High-Temperature Solvent Injection for Heavy-Oil Recovery From Oil Sands:Determination of Optimal Application Conditions Through Genetic Algorithm

摘要

Our recent experimental studies on superheated solvent injection for heavy-oil recovery showed that when a solvent is injected into the reservoir,the process is highly sensitive to pressure and temperature.The effects of these parameters on the recovery factor are accentuated when the operating conditions are closer to the saturation curve of the solvent injected.This paper investigates this process and formulates the optimal field scale application conditions. First,the injection of propane and steam was simulated by a 3D numerical model alone into a glass beads core.The results were matched to data from experiments in which heavy oil saturated samples were exposed to solvent vapor at high temperature.A pressure-temperature sensitivity analysis was carried out for different core sizes to understand the dynamics of gravity drainage process associated with asphaltene precipitation.Asphaltene pore plugging behavior was modeled and the diffusion of solvent into heavy oil/bitumen was analyzed to determine both ideal solvent type and optimal operating conditions for solvent injection at high pressures and temperatures.We observed that the solvent should be in gas phase and its sensitivity to temperature and sample height(for effective gravity drainage)is more critical compared to the pressure.Next,the core scale model was upscaled to the field scale and the process was simulated for a two-horizontal injection/production pattern.An optimization study was performed to identify the relative contributions of the effective parameters(pressure,temperature,and injection rate) and to propose an optimal application scheme using genetic algorithm.The critical pressure and temperature yielding maximum production and highest profit considering solvent retrieval were defined for different injection rates and application scenarios.