Injeção de vapor e sistemas micro/nanoemulsionados para recuperação de óleo pesado em reservatórios areníticos

Abstract

Oil production in onshore Northeast Brazil fields is in sharp decline, requiring the application of enhanced oil recovery methods to reverse this tendency. For these fields, steam flooding is widely used, however, in advanced stages of injection, it can have a high cost and low efficiency. In this case, the use of chemical methods associated with steam can lead to an increase in oil recovery by reducing interfacial properties. Furthermore, the high volume of water produced in onshore fields poses a significant problem due to the high cost associated with its treatment. Therefore, this study aims to develop and characterize micro and nanoemulsion solutions using produced water in their composition and evaluate the efficiency of applying these systems, combined with steam, in the recovery of heavy oils. Th systems composed of Ultranex NP 100 (surfactant), n-butanol (cosurfactant), synthetic produced water (aqueous phase), and kerosene (oil phase), were characterized in terms of droplet size, surface and interfacial tension, rheological behavior and viscosity, and evaluated for their effect on modifying wettability of the sandstone rocks used, Berea sandstone and sandstone from the Brazilian Northeast. In the coreflooding tests, the parameters of surfactant concentration, injection order of the steam and solution banks, injection method (co-injection or alternating injection), injection flow rate and volumetric proportion of the injected fluids were evaluated. All developed solutions showed a reduction in surface and interfacial tension and changed the wettability of the sandstones to water-wet, characteristics desired for use as EOR (Enhanced Oil Recovery) method. The use of a microemulsion solution with 8.66% surfactant in its composition co-injected with steam in the same proportion at a flow rate of 0.125 mL/min showed the best result for oil recovery factor (70.10%) in the Berea sandstone and in the reservoir sandstone (54.34%). The results of this study validated the proposed technique of using an new hybrid recovery method (thermal method associated with the chemical) for heavy oil, which can boost the revitalization of mature fields, ensuring the extension of production and the stimulation of regional development.