Experimental study on a novel wettability alteration agent in tight sandstone gas reservoir

This paper introduces a hydrophobic wettability alteration agent named FCS that effectively eliminates «water blocking» by forming a tight molecular film on the sandstone surface. Wettability alteration experiments show that a tight molecular film forms, making it hydrophobic with a contact angle greater than 90°. The inner wall of a capillary tube after FCS treatment changes from liquidwetting to gas-wetting, and the capillary pressure becomes a positive driving force. Experimental study demonstrates that altering wettability of tight sandstone to produce a hydrophobic surface is a viable method for recovering permeability and eliminating «water blocking».