开关井不同程度应力敏感效应对井底压力动态的影响

Influence of different stress sensitivities on bottom hole pressure behaviors during well opening and shut-in

刘启国 唐伏平 冯国庆 颜泽江 胡新平 陈军 李允

Liu Qiguo Tang Fuping Feng Guoqing Yan Zejiang Hu Xinping Chen Jun Li Yun

依据渗流实验建立的应力敏感效应经验关系式,从渗流力学基本理论出发,建立了考虑渗透率应力敏感、井筒储存效应和表皮效应影响的均质气藏试井分析数学模型。应用摄动技术和拉普拉斯变换方法求解数学模型,据此研究应力敏感性气藏的渗流特征以及开关井不同程度应力敏感效应对井底压力动态的影响。研究表明,随着渗透率应力敏感效应的增大,压降压力导数曲线向上翘起的幅度增大,而压恢压力导数曲线则可能出现下掉。当升、降压对渗透率的应力敏感不可逆时,升压过程不能使渗透率完全复原,其压力恢复的程度则更低。

Basing on the empirical equation of pressure stress-sensitive effect and the basic theory of fluid flowing mechanics in porous medium,a mathematical model for well testing analysis in homogeneous gas reservoirs is established with considerations of permeability sensitivity to stress,effect of wellbore storage,and skin effect.The perturbation technique and Laplace transform method are employed in the calculation of the model to study the features of percolation in stress-sensitive gas reservoirs and the influence of different stress sensitivities on bottom hole pressure behaviors during well opening and shut-in.The results show that along with the stress sensitivity of permeability increases,derivative curve may upturning higher during drawdown test,while the derivative curve may drop down during pressure build-up test.If the damage to permeability caused by stress sensitivity during drawdown/build-up test is irreversible,the permeability can not be fully recovered through pressure boosting and the degree of pressure buildup is still lower.

10.11743/ogg20070414