Discontinuous Displacement at Solvent–Immobile Hydrocarbon Interfaces

Abstract

Concerns over the environmental impacts of thermal production methods for bitumen and heavy oil have led to the exploration of alternative technologies including solvent-assisted production methods. While solvent-assisted production methods have been studied extensively, the apparent diffusion coefficients of the penetrating solvent 1–2 orders of magnitude greater than those predicted for Fickian diffusion applicable to liquid mixtures are required to match production histories. “Surface renewal” and “sloughing” mechanisms have been advanced to explain these higher solvent penetration rates into reservoirs during production but have not been observed directly or included in physical models. In this work, we use high-resolution X-ray videography to investigate solvent penetration at interfaces between a model solvent (n-pentane) and model immobile reservoir fluid (octacosane) over time to observe “surface renewal” and “sloughing” directly for the first time. We show that for horizontal interfaces (octacosane below), interface displacement arises solely from diffusion and rates of displacement are slow (∼10–2 μm/s). For vertical pentane–octacosane interfaces and horizontal pentane–octacosane interfaces (pentane below), steady displacement rates, an order of magnitude greater than for diffusion alone, are punctuated by a rapid detachment of ∼30 μm layers of octacosane-enriched liquid from the interface at ∼150 s intervals. For vertical interfaces that dominate production processes especially in thin reservoirs, average interface displacement rates around 0.5 μm/s are realized. Our findings highlight the impact of interface orientation on interface displacement rate and provide quantitative insights into the kinetics of solvent-assisted bitumen and heavy oil production processes in high permeability reservoirs. Further experimental and theoretical study is required to understand and quantify interfacial displacement effects in low permeability reservoirs.

Effect of Colloidal Stability and Miscibility of Polar/Aromatic Phases on Heavy Oil Demetallization

“…However, the excellent aqueous solubility would prevent the mass transfer of chemical reagents into the oil phase to make effective collisions with the organometallic compounds in the oil bulk, making it an interface reaction. Also, the liquid–liquid interface properties, such as apparent diffusion coefficients, solvent penetration, and phase separation rate, have great impacts on reactions. − Therefore, there is an irreconcilable contradiction between hydrophilicity and lipophilicity of chemical reagents during chemical demetallization.…”

Investigation of Mechanisms for Gravity Drainage of Heavy Oil and Solvent Mixtures in a Hele-Shaw Cell

“…However, they did not explain why the increased solvent fraction in the diluted oil would not lead to a higher velocity and, consequently, higher dispersion. Recently, Wang et al 38 demonstrated that mass transfer rates in a drainage process can be enhanced significantly in gravity unstable configurations, which lead to convection, surface renewal, and cyclic sloughing. Hence, both convection and gravity instability can contribute to enhanced mass transfer and more rapid bitumen recovery.…”