Investigation of scaling criteria and multiscale experiments for hydrate-based CO2 sequestration in marine sediment and depleted NGH reservoir via CO2/N2 injection

Abstract

To analyze the potential of hydrate-based CO₂ sequestration as a strategy for carbon removal, this study establishes scaling criteria for hydrate formation in marine sediments and depleted natural gas hydrate (NGH) reservoirs based on models describing hydrate formation kinetics, heat transfer, and diffusion, predicting the CO₂ storage capacity and efficiency at field-scale. The mixed hydrate formation experiments via CO₂/N₂ injection were simulated using small-scale (V = 0.14 L) and pilot-scale (V = 22.0 L) reactors, verifying similarity and modifying the scaling criteria. Heterogeneity in hydrate growth within sediments was observed under different injection strategies, temperature–pressure, and residual gas scenarios. Field-scale predictions show that marine sediments (H, L = 100 m) in the Shenhu region of the South China Sea (P = 12.4 MPa, T = 278.2 K), can store 9120 tons of CO₂ in hydrate, reaching hydrate saturation (s_h) = 15 % in 2273.84 days. In depleted NGH reservoirs (H, L = 100 m) at the SHSC-4 site, (P = 14.5 MPa, T = 285.2 K), 5140 tons of CO₂ can be stored, with 4191.07 days to reach s_h = 15 %. The findings contribute to the understanding of field-scale hydrate formation kinetics in sediments, supporting the development of regional carbon removal.