考虑气体加速效应的高压气井产能方程推导及其应用

高压气体径向渗流中气体加速效应非常显著,因此传统二项式或三项式产能方程中的非Darcy项不能反映带有气体加速效应的非Darcy渗流特征.气体加速效应影响的忽略导致无阻流量计算的误差增大,不利于合理产能和开发方案的确定.采用考虑了气体加速效应的高压气体运动方程,通过质量守恒方程、真实气体状态方程和气体运动方程,推出考虑加速效应的高压气井产能新方程,此方程同样可反映传统的二项式产能方程,提高了无阻流量的预测精度.由于此方程没有解析解,采用类比法进行简化,再利用试凑法,求解此产能方程的相关系数.为了验证准确性,将该方程应用到了四川盆地高压气藏西35?1井的试井资料中,其解释结果与陈春燕和罗银富等所得结果进行对比分析,结果表明该方法所获得的产能精度明显提高,并且能够消除随着压差增大而产能相对误差增大的弊端,更加有利于高压气井无阻流量的精确计算.研究结果丰富了高压气井产能预测方法,同时无阻流量的准确计算保障了高压气井合理产能的确定.

Derivation and Application of Productivity Equations for High-Pressure Gas Reservoirs With Gas Acceleration Effects

Non?Darcy flow in a gas well cannot be expressed with traditional binomial equa?tions or trinomial equations for ultra?deep high pressure gas reservoirs,which leads to large er?rors of open flow capacities for the neglect of gas acceleration effects.A new method was pres?ented with gas acceleration effects.Under the assumption of high?pressure radial gas flow,through combination of the continuity equation,the Darcy?Forchheimer equation with accelera?tion and the isothermal state equation,the productivity equation was derived.The proposed e?quation is also able to replace traditional binomial equations,but has no analytical solution.It can be simplified by analogy,and the related coefficients can be solved by trial and error.The application of the proposed method in data process of ultra?deep high pressure gas well XI 35?1 in Sichuan Basin is effective,and the comparison with the real production data proves the pre?cision of the calculated productivity.The proposed method avoids the disadvantages of the rela?tive error increase with the differential pressure.The work enriches the productivity prediction methods,with accurate calculation of open flow capacities and reasonable determination of high pressure gas well productivities.