The paper describes an approach to production optimization, including production of heavy oil, using chemical stimulation methods. Two mechanisms of surfactant flooding were considered: (1) reduction of residual oil saturation due to decrease of interfacial tension as a function of surfactant concentration, (2) forming of stable oil-water-surfactant emulsion with lower viscosity and residual saturation as compared to ‘pure’ oil phase. The authors discuss modeling methods, main aspects of the automatic production history matching method realized in the reservoir model, ways to optimize oil production through two surfactant flooding mechanisms. A reservoir model based on the automatic production history matching was used to solve the optimization problem. The objective function included main reservoir performance indicators (a desired or maximum production level, minimization of the injected volume and chemical agents) and regularizing components. For each additive component, a weighting factor was applied to realize optimization under different development strategies. To minimize corresponding functional in both problems, the Gauss – Newton method was used. A reservoir simulator was used to solve both automatic history matching and optimization problems. In the former case it was used to calculate oil production data for the reservoir model approximation and the production data sensitivity to the model parameters, in the latter case – to calculate reservoir performance under development strategies and sensitivity of reservoir performance indicators to parameters describing well operation conditions. The approach to production optimization based on reservoir modeling allows optimization of reservoir performance through two mechanisms of chemical stimulation. However, considering difference in the surfactant flooding mechanisms, concrete recommendations shall be based on results of laboratory tests involving different surfactant concentrations and injection rates considering specific reservoir conditions.
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