Version 1
: Received: 8 October 2024 / Approved: 8 October 2024 / Online: 8 October 2024 (07:35:51 CEST)
How to cite:
Zhu, Y.; Wang, X.; Kang, Y.; Guo, C.; He, Q.; Li, C. Characterization of Stages of CO2-EOR Process in Low-Permeability Oil Reservoirs Based on Core Flooding Experiments. Preprints2024, 2024100556. https://doi.org/10.20944/preprints202410.0556.v1
Zhu, Y.; Wang, X.; Kang, Y.; Guo, C.; He, Q.; Li, C. Characterization of Stages of CO2-EOR Process in Low-Permeability Oil Reservoirs Based on Core Flooding Experiments. Preprints 2024, 2024100556. https://doi.org/10.20944/preprints202410.0556.v1
Zhu, Y.; Wang, X.; Kang, Y.; Guo, C.; He, Q.; Li, C. Characterization of Stages of CO2-EOR Process in Low-Permeability Oil Reservoirs Based on Core Flooding Experiments. Preprints2024, 2024100556. https://doi.org/10.20944/preprints202410.0556.v1
APA Style
Zhu, Y., Wang, X., Kang, Y., Guo, C., He, Q., & Li, C. (2024). Characterization of Stages of CO2-EOR Process in Low-Permeability Oil Reservoirs Based on Core Flooding Experiments. Preprints. https://doi.org/10.20944/preprints202410.0556.v1
Chicago/Turabian Style
Zhu, Y., Qingcheng He and Cai Li. 2024 "Characterization of Stages of CO2-EOR Process in Low-Permeability Oil Reservoirs Based on Core Flooding Experiments" Preprints. https://doi.org/10.20944/preprints202410.0556.v1
Abstract
Understanding the CO2 displacement mechanism in ultra-low permeability reservoirs is essential for improving oil recovery. In this research, a series of displacement experiments were conducted on sandstone core samples from the Chang 6 reservoir in the Huaziping area, using a multifunctional core displacement apparatus and Nuclear Magnetic Resonance (NMR) technology under conditions of constant pressure, variable pressure, and constant effective confining stress. The results revealed that the distribution characteristics of pore structure in the rock samples were critical factors influencing CO2 displacement efficiency. Under the same conditions, cores with more large pores exhibited higher oil recovery. Though fractures can facilitate CO2 flowing through pores, but the confining pressure applied during displacement caused partial closure of fractures, resulting in reduced rock permeability. Based on the oil-to-gas ratio and oil recovery in the outlet section of fractured rock samples, the CO2 displacement process exhibited five stages of no gas，a small amount of gas, gas breakthrough, large gas channeling, and gas fluctuation. Although the displacement stage of different cores is different, it is in the breakthrough stage in the range of 2PV.
Keywords
Low permeability; Chang 6 reservoir; CO2 flooding; NMR; Oil recovery
Subject
Environmental and Earth Sciences, Geophysics and Geology
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
