AUTHOR=Wang Xiangzeng , Zhang Quan , Wan Yongping TITLE=A two-phase, multi-component model for efficient CO2 storage and enhanced gas recovery in low permeability reservoirs JOURNAL=Frontiers in Energy Research VOLUME=12 YEAR=2024 URL=https://www.frontiersin.org/journals/energy-research/articles/10.3389/fenrg.2024.1373851 DOI=10.3389/fenrg.2024.1373851 ISSN=2296-598X ABSTRACT=

Introduction: Carbon dioxide (CO₂) enhanced gas recovery represents a viable strategy for sequestering CO₂ while concurrently augmenting gas production from subsurface reservoirs. Gas reservoirs, as inherent geological formations, are optimal repositories for gaseous compounds, rendering them suitable for CO₂ storage. Nevertheless, the economic viability of pure CO₂ storage necessitates integration with oil and gas recovery mechanisms to facilitate widespread CO₂ utilization.

Method: This study addresses the complexities of CO₂ enhanced gas recovery through a comprehensive approach that combines theoretical model and numerical simulations. A numerical model is developed to simulate three-component diffusion involving CO₂, and methane (CH₄) in a two-phase system comprising gas and water.

Results: The investigation systematically explores the process of enhanced CH₄ extraction and CO₂ injection into the reservoir and examines the influencing factors on extraction. Simulation results reveal a power-law decrease in CH₄ production rate, stabilizing at a constant extraction rate. Enhanced CH₄ extraction benefits from increased porosity, with higher porosity levels leading to greater CH₄ extraction. Permeability augmentation positively influences CH₄ production, although with diminishing returns beyond a certain threshold. The CO₂ injection rate shows a direct proportionality to CH₄ production. However, elevated CO₂ injection rates may increase reservoir pressure, potentially causing cap rock damage and CO₂ gas flushing.

Discussion: This study contributes valuable theoretical insights to the field of CO₂ enhanced gas recovery engineering, shedding light on the intricate dynamics of multi-component fluid transport processes and their implications for sustainable CO₂ utilization.