Impact of energized pre-fracturing on fracture network evolution and imbibition in tight oil reservoirs
Abstract
Energized pre-fracturing has emerged as an effective approach for enhancing reservoir energy, fracture complexity and oil recovery in tight reservoirs. However, the mechanisms by which fracture propagation induced by different energized pre-pad fluids governs subsequent imbibition-driven oil recovery remain insufficiently understood. To address this issue, an integrated experimental framework was established to investigate the coupled evolution of fracture networks and pore-scale oil displacement during energized prefracturing. By combining X-ray computed tomography for quantitative fracture characterization and dynamic nuclear magnetic resonance for monitoring imbibition-driven oil recovery, the interactions between fracture-scale architecture and pore-scale fluid redistribution were systematically elucidated. The results demonstrate that, compared to conventional fracturing, energized pre-fracturing not only lowers breakdown pressure but also promotes the formation of more complex, highly connected fracture networks, which in turn substantially enhance ultimate oil recovery. Notably, gaseous pre-pad fluids exhibit clear advantages over aqueous systems, with supercritical CO2 generating the lowest breakdown pressure and the most intricate multi-branch fracture networks, as indicated by higher fracture fractal dimension and area ratio. These fracture characteristics significantly facilitate imbibition efficiency, resulting in higher oil recovery. Pore-scale analysis further reveals that oil mobilization is dominated by contributions from micropores and mesopores, underscoring the critical role of energized pre-fracturing in activating oil stored in small-scale pore systems. The proposed multi-scale methodology, integrating fluid properties, fracture network evolution, and imbibition dynamics, provides a mechanistic basis and practical guidance for optimizing energized fracturing and improving the efficient development of tight conglomerate reservoirs.
Document Type: Original article
Cited as: Qu, H., Wu, M., Gan, J., Peng, Y., Zhou, F., Chen, Z. Impact of energized pre-fracturing on fracture network evolution and imbibition in tight oil reservoirs. Advances in Geo-Energy Research, 2026, 19(2): 131-145. https://doi.org/10.46690/ager.2026.02.03
DOI:
https://doi.org/10.46690/ager.2026.02.03Keywords:
Energized pre-fracturing, tight conglomerate reservoir, supercritical CO2, fracture propagation, imbibition enhanced oil recoveryReferences
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Copyright (c) 2025 Hongyan Qu, Mengyao Wu, Jiayue Gan, Yan Peng, Fujian Zhou, Zhongwei Chen
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