非均质低渗透气藏压裂直井产能计算

Productivity calculating study of fracturing vertical well in low-permeability heterogeneous gas reservoir

针对低渗透气藏非均质性对气井产能的影响,文中给出了6种渗透率非常数分布模式,综合考虑低渗透气藏启动压力梯度和应力敏感效应的影响,将考虑应力敏感效应的非均质渗透率构型引入启动压力梯度函数的表征方程,进而得到低渗透气藏的压裂直井产能方程。实例计算说明推导的产能方程具有可靠性,通过产能曲线分析了渗透率构型、启动压力梯度和应力敏感对压裂直井产能的影响。结果表明:当渗透率递减时,线性递减型产量高,对数递减型产量低;当渗透率递增时,对数递增型产量高,线性递增型和指数递增型产量低;气井的产能随启动压力梯度特征参数和应力敏感系数的增大而降低,但随着应力敏感系数的继续增大,气井产量的降幅逐渐减小。

Aiming at the influence of heterogeneity of low-permeability gas reservoir on gas well productivity, six kinds of permeability distribution models are given in this paper. Considering the influence of low pressure gas reservoir start-up pressure gradient and stress sensitivity effect, the heterogeneous permeability configuration considering stress sensitive effect is introduced into the characterization equation of start-up pressure gradient function, and the fracturing vertical well productivity equation of the low permeability gas reservoir is obtained. The example calculation shows that the derived productivity equation has reliability. The influence of the permeability configuration, the start-up pressure gradient and the stress sensitivity on the productivity of the fractured vertical well is analyzed by the productivity curve. The results show that when the permeability decreases, the linear decreasing type permeability is higher, the yield is higher, and the logarithmic decreasing type yield is lower. When the permeability increases, the logarithmic increasing type yield is high, and the linear increasing type and the exponential increasing type are low.The productivity of the gas well decreases with the increase of the start-up pressure gradient characteristic parameter and the stress sensitivity coefficient, but as the stress sensitivity coefficient continues to increase, the gas well production decreases gradually.