Effect of Organosilane Structures on Mineral Surface Energy and Wettability.

The use of organosilanes has been shown to be an effective method for wettability alteration. This work explored for the first time how the structure of organosilanes impacts their ability to modify the wettability of different mineral surfaces, including pure quartz, pure calcite, sandstone, and limestone. Seven organosilanes were selected with different numbers of hydrolyzable groups, alkyl chain lengths, alkyl chain structures, and number of silicon atoms. Contact angle measurements, residual fluid saturations, and capillary pressure curves consistently showed that more hydrolyzable groups create more hydrophobic surfaces. As the number of carbon atoms increases in the silane alkyl chain, the hydrophobicity increases. The structure of the alkyl chain does not have an observable impact on the degree of wettability alteration. Finally, dipodal silanes with two silicon atoms create a much less hydrophobic surface than a single silicon atom silane. By understanding organosilane structure-property relationships with sandstone and limestone surfaces, it is possible to design tailored treatments for specific subsurface applications. Particularly in geosystems engineering, the results presented here can offer insights into enhanced oil recovery processes such as improving gas well deliverability and addressing injectivity issues during water-alternating-gas injection, as well as geological carbon sequestration processes such as improving storage capacity and caprock integrity.