Optimization of the WAG Injection Process

Abstract

Availability of hydrocarbon gases at the field makes it attractive for gas-based enhanced oil recovery (EOR) methods such as water alternating gas (WAG) injection. Optimization of EOR methods requires too many simulation runs, which are time consuming and expensive. Therefore, developing a proxy model, which emulates simulator outputs, is considered as an appropriate alternative technique. In this work, effects of composition changes of injection gas, WAG ratio, and slug size on produced oil and water were investigated. In addition, the optimum value of the previous parameters, including some constraints, are presented using response surface methodology. Experimental design is also applied to construct different polynomial regression models as proxy models for a sector of an Iranian oil reservoir under the WAG injection scenario. A new workflow is introduced for optimization of the WAG parameters, for which all effecting parameters are changing simultaneously.

Keywords:

• WAG injection method
• CH₄-CO₂ mixture gas
• WAG ratio
• polynomial regression
• experimental design
• response surface methodology