The Effects of Reservoir Heterogeneity and CO₂/H₂S Mixing from CO₂ Storage: Insights from Reactive Transport Modeling

Yitian Xiao¹, Tianfu Xu², and Karsten Pruess^2
1ExxonMobil Upstream Research Company, Houston, TX
²Lawrence Berkeley National Laboratory, Berkeley, CA

Possible means of reducing atmospheric CO₂ emissions include injecting CO₂ in petroleum reservoirs for Enhanced Oil Recovery or storing CO₂ in deep saline aquifers. Large-scale injection of CO₂ into subsurface reservoirs would induce a complex interplay of multiphase flow, capillary trapping, dissolution, diffusion, convection, and chemical reactions. Reactive Transport Modeling is a promising approach that can be used to predict the spatial and temporal evolution of injected CO₂/H₂S and associated formation alteration. This presentation will summarize recent advances in reactive transport modeling of CO₂ storage and review key technical issues on (1) the long term fate of injected CO₂ in geological formations; (2) the role of reservoir heterogeneity on injection performance; (3) the effect of gas mixtures (e.g., H₂S and SO₂) on CO₂ storage; and (4) the physical and chemical processes during potential leakage of CO₂ from the primary storage reservoir. In particular, the presence of reservoir heterogeneity and the requirement of co-injecting CO₂ and H₂S add significant complexity and challenges to identifying and characterizing potential storage sites, designing and analyzing tests, and managing injection performance and reducing costs. The results from Reactive Transport Modeling provide valuable insights for describing, analyzing, interpreting, and assessing the physical properties and dynamic behaviors of injected CO₂ and facilitating the screening and evaluation of storage strategy.

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas