考虑非达西流的低渗透油藏水力压裂优化研究

Optimization of hydraulic fracturing considering non-Darcy flow in low permeability reservoirs

建立充分考虑低渗透油藏渗流特征以及压裂井导流能力失效性的数学模型,并在原有黑油模拟器的基础上,实现该模型的数值求解。以井生产时所诱发的压力波为基础,基于渤海湾某低渗透油田实际数据,从极限波及区域的角度对水力压裂进行优化研究。结果表明:压裂后波及区域的增加是单井增产的主要原因;发生井间干扰时,干扰部位的极限波及区域形态可以比较直观地反映井网控制程度及剩余油分布情况;可以根据注水井和采油井在投产后压力波及系数变化开始减缓时的波及区域,确定压裂注采井的合理井距,当注采井连线与裂缝方向的夹角大于70°时,井组系统和裂缝系统的匹配性最优。

A mathematical model was established considering non-Darcy flow in low permeability reservoirs as well as fracture flow conductivity failure, and the numerical solution was obtained based on the existing black oil simulator. A real Bohai reservoir model was developed to analyze hydraulic fracturing treatment on the basis of pressure propagation during well producing. The results show that the increase of drainage area after fracturing is the main factor of productivity improvement. When the well interference occurs between oil and water wells, the maximum drainage area of disturbance parts can directly reflect well pattern control degree and residual oil distribution. According to the drainage area that pressure spread speed begins to slow down during well producing, the reasonable injector-producer spacing is confirmed. The key factor of integral hydraulic fracturing is to make well system and fracture system be a perfect match. Taking the basic well unit as example, the optimum assembly of well unit and fracture system is gained when the angle between the fractures and the injection-production well line is above 70°.