,front of middle fan,lateral margin of middle fan,outer fan,lacustrine mud and turbidite sand body.The single-stage fan body went into the lacustrine sedimentation with same angle along the provenance orientation.The fan bodies in the region of main part of middle fan override directly to form the thick glutenite bodies because of the absent of the depositional interface in the different stage fan bodies.The mudstone intercalations among the different-stage fans are intact in the region of the front of middle fan and outer fan.The distribution scale of the fan bodies tapered off in ascending order and retrograded to northern provenance step by step.