This article, written by Senior Technology Editor Dennis Denney, contains highlights of paper SPE 121724, "Effect of Salinity on Wettability Alteration of Porous Media From Liquid-Wetting to Intermediate Gas- Wetting," by Stanley Wu, SPE, and Abbas Firoozabadi, SPE, Reservoir Engineering Research Institute, prepared for the 2009 SPE International Symposium on Oilfield Chemistry, The Woodlands, Texas, 20–22 April. The paper has not been peer reviewed. The synergetic effect of salinity and fluorochemicals on wettability alteration from water-wetting to intermediate gas-wetting was studied. NaCl salinity increased water-wetting when a core was saturated with brine. NaCl also reduced absolute gas permeability. CaCl2 salinity had a minor effect on permeability. NaCl, KCl, and CaCl2 brines have an adverse effect on wettability alteration. Introduction A reduction in effective gas permeability, observed in tight formations and in low-permeability gas reservoirs, often is attributed to water blocking and condensate accumulation. Water blocking is induced by the injection of water during hydraulic fracturing. Condensate accumulates at the wellbore as the pressure drops below the dewpoint pressure. A major factor of liquid retention in a rock is the liquid's low mobility because of strong liquid-wetting. By altering the wettability of the rock from liquid-wetting to intermediate gas-wetting, an increase in liquid mobility can be achieved resulting in a higher rate of gas production. One concern about the salinity in chemical treatment is that the dissociated ions may destroy the stability of chemical polymers, resulting in colloidal coagulation leading to permeability reduction. The alcohols, which often are used as a solvent for chemical solutions to reduce gas-hydrate formation in drilling and production operations, have a significant and adverse effect on the solubility of salts, increasing the risk of salt deposition. An understanding of the effect of salinity and initial liquid saturation on chemical treatment is necessary for effective design and implementation of wettability-alteration strategies in complex systems. This study reported the gas absolute-permeability and gas/water effective-permeability data before and after treatment with fluorinated polymeric surfactants in isopropanol (IPA) solutions. Experiments Wettability alteration was carried out by injecting a chemical solution into Berea and reservoir-sandstone cores and aging them at high temperature and pressure. Treatment conditions were analyzed by varying the fluids used in initial saturation and pretreatment process before chemical injection. The effectiveness of chemical treatment was evaluated by measuring gas/liquid/rock three-phase contact angle, liquid saturation in imbibition tests, gas mobility in single-phase gas flow, and liquid mobility in two-phase gas/liquid flow.