ANALYSIS OF THE THERMAL EFFICIENCY FOR A STEAM INJECTION PROCESS APPLIED TO A THIN HEAVY OIL RESERVOIR FROM THE NORTHEAST OF BRAZIL

The use of steam injection in the recovery of heavy oils leads to improved results. During the process, only a fraction of the injected heat will warm up the porous media effectively due to heat losses within the injection lines and to formations adjacent to the productive zone. One way of measuring the amount of heat present in the porous media is through thermal efficiency. Therefore, this research proposes a more accurate way of investigating the amount of heat provided and actually used within the reservoir rock. To perform this study, a semi synthetic numerical model was developed, in a system with a Cartesian grid. It used a high viscosity oil, similar to those found in the Northeast region of Brazil, specifically in the Potiguar Basin, produced through an inverted quarter five spot. By varying the operational parameters (steam injection and steam quality), one observed the behavior of thermal efficiency curves, through a period of 15 years, for an oil net pay of 10m. The study concluded that high steam qualities and steam injection rates were associated to the lowering of the fraction of the remaining heat at the end of the project. Also, increased values of steam injection rates resulted in higher thermal efficiencies, before the steam breakthrough.