考虑应力敏感的产水气井产能方程

Deliverability Equation for Water-Production Gas Well Considering Stress-Sensitivity

在气藏开发过程中,随着地层压力下降,有效应力增加,孔隙度和渗透率均降低,再加上气井产水的影响,将导致气井产能大幅下降。为综合研究储集层应力敏感性和产水对气井产能的影响,基于渗透率随压力的指数式变化关系式,建立了考虑应力敏感的产水气井产能方程。通过推导与求解,获得了受应力敏感指数与水气比同时影响的二项式气井产能方程,提出了产能方程预测IPR曲线求解方法。最后结合实例进行分析,定量展示了应力敏感和产水对气井产能变化的影响,同时也证实了该产能方程的可靠性和实用性。

In the development process of gas reservoirs, the increase of effective stress, the descent of porosity and permea- bility with the decline in reservoir pressure and influence of the water output of the gas well will result in decreasing in the gas well productivity. With the increasing degree of reserve recovery, the gas-water ratio caused by water output of the gas well will be raised during production, meanwhile underground flow condition will be destroyed, eventually influence well flow potential. In order to study the influence of stress-sensitivity and producing water comprehensively, the deliverability model for water-production gas well with stress-sensitivity being taken into consideration is established based on the exponential re- lationship of permeability and pressure. Through the derivation and resolution of the model, binomial deliverability equation of gas well considering the affection of stress-sensitivity and water-gas ratio has been built up, at the same time the solving method to predicting IPR curve by deliverability equation has been given. Finally, the analysis combining a case shows that the deliverability model is reliable and practical.