Impact of environmental variables on hydrate formation kinetics in porous media systems and their contribution to CO2 capture and storage

Abstract

Global dependence on fossil fuels has led to escalating atmospheric carbon dioxide emissions. The consecutive greenhouse effect poses a serious threat to the human habitat, rendering carbon dioxide abatement a key focus in contemporary research. Hydrate-based CO₂ sequestration offers a promising pathway for carbon capture and storage, though its efficiency is strongly influenced by pressure, salinity, and sediment properties. In this study, the kinetic characteristics and occurrence states of CO₂ hydrates in porous media were systematically investigated under varying pressures (3.0-3.6 MPa), NaCl concentrations (0-3.5%), and sediment types (quartz sand vs kaolinite). Results reveal a non-linear pressure dependence—gas storage capacity increases by 16.3% as pressure rises from 3.0 MPa to 3.3 MPa, but diminishes to 9.4% with further increase to 3.6 MPa. NaCl exhibits dual inhibitory effects: Thermodynamically shifting the phase equilibrium leftward in the P-T domain and kinetically suppressing growth, with 3.5% NaCl systems exhibiting persistently slow hydrate formation. Sediment type also plays a critical role, as kaolinite’s low-permeability clay structure substantially impedes hydrate formation compared to quartz sand while altering hydrate distribution patterns. Understanding the interplay between pressure-driven efficiency gains and inhibitor-mediated stability control across diverse geological environments is essential for optimizing hydrate-based CO₂ storage strategies.