Seismic velocities and quantification of gas-hydrates from AVA modeling in the western continental margin of India |
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| Authors: | Maheswar Ojha Kalachand Sain |
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| Institution: | (1) National Geophysical Research Institute, Uppal Road, Hyderabad, 500007, India |
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| Abstract: | The most commonly used marker for the investigation of gas-hydrates is the bottom simulating reflector (BSR), which is caused
by gas-hydrate laden sediment underlain by either brine or gas-saturated sediment. A BSR has been identified by seismic experiment
in the Kerala-Konkan Basin of the western continental margin of India. Here we perform AVA modeling of seismic reflection
data from a BSR to investigate the seismic velocities for quantitative assessment of gas-hydrates and to understand the origin
of the BSR. The result reveals a P-wave velocity of 2.245 km/s and an S-wave velocity of 0.895 km/s for the sediments above the BSR. This corresponds to a Poisson ratio of 0.406 and hydrates saturation
of ∼30% in the study area. The comparison of estimated P-wave velocity (1.77 km/s) above the hydrates-bearing sediment to that (1.78 km/s) below the BSR implies that the origin of
the BSR is mainly due to gas-hydrates, as the presence (even in small quantities) of free-gas reduces the P-wave velocity considerably. |
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| Keywords: | Gas-hydrates BSR Seismic velocities AVA modeling Quantification |
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