digilib@itb.ac.id +62 812 2508 8800

More than half of the discovered reservoirs are carbonate rock type. Commonly industry will perform tertiary EOR in order to lower either Sor, IFT, even alter wettability of those rocks. Actually that logic isn't totally true since water tend to make path in the reservoir after flooding treatment. The injection of surfactant unluckily will follow that water path and make less swept efficiency. The concepts of surfactant injection are: change the interaction between fluids and rock, and or fluids/fluids. In other words wettability and IFT. Wettability is related to the interaction between rock and fluid. Carbonate rock tends to be oil wet; it means carbonate rock more adhere to oil than water, differ with sandstone. IFT means how soluble fluid to other fluid. High IFT mean there are concrete boundary between two different fluids. Low IFT means two different fluids with transitional boundary, so the fluids seem to be soluble to each other. Theoretically surfactant able to change the wettability of rock using its ionic and anionic tail-head structure, so undesired oil wet rock can alter into water wet. Surfactant also possible to lower IFT then two insoluble fluids can form micro-emulsion and produced altogether. In order to work successfully, surfactant needs soaking time to interact with rock and penetrate to the deeper pore. Sometime it is not concerned by the company due to the economical limitation. This project focuses on surfactant injection on reservoir carbonate rock with modified water flooding treatment. Sensitivity is run using various constant injections rate, at the lowest rate, 0.06 cc/m, oil recovery yield highest value since surfactant able to penetrate deeply into the deepest pore in rock. The Dynamic Imbibition Tester is designed to simulate the process of surfactant injection with various rates, this apparatus concept is close to core flooding apparatus with simplification function.