Research Article
Research on Microscopic Pore-throat Structure Characteristics Using Multiple Methods: A Case Study of the Chang 9 Reservoir in Ansai Oilfield
Wang Xixi*,
Meng Yue,
Li Yongfeng,
Hu Guilin
Issue:
Volume 13, Issue 2, April 2025
Pages:
16-24
Received:
7 March 2025
Accepted:
27 March 2025
Published:
31 March 2025
DOI:
10.11648/j.sd.20251302.11
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Abstract: This study presents a comprehensive investigation of the pore-throat characteristics in the Chang 9 tight sandstone reservoir of Ansai Oilfield, Ordos Basin, utilizing an integrated multiscale characterization approach. By combining image-based pore analysis, high-pressure and rate-controlled mercury intrusion porosimetry, nuclear magnetic resonance (NMR) relaxation spectroscopy, and nano-CT three-dimensional reconstruction, we established a complete pore-throat characterization methodology spanning multiple scales.The experimental results demonstrate that the reservoir exhibits a bimodal pore-throat distribution, with an average two-dimensional pore radius of 21.51 μm. The three-dimensional pore-throat network is characterized by predominant throat sizes of 0.15 μm (ranging 0.006-1 μm) and pore sizes of 120 μm (60-270 μm). NMR analysis reveals that the lower threshold radius for movable fluids ranges from 0.88 to 8.94 μm, showing significant positive correlation with reservoir quality parameters.A well-developed microfracture network with apertures of 0.07-4.80 μm was identified, which substantially enhances the reservoir's flow capacity. The successful integration of multiple characterization techniques enables complete pore-throat structure characterization across all relevant scales in tight sandstone reservoirs.These findings provide both theoretical foundations and practical guidance for sweet spot identification, reservoir evaluation, and hydrocarbon exploration/development in tight sandstone formations. The established methodology offers valuable insights for understanding fluid storage and flow mechanisms in low-permeability reservoirs.
Abstract: This study presents a comprehensive investigation of the pore-throat characteristics in the Chang 9 tight sandstone reservoir of Ansai Oilfield, Ordos Basin, utilizing an integrated multiscale characterization approach. By combining image-based pore analysis, high-pressure and rate-controlled mercury intrusion porosimetry, nuclear magnetic resonanc...
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