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Abstract
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One of the most important challenges in gas condensate reservoir is condensate trapping, when reservoir pressure drops below dew point pressure, which can reduce gas productivity [1]. Modification of rock wetting properties, using chemical treatment is a novel approach to shift the gas and oil relative permeability towards gas wetting condition. This concept has been considered by experimental and numerical studies, as well as field attempts. Li and Firozabadi investigated performance of fluorine functional group chemicals for permanent alteration of chalk and Berea toward gas wetting condition. Their study showed, liquid mobility can be increased resulting gas production enhancement [2]. Kumar et al also used limestone cores to treat them by surfactants under reservoir condition. They observed the considerable change in relative permeability. Among wettability modifiers, nanofluid by size 1-100 nm attract attention for changing wettability due to creating roughness on surface. Condensate can be repelled from surface, resulting high condensate production compared before wettability alteration [3, 4]. Esmaeilzadeh et al used liquid repellency nanoparticle combined surfactant (COBET, COBST) to treat carbonate rock types. Significant improvement in altering wetting condition is observed, even for liquids with high surface energy [5]. Jiafeng et al performed contact angle measurements to compare nanofluid and surfactant in altering wettability of sandstone reservoir. Their results showed Gas-wetting surface can be obtained by FG40-modified-nano-silica treatment. In addition, increasing the contact angle from 33 to 118 is strong evidence that surfactants have higher effectiveness in presence of nanofluid to change wettability of rocks [6].
Sabori et al used fluorine-doped silica coated by fluorosilane nanofluid to change carbonate surface wettability. They showed that The enhancement in contact angle of liquids is attributed to reduction of surface free energy as a resul
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