双重介质水平井产量递减分析方法

水平井开发特殊类型油气藏有其独到优势，针对双重孔隙介质水平井复杂渗流，以Warren-Root双重介质模型为基础，建立了水平井三维不稳定渗流模型，采用Laplace变换、有限Fourier余弦变换及叠加积分等方法对模型进行求解，获得定产条件下无量纲井底压力解，再利用Duhamel褶积原理将定产条件压力解变换为井底定压条件下的产量解；通过重新定义无量纲量建立McCray型产量积分平均递减方程，结合Stehfest数值反演，获得无量纲产量积分平均递减曲线及其导数曲线图版。计算结果表明，产量积分平均导数曲线上出现双重介质特有的“凹子”， 应用该类图版拟合生产数据可方便进行产量预测及储层动态参数求取。

Analysis of Production Decline for Horizontal Well in Dual Porosity Media

Horizontal wells have advantages for the development of particular reservoirs. In order to solve the complicated seepage flow problem of horizontal wells in dual porosity media, based on Warren Root model, the 3D transient model was established in this paper. The solutions of dimensionless bottomhole pressure at constant rate condition were obtained by modern mathematical methods including the Laplace transformation, finite Fourier cosine transform, and superposition integral. The solutions of rate at constant bottomhole pressure were solved by Duhamel convolution principle. McCray integral average production decline equation was built based on redefined dimensionless groups. Dimensionless production integral average decline and its derivative at constant pressure condition were programmed and plotted by Stehfest numerical inversion. The results show that type curves of production integral average decline derivative exhibit characteristics of dual porosity media. Applications of type curves matching production data can predict rate and calculate reservoir parameters.