海相砂岩油藏沉积微相特征及对剩余油的控制——以南海东部X油田为例

Sedimentary microfacies characteristics of marine sandstone reservoirs and their control on remaining oil——by taking X oilfield in the east of South China Sea as an example

X油田为南海东部典型的海相砂岩油田,开发中后期剩余油特征不清晰,充分利用动静态资料,展开沉积微相及动油水界面研究。结果表明:研究区油藏范围内发育水下分流河道主体、河道侧缘、河口坝、远砂坝及分流间湾等微相,河道主体厚度较大,动油水界面在构造高部位趋于水平;河道侧缘、河口坝、远砂坝等砂体储层较薄,横向连续性受物源方向控制,在开发中后期,来水方向受砂体展布方向控制,波及程度较弱,从而产生剩余油富集区。

X oilfield is a typical marine sandstone oilfield in the eastern South China Sea,but the characteristics of remaining oil in the middle and late stage of development are not clear.By making full use of dynamic and static data,the research on sedimentary microfacies and dynamic oil-water interface was carried out.The results show that underwater distributary channel main body,channel side edge,estuary bar,distal sand bar and interdistributary bay are developed within the oil reservoir in the study area,the main body of the channel is thick,and the movable oil-water interface tends to be horizontal at the high part of the structure.Sand bodies such as channel side source,estuarine bar and far sand bar have thin reservoirs,and the horizontal continuity is controlled by the source direction.In the middle and late stage of development,the watered-out direction is controlled by the distribution direction of sand bodies,and the degree of spread is weak,resulting in residual oil enrichment areas.