Experimental study on enhanced oil recovery by advanced CO2 flooding in tight oil of ordos basin using nuclear magnetic resonance technology
Year: 2026
Type: article
Abstract: The poor physical properties and low pressure coefficient of tight reservoirs hinder the direct application of advanced water injection technologies developed for low-permeability reservoirs. As an emerging enhanced oil recovery (EOR) technique, advanced CO 2 flooding has attracted increasing attention. In this study, core samples from the Long 8 reservoir in the West 331 block of the Ordos Basin were investigated through water flooding, CO 2 flooding at different pressures, and advanced CO 2 flooding experiments, combined with nuclear magnetic resonance (NMR) analysis. The results show that water flooding achieves an oil recovery of approximately 40%, mainly from macropores. The oil recovery of CO 2 flooding increases with injection pressure and reaches 76% under miscible conditions. Advanced CO 2 flooding further improves sweep efficiency, significantly enhancing the utilization of mesopores and micropores, and increases oil recovery to 87%. After immiscible CO 2 flooding, residual oil is mainly present as contiguous oil, with increasingly heterogeneous distribution and more isolated droplets at higher pressures. Following advanced CO 2 flooding, the remaining oil primarily exists as isolated droplets, and crude oil in some regions is completely dis-placed. The lower limit of pore utilization decreases with increasing miscibility, reaching approximately 50 nm for miscible flooding and 20 nm at 1.2 times the mini-mum miscibility pressure for advanced CO 2 flooding.
Source: Scientific Reports
Authors: Jiwei Wang, Wenhao Duan, Yongjian Feng, Qiuya Han, Dong Sun, Shuting Shi, Jing Ma
Language: English
Subfield: Ocean Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,690
OpenAlex ID: W7203626726