Energies (Jul 2021)

Characterization of Thin Gas Hydrate Reservoir in Ulleung Basin with Stepwise Seismic Inversion

  • Bo-Yeon Yi,
  • Young-Ho Yoon,
  • Young-Jun Kim,
  • Gil-Young Kim,
  • Yong-Hwan Joo,
  • Nyeon-Keon Kang,
  • Jung-Ki Kim,
  • Jong-Hwa Chun,
  • Dong-Geun Yoo

DOI
https://doi.org/10.3390/en14144077
Journal volume & issue
Vol. 14, no. 14
p. 4077

Abstract

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Natural gas hydrates (GHs) filling sand layer pores are the most promising GHs that can be produced via conventional mechanisms in deep-sea environments. However, the seismic tracking of such thin GH-bearing sand layers is subject to certain limitations. For example, because most GH-bearing sand layers are thin and sparsely interbedded with mud layers, conventional seismic data with a maximum resolution of ~10 m are of limited use for describing their spatial distribution. The 2010 Ulleung Basin drilling expedition identified a relatively good GH reservoir at the UBGH2-6 site. However, the individual GH-bearing sand layers at this site are thin and cannot therefore be reliably tracked using conventional seismic techniques. This study presents a new thin layer tracking method using stepwise seismic inversion and 3D seismic datasets with two different resolutions. The high-resolution acoustic impedance volume obtained is then used to trace thin layers that cannot be harnessed with conventional methods. Moreover, we estimate the high-resolution regional GH distribution based on GH saturation derived from acoustic impedance at UBGH2-6. The thin GH layers, previously viewed as a single layer because of limited resolution, are further subdivided, traced, and characterized in terms of lateral variation.

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