Study on rapid construction of microemulsion system based on EACN of crude oil measured by the direct method

The purpose of this study is to delineate the applicability of the direct method for determining the equivalent alkane carbon number (EACN), a crucial parameter in the hydrophilic-lipophilic deviation (HLD) theory, and to validate the efficacy of microemulsion systems formulated using this theory. The workload associated with constructing microemulsion systems can be substantially minimized through the application of the HLD theory, yet the accuracy and efficiency of this approach necessitate verification. Notably, the scope of application for the direct method in measuring EACN remains ambiguous. To address this, three different crude oil samples were analyzed, with their EACN values measured using the direct method. Subsequently, based on these measurements, microemulsion systems were screened and constructed according to the HLD theory. Adaptability experiments, interfacial tension assessments, and core displacement experiments were conducted to evaluate the system’s performance and its capacity to enhance oil recovery. The results indicate that the direct method has limitations in measuring the EACN of crude oil, particularly for heavy oils with complex compositions, but it is suitable for light oils with simpler compositions. Furthermore, the core displacement experiment revealed that for light oil from Xinghua Oilfield, the formulated system achieved a notable increase in recovery by 15.44%, demonstrating a significant enhancement in oil recovery.