Efficiency estimation of super-viscous oil recovery by in-situ catalytic upgrading in cyclic steam stimulation: from laboratory screening to numerical simulation

This article describes a method of predicting super-viscous oil deposit development performance by catalytic aquathermolysis process in cycling steam simulation (CSS). This technology involves the injection of an oil-soluble catalyst into the reservoir after several cycles of steam injection and oil production. According to the results of laboratory studies, the effect of catalytic oil upgrading in the reservoir is expressed in non-instantaneous reduction in oil viscosity and increase in sweep efficiency. To assess the effectiveness of the technology on the field-scale thermal numerical simulation model, based on the results of laboratory studies, is used. The oil upgrading process is represented in the model by the oil upgrading reaction and dependence of oil viscosity and residual oil saturation on the degree of oil upgrading. The kinetic parameters of the reaction and the properties of the converted oil are adjusted according to the results of experiments in a high-pressure reactor and tube tests. Field scale numerical simulation resulted in dependance of catalytic upgrading efficiency on the uniformity of well temperature profile, presence of residual oil and reservoir properties at the effective wellbore radius. It is shown that the effect of catalytic upgrading on a CSS well is determined not only by physical and chemical changes in oil composition but also by adsorption properties of the catalyst itself, heating the wellbore region and matrix and fracture interaction in reservoir. According to simulation results, choosing an optimal catalytic volume and injection scenario allows the recovery of up to 25% of additional oil, that reveals good perspectives of improving steam-based technologies by in-situ catalytic upgrading.