Seismic imaging of a fractured gas hydrate system in the Krishna–Godavari Basin offshore India

Riedel, Michael; Collett, Timothy S.; Kumar, Pushpendra; Sathe, A. V.; Cook, Ann E.

doi:10.1016/j.marpetgeo.2010.06.002

Cited by 112 publications

(71 citation statements)

References 18 publications

(21 reference statements)

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“…The temperature and pressure conditions required for gas hydrates formation are available in continental slope and permafrost environments (Sloan, 1998). The presence of marine gas hydrates in continental margins has been confirmed from different drilling activities (Collet et al, 1999;Collett and Ladd, 2000;Zhang et al, 2007;Riedel et al, 2010;Liu et al, 2012;Ryu et al, 2013). Seismic methods are commonly used to remotely identify gas hydrates in the marine sediments.…”

Section: Introductionmentioning

confidence: 99%

“…The presence of gas hydrates in sediments has a pronounced effect on the amplitude and frequency characteristics of a seismic signal also (Guerin and Goldberg, 2002;Pratt et al, 2003;Chand and Minshull, 2004). Hydrates in sediments show contradicting amplitude characteristics in seismic sections such as amplitude blanking (Korenaga et al, 1997) and amplitude enhancements (Nouzé et al, 2004;Riedel et al, 2010;Yoo et al, 2013) at different geologic settings.…”

Section: Introductionmentioning

confidence: 99%

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Gas hydrate and free gas detection using seismic quality factor estimates from high-resolution P-cable 3D seismic data

et al. 2016

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We have estimated the seismic attenuation in gas hydrate and free-gas-bearing sediments from high-resolution P-cable 3D seismic data from the Vestnesa Ridge on the Arctic continental margin of Svalbard. P-cable data have a broad bandwidth (20-300 Hz), which is extremely advantageous in estimating seismic attenuation in a medium. The seismic quality factor (Q), the inverse of seismic attenuation, is estimated from the seismic data set using the centroid frequency shift and spectral ratio (SR) methods. The centroid frequency shift method establishes a relationship between the change in the centroid frequency of an amplitude spectrum and the Q value of a medium. The SR method estimates the Q value of a medium by studying the differential decay of different frequencies. The broad bandwidth and short offset characteristics of the P-cable data set are useful to continuously map the Q for different layers throughout the 3D seismic volume. The centroid frequency shift method is found to be relatively more stable than the SR method. Q values estimated using these two methods are in concordance with each other. The Q data document attenuation anomalies in the layers in the gas hydrate stability zone above the bottom-simulating reflection (BSR) and in the free gas zone below. Changes in the attenuation anomalies correlate with small-scale fault systems in the Vestnesa Ridge suggesting a strong structural control on the distribution of free gas and gas hydrates in the region. We argued that high and spatially limited Q anomalies in the layer above the BSR indicate the presence of gas hydrates in marine sediments in this setting. Hence, our workflow to analyze Q using high-resolution P-cable 3D seismic data with a large bandwidth could be a potential technique to detect and directly map the distribution of gas hydrates in marine sediments.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Gas hydrate and free gas detection using seismic quality factor estimates from high-resolution P-cable 3D seismic data

et al. 2016

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“…This occurs both locally as a reservoir for individual hydrate grains and assemblages and also on a much larger scale by influencing fault patterns and characteristics (Minor and Hudson, 2006) that are responsible for regional fluid and gas flow that feed hydrate reservoirs (e.g., Riedel et al, 2010a). Furthermore, faults might serve as mechanisms to locally change sediment porosity (Busch, 1989).…”

Section: Introductionmentioning

confidence: 99%

Comparison of the physical and geotechnical properties of gas-hydrate-bearing sediments from offshore India and other gas-hydrate-reservoir systems

