低渗透油藏不同井网系统注采井距研究

根据渗流理论,推导了水平井注采井网井间压力及压力梯度分布公式,分析了水平井注采井网、混合井网和直井井网不同井网系统沿程压力及压力梯度分布规律,提出了低渗透油藏极限注采井距确定方法,并对其影响因素进行了分析。结果表明,直井井网系统驱替压力梯度在注采井附近较大,而在注采井间较大范围内较小;水平井井网系统的流体在注采井间内为近似线性流动,压力降几乎呈线性变化,压力损失明显低于直井,具有更大的驱替压力梯度,且沿程基本保持不变。因此对于低渗透油藏,水平井注采井网更容易形成有效驱替,其极限注采井距为直井井网的3~4倍,混合井网的2~3倍。

Injection-production well spacing of low permeability reservoir under different well pattern systems

Based on the seepage theory,the formulas of interwell pressure and pressure gradient under different injection-production well patterns,namely injection-production pattern,the combination well pattern and the vertical well pattern,for the horizontal wells have been derived,and the pressure along various well patterns and the pressure gradient distribution regularity have been analyzed.The determination method for the critical injection- production well spacing of low permeability reservoir has been established and its influencing factors have also been analyzed.The results indicate the displacement pressure gradient of the vertical well pattern is bigger around the injection-production wells,while when the injection-production well spacing is bigger,the pressure gradient is relatively smaller.Its displacement pressure gradient is approximately 3~4 times as much as the vertical wells pattern.It is easier to create an effective displacement for combination pattern compared to vertical wells pattern,and it can take greater injection-production well spacing.