塔河断溶体油藏典型断溶体注水驱替规律及剩余油分布特征

Study on water drive law and characteristics of remaining oil distribution of typical fault-karst in faultkarst reservoirs,Tahe Oilfield

塔河断溶体油藏受岩溶水选择性溶蚀和裂缝发育程度的影响,油藏内部结构极其复杂,缝洞体分隔性明显,非均质性极强,导致注水驱替规律认识困难。为此,以油藏储流关系和5种典型断溶体为基础,根据流体动力学,侧重从注入速度、注采位置和裂缝发育程度3个方面对5种典型断溶体的注水驱替规律和剩余油分布特征开展数值模拟研究。结果表明:"Y"字型和复合型2种断溶体随着注入速度增大和注采位置由低到高,驱替效率均不断提高,而"V"字型、"T"字型和条带型3种断溶体的驱替效率受注入速度和注采位置影响较小;裂缝发育降低了断溶体的注水驱替效率;剩余油分布取决于注采位置和断溶体间的连通方式,主要分布在非优势流动通道的分支断裂溶洞、小型突起和断溶体的底部。

Influenced by selective dissolution and fracture development degree,fault-karst reservoirs in Tahe Oilfield have the characteristics of extremely complex inner structure and obvious fracture-vug separation,which results in difficulty in understanding of water flood development.Based on the relationship between storage and flow in the oil reservoirs and five typical types of fault-karst,numerical simulation was carried out to study water drive law and remaining oil distribution characteristic of the five typical types of fault-karst from the aspects of injection velocity,injection-production position and fracture participation based on fluid dynamics.The results show that the displacement efficiency of the type"Y"faultkarst and the compound type fault-karst increases continuously when the injection velocity increases and the injection-pro-duction position changes from low to high.However,the displacement of type"V"fault-karst,type"T"faultkarst and belt-shaped fault-karst are hardly influenced by the above factors.The existefficiency ence of fractures makes the displace-ment efficiency of the fracture-karst decrease.The distribution of remaining oil depends on the injection-production posi-tion and the connectivity mode of the fracture-karst.The remaining oil mainly distributes in bypass fault-karst of non-dom-inant channel,small arch and the bottom of fault-karst.