存在有限导流断层的油藏压力动态分析

Pressure Transient Behavior in Reservoirs with Finite-Conductivity Fault

国内外现有的试井解释模型均忽略了流体在断层内部流动,从而使存在有限导流断层边界的油气藏试井资料解释所得结果往往并不理想。综合运用渗流力学、数学物理方法、计算数学基础理论,建立无限大复合油藏中存在有限导流断层的试井解释模型。模型不仅考虑了流体通过断层面,还考虑了断层内部流体的流动。通过点源函数和拉普拉斯变换,运用Stehfest数值反演算法,绘制了井底压力响应特征曲线,并用实例对模型进行了验证。分析表明:FCD值越大,曲线下凹越多;Sf值越大,曲线上翘越多,当Sf值足够大时,表现为封闭断层的特征。为类似油藏的试井解释提供了理论参考和技术支持。

Scholars mainly considered the fault as no flow closed boundary at home and abroad,when using the existing well testing interpretation models to interpret the actual reservoir well test data with finite-conductivity fault boundary,the results of which are not always ideal. Based on the theory of fluid flow in porous media,a well testing model for wells located near a finite-conductivity fault in a two-zone,composite reservoir was established. The solution considered not only fluid flow across the fault but also transient flow within the fault which had been disregarded in all previous studies. The solutions for constant production rate were obtained by the point source function and the Laplace transform techniques. With the Stehfest numerical inversion algorithm method,the transient pressure type curves were analyzed and the model was verified with cases. The result showed that the greater the value of FCD,the more concave curve. The bigger the Sfvalue,the more upward curve. When Sfis large enough,the feature of closed fault is presented. This provides theoretical reference and technical support for the interpretation of well testing of similar reservoirs.