چكيده به لاتين
Well productivity in gas condensate reservoirs is reduced by condensate banking when the bottom hole flowing pressure drops below the dew point pressure. Among the several methods that have been proposed for condensate removal, wettability alteration of reservoir rock to gas-wetting in the near wellbore region appears to be one of the most promising techniques. In this work, we used superamphiphobic nanofluids to change the wettability of the carbonate rocks to ultra gas-wetting state. Application of nanofluids in the wettability alteration of carbonate rocks to ultra gas-wetting has not been reported previously and is still an ongoing subject. In this study, we report the synthesis of some nanoparticles such as TiO2, SiO2, CNT and ZnO/SiO2 to create superhydrophobic surface with self-cleaning properties on carbonate rock substrate. We have also studied a new feature for nano-sized perovskite-structured oxides as hydrophobicity by synthesizing CoBST and CeBST nanoparticles, which are able to repel water droplet after coating on a rock surface. Next, we introduced novel superamphiphobic nanofluids based on the synthesized nanoparticles and fluorochemicals as PTFE and PFOS mixture. It was observed that treating rock plates with the fabricated nanofluids resulted in formation of rough nanostructure coatings on the solid surface, showing multi-functions including super water and oil repellency toward various liquids ranging from 23 to 72.3 mN/m, sliding angle of 0°, self-cleaning property and well thermal and mechanical stability. Surface characterization of the treated core plugs were carried out by SEM, SP and EDX analyses. Accordingly, the ultra gas-wetting is attributed to the combined effect of roughness created by adsorption of nanoparticles on the microscale structure of rock surface and low surface energy of fluoro-containing materials. Using free imbibition test, we showed that the nanofluid could imbibe interestingly into the core sample, resulting in notable ultimate gas-condensate liquid recovery. Moreover, we studied the effect of nanofluid on relative permeability and recovery performance of gas/water and gas/oil systems for a carbonate core under reservoir conditions. The results of coreflooding tests demonstrates that the relative permeability of both gas and liquid phase increased significantly as well as the liquid phase recovery enhanced greatly after the wettability alteration to gas-wetting.
