Enhancing Co2 Hydrate Sequestration Through Underlying Methane Hydrate Production: A Novel Strategy for Carbon Storage

Abstract

Seafloor CO2 sequestration in the form of gas hydrates offers expansive geological opportunities for carbon neutrality strategies. Guided by phase equilibrium conditions, this study employs a self-developed multi-physical simulator to investigate how methane hydrate production beneath a CO2 sequestration zone can facilitate carbon storage. A dual-horizontal-well model is constructed and validated based on field measurements. Through numerical simulations, the effects of methane hydrate production timing, CO2 injection rate, and injection depth on carbon sequestration over a 100,000-year timescale are examined. Two novel metrics—sequestration efficiency and safe distance—are introduced. Results indicate that extracting methane hydrates in the later stages of CO2 injection is optimal. Furthermore, an efficient sequestration window exists for both injection rate and depth. By exploring the relationship between sequestration efficiency and storage safety, this study provides a new perspective for implementing CO2 sequestration pathways.

Keywords: CO2 sequestration, Methane hydrate production, Multi-physical, Sequestration efficiency, Storage safety