Marine gas hydrate: Fabric, quantification and free gas content. Examples from Hydrate Ridge–Cascadia margin

2003 ◽  
Vol 114 (4) ◽  
pp. 2317-2317 ◽  
Author(s):  
Friedrich Abegg ◽  
Johannes Freitag ◽  
Gerhard Bohrmann
Keyword(s):  
Gas Hydrate ◽  
Gas Content ◽  
Free Gas ◽  
Hydrate Ridge ◽  
Marine Gas Hydrate ◽  
Cascadia Margin

Gas hydrate growth, methane transport, and chloride enrichment at the southern summit of Hydrate Ridge, Cascadia margin off Oregon

2004 ◽  
Vol 226 (1-2) ◽  
pp. 225-241 ◽  
Author(s):  
M.E. Torres ◽  
K. Wallmann ◽  
A.M. Tréhu ◽  
G. Bohrmann ◽  
W.S. Borowski ◽  
...  
Keyword(s):  
Gas Hydrate ◽  
Hydrate Ridge ◽  
Cascadia Margin

Co-existence of gas hydrate, free gas, and brine within the regional gas hydrate stability zone at Hydrate Ridge (Oregon margin): evidence from prolonged degassing of a pressurized core

2004 ◽  
Vol 222 (3-4) ◽  
pp. 829-843 ◽  
Author(s):  
Alexei V. Milkov ◽  
Gerald R. Dickens ◽  
George E. Claypool ◽  
Young-Joo Lee ◽  
Walter S. Borowski ◽  
...  
Keyword(s):  
Gas Hydrate ◽  
Stability Zone ◽  
Free Gas ◽  
Hydrate Ridge ◽  
Hydrate Stability

AVO inversion of BSRs in marine gas hydrate studies

Geophysics ◽  
2007 ◽  
Vol 72 (2) ◽  
pp. C31-C43 ◽  
Author(s):  
Marc-André P. Chen ◽  
Michael Riedel ◽  
Roy D. Hyndman ◽  
Stan E. Dosso
Keyword(s):  
Gas Hydrate ◽  
Probability Distributions ◽  
Rock Physics ◽  
Inversion Method ◽  
Physical Parameters ◽  
Sufficient Information ◽  
Variable Degree ◽  
S Wave ◽  
Free Gas ◽  
Marine Gas Hydrate

We examine the usefulness of amplitude versus offset (AVO) analysis of bottom-simulating reflections (BSRs) for estimating associated marine gas hydrate and free-gas concentrations. A nonlinear Bayesian inversion is applied to estimate marginal probability distributions (MPDs) of physical parameters at a BSR interface, which are related to overlying gas hydrate and underlying free-gas concentrations via rock physics modeling. The problem is constrained further by prior information and re-parameterization of inversion results. Inversion of BSR AVO data from offshore Vancouver Island, Canada, shows that gas hydrate and free-gas concentrations are, respectively, 0%–23% and0%–2% of the pore volume, at a 90% credibility level. This result indicates that the data do not provide sufficient information to independently resolve gas hydrate and free-gas concentrations to useful accuracy. The study is directed primarily at AVO for gas-hydrate-related BSRs, but may have important applicability in testing the degree of constraint of formation characteristics in other AVO studies. The inversion method is applied also to syn-thetic AVO data generated from Ostrander’s gas-sand model. In this case, MPDs sufficiently constrain the relationship between P- and S-wave velocities in the sandstone unit to determine if it is gas-charged. The variable degree of model constraint obtained in this AVO study highlights the need to include rigorous quantita-tive uncertainty analysis in all AVO studies.

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