莱州湾凹陷沙三段低位域湖底扇沉积特征及水道构型

莱州湾凹陷沙三段低位域发育断裂斜坡背景下的湖底扇，具有明显地震反射外形，但湖底扇内部结构杂乱，砂体垂向叠置关系及平面富集位置在勘探及早期评价阶段难以预测，基于钻井、测井、分析化验及三维地震资料,依据湖底扇重力流水道流变学性质及流体浓度分类的原则，将湖底扇水道砂体成因搬运机制分为滑动、滑塌、碎屑流、浊流，其中碎屑流分为泥质碎屑流和砂质碎屑流，结合不同成因搬运机制的水道砂体地震反射特征，在湖底扇不同相带识别刻画5种沉积结构单元，分别是叠覆型水道、复合型水道、水道侧翼、单一型水道及水道间，并通过模型正演验证不同单元分类可靠性及富砂差异。结果表明，内扇叠覆型水道发育多期滑动-滑塌沉积，储层总体厚度大，中扇低部位复合型水道发育砂质碎屑流储层物性好，二者均为油气勘探实施钻探的有利部位，外扇储层发育程度较低。来自肯东凸起物源的高建设性辫状河三角洲为湖底扇提供大量砂质基础，坡折带与古地貌共同控制湖底扇沉积搬运机制和水道走向及水道类型。

Sedimentary Characteristics and Channel Configuration of Lowstand System Tract Sub Lacustrine Fan in theThird Member of Shahejie Formation, Laizhouwan Sag

Sub lacustrine fan on the background of fault slope development in the lowstand system tract of the third member of the Shahejie Formation, Laizhouwan sag.It has a clear seismic reflection geometric appearance, but the internal structure of the sub lacustrine fan is chaotic, the vertical stacking relationship and plane enrichment position of the sand body are difficult to predict in the exploration and early evaluation stages.Based on drilling,logging,laboratory date,and three-dimensional seismic data, the principles of rheological properties and fluid concentration classification of gravity flow channels in sub lacustrine fan are applied, the sedimentary transport forms of gravity flow are divided into sliding, collapse, debris flow and turbidity flow, Based on the seismic reflection characteristics of channel sand bodies with different genetic transport mechanisms, five sedimentary structural units were identified and characterized in different facies zones of the sub lacustrine fan,they are stacked channels, composite channels, channel wings, single channels, and inter-channels,in addition, verify the reliability of different unit classification and the differences in sand content through model forward modeling.The results indicate that the superimposed channel of the inner fan has developed multi-stage sliding collapse sedimentation, and the overall thickness of the reservoir is large. The composite channel in the lower part of the middle fan has developed sandy debris flow reservoirs with good physical properties, both of which are favorable locations for oil and gas exploration and drilling.The development level of the outer fan reservoir is relatively low. The highly constructive braided river delta from the Kendong uplift provides a large amount of sandy foundation for the sub lacustrine fan, and the slope break zone and ancient landforms jointly control the sedimentary transport mechanism, channel direction, and channel type of the sub lacustrine fan