托普台南区块断溶体油藏栅状断片结构数值模拟

Numerical Simulation of Grid⁃Like Fragmented Structure of Fault⁃Karst Reservoirs in Southern Tuoputai Block

塔河油田托普台南区块断溶体油藏开发初期产量高,后期暴性水淹和快速见水井多,产量递减快,针对此类特征,目前尚未建立较好的模拟方法。结合断溶体油藏岩溶特征、地震特征、实钻井井储关系以及三带结构提出断溶体油藏栅状断片结构,根据此认识,通过融合断层自动提取技术和蚂蚁体属性,得到断裂指示因子,用以刻画栅状断片储集体,利用张量属性刻画溶蚀孔洞型储集体,建立双重介质组分模型,开展数值模拟研究。结果表明:栅状断片结构是断溶体油藏的主要导流通道;断裂指示因子比断层自动提取技术和最大似然更适合表征栅状断片结构,并在通水源处与张量属性匹配度高,在其他区域匹配性差;与单重介质模型相比,基于栅状断片结构的双重介质模型拟合精度更高,更能反映断溶体油藏生产动态特征。

The fault⁃karst reservoirs in the southern Tuoputai block of the Tahe oilfield exhibit a high initial production capacity,but a sharply declining production in the late development stage due to serious water flood and rapid water breakthrough occurred in many wells.There is no efficient simulation method for this phenomenon.Based on the karst features,seismic characteristics,actual well⁃reservoir configuration,and three⁃zone structure of fault⁃karst reservoirs,a grid⁃like fragmented structure of the fault⁃karst reservoirs was proposed.Accordingly,by combining the automatic fault extraction(AFE)technology with the ant body attributes,the fracture indicator was derived for characterizing the grid⁃like fragmented reservoir.Tensor attributes were used for characterizing the karst⁃vug reservoir,and a dual⁃porosity compositional model was established for numerical simulation.The results indicate that the grid⁃like fragmented structure serves as the primary flow channel in fault⁃karst reservoirs.The fracture indicator is better applicable to characterize the grid⁃like fragmented structure than AFE and maximum likelihood,and it is highly compatible with tensor attributes in water source zone but poorly compatible in other areas.Compared to single⁃porosity model,the dual⁃porosity model based on the grid⁃like fragmented structure can offer higher matching accuracy and better reflect the production performance of the fault⁃karst reservoirs.