Introduction
The decrease of oil recovery mainly happens in mature reservoir. As a solution, chemical injection into the reservoir (chemical flooding) can be done using Enhanced Oil Recovery (EOR).
Super-IOR, is a special chemical modified to accelerate recovery of oil fields. On a low concentration in a system, Super-IOR has the ability to imbibe and alter the amount of energy on the surface or interfacial layers of the system. Super-IOR injection is one of EOR methode that uses a chemical to mobilize the residual oil saturation. Super-IOR is also known as a wetting agent that takes part on lowering the interfacial tension of a fluid and helps distribute the fluid on the surfaces of the rock.
Super-IOR has a surface active characteristic, its monomer will accumulate and form a single layer (monolayer) between the surface of water and oil. This monolayer is called a micelle. The structures of a micelle are varying and non-static. The inner side of the micelle has the ability to dissolve the oil phase. A Micelle that has many dissolved components (oil-in-water and water-in-oil) is called microemulsion.
In the Super-IOR injection process, the pores undergo an oil release phenomenon which allows the oil to flow with the water. This phenomenon is called oil stripping. In the oil stripping process, there is an interaction between Super-IOR, oil-water, and the core which involves the mass transfer and imbibition phenomena. The mass transfer process in the Super-IOR, oil-water, and core system could affect the petrophysical and petrochemical properties which able to enhance the oil mobility. The mass transfer between Super-IOR and oil-water afford to alter the interfacial tension between water and oil resulting in the mixing of water and oil together. The mass transfer process between Super-IOR and the formation causes a wettability alteration.
Wettability is defined as the ability of a fluid to flow and stick to solid surfaces because of the present of immiscible fluid. The preference of a solid to contact one liquid or gas, known as the wetting phase. The wetting phase will tend to spread on the solid surface and a porous solid will tend to imbibe the wetting phase, in both cases displacing the nonwetting phase. When the fluid involved contains water and oil, wettability can be defined as the ability of a rock to absorb oil, water, or both fluids at once. Rock wettability is an important property to control the location, flow and distribution of fluids in the reservoir.
Imbibition is the process of absorbing a wetting phase into a porous rock. Spontaneous imbibition refers to the process of absorption with no pressure driving the phase into the rock. On the drainage process (replacement of oil with water), the non-wetting phase pressure (oil) is higher than the present capillary pressure, resulting in the distribution of the wetting phase (water) into the pores. During the imbibition process on capillary condition, the wetting phase replaces the non-wetting phase without any outside pressure to the core. In the imbibition process, the oil recovery efficiency is determined by the microscopic displacement efficiency. Microscopic displacement is strongly related to the oil mobility in the pores which involves the interaction between Super-IOR, oil, dan core. Therefore, the Super-IOR injection method able to improve the microscopic displacement efficiency.