Interfacial dilatational rheology and displacement mechanism of nano‐flooding system

Abstract In the field of crude oil extraction, nano‐flooding technology can significantly improve the oil displacement efficiency and provide important technical support for tertiary oil recovery. Although a host of studies have been carried out in this domain, its dilatational rheology and displacement mechanism are rarely reported. In order to address this gap in the extant literature, as a crucial component of this investigation, the interfacial rheology of the nano‐flooding system and the simulated crude oil was systematically studied with the aid of the JMP2000A interface expansion rheometer. Meanwhile, a micro‐displacement experiment was carried out to elucidate its displacement mechanism. The obtained results show that the nano‐flooding system initially increases as its concentration, solution pH, and aging time increase, after which a decline is observed. However, with the change of salinity, it shows a trend of increasing first and then decreasing. Moreover, according to the multi‐factor test results yielded by the relevant software, the relative error is less than 5%, which fully meets the needs of the field and provides an important basis for the field construction. The findings further suggest that the modulus between the nano‐flooding system and the simulated crude oil can be increased by 84‐fold (i.e., from 0.9271 to 78.0739 mN/m). In addition, during the displacement process, the fingering phenomenon of the displacement fluid can be reduced via piston‐like displacement. The swept volume also improves the oil washing efficiency of crude oil, demonstrating that the proposed strategy achieves the purpose of enhancing oil recovery.