As water approaches the critical point, the dielectric constant lowers enabling solution of heavy oil components. Simultaneously, enhanced water dissociation enhances cracking to lighter fractions. We evaluated this effect for three heavy oils concentrating on the effect of processing on feed viscosity. Reductions of up to 90?% were observed and these could be achieved in a few hours. Although more applicable to surface processing of oil sands in the short term, ultimately this technique could also be applied to immature oils for in situ processing and recovery. This may already be happening in some steam-assisted gravity drainage scenarios. In situ application would be limited to reservoirs where formation pressure is higher than the pressure required to generate these subcritical effects.
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