修正二项式产能方程在致密气藏中的应用

Application of modified binomial productivity equation in tight gas reservoirs

目前致密气藏产能研究主要考虑压敏效应和启动压力梯度,极少考虑滑脱效应,且缺少相应的非达西渗流影响程度评价方法。因此,针对致密气藏的渗流特征,通过设置拟压力函数,采用等值渗流阻力方法,推导了非达西渗流特征影响下的气井产能方程,并修正了二项式产能方程,进行了敏感性分析。实例计算表明:压敏效应影响最大,启动压力梯度和滑脱效应次之,但不能忽略其对水平气井产能的影响。滑脱效应使气井产量升高,平均升高幅度约为1. 91%;压敏效应使气井产量降低,最大可降低13. 72%,平均降低幅度约为7. 19%;启动压力梯度使气井产量降低,平均降低幅度约为1. 86%。修正二项式产能方程在致密气藏中的应用,为致密气藏产能建设及其优化提供了一定的技术支持。

The pressure-sensitive effect and starting pressure gradient are the main considerations in the present study of tight gas productivity,while the slippage effect is seldom considered.Moreover,the evaluation method for the impact degree of non-Darcy seepage is needed to set up.Therefore,according to the seepage characteristics of tight gas reservoirs and through setting up the pseudo pressure function,the productivity equation of gas well was derived under the influence of non-Darcy seepage characteristics with equivalent seepage resistance method.The binomial productivity equation was corrected;the sensibility analysis was made as well.Actual calculation showed that pressure-sensitive effect was the most significant,starting pressure gradient and slippage effect were secondary,but the effect of those on the productivity of horizontal gas well can′t be neglected.The slippage effect enhances the gas well production with the average increment of about 1.91%;the pressure-sensitive effect reduces the gas well production with the maximum decrement of 13.72%and the average decrement of 7.19%;and the starting pressure gradient reduces the gas well production with the average decrement of about 1.86%.The application of modified binomial productivity equation in the tight gas reservoirs can provide a certain technical support for productivity construction and optimization of tight gas reservoirs.