Co-injeção de vapor e solução de tensoativo como método de recuperação avançada de óleo pesado

Abstract

Enhanced Oil Recovery Methods comprise a set of techniques aimed at increasing the recovered fraction of oil from a reservoir, thereby extending its lifespan. The hydrocarbon reserves in Northeast Brazil consist mainly of heavy oil fields, which are oils with high density and viscosity, making their extraction challenging. In this context, thermal methods are more efficient as they reduce the oil viscosity by injecting heat into the reservoir. However, over time, the use of surfactants as a chemical method for enhanced oil recovery has also become widely adopted. These molecules reduce the interfacial tensions between fluids, facilitating the displacement of oil in the porous medium. Based on the above, this study aims to elucidate a method to enhance the production of heavy oils by combining thermal and chemical approaches through the co-injection of steam and surfactant solution in different injection configurations. The methodology consists of three steps: preparation of the surfactant solution, characterization of the oil and rock, and conducting flow tests in a porous medium. Berea Sandstone samples were used for the tests, characterized for porosity and permeability, exhibiting an average porosity of 21.25% and permeability of 530 mD, respectively, with an oil viscosity of 247.77 cP (20.7 °API), characteristic of the study region. In the flow tests, a 0.5% m/m solution of non-ionic surfactant (Nonylphenol Ethoxylated NP 100EO) was used in association with steam injection in different configurations: 100%V (100% Steam), 75%T25%V (75% Surfactant Solution and 25% Steam), 50%T50%V (50% Surfactant Solution and 50% Steam), 25%T75%V (25% Surfactant Solution and 75% Steam), and 100%T (100% Surfactant Solution). From the recovery tests, it was observed that the co-injection of NP-100EO surfactant solution with a higher proportion of steam (25%T75%V) resulted in higher oil recovery (50.27 %FR) compared to single steam injection (45.19 %FR). As a result, it was observed that the synergy between the methods enhances oil production, especially when a higher proportion of steam is injected, with an absolute gain of 5.08 percentage points compared to steam injection alone. Thus, the co injection of steam and surfactant solution has proven to be an effective technique for increasing the recovery of heavy oils.