SIMULATION INVESTIGATION OF SOLVENT CO INJECTION IN VAPOR AND LIQUID PHASE TO REDUCE SHALE BARRIER IMPACT ON SAGD PERFORMANCE

Heterogeneous, especially the shale barrier, significantly reduce steam‑assisted gravity drainage (SAGD) performance at Athabasca field. The objective of this experiment study is to investigate the drainage mechanism for solvent co‑injection in vapor and liquid phase to reduce the shale barrier effect in field. An extensive 2D simulation study shows that the throttling effect at the end of shale barriers and the extra heat required by the residual water inside the unproductive shale barrier are the main reasons for the shale barrier effect. A long continuous shale barrier located vertically above or near the wellbore reduces production performance significantly. We investigated potential strategies, including solvent co‑injection, top injector application, or combining both, to reduce the shale barrier impact. Solvent in vapor phase can pass though the narrow flow path at the end of shale barrier, meanwhile its phase condensing from vapor to liquid reduces the throttling effect of shale barrier efficiently. Liquid solvent co‑injection can accelerate the near‑wellbore flow and reduce the residual oil saturation significantly at the wellbore vicinity. Co‑injecting multi‑component solvent can take advantage of both vaporized and liquid solvents. Top steam injector applications show only marginally improvement. The conclusions from this study can be used to design suitable solvent mixture and solvent co‑injection strategy to reduce shale barrier impact on SAGD Performance with higher production rate, higher recovery factor with lower steam to oil ratio (SOR).