Estudo paramétrico da injeção alternada de vapor e solvente em reservatórios de óleos pesados

Abstract

In the world, there are countless oil reservoirs with a long production history, but their production was ended, because they reached the limit of their economic viability, even still having a significant amount of oil. In the northeast of Brazil, this history is also repeated, because in this region it presents a long production of heavy oil. The oil within those reservoirs has high viscosity and low oil mobility that minimizes the displacement efficiency in the porous media, but can be mitigated by the application of thermal methods and miscible methods to make possible improving oil recovery. One of the promising process for recovery of this oil is the steam and solvent alternate injection which uses two parallel horizontal wells, where the injection well is situated vertically above the production well, and the injection always occurs alternately. The steam adds heat to reduce the viscosity of the oil and solvent aids in reducing the interfacial tension between oil/solvent. In this study was used the discretized wellbore model, where the well is discretized in the same way that the reservoir and each section of the well treated as a block of grid, with interblock connection with the reservoir. The present study aims to apply the process of alternating steam and solvent injection, in a homogeneous reservoir model that contains as main characteristics of the reservoir those of the brazilian northeast region to verify the optimization of the method, minimized the amount of solvent injected, increasing oil production. The numerical simulations were performed using the STARS thermal simulator form CMG (Computer Modelling Group). The operational parameters analyzed were: the flow of solvent injection, the flow of steam injection, vertical distance between the wells, steam quality and time between alternated steam injection and solvent injection. The results showed that high solvent injection flow have a lower oil production. However, with a lower solvent injection flow it was possible optimize the process with very satisfactory results.