A fully coupled fluid flow and geomechanics model is proposed for ECBM and CO2 underground storage with consideration of multi⁃component multi⁃process transportation in porous media to investigate the complicated geomechanical effects, and the corresponding numerical solver is developed. The effect of geomechanical effects and injection gas components on permeability and injection/production index were also investigated. The results indicate that both effective stress effect and matrix swelling/shrinkage can significantly affect porosity and permeability, but in opposite direction. Matrix swelling induced by CO2 injection can lead to about 90% loss in permeability around injector. The increasing of Young's modulus or decreasing of matrix Langmuir strain, will induce earlier CO2 breakthrough time and lower coalbed methane recovery and CO2 sequestration amount. These results can provide better methane production prediction and support high⁃efficient productivity improvement.

The computational efficiency of the existing polymer flooding simulator is difficult to adapt to the large complex reservoir simulation of the meshing scale of more than one million nodes, which seriously restricts the decision speed of the reservoir development. Hence, we propose a new concise brinebased simulation method for polymer flooding in this study, which can not only significantly improve the speed of numerical simulation, but also can comprehensively consider the key mechanism of enhanced oil recovery by polymer flooding. The accuracy and applicability of the new method are demonstrated in three aspects: the comparison of the simulation results with the traditional polymer flooding, the significant effect of the void volume and the significant effect of the adsorption loss. The new method is used to simulate the polymer flooding in a large river heavy oil field with a large scale of nearly 5 million grid. It takes only 5.8 h to complete a single virtual development simulation, while the traditional simulator takes 518.4 h and the calculation efficiency is nearly 90 times under the same condition, which confirms the high efficiency and application value of the new method.