低渗透油藏混合井网极限注采井距确定新方法

New method for determining the limit injection production well spacing of hybrid pattern in low permeability reservoir

为确定低渗透油藏混合井网极限注采井距,以新疆油田某低渗透油藏为例,引入压力梯度特征等值线的概念,并借助于comsol仿真软件建立物理模型,在模型中采用试算法,达到实际注采压差下压力梯度特征等值线恰好经过压裂水平井裂缝端点,得到极限注采井距,同时分析了压裂水平井的裂缝条数、裂缝间距和裂缝半长对极限注采井距的影响。通过上述研究表明:随着压裂水平井裂缝条数、裂缝间距的增大以及裂缝半长的减小,混合井网极限注采井距减小;注水井位于2条裂缝之间时波及效果好;裂缝间距比裂缝半长对注采井距的影响大,裂缝间距超过160m时混合井网极限注采井距减小幅度加大。

To determine the limit injection production well spacing of mixed well pattern,a low permeability reservoir in Xinjiang Oilfield was taken as an example.The concept of pressure gradient feature contour was introduced,and the physical model was built by using the comsol simulation software according to the geological characteristics of a practical low permeability reservoir.The fracture of the fractured horizontal well was in touch with pressure gradient feature contour under the actual injection production pressure,which was the constraint condition.By trial and error method,injection production well distance need to be continuous adjusted until meet the constraints,so the ultimate injection production well spacing can be decided.The influence of the crack number,the crack spacing and the crack length on the limit injection production well were also analyzed.Results show that with the increasing of the number of the crack,the crack spacing and the decreasing of half length in the mixed well,the distance between injection and production wells is reduced.There is a good effect on waterflood sweep area when the water injection well is located between the two cracks.The crack spacing has a greater influence on limit injection production well distance than the crack half length in mixed well pattern.When the crack spacing exceeds 160 m,the limiting injection production well spacing decreases faster.