Understanding the interfacial wettability of reservoir rock at nanoscale

As novel and unconventional energy sources, tight oil and gas reservoirs are an important research topic and are highly significant for crude-oil-based economies. The quality of tight oil and gas reservoirs is related to the ability of transportation and storage of crude oil liquid-phase components in the internal pore throats, which, in turn, is determined by the wettability of the interfaces between the solid and liquid phases. To evaluate such tight oil reservoir rock, it is necessary to understand the transportation and storage behaviors of oil in the corresponding environment, which, in turn, requires an understanding of interfacial wettability. In this study, we applied the theory of the interfacial wettability of solids and liquids to the observation of real reservoir rock. Chemical methods are used for surface modification of the natural reservoir rock, and influence of the physical and chemical compositions on the solid-liquid interfacial wettability of reservoir rock is analyzed. The results show that the interfacial wettability of tight reservoir rock for water, light oil, and other compositions can be tuned from oleophilic to oleophobic. The findings are expected to further develop our understanding of the transportation and storage status of liquid-phase compositions in internal spaces in tight oil and gas reservoirs and provide theoretical support for evaluating the quality of oil and gas reservoirs and the content of tight oil and gases.