基于配点法的体积压裂页岩气藏数值模拟方法及其应用

A numerical simulation method of volume fractured shale gas reservoir based on collocation method and its application

为解决传统裂缝性油气藏数值模拟方法网格剖分过程复杂、计算耗时长、收敛难度大的缺陷,基于径向基函数和配点法,构建了体积压裂页岩气藏数值模拟新方法,实现了基质-裂缝质量交换表征及体积压裂页岩气藏生产过程的高效准确模拟。模拟结果表明:基于配点法的体积压裂页岩气藏数值模拟方法,可以在保证计算精度的前提下,显著提高计算效率,并改善收敛性,且目标求解问题越复杂计算效率改善效果越好;布点密度、超参数及核函数是影响配点法求解精度的主要影响因素,当核函数选择高斯核函数时,布点密度及超参数取值越大,计算精度越高,同时,超参数及核函数的改变并不影响计算成本。实例验证表明,此方法在实现有效历史拟合的基础上可提高计算效率6.45倍,从而证明了该模型在现场应用中的有效性。研究结果可为裂缝性油气藏高效模拟提供理论基础及借鉴。

In order to solve the defects of conventional numerical simulation method for fractured oil and gas reser‑voirs,including complex grid generation process,long calculation time and difficult convergence,a new numerical simulation method for volume fractured shale gas reservoirs based on radial basis function and collocation method is established,which realizes characterization of matrix-fractures mass exchange and effectively accurate simulation of production performance of volume fractured shale gas reservoir.The results show that numerical simulation method of volume fractured shale gas reservoir based on collocation method can significantly improve calculation efficiency and convergence in the premise of ensuring calculation accuracy,and the more complex the target solving problem is,the better the improvement effect of calculation efficiency is.Distribution density of nodes,super parameters and kernel function are main factors affecting solution accuracy of collocation method.When Gaussian kernel func‑tion is selected as the kernel function,the larger the distribution density and super parameters are,the higher the calculation accuracy is.Meanwhile,the changes of super parameters and kernel function do not affect calculation cost.Case study verifies that the method increases calculation efficiency by 6.45 times on the basis of realizing effec‑tive history matching,which proves effectiveness of this model applied in the field.The research provides theoreti‑cal basis and reference for efficient simulation of fractured oil and gas reservoirs.