Sammendrag
This paper presents experimental and numerical sensitivity studies to assist injection strategy
design for an ongoing CO2 foam field pilot. The aim is to increase the success of in-situ CO2 foam generation
and propagation into the reservoir for CO2 mobility control, enhanced oil recovery (EOR) and CO2 storage.
Un-steady state in-situ CO2 foam behavior, representative of the near wellbore region, and steady-state foam
behavior was evaluated. Multi-cycle surfactant-alternating gas (SAG) provided the highest apparent viscosity
foam of 120.2 cP, compared to co-injection (56.0 cP) and single-cycle SAG (18.2 cP) in 100% brine saturated
porous media. CO2 foam EOR corefloods at first-contact miscible (FCM) conditions showed that multi-cycle
SAG generated the highest apparent foam viscosity in the presence of refined oil (n-Decane). Multi-cycle
SAG demonstrated high viscous displacement forces critical in field implementation where gravity effects
and reservoir heterogeneities dominate. At multiple-contact miscible (MCM) conditions, no foam was
generated with either injection strategy as a result of wettability alteration and foam destabilization in presence
of crude oil. In both FCM and MCM corefloods, incremental oil recoveries were on average 30.6% OOIP
regardless of injection strategy for CO2 foam and base cases (i.e. no surfactant). CO2 diffusion and miscibility
dominated oil recovery at the core-scale resulting in high microscopic CO2 displacement. CO2 storage
potential was 9.0% greater for multi-cycle SAGs compared to co-injections at MCM. A validated core-scale
simulation model was used for a sensitivity analysis of grid resolution and foam quality. The model was robust
in representing the observed foam behavior and will be extended to use in field scale simulations.
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