摘要
致密气藏的气水渗流会出现非线性特征,主要原因是受启动压力的影响。目前致密气藏的常规试井解释通常不考虑启动压力的影响,存在较大误差。针对此问题建立考虑启动压力和动边界影响的直井不稳定试井模型并求解,研究各因素对直井不稳定试井曲线特征的影响。结果表明,压力降落曲线晚期上翘段的斜率受到启动压力梯度大小的影响,启动压力越大,曲线上翘程度越大;动边界的影响主要在井筒储存阶段后,启动压力越大时,动边界向外扩展的速度越慢,出现边界反应的时间越晚;无量纲半径只影响动边界扩展到封闭外边界后的井底压力动态,无量纲半径越大,出现边界反应的时间越晚,稳定的井底流压越低。实际应用表明,气井的压力恢复曲线拟合效果良好,该模型适用于低渗透气田的试井解释,解释结果合理可靠。
Due to the influence of threshold pressure,gas and water seepage are featured with nonlinear characteristics,and conventional well test interpretation usually does not consider this influence,which results in some errors.Therefore,a transient well test model for vertical wells was established with the consideration of the influence of threshold pressure and moving boundary,and analyzed the various factors influencing the transient well test curves.Results showed that the threshold pressure has an impact on the slope of upward curve when pressure drops at the late period,the larger the threshold pressure,the greater the degree of curve upwards;After gas is filled in wellbore,the influence of moving boundary will appear,and the higher the threshold pressure,the slower the extension of moving boundary outwards,and the boundary reflection appears later;the dimensionless radius only affect the bottom hole pressure response when the moving boundary has extended to the sealed outer boundary,the longer the dimensionless radius,the later the boundary reflection appears,and the stable bottomhole flowing pressure is lower.Practical application showed that the pressure recovery curve was fitted very well,the model is suitable for well test interpretation in low permeability gas field,and the result is reasonable and reliable.
出处
《非常规油气》
2016年第4期71-78,共8页
Unconventional Oil & Gas
关键词
启动压力
致密气藏
不稳定试井
动边界
threshold pressure
tight gas reservoir
transient well testing
moving boundary
