Long-term Containment Evaluation of the Carbon Storage Feasibility Study in Offshore China

ABSTRACT: This study conducted a comprehensive integrity analysis for a CO2 storage site in offshore China, verifying long-term containment for proposed injection plans. Using petrophysical data from four wells, structural surfaces, and seismic inversion, a 3D geological model with 32 million cells was built to map reservoir and cap rock properties. A 3D mechanical earth model (MEM) was developed using a non-linear FEM simulator, considering geology, lithology, and faults. Pre-injection analysis identified potential saline formations and cap rocks based on facies, thickness, stress barriers, and fault sealing. A synthetic injection plan determined the critical reservoir pressure at 1.38 times the initial pressure. Over 20 injection plans were analyzed for various well sites, types, rates, and periods. Coupled geomechanical simulations confirmed long-term containment, addressing risks like hydro-fracturing, fault reactivation, induced seismic events, and seabed uplift. The best injection plan was recommended based on capacity, injectivity, and containment. This first site-specific CO2 storage feasibility study in offshore China proposed an optimized injection plan and introduced an integrated workflow for global offshore CCS projects.