Current thermal methods for bitumen recovery are effective but require both environmental and economic performance improvements. Solvent based recovery method is an alternative to steam injection that has the potential to reduce greenhouse gas emissions associated with recovery. However, the pore-scale behavior of the solvent-bitumen system is very complex and poorly characterized to date. In the first part of the work, a high-pressure high-temperature micromodel with reservoir-relevant geometry combined with imaging tools is used to provide pore-scale of condensing solvent injection using propane and butane. The combination of two-phase dynamics and solvency at the condensing edge leads to significant bitumen production, similar in both propane and butane injections. In the liquid zone ahead of the condensing edge, butane results in dense, small, and immobile solvent-in-residue emulsions. In contrast, liquid propane produces larger emulsions with some mobility. Spectroscopy combined with fluorescence imaging indicates that the residual immobile emulsions in the butane case are bitumen heavy fractions, and largely asphaltenes. Motivated by the large amount of asphaltenes precipitated by liquid propane and butane, we extend the study to other commonly used hydrocarbon solvents for steam co-injection process, namely pentane, heptane, condensate, and naphtha. A set of microfluidic chips is uniquely designed to investigate the pore damage due to asphaltene deposition from different solvents in different pore geometries. It is observed that the pure pentane has the most damage to the reservoir while the naphtha produces the least amount of asphaltenes. Lastly, we evaluated the solvent-steam co-injection method inside the micromodel. Naphtha yields the best performance which can be attributed to both high azeotropic temperature and minimal asphaltene precipitation.
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