地层系数法确定气井的产能方程

Determination of productivity equation of gas well using formation coefficient

气井产能方程是认识气井生产规律和分析预测气藏动态的重要依据,是确定合理的气井产量或气藏产量的基础.目前用于确定低渗透气井产能方程的方法存在诸多局限性.本文提出一种简便的确定气井产能方程的方法——KH值法.该方法将修正等时试井资料得到的无阻流量与单点法二项式公式计算的无阻流量进行对比,当二者相等时,可以获取非达西系数D,然后根据同一区块上的测试资料得到其他的储层物性参数,从而求得该区块的产能方程通式,进而根据每一口单井的实际地层系数得到该单井的产能方程.与实际生产数据对比表明,采用该方法得到的单井产能方程符合气井的实际生产规律.

The productivity equation of gas wells is the important basis for understanding the production rule of the gas wells and analyzing and predicting the performance of gas reservoir,and it is also the base for determining the reasonable yield of the gas well or gas reservoir.The present methods for determining productivity equation of gas well are of their limitations,so a new method is put forward.This method determines the productivity equation of gas well by formation coefficient KH.To be specific,comparing the open-flow capacities obtained by modified time-contour well test with single point productivity test,the non-Darcy flow coefficient D can be determined when the open-flow capacities obtained by two methods are equal or close.And then,other reservoir physical property parameters(such as gas viscosity,gas density,compressibility factor,gas reservoir temperature and skin factor) are got according to the test data in the same block by average method.The general formula of productivity equation for the gas reservoir can be obtained,and then the productivity equation of single well can be obtained if its KH is known.Verified by production data,the single-well productivity equation accords with the factual production law of the gas well.