Oil Recovery Mechanisms via Multicontact Miscible Gas Injection Process within Lensed Systems

Abstract

The experiments performed in this study are the first of their kind as they report the significance of nonequilibrium on gas-oil multicontact miscible (MCM) process prediction and the influence of lenses' heterogeneities on MCM injection. This was achieved using a combination of well-characterized laboratory experiments and detailed numerical simulation. Particularly, the aims were to (a) quantify the recovery efficiency of MCM displacements conducted at different flow conditions, (b) provide a set of benchmark experimental data for MCM displacements performed within lensed, porous media, and (c) validate conventional compositional simulation of MCM displacements. The novel experimental studies were conducted in specially designed lenses visual models packed with unconsolidated glass beads and used a two-phase, three-component (Isopropyl alcohol [IPA]/water/cyclohexene) liquid system that exhibits an upper critical point at ambient conditions. First contact miscible (FCM), immiscible, and MCM displacements were performed under different flow conditions. They were then simulated using a commercial compositional simulator without using history matching. The produced oil and gas in the experiments were found not to be in compositional equilibrium. Consequently, the oil recoveries and gas cuts predicted by compositional simulation for MCM displacements differed significantly from the experimental results, although an excellent match was obtained for the FCM and immiscible displacements.