Applied Geophysics

, Volume 14, Issue 2, pp 205–215 | Cite as

Nuclear magnetic resonance T2 spectrum: multifractal characteristics and pore structure evaluation

  • Jian-Ping Yan
  • Xu He
  • Bin Geng
  • Qin-Hong Hu
  • Chun-Zhen Feng
  • Xiao-Pan Kou
  • Xing-Wen Li
Article

Abstract

Pore structure characteristics are important to oil and gas exploration in complex low-permeability reservoirs. Using multifractal theory and nuclear magnetic resonance (NMR), we studied the pore structure of low-permeability sandstone rocks from the 4th Member (ES4) of the Shahejie Formation in the south slope of the Dongying Sag. We used the existing pore structure data from petrophysics, core slices, and mercury injection tests to classify the pore structure into three categories and five subcategories. Then, the T2 spectra of samples with different pore structures were interpolated, and the one- and three-dimensional fractal dimensions and the multifractal spectrum were obtained. Parameters α (intensity of singularity) and f (α) (density of distribution) were extracted from the multifractal spectra. The differences in the three fractal dimensions suggest that the pore structure types correlate with α and f (α). The results calculated based on the multifractal spectrum is consistent with that of the core slices and mercury injection. Finally, the proposed method was applied to an actual logging profile to evaluate the pore structure of low-permeability sandstone reservoirs.

Keywords

NMR T2 spectrum multifractal interpolation pore structure permeability sandstone 

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Notes

Acknowledgments

We would also like to thank Hu Falong and Tan Maojin for the constructive suggestions that significantly improved the manuscript.

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Copyright information

© Editorial Office of Applied Geophysics and Springer-Verlag GmbH Germany 2017

Authors and Affiliations

  • Jian-Ping Yan
    • 1
    • 2
  • Xu He
    • 2
  • Bin Geng
    • 3
  • Qin-Hong Hu
    • 4
  • Chun-Zhen Feng
    • 5
  • Xiao-Pan Kou
    • 5
  • Xing-Wen Li
    • 5
  1. 1.State Key Laboratory of Oil & Gas Reservoir Geology and Exploitation (Southwest Petroleum University)ChengduChina
  2. 2.School of Geoscience and TechnologySouthwest Petroleum UniversityChengduChina
  3. 3.Institute of Exploration and DevelopmentShengLi Oil Field, SINOPECDongyingChina
  4. 4.Department of Earth and Environmental ScienceUniversity of Texas at ArlingtonTexasUSA
  5. 5.Changqing Division of PetroChina Logging CompanyXi’anChina

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