低渗透油藏混合井网系统合理注采井距确定

从渗流理论出发,首次推导了直井注-水平井采混合井网系统井间沿程压力与压力梯度分布公式,并对其分布规律进行了分析。结合物理模拟实验得到的启动压力梯度数学表达式,提出了计算低渗透油藏混合井网注采井距的方法,分析了注采压差、渗透率和水平段长度对注采井距的影响。研究表明,混合井网系统所需要的生产压差远小于直井井网,因此混合井网更容易形成有效驱替,可以采取更大的注采井距。

Study on Proper Well Spacing of Hybrid Pattern of Vertical Injector and Horizontal Producer in Low Permeability Reservoir

Based on percolation theory, the formulae of interwell on-way pressure and pressure gradient distribution for vertical injectorhorizontal producer hybrid pattern system are deduced for the first time, and their variations are analyzed. Integrated with mathematic expression of the start-up pressure gradients given by physical modeling experiment, the method for well spacing of this hybrid pattern in low permeability reservoir is proposed, by which the influences of injection-production pressure differential, permeability and horizontal section length on this well spacing are analyzed. The study shows that the producing pressure differential required by this hybrid pattern system is much smaller than that by vertical well pattern. It is easier to create an effective displacement compared with vertical wells pattern, and larger injection-production well spacing can be taken.