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Applied Geophysics

, Volume 16, Issue 2, pp 185–198 | Cite as

Seismic AVAZ inversion for orthorhombic shale reservoirs in the Longmaxi area, Sichuan

  • Teng Luo
  • Xuan Feng
  • Zhi-Qi GuoEmail author
  • Cai Liu
  • Xi-Wu Liu
Seismic Migration/Inversion

Abstract

Seismic AVAZ inversion method based on an orthorhombic model can be used to invert anisotropy parameters of the Longmaxi shale gas reservoir in the Sichuan Basin.. As traditional seismic inversion workflow does not sufficiently consider the influence of fracture orientation, we predict fracture orientation using the method based on the Fourier series to correct pre-stacked azimuth gathers to guarantee the accuracy of input data, and then conduct seismic AVAZ inversion based on the VTI constraints and Bayesian framework to predict anisotropy parameters of the shale gas reservoir in the study area.We further analyze the rock physical relation between anisotropy parameters and fracture compliance and mineral content for quantitative interpretation of seismic inversion results. Research results reveal that the inverted anisotropy parameters are related to P- and S-wave respectively, and thus can be used to distinguish the effect of fracture and fluids by the joint interpretation. Meanwhile high values of anisotropy parameters correspond to high values of fracture compliance, so the anisotropy parameters can reflect the development of fractures in reservoir. There is two sets of data from different sources, including the content of brittle mineral quartz obtained from well data and the anisotropy parameters inverted from seismic data, also show the positive correlation. This further indicates high content of brittle mineral makes fractures developing in shale reservoir and enhances seismic anisotropy of the shale reservoir. The inversion results demonstrate the characterization of fractures and brittleness for the Longmaxi shale gas reservoir in the Sichuan Basin.

Keywords

shale fracture orthorhombic AVAZ inversion 

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Notes

Acknowledgments

We truly appreciate the reviewers and the Editor for their very constructive comments and suggestions.

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Copyright information

© The Editorial Department of APPLIED GEOPHYSICS 2019

Authors and Affiliations

  • Teng Luo
    • 1
  • Xuan Feng
    • 1
  • Zhi-Qi Guo
    • 1
    Email author
  • Cai Liu
    • 1
  • Xi-Wu Liu
    • 2
    • 3
    • 4
  1. 1.College of Geo-Exploration Science and TechnologyJilin UniversityChangchunChina
  2. 2.State Key Laboratory of Shale Oil and Gas Enrichment Mechanism and Effective DevelopmentBeijingChina
  3. 3.SinoPEC Key Laboratory of Shale Oil/Gas Exploration and Production TechnologyBeijingChina
  4. 4.SinoPEC Petroleum Exploration and Production Research InstituteBeijingChina

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