Seyyed Shahram Khalili Nezhad - Master of Science In Reservoir Engineering, Young Researchers Club, Quchan Branch, Islamic Azad University, Quchan, Iran
Amin Javadi Beygan - Bachelor of Science In Production Engineering, Department of Chemical and Petroleum Engineering, Quchan Branch, Islamic Azad University, Quchan
Omid Mahmoodi - Student of Bachelor Degree In Production Engineering, Department of Chemical and Petroleum Engineering, Quchan Branch, Islamic Azad University, Quchan
Milad Omidvar Sorkh Abadi - Bachelor of Science In Production Engineering, Department of Chemical and Petroleum Engineering, Quchan Branch, Islamic Azad University

There has been an increasing interest in Surfactant-Polymer (SP) and Alkali-Surfactant-Polymer(ASP) flooding because of the need to increase oil production from water-flooded reservoirs.Chemical Enhanced Oil Recovery (CEOR) methods are some of the most important ones to unlocksignificant amount of trapped oil from oil reservoirs. When surfactant, water, and oil are mixedtogether, they form a thermodynamically stable phase called microemulsion, which can becharacterized by ultra-low interfacial tension and the ability to solubilize both aqueous and oilcompounds. Typically, polymer, surfactant and/or alkali are injected alone or in combination. Ifdesigned correctly, the surfactant increases the capillary number, which is crucial for the mobilizationand recovery of tertiary oil, and the polymer increases the sweep efficiency by lowering the mobilityratio. If the reservoir crude oil has sufficient saponifiable components, the soap is generated in situ bythe reaction of these components with injected alkali. The IFT between the middle phasemicroemulsion and oil and again between the middle phase microemulsion and water depend on manyfactors such as all the electrolytes in the brine, temperature, pressure, oil composition, surfactant, cosurfactant,alkali, and salinity. Salinity plays an important role in achieving low IFT between both themicroemulsion and oil and between the microemulsion and brine. Therefore, phase behavior studies ofmicroemulsion are very important for numerous reasons including IFT. In this paper, an experimentalASP core flood is history matched using chemical compositional simulator. Moreover, the mainobjective of this study is to explore the effect of salinity gradient and optimum salinity on theperformance of chemical flooding by performing a series of numerical simulations. The simulationresults show that injecting the chemicals at their optimum salinity or designing the salinity gradientduring chemical flooding will increase the efficiency of SP flooding even more than ASP flooding.

Chemical Flooding, Optimum Salinity, Salinity Gradient, UTCHEM