Volume 49

Imbibition Distance and Influencing Factors of Surfactant in Tight Reservoir: An Experimental Study Jinxin Cao, Yiqiang Li, Yuling Zhang, Yaqian Zhang, Yifei Cai, Qihang Li, Xuechen Tang, Tao Song, Zheyu Liu

Abstract

The process of imbibition agents entering pore throats under capillary pressure, displacing and extracting crude oil through spontaneous imbibition, is an important mechanism for enhancing oil recovery in tight reservoirs. Current research primarily focuses on the mechanism of imbibition to improve oil recovery in tight reservoirs, with relatively few studies on the distance of imbibition. Utilizing nuclear magnetic resonance techniques, this study has established a quantitative characterization method for the imbibition distance of surfactants in tight cores based on nuclear magnetic resonance T2 spectrum and projection curve. Through one-dimensional core inlet imbibition experiments and multi-cycle two-dimensional imbibition experiments, the study analyzed the effects of imbibition pressure, core permeability, initial oil saturation, and other factors on the imbibition distance. The results showed that for a core with a permeability of 0.1mD, as the imbibition pressure increased, the imbibition distance increased from 42mm to 60mm, and the oil saturation at inlet decreased by 0.09. As permeability increased, the imbibition distance increased significantly. Under experimental conditions, core permeability had the greatest impact on imbibition distance, followed by imbibition pressure, and initial oil saturation had the smallest impact. In the case of multi-cycle two-dimensional imbibition, the ultimate imbibition distance increased from 60mm for one-dimensional cores to 85mm for multi-cycle two-dimensional cores, representing a 16.8% increase in sweep distance compared to single-cycle development. This study provides quantitative insights and experimental methods for understanding the reverse imbibition distance of surfactants in tight reservoirs, laying a theoretical foundation for the development of imbibition in tight reservoirs.

Keywords imbibition distance, projection curve, large scale physical simulation experiments, nuclear magnetic resonance