砂砾岩体是断陷盆地陡坡带主要的油气储集体。结合地震、测井、录井、岩心、镜下薄片、粒度分析、孔渗化验等资料,对山东省东营市盐家油田永921—920区块沙四上亚段砂砾岩体的沉积特征、成因机制及储层特征进行了研究。结果表明,该区块砂砾岩体受控于北部边界断裂控制的近岸水下扇,岩石结构成熟度与成分成熟度均低,粒度概率曲线发育缓慢上拱形与低斜两段式以及块状层理、反粒序层理、鲍马序列(Ta,Tb,Td段)、截切构造、泥岩撕裂屑、滑塌揉皱变形层理等均反映了重力流沉积特.电,同时也可见槽状交错层理、平行层理、沙纹层理及水平层理等反映引流的沉积构造;识别出4期砂砾岩扇体,早期叠置连片,晚期孤立分散,呈退积型沉积复合体,第Ⅰ、Ⅱ及Ⅲ期上部砂砾岩体储层质量较好,其中扇中辫状水道物性最好,扇中前缘与内扇主水道物性相对较差。
Glutenite fan is the main reservoir body in the steep slope zone of fault basin. Three-dimensional seismic, well-log, core, thin section, grain size and por-pemeability data from the upper Es4 member, Yong 921-920 area in Yanjia Oilfield, are integrated to investigate its sedimentary types, genetic mecha- nism and reservoir characteristics. These glutenite fans present in nearshore subaqueous fan are controlled by the boundary fault in northern study area. The compositional maturity and textural maturity of gluten- ite are relatively lower in this area. Two main grain size accumulation curve types are identified, which are uphill arched arc and low slope two segments patterns. Massive bedding, inverse bedding, Bouma se- quence (Ta, Tb, Td section), truncated structure, mudstone torn scraps, crumpled deformed bedding slump can be identified which reflect gravity flow sedimentation. Trough cross-bedding, parallel bedding, ripple bedding and horizontal bedding which reflect traction current flow were also observed. Four periods of glutenite fans are identified as a retrograding depositional sequence. The reservoir quality is good in the Ⅰ Ⅱand upper Ⅲ phase of glutenite, especially, braided channel sandbodies are better than main channel and middle fan fronts_