Journal of Petroleum Science and Technology

Journal of Petroleum Science and Technology

AVO Analysis of Bottom Simulating Reflector (BSR) for Hybrid Model of Gas Hydrate Distribution

Document Type : Research Paper

Authors
Hoda Yari 1
Majid Nabi-Bidhendi 2
Naser Keshavarz 3
Reza Heidari 1
1 Department of Earth Sciences, Science and Research Branch, Islamic Azad University, Tehran, Iran
2 Institutes of Geophysics, University of Tehran, Iran
3 Geoscience Faculty, Research Institute of Petroleum Industry (RIPI), Tehran, Iran
10.22078/jpst.2022.4818.1805
Abstract
Due to the substantial effect of the gas hydrate distribution model (cement, un-cement, or hybrid of both models) on the elastic properties (such as shear modulus, bulk modulus, Poisson’s ratio, etc.), determining the distribution model in the hydrate-bearing sediments is a requirement for decreasing uncertainty in quantitative studies based on seismic velocities. Many different empirical and theoretical rock physics theories cover different ranges of rock properties. Among them, the Effective Medium Theory (EMT) is the most appropriate in quantitative studies of gas hydrate resources. Four types of hydrate distributions have been considered and divided into two cemented and un-cemented categories. EMT is one of the advanced rock physics modeling tools. This theory has been modified by introducing hybrid distribution models of gas hydrate instead of having assumptions about single models of hydrate distribution. Moreover, when a scientific manuscript is written, using dangling and misplaced modifiers are not suggested. On the other hand, one method to determine the gas hydrate distribution model can be performed by identifying AVO’s class on the bottom simulating reflector (BSR); caused by the contrast between an overlying gas hydrate and underlying free gas sediments. This reflector mimics seafloor topography, cross-cuts stratigraphic reflections, and is controlled by thermodynamic conditions. The results of this study on conceptual models showed that in hybrid approach for hydrate distribution, AVO’s class on BSR shows sensitivity to (1) the combination type of gas hydrate distributions models, (2) the total saturation of the gas hydrate and free-gas across the BSR.
Keywords
Gas Hydrate Distribution
Effective Medium Theory (EMT)
Hybrid Models
Amplitude Variation vs Offset (AVO)
  1. Khadem B, Javaherian A, (2019) Amplitude variation with offset inversion analysis in one of the western oilfields of the Persian Gulf: Iranian, Journal of Oil and Gas Science and Technology, 8, 2: 15-33. ##
  2. Zoeppritz K (1919) On the reflection and penetration of seismic waves through unstable layers: Erdbebenwellen VIIIB, Goettinger Nachrichten, 1: 66–84. ##
  3. Aki K, Richards P G (1980) Quantitative seismology; theory and methods, W. H. Freeman and Company, 703. ##
  4. Wiggins R, Kenny G S, McClure C D (1983) A method for determining and displaying the shear-velocity reflectivities of a geologic formation, European Patent Application, 0113944. ##
  5. Rutherford SR, Williams RH (1989) Amplitude-versus-offset variations in gas sands, Geophysics, 54: 680–688. ##
  6. Muller C, Bonnemann C, Neben S (2007) AVO study of a gas hydrate deposit; offshore Costa Rica: Geophysical Prospecting, 55: 1–17. ##
  7. Castagna J P, Swan H W, Foster D J (1998) Framework for AVO gradient and intercept interpretation, Geophysics, 63: 948–956. ##
  8. Bo Y Y, Lee G H, Horozal S, Yoo D G, Ryu B J, Kang N K, Kim H J (2011) Qualitative assessment of gas hydrate and gas concentrations from the AVO characteristics of the BSR in the Ulleung Basin, East Sea (Japan Sea), Marine and Petroleum Geology, 28, 10: 1953-1966. ##
  9. Fohrmann M, Pecher I A (2012) Analyzing sand-dominated channel systems for potential gas-hydrate-reservoirs using an AVO seismic inversion technique on the Southern Hikurangi Margin, New Zealand, Marine and Petroleum Geology, 38: 19–34. ##
  10. Ojha M, Sain K (2007) Seismic velocities and quantification of gas-hydrates from AVA modeling in the western continental margin of India, Marine Geophysical Research, 28: 101–107. ##
  11. Ojha M, Sain K (2008) Appraisal of gas-hydrates/free-gas from VP/VS ratio in the Makran accretionary prism, Marine and Petroleum Geology, 25: 637–644. ##
  12. Lu S, McMechan G A (2004) Elastic impedance inversion of multichannel seismic data from unconsolidated sediments containing gas hydrate and free gas, Geophysics, 69: 164-179. ##
  13. Ecker C (1997) Characterization of a hydrate reservoir: Stanford Exploration Project Report, 94: 1-16. ##
  14. Wang X, Pan D (2017) Application of AVO attribute inversion technology to gas hydrate identification in the Shenhu Area, South China Sea, Marine and Petroleum Geology, 80: 23-31. ##
  15. Choi Y, Kang S G, Jang U G, Kuk Hong J, Jin Y K, Keen Chung W, Shin S R (2018) AVO analysis to gas hydrates BSR in the continental shelf of canadian beaufort sea, In EGU General Assembly Conference Abstracts, 13844. ##
  16. Zhang X, Yin C, Zhang G (2021) Confirmation of AVO attribute inversion methods for gas hydrate characteristics using drilling results from the shenhu area, South China Sea, Pure Appl Geophys, 178: 477–490. ##
  17. Shoar B H (2008) Identification of gas hydrate sediments in the Oman Sea and their seismic survey, Faculty of Mining Engineering, Metallurgy and Petroleum of Amirkabir University of Technology: Master Thesis. ##
  18. Shoar B H, Javaherian A, Farajkhah N K, Arabani M S (2014) Reflectivity template, a quantitative intercept-gradient AVO analysis to study gas hydrate resources–A case study of Iranian deep-sea sediments, Marine and Petroleum Geology, 51: 184-196. ##
  19. Salehi E, Javaherian A, Ataeepour M, Farajkhah N K (2013) Quantitative seismic pre-stack analyses of potential gas-hydrate resources in the Makran Accretionary Prism, offshore Iran, Marine and Petroleum Geology, 48: 160-170. ##
  20. Ecker C (1998) Seismic characterization of methane hydrate structure, Ph.D. Thesis, Stanford University. ##
  21. Yari H, Nabi Bidhendi M, Keshavarz Faraj Khah N, Heidari R (2019) Development of hybrid models of rock physics based on effective medium theory, SE Iran, 3th National Iranian Conference on Gas Hydrate, University of Science and Technology of Mazandaran, Iran, 1-10. ##
  22. Sloan E D (1998) Clathrate hydrate of natural gases, Marcel Dekker, Inc, New York. ##