塔里木盆地深层东河砂岩油藏剩余油地震预测——以东河1油藏为例

“长期浅埋”和“晚期快速深埋”的两段式深埋过程，在塔里木盆地深层形成了三项独特的地质特征：①深埋砂岩储层的物性保持较好，岩石孔隙度较大；②泥岩的速度、密度显著增大，一般大于砂岩；③储层内地层压力大、耐压性好、不易变形。上述特征成为塔里木盆地深层剩余油地震预测的重要地质基础。根据东河1油藏的实际参数建立了东河砂岩油藏的储层地质改造模型，开展了地震定量研究，结果表明：①含水饱和度上升、泥质含量下降均引起反射振幅减小，0~100%范围内的含水饱和度变化与10%~0范围内的泥质含量变化产生的振幅变化相当；②孔隙度上升引起反射振幅增大，14%~24%范围内的孔隙度变化产生的振幅变化10倍于10%~0范围内的泥质含量变化产生的振幅变化；③在本文假设条件下，孔隙度上升与泥质含量下降是共生关系，两者产生的振幅变化同时出现、方向相反，综合响应以孔隙度变化产生的振幅变化为主。以油藏开发中后期新采集的地震资料为基础，结合注水井和高含水采油井的相对位置分析目的层反射振幅平面图上的明显分块特征，即可识别长期水驱开发活动引起的储层物性定向改变与油水置换作用的综合响应区域，确定主要的注水受效方向和近似的水驱前缘形态、边界，其外部即为主要的剩余油富集区，并得到东河1油藏新钻井的验证。

Residual oil prediction on seismic data in a deep sand reservoir,Tarim Basin: A case study of the Reservoir Donghe 1

Deep burial reservoirs in Tarim Basin went through long-period shallow buried and rapid deep burial.This two-stage burial process forms three unique geological conditions:①Physical properties of deep buried sand reservoirs are well kept with medium or good porosity; ②The velocity and density of mudstone are obviously increased,generally larger than sandstone; ③Reservoirs have large internal pressure and good anti-compression ability,they are not easy to be deformed.All these constitute an important geological foundation for the residual oil prediction in deep burial sand reservoirs in Tarim Basin on seismic data.Based on available data of Donghe 1,geological models of sand reservoirs are reconstructed,and a seismic quantitative prediction is carried out.The following understandings are obtained:①Both water saturation increase and shale content decrease can weaken of seismic amplitude,and the influence of water saturation variation in the range of 0~100% is equivalent to that of the shale content variation in the range of 10%~0; ②The porosity increase can strengthen the amplitude,and the influence of porosity variation in the range of 14%~24% is ten times more than that of shale content variation in the range of 10%~0; ③Under the assumption of this article,the porosity increase and the shale content decrease form a symbiotic relationship,and their influence on the amplitude appears at the same time but in the opposite direction,the overall response is mainly caused by the porosity variation.Based on a newly acquired 3D seismic data associated with the position of injection wells and high water-cut production wells,target plots are characterized by distinct amplitude blocks.So we can distinguish response areas of reservoir physical orientation change from that of oil-water replacement caused by long-term water flooding,and then confirm the main effective direction of water injection and the approximate boundary shape of the water flooding front.Remaining oil enrichment areas are located outside.Such observations are proved by newly drilled wells in the Donghe 1 Area.