确定低渗致密气藏气井无阻流量的方法

A METHOD TO DETERMINE THE AOF POTENTIAL OF GAS WELLS IN LOW PERMEABILITY TIGHT GAS RESERVOIRS

用稳定回压法或一点法求取低渗致密气藏的无阻流量时，不仅很难测得稳定的数据点，而且计算所采用的储层渗透率也偏大。为了解决上述问题，提出了针对低渗致密气藏的无阻流量确定方法——压裂稳态法。该法是基于稳定状态下的一种方法，考虑了低渗致密气藏的应力敏感特性，计算所需的参数都是存稳定状态下获得的，且地层渗透率采用的是储层裂缝闭合后的稳定地层渗透率。通过应用压裂稳态产能公式，采用迭代法就能计算出气井的无阻流量。压裂稳态法很好地解决了多点稳定试井耗时长，以及一点法计算结果偏高的问题。给出了实例计算，并与一点法计算的结果进行了对比分析。结果表明，压裂稳态法结果更准确。

When applying the stable back pressure method or one-point method to determine the AOF potential of gas wells in low permeability tight gas reservoirs, it will be difficult to obtain the stable test points and the calculated reservoir permeability is also lower. In order to solve these problems, a new method to determine the AOF potential, fracturing stable state method, is proposed in this paper in view of low permeability tight gas reservoirs. This technique is based on the steady state and the stress sensitivity of low permeability tight gas reservoirs is taken into account. All parameters used for calculation are obtained under the stable state and the value of formation permeability adapted is the stable formation permeability after the closing of reservoirs fractures. The AOF potential of gas wells can be calculated through iteration based on the stable state flow potential equation of fracturing. The stable fracturing method is not as time-consuming as multipoint open flow potential test, and the calculation results are not as higher as those of the one point method. Example calculation is established and the calculated result is compared with that of one point method. The result suggests that the results from the fracturing stable state method is more accurate.