عنوان مقاله [English]
Gravity drainage is one of the most important production processes in all reservoirs, where the gravity force is the main driving mechanism. Gravity drainage is responsible for production from various gigantic reservoirs south Iran which have over a half century old. Relative permeability is one of the most important and effective parameters in this process. Also it is a strong function of Interfacial Tension (IFT). Actually in most of EOR projects, production increased by decreasing IFT between fluids, and all of the production mechanisms (e.g. gravity drainage) are encountered with different values of IFT.In this paper we study the effect of IFT on relative permeability curves. In order to simulate the gravity drainage process, various experiments were performed utilizing a centrifuge apparatus. Different IFT values were obtained by applying different temperatures. Relative permeability curves were also obtained by conducting tests by unsteady-state method. These results are analogous with the ones by centrifuge method.The relative permeability curves for different IFT values were plotted utilizing the experimental data. Comparison of these curves demonstrate the pronounce effect of IFT on displacement efficiency of fluid and relative permeability curves. As the IFT decreases, the relative permeability increases and hence reduces the residual saturation of fluid in the sample.