Effect of a synthesized anionic fluorinated surfactant on wettability alteration for chemical treatment of near-wellbore zone in carbonate gas condensate reservoirs

The pressure drop during production in the near-wellbore zone of gas condensate reservoirs causes condensate formation in this area. Condensate blockage in this area causes an additional pressure drop that weakens the effective parameters of production, such as permeability. Reservoir rock wettability alteration to gas-wet through chemical treatment is one of the solutions to produce these condensates and eliminate condensate blockage in the area. In this study, an anionic fluorinated surfactant was synthesized and used for chemical treatment and carbonate rock wettability alteration. The synthesized surfactant was characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis. Then, using surface tension tests, its critical micelle concentration (CMC) was determined. Contact angle experiments on chemically treated sections with surfactant solutions and spontaneous imbibition were performed to investigate the wettability alteration. Surfactant adsorption on porous media was calculated using flooding. Finally, the surfactant foamability was investigated using a Ross–Miles foam generator. According to the results, the synthesized surfactant has suitable thermal stability for use in gas condensate reservoirs. A CMC of 3500 ppm was obtained for the surfactant based on the surface tension experiments. Contact angle experiments show the ability of the surfactant to chemical treatment and wettability alteration of carbonate rocks to gas-wet so that at the constant concentration of CMC and at 373 K, the contact angles at treatment times of 30, 60, 120 and 240 min were obtained 87.94°, 93.50°, 99.79° and 106.03°, respectively. However, this ability varies at different surfactant concentrations and temperatures. The foamability test also shows the suitable stability of the foam generated by the surfactant, and a foam half-life time of 13 min was obtained for the surfactant at CMC.