考虑应力敏感的异常高压气藏产能新方程

A New Method of Deliverability Equation Considering Stress Sensitivity in Abnormal Pressure Gas Reservoirs

异常高压气藏随着天然气的采出,地层压力的降低,渗透率不可逆转地降低,即所谓的应力敏感现象。常规的二项式压力平方法和指数式经验产能方程由于没有考虑应力敏感现象无法建立适用于异常高压气藏的产能方程,而考虑了应力敏感现象的拟压力产能方程又由于计算过程复杂,难以在现场应用。二项式压力指数法在拟压力产能方程的基础上进行简化替代,实例结果表明,新方法与拟压力二项式产能方程计算出来的无阻流量相对误差小于10%,可以方便地用于异常高压气藏产能评价中。

In the production of natural gas in abnormal pressure gas reservoirs,formation pressure and permeability decreased irreversibly,it was so-called stress sensitive phenomenon.It was not accurate by using binomial pressure-square and common exponent methods to establish a proper deliverability equation in abnormal pressure gas reservoirs.While the pseudo-pressure deliverability equation considering the stress sensitive phenomenon was hard to be used in oilfields for complex calculation.However,a binomial pressure-exponent method was simplified and replaced on the basis of pseudo-pressure deliverability equation.Case study result indicates that the relative error of open flow potential between them is less than 10%.It is easy to be applied for deliverability evaluation in abnormal pressure gas reservoirs.