Experimental investigation of in-situ solvent generation for SAGD and Its effectiveness in heavy oil recovery

Abstract

In-situ solvent generation enhanced steam assisted gravity drainage (ISSG-SAGD) is proposed to enhance heavy oil recovery while reducing steam use and carbon emissions. The study experimentally investigated the generation, migration, and condensation of light hydrocarbons (LHs) during thermal cracking of heavy oil (TCHO). The key objective was to assess the feasibility of in-situ solvent generation as a replacement for external solvent injection in SAGD processes. Experiments were conducted under high-temperature and high-pressure conditions to facilitate LHs generation, followed by distillation to simulate solvent migration and condensation within the steam chamber. The composition of generated LHs was analyzed using gas chromatography-mass spectrometry (GC-MS). Under conditions of 360–400 ℃ and reaction times of 12–96 hours, target solvent yields varied from 3.29 to 35.04 wt%, primary consisting of C₁-C₁₃ components. Notably, at 360 ℃ for 12 hours, the solvent concentration reached approximately 0.25–0.99 wt%, which is comparable to successful solvent assisted SAGD projects that utilize solvent concentrations of ≥ 1 wt%. The results suggest that in-situ solvent generation can enhance SAGD efficiency similarly to external solvent injection, without the additional costs of solvent procurement and injection. This research highlights the potential of ISSG-SAGD to optimize steam use and improve economic efficiency while maintaining effective oil drainage, paving the way for more efficient heavy oil recovery.