Modeling and simulation of carbon sequestration at Cranfield incorporating new physical models

Abstract

Numerous experimental and field-demonstration tests have been conducted to investigate the feasibility of large-scale long-term storage of CO2 in subsurface formations and to monitor the fate of the injected gas. The Cranfield reservoir in western Mississippi is the location of an injection test and monitoring program conducted by The University of Texas at Austin, Bureau of Economic Geology. Geological carbon sequestration involves injecting CO2 into subsurface formations and storing it using several chemical, physical, and geological mechanisms. CO2 behavior in the subsurface results from the interplay of multiphase flow, fluid-phase behavior, relative permeability, wettability, and gravity. This paper presents findings of a research numerical simulator for modeling CO2 injection at Cranfield. Simulations focusing on a future postinjection period were carried out with sensitivities to uncertain parameters, i.e., relative permeability and its variations due to interfacial tension and buoyancy. Numerical results were consistent with bottom-hole injection flowing pressure for the first 350 days prior to the rate increase and also observed-CO2 breakthrough time at the first observation well. Results also illustrate the importance of using accurate trapping models to predict CO2 immobilization behavior. The impact of CO2/brine relative-permeability curves and trapping model on bottom-hole injection pressure was also demonstrated.