Winters

Wilcox-Cline

Long

et al. 2014

Marine and Petroleum Geology

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a b s t r a c tThe sediment characteristics of hydrate-bearing reservoirs profoundly affect the formation, distribution, and morphology of gas hydrate. The presence and type of gas, porewater chemistry, fluid migration, and subbottom temperature may govern the hydrate formation process, but it is the host sediment that commonly dictates final hydrate habit, and whether hydrate may be economically developed.In this paper, the physical properties of hydrate-bearing regions offshore eastern India (KrishnaGodavari and Mahanadi Basins) and the Andaman Islands, determined from Expedition NGHP-01 cores, are compared to each other, well logs, and published results of other hydrate reservoirs. Properties from the hydrate-free Kerala-Konkan basin off the west coast of India are also presented. Coarser-grained reservoirs (permafrost-related and marine) may contain high gas-hydrate-pore saturations, while finer-grained reservoirs may contain low-saturation disseminated or more complex gas-hydrates, including nodules, layers, and high-angle planar and rotational veins. However, even in these finegrained sediments, gas hydrate preferentially forms in coarser sediment or fractures, when present. The presence of hydrate in conjunction with other geologic processes may be responsible for sediment porosity being nearly uniform for almost 500 m off the Andaman Islands.Properties of individual NGHP-01 wells and regional trends are discussed in detail. However, comparison of marine and permafrost-related Arctic reservoirs provides insight into the inter-relationships and common traits between physical properties and the morphology of gas-hydrate reservoirs regardless of location. Extrapolation of properties from one location to another also enhances our understanding of gas-hydrate reservoir systems. Grain size and porosity effects on permeability are critical, both locally to trap gas and regionally to provide fluid flow to hydrate reservoirs. Index properties corroborate more advanced consolidation and triaxial strength test results and can be used for predicting behavior in other NGHP-01 regions. Pseudo-overconsolidation is present near the seafloor and is underlain by underconsolidation at depth at some NGHP-01 locations.Published by Elsevier Ltd.

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“…Shale tectonics (diapirism) induced deep fault system has been amply demonstrated from the K-G Basin (Mazumdar et al, 2009b;Dewangan et al, 2010;Shankar and Riedel, 2010;Riedel et al, 2010;Choudhury et al,2011). Shale tectonic is driven by the downward movement of thick sediment mass over a deeply buried over pressured shale strata (Damuth, 1994;Wu and Bally, 2000).…”

Section: Gas Hydrate Destabilzation: Tectonics and Perturbed P-t Condmentioning

confidence: 99%

Gas hydrate destabilization and methane release events in the Krishna–Godavari Basin, Bay of Bengal

Joshi¹,

Mazumdar²,

Peketi³

et al. 2014

Marine and Petroleum Geology

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Methane release events have been linked to global warming, alteration of the carbon cycle and influence on biota. However, unequivocal evidence of paleomethane release events are limited. We report several negative carbon stable isotope excursions in planktic and benthic foraminifera in a core (MD161-8) from the Krishna-Godavari (K-G) Basin, Bay of Bengal. The most negative δ 13 C spikes are recorded during the marine isotope stages MIS-4 and at the transition of MIS-5 to 4. Occurrence of highly 13 C depleted (average δ 13 C = -48±2.4 ‰ VPDB) authigenic high magnesian calcite are also reported within this time window from the core MD161-8. In the present work an unequivocal explanation for the observed 13 C depletion in the marine planktic and benthic foraminifera is difficult to achieve solely from the optical/ electron microscopy or C-O stable isotope ratio analyses due to possible influence of diagenetic alteration. We attribute the observed episodic methane expulsion events, as inferred from the negative δ 13 C excursions and earlier reports on the occurrence chemosynthetic bivalves and Mo concentration anomaly to the destabilization of the base of gas hydrate stability zone (BGHSZ). Sea level drop and shale tectonics induced focused fluid flow are the two possible causes of hydrate destabilization discussed here. Shale tectonics were possibly responsible for creating fault systems which acted as the conduit for gas flow through the sediment column and subsequent seepage. Shale and salt tectonics in the passive continental margins being a globally observed phenomenon, its role as an important driving force for enhanced methane emission needs detailed investigation to understand the climatic perturbations through geologic time. Additional evidence of methane emission from site MD161-15 further supports the link between shale tectonics and methane emission.

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Seismic imaging of a fractured gas hydrate system in the Krishna–Godavari Basin offshore India

Cited by 112 publications

References 18 publications

Gas hydrate and free gas detection using seismic quality factor estimates from high-resolution P-cable 3D seismic data

Gas hydrate and free gas detection using seismic quality factor estimates from high-resolution P-cable 3D seismic data

Comparison of the physical and geotechnical properties of gas-hydrate-bearing sediments from offshore India and other gas-hydrate-reservoir systems

Gas hydrate destabilization and methane release events in the Krishna–Godavari Basin, Bay of Bengal

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