Reservoir Permeability Evolution during the Process of CO2-Enhanced Coalbed Methane Recovery

Energies

Shugang Wang¹  Ke Wang²  Gang Wang²  Yujing Jiang³ 

[1] Geotechnical and Structural Engineering Research Center, Shandong University, Jinan 250061, China;Shandong Provincial Key Laboratory of Civil Engineering Disaster Prevention and Mitigation, Shandong University of Science and Technology, Qingdao 266590, China;State Key Laboratory Breeding Base for Mine Disaster Prevention and Control, Shandong University of Science and Technology, Qingdao 266590, China;

关键词: CO₂-enhanced coalbed methane (CO₂-ECBM);    porosity and permeability;    adsorption and desorption;    effective stress;    dual porosity media;   

DOI  :  10.3390/en11112996

来源: DOAJ

【 摘 要 】

In this study, we have built a dual porosity/permeability model through accurately expressing the volumetric strain of matrix and fracture from a three-dimensional method which aims to reveal the reservoir permeability evolution during the process of CO₂-enhanced coalbed methane (CO₂-ECBM) recovery. This model has accommodated the key competing processes of mechanical deformation and adsorption/desorption induced swelling/shrinkage, and it also considered the effect of fracture aperture and effective stress difference between each medium (fracture and matrix). We then numerically solve the permeability model using a group of multi-field coupling equations with the finite element method (FEM) to understand how permeability evolves temporally and spatially. We further conduct multifaceted analyses to reveal that permeability evolution near the wells is the most dramatic. This study shows that the farther away from the well, the gentler the evolution of permeability. The evolution of reservoir permeability near the injection well (IW) and the production well (PW) are very different, due to the combined effects of effective stress changes and gas adsorption and desorption. Furthermore, adsorption is the main controlling factor for the change of permeability for regions near the IW, while the change in effective stress is the main cause for the change in permeability near the PW. Increasing the injection pressure of CO₂ will cause the reservoir permeability to evolve more quickly and dynamically.

【 授权许可】

Unknown