Wu, J.; Zhu, Y.; He, Y.; Wang, Q.; Guo, J.; Shao, S.; Li, R.; Bao, Y. Dynamic Characterization of Microscopic Pore Structure in Mid-High Permeability Sandstones during Long-term Water-flooding. Preprints2024, 2024061774. https://doi.org/10.20944/preprints202406.1774.v1
APA Style
Wu, J., Zhu, Y., He, Y., Wang, Q., Guo, J., Shao, S., Li, R., & Bao, Y. (2024). Dynamic Characterization of Microscopic Pore Structure in Mid-High Permeability Sandstones during Long-term Water-flooding. Preprints. https://doi.org/10.20944/preprints202406.1774.v1
Chicago/Turabian Style
Wu, J., Rubin Li and Yi Bao. 2024 "Dynamic Characterization of Microscopic Pore Structure in Mid-High Permeability Sandstones during Long-term Water-flooding" Preprints. https://doi.org/10.20944/preprints202406.1774.v1
Abstract
Most of the mid-high permeability sandstone oilfields in China have entered the ultra-high water cut stage, accompanied with the highly-dispersed residual oil, and the control effect of mi-cro-heterogeneity on the residual oil is increasingly prominent. Understanding the microscopic characteristics of pore structural and its evolution during the long-term waterflooding is critical for enhancing the accuracy and efficiency of oil field exploitation. While the previous insights paid more attention to the geometrical and morphological features of pore structure and ignores the relation of pore structure with the fluid flow capacity. In this study, we propose a microscopic pore structure classification method considering pore size and local permeable capacity, which realizes the physical classification and quantitative evaluation of pore structure characteristics for different permeability rocks. The micro-pore structure is classified into 6 types based on the key evaluation parameters of pore diameter and flow flux area. By taking six mid-high permea-bility sandstone core samples from Daqing oilfield in China, a series of long-term waterflooding experiments are carried out and the interior pore structure was captured using high precision CT scanning technique. The results reveals that high-permeability reservoirs exhibit concentrated pores diameters and finer throats, whereas mid-permeability reservoirs exhibit smaller pores and throats in greater quantity. With the increase of water injection volumes, the permeable ca-pacity and connectivity of the high-connectivity pore space in ultra-high- and high-permeability reservoirs are enhanced, and in mid-permeability reservoirs, the micro-heterogeneity intensifies the increase in low-connectivity small pores. These findings provide new insights for the micro-scopic heterogeneity and a solid theoretical basis for investigating the occurrence of microscopic residual oil and optimising enhanced oil recovery strategies at the late stage of ultra-high water cut.
Copyright:
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