Effect of Operating Parameters on Solution-Gas Drive and Foamy Oil Flow during Cyclic Solvent Injection: An Experimental and Modeling Study

Summary Despite extensive studies on cyclic solvent injection (CSI), it remains poorly understood how injection pressure (Pinj) and depletion rate (DR) affect solution-gas drive (SGD) and foamy oil flow (FOF) mechanisms, and whether a soaking stage is essential for improving bitumen recovery. The main objective of this study is to visualize solvent/oil-sand interactions and quantify oil recovery under different operating conditions. We use a custom-designed visualization setup to conduct six CSI experiments using propane. We implement a black oil model to quantify propane transport into oil-sand to complement the experimental observations. Unlike most CSI studies that incorporate intentional soaking, this study evaluates CSI without extended soaking and systematically compares oil recovery factors under partial vs. complete SGD across a range of Pinj and DR values. The results indicate that increasing Pinj increases oil recovery under both slow and fast depletion conditions. Likewise, increasing DR increases oil recovery under both partial and complete SGD. Although liquid propane (C3,L) achieves higher oil recovery, the presence of a free gas phase at the end of depletion is essential for mobilizing oil toward the production face. In contrast, when vapor propane (C3,V) is present, the lack of SGD limits oil recovery, and DR variations have little to no influence on oil recovery. Furthermore, DR can have a greater impact on oil recovery than Pinj, such that higher oil recovery can be achieved at lower Pinj and faster DR. Modeling results indicate that more propane accumulates near the sandface at higher Pinj. Additionally, the amount of propane transported into the oil-sand plateaus at the end of the injection stage, and it cannot be considerably enhanced by incorporating a soaking stage. It is concluded that an extended soaking stage does not inherently increase oil recovery; instead, its impact is strongly pressure-dependent.