To date significant reduce of bituminous oil viscosity is the only way to start its production. Among the most common injected agents is steam, solvent or their combinations. When developing bituminous oil reserves, due to their high viscosity, modern approaches are required, from creation of new solvent compositions to implementation of cost-effective technologies for natural bitumen production. Cyclic steam – solvent stimulations results in residual bituminous oil recovery and increase of bituminous oil displacement efficiency.
The article presents the results of pilot tests of steam and solvent composition injections. The solvent composition was developed at Almetyevsk State Oil Institute during the implementation of the project with federal support in 2017-2020 to increase the efficiency of bituminous oil reserves development in marginal zones of deposits under conditions of high reservoir heterogeneity. Previously laboratory studies ware carried out and solvent composition was developed. During filtration tests this solvent effectively reduced oil viscosity and prevented asphaltene precipitation in the reservoir, resulting in an increase of displacement efficiency. These results were fully confirmed in pilot tests. According to the results of pilot tests injection of developed solvent composition into steam-cycle wells increases oil production rate of steam-cycle wells due to additional oil recovery with the solvent in comparison with pure steam injection. Moreover, it was found that the injected solvent spread laterally through the reservoir and reached neighboring pairs of injection and production wells operating in the steam-gravity drainage mode. As a result due to solvent injection areal sweep efficiency increases and additional oil reserves are involving into development.
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