Simulation Study on Effect of Slug Size In Foam-Assisted Water Alternating Gas (FAWAG-CO2) Injection with Presence of Asphaltene In Light Oil Reservoir

Enhanced Oil Recovery (EOR) is an essential method in extracting residual oil after waterflooding. Around 40% of recovery from primary until secondary for a typical oil field around the world which drives many company to implement EOR to squeeze more oil. Foam-Assisted Water Alternating Gas (FAWAG- CO2) is one of the improved techniques of Water Alternating Gas (WAG-CO2) in enhancing gas mobility control and preventing viscous fingering and gravity overriding which could cause early gas breakthrough. The situation becomes more complex with presence of asphaltene in light crude oil reservoir. Asphaltene precipitation, flocculation and deposition can cause serious problems especially in production stage whereby it can adversely affect the economy of producing oilfield.
This project aims to study the impact of asphaltene precipitation and minimize the precipitation by controlling FAWAG-CO2 injection parameters; pore volume ratio, injection rate and concentration of surfactant. Simulation studies were performed with both WAG and FAWAG injection to study effect of asphaltene deposition.
The simulation study results concluded that recovery in FAWAG injection is higher than WAG injection in both with and without asphaltene presence. FAWAG with asphaltene is higher than FAWAG without asphaltene. Ratio of 2:1 is optimum for both FAWAG-CO2 and WAG- CO2 with and without asphaltene presence. For surfactant concentration, the higher surfactant concentration, the higher the recovery factor until it reached optimum concentration. Higher concentration than optimum will result in lower recovery due to clogged pore throat as effect of adsorption of surfactant