In this paper, we find that the numerical simulation of gas flow in dual-continuum porous media may generate unphysical or non-robust results using regular finite difference method. The reason is the unphysical mass loss caused by the gas compressibility and the non-diagonal dominance of the discretized equations caused by the non-linear well term. The well term contains the product of density and pressure. For oil flow, density is independent of pressure so that the well term is linear. For gas flow, density is related to pressure by the gas law so that the well term is non-linear. To avoid these two problems, numerical methods are proposed using the mass balance relation and the local linearization of the non-linear source term to ensure the global mass conservation and the diagonal dominance of discretized equations in the computation. The proposed numerical methods are successfully applied to dual-continuum gas reservoir simulation. Mass conservation is satisfied while the computation becomes robust. Numerical results show that the location of the production well relative to the large-permeability region is very sensitive to the production efficiency. It decreases apparently when the production well is moved from the large-permeability region to the small-permeability region, even though the well is very close to the interface of the two regions. The production well is suggested to be placed inside the large-permeability region regardless of the specific position.

在本文中，我们发现使用正则有限差分法对双连续介质多孔介质中的气体流动进行数值模拟可能会产生非物理或非鲁棒的结果。原因是由气体可压缩性引起的非物理质量损失，以及由非线性井期引起的离散方程的非对角优势。井期包含密度和压力的乘积。对于油流，密度与压力无关，因此油井时间是线性的。对于气体流量，气体定律将密度与压力相关联，因此，井期是非线性的。为了避免这两个问题，提出了一种利用质量平衡关系和非线性源项的局部线性化的数值方法，以确保整体质量守恒和离散化方程的对角占优。所提出的数值方法已成功地应用于双连续气藏模拟。在计算变得健壮的同时，满足了质量守恒。数值结果表明，生产井相对于大渗透率区域的位置对生产效率非常敏感。当生产井从大渗透率区域转移到小渗透率区域时，即使该井非常靠近两个区域的界面，它也会明显降低。建议将生产井放置在大渗透率区域内，而不管其具体位置如何。数值结果表明，生产井相对于大渗透率区域的位置对生产效率非常敏感。当生产井从大渗透率区域转移到小渗透率区域时，即使该井非常靠近两个区域的界面，它也会明显降低。建议将生产井放置在大渗透率区域内，而不管其具体位置如何。数值结果表明，生产井相对于大渗透率区域的位置对生产效率非常敏感。当生产井从大渗透率区域转移到小渗透率区域时，即使该井非常靠近两个区域的界面，它也会明显降低。建议将生产井放置在大渗透率区域内，而不管其具体位置如何。