Does injection sequence matter: A simulation study of chemical enhanced oil recovery processes

Abstract

In this study, CMG STARS was employed to simulate the experimental results conducted by Surtek in the lab, specifically focusing on a linear core flooding using alkaline, surfactant, polymer, and their combinations in different sequences to enhance oil recovery in the Warner Field.

To begin with, experimental data, including essential core and reservoir information, oil and chemical properties, injection schemes, chemical adsorption data, interfacial tension (IFT) data, relative permeability data, and oil production data was extracted from the Surtek report.

Subsequently, a comprehensive step-by-step procedure detailing the construction of the simulation model in CMG was described. This paper then presented the simulation data, followed by a comparison with the experimental data. The oil cut based on simulation results was plotted as well. It was found that there was improvement in oil cut when the chemicals were applied. It is noteworthy that, to achieve a better match with the experimental data, it was necessary to modify the relative permeability curve and chemical adsorption data. After matching the experimental data, sensitivity analysis was conducted by using the tuned simulation model. Specifically, the order of the ASP injection was modified by placing the ASP slug 3 with a lower polymer concentration ahead of ASP slug 1. A notable decrease in the oil production was found in the early stage but a higher final recovery factor was achieved in this injection strategy.

This study reports a successful alignment between the simulation and experimental data. The sensitivity analysis using the predictions of the simulation model suggests the injection sequence is important in the chemical EOR processes. Depending on the priority of a high recovery rate or a high final recovery factor, a certain injection sequence may be selected for practical applications.

Keywords: Chemical EOR; ASP Flooding; Reservoir Simulation; CMG; History Matching; Injection strategy