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Seismic characterization of hydrates in faulted, fine-grained sediments of Krishna-Godavari Basin: Full waveform inversion

DRS at CSIR-National Institute of Oceanography

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Title Seismic characterization of hydrates in faulted, fine-grained sediments of Krishna-Godavari Basin: Full waveform inversion
 
Creator Jaiswal, P.
Dewangan, P.
Ramprasad, T.
Zelt, C.A.
 
Subject sediments
fault zones
seismic activity
gas hydrates
 
Description In fine-grained, faulted sediments, both stratigraphic and fault-induced structural variations can simultaneously determine the gas hydrate distribution. Insights into hydrate distribution can be obtained from P wave velocity (V sub(P)) and attenuation (Q sub(P) sup(-1)) character of the gas hydrate stability zone (GHSZ). In this paper, we apply frequency domain full-waveform inversion (FWI) to surface-towed 2D multichannel seismic data from the Krishna-Godavari (KG) Basin, India, to image the fine-scale (100×30m) V sub(P) and Q sub(P) sup(-1) variations within the GHSZ. We validate the inverted VP model by reconciling it with a sonic log from a nearby (apporx. 250 m) well. The V sub(P) model shows a patchy distribution of hydrate. Away from the faults-dominated parts of the profile, hydrates demonstrate stratigraphic control which appears to be permeability driven. The Q sub(P) sup(-1) model suggests that attenuation is relatively suppressed in hydrates-bearing sediments. Elevated attenuation in non-hydrate-bearing sediments could be driven by the apparent pore fluid immiscibility at seismic wavelengths. The V sub(P) and the Q sub(P) sup(-1) models also suggest that fault zones within the GHSZ can be hydrate- or free-gas-rich depending on the relative supply of free gas and water from below the GHSZ.
 
Date 2013-01-09T11:20:57Z
2013-01-09T11:20:57Z
2012
 
Type Journal Article
 
Identifier Journal of Geophysical Research, vol.117; 2012; B10305, 13pp.; doi:10.1029/2012JB009201
http://drs.nio.org/drs/handle/2264/4223
 
Language en
 
Rights An edited version of this paper was published by AGU. Copyright [2012] AGU. To view the published open abstract, go to http://dx.doi.org/10.1029/2012JB009201
 
Publisher American Geophysical Union