Volume 35: CCUS Technologies for the Carbon Neutrality: Part III

Study on Transport Mechanism of CO2-CH4 Binary System in Coalbed Methane Reservoir Nanopore with Multiple Inducement Deformation Field Xiangji Dou, Pengfei Zhu,Zhengdong Lei,Nan Pan,Run Duan,Luyao Guo

Abstract

Shale gas, as a strategic supplement to conventional oil and gas resources, has become the focal point of China’s oil and gas exploration and development. CO2 huff and puff, a pivotal technique in shale gas exploitation, not only effectively enhances shale gas recovery but also aligns with the goal of carbon neutrality. The nano-scale phenomena of CO2-multi-component gas micro-mobility extensively occur during the CO2 huff and puff process in shale gas reservoirs. Under the coupled variable conditions within the pore structure, the adsorption characteristics and storage state of the gas within the pores also change. This paper uses molecular simulation methods to study the adsorption characteristics of mixed gases in synergistically deforming organic nanopores, as well as the transport mechanism of mixed gases in inorganic nanopores of shale. The research found that when CO2 has the maximum proportion, the deformation is greater than at other proportions, and the maximum deformation at different proportions all occur at 5MPa. With the increase of the initial pore diameter, the amplitude of pore deformation also increases. When gas molecules begin to move in the pores, the change in cohesive energy will provide some resistance. However, when gas molecules stably move in the pores, the resistance effect produced by the cohesive energy will relatively weaken. The pore diameter at the nano-scale will change under the influence of the water film. If this effect is ignored, it will lead to a significant deviation in the calculation results of capillary pressure.

Keywords shale gas, molecular simulation, adsorption characteristics, mobility