Could WAG be the Right EOR Process for Libyan Carbonate Reservoirs?

n the Nafoora Augila Unit (NAU), one of AGOCO’s major oil fields, a significant volume of oil is expected to remain unrecovered within the prolific carbonate formations following conventional waterflooding. This paper highlights the critical role of experimental studies and technological research in supporting integrated simulation efforts aimed at assessing the technical and economic feasibility of Enhanced Oil Recovery (EOR) methods. Special Core Analysis (SCAL) data serve as a vital tool for calibrating reservoir models. Laboratory experiments conducted under actual reservoir conditions are essential to accurately represent fluid properties, wettability, and saturation endpoints.
CO₂ gravity drainage experiments showed early CO₂ breakthrough and low displacement efficiency. In contrast, immiscible Water Alternating Gas (IWAG) displacement tests achieved oil recovery levels comparable to those observed in slim tube tests conducted at the Minimum Miscibility Pressure (MMP). This suggests that IWAG could be a viable EOR method for other immiscible gas injection processes—such as those using hydrocarbon gas, nitrogen, or fuel gases—at significantly lower pressures than MMP, particularly in carbonate reservoirs with similar depositional environments and diagenetic characteristics, including selective dissolution.