Modifying the Wettability of Sandstones Using Nonfluorinated Silylation: To Minimize the Water Blockage Effect

Multiphase fluid flow characteristics of a reservoir rock, such as capillary pressure, displacement efficiency, relative permeability, and saturation distribution are substantially influenced by the wettability state of the rock. Being able to change the affinity of the rock toward different fluid phases present in the formation has implications in various petroleum applications (e.g., CO2 geo-sequestration, EOR, gas production). In this study, silylation of sandstone core samples using nonfluorinated compounds is accomplished using supercritical CO2 as a solvent and carrier. This approach is cost-effective and less environmentally sensitive compared to other approaches which use fluorinated silylation reagents. By using small molecules to only change the wettability characteristics of core samples without altering other parameters (e.g., rock pore structure) noticeably, the effects of wettability alteration alone on multiphase flow (i.e., relative permeability) can be identified. Spontaneous imbibition t...