气藏复杂水侵动态巨量网格精细数值模拟

Massive-grid fine numerical simulation on the complex water invasion performance of gas reservoirs

传统数值模拟研究由于计算机能力的限制,通常要先对精细的地质模型进行粗化,从而导致数模模型与实际地质情况存在较大差异,难以对气藏复杂的水侵动态进行模拟,影响了模拟的准确性。新一代精细数值模拟基于AMG-CPR代数多重网格与约束压力残差预处理技术,结合更高效的并行剖分技术,在网格规模和运算速度上相对于传统数值模拟有了巨大的提升,并使数模模型更加逼近真实的地质实体。通过裂缝地质建模建立了四川盆地磨溪区块龙王庙组气藏7 800万网格数量的双重孔隙介质模型,不进行粗化直接进行新一代精细数值模拟应用研究,其网格数量规模位目前居国内第一。将巨量网格模型在服务器集群上进行上千核的大型并行计算,其计算效率和能力相对于传统数值模拟均有新的突破,以往难以实现的巨量网格模型数值模拟能在2 h完成模拟运算,极大地提高了运算性能。从模拟计算结果来看,相对于传统数值模拟,高精度的双重孔隙介质模型能够对气藏的非均质性有较好的描述,对实际气藏楔形区底水的水窜和边水水侵均能进行较好地模拟。

Due to the restriction of computer capacity, the fine geological model shall be generally coarsened when the traditional nu- merical simulation is carried out. As a result, the numerical model cannot reflect the actual geological situations, the complex water invasion dynamic of gas reservoirs cannot be simulated, and the simulation accuracy is impacted. The fine numerical simulation of the new generation is based on AMG-CPR algebraic multigrid and constraint pressure residual pre-treatment technology, combined with more efficient parallel generation technology, so its grid size and arithmetic speed are much higher than those of traditional numerical simulation, and it can reflect the actual geological entity more accurately. In this paper, a dual porosity medium model with 78 million grids was established for the Longwangmiao Formation gas reservoir in Moxi Block of the Sichuan Basin by means of fracture geo- logical modeling, and the fine numerical simulation of new generation was applied directly without coarsening. And its grid quantity is currently top one in China. When the massive grid model is used in the server cluster for large-scale concurrent computation of over one thousand cores, the computation efficiency and capacity are broken through compared with the traditional numerical simulation, and the computation performance is improved greatly. The numerical simulation of massive grid model which was hardly realized in the past can be now completed within 2 hours. It is shown from the simulation calculation results that compared with the traditional numerical simulation, the high-accuracy dual porosity medium model can better describe the heterogeneity of gas reservoirs and better simulate bottom water channeling and edge water invasion in the wedged zone of actual gas reservoirs.