The structure of methane gas hydrate bearing sediments from the Krishna–Godavari Basin as seen from Micro-CT scanning

Rees, E. V.; Priest, Jeffrey A.; Clayton, C. R. I.

doi:10.1016/j.marpetgeo.2011.03.015

Cited by 82 publications

(62 citation statements)

References 39 publications

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“…However, sampling effects, including effective stress reduction, fracture formation, and hydrate reformation, may be responsible for some coring-related artifacts (Yun et al, 2010). Hydraulic fracturing caused by the advection of pore fluids may have caused some hydrate to form at Site NGHP-01-10 in the KG Basin (Rees et al, 2011). The chaotic nature of the fractures at Site NGHP-01-10 also imply high gas flux (Cook and Goldberg, 2008b), unlike at Site NGHP-01-5 in the KG Basin where fractures are thought to be limited to less than a few meters in length (Cook and Goldberg, 2008a).…”

Section: Wj Winters Et Al / Marine and Petroleum Geology 58 (2014)mentioning

confidence: 99%

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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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Section: Wj Winters Et Al / Marine and Petroleum Geology 58 (2014)mentioning

confidence: 99%

“…3B, 4), then large quantities of gas hydrate may form in a fine-grained environment. Although the processes responsible for forming fracture-filling reservoirs is still being studied, hydraulic fracturing and high gas flux may be involved (Cook and Goldberg, 2008b;Cook et al, 2010;Rees et al, 2011).…”

Section: Grain Sizementioning

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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“…Formation of hydrate is analogous in several respects to frost heave formation (Cook et al 2008; J. Y. Rees et al 2011).) Once the aqueous phase saturation becomes close to the S w,irr , further decrement of the aqueous phase saturation due to hydrate formation, would cause a large capillary pressure gradient.…”

Section: Resultsmentioning

confidence: 99%

Effect of Relative Permeability Characteristics and Gas/Water Flow on Gas-Hydrate Saturation Distribution

Behseresht

Bryant

2011

All Days

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The descent of the base of gas hydrate stability zone (BGHSZ) through gas accumulated in a sediment is analyzed. A mechanistic model enables estimating hydrate saturation from initial distribution of gas phase saturation in sediment with known grain size distribution. The initial gas phase saturation is estimated from the profile of capillary entry-pressure with depth. The latter is estimated from grain size variations. A mechanistic model is proposed to determine the relative rates of methane and water transport into the HSZ during hydrate formation. The gas accumulation is assumed to be isolated so that methane transport occurs only within it. If water transport occurs only by co-current flow of gaseous and aqueous phases up to the hydrate stability zone (HSZ), it is not possible to create large hydrate saturations from large initial gas saturations due to limitations on water flux imposed by typical relative permeability curves. Thus the observed large hydrate saturations, such as that observed in Mt. Elbert, Alaska and Mallik, NW Territories and deep Indian Ocean, above the BGHSZ suggest another form of water flow: water moves down through accumulated hydrate from above. This requires the aqueous phase to remain connected within the hydrate-bearing sediment. The ratio of aqueous phase permeability in the hydrate-bearing sediment to the aqueous phase relative permeability at residual gas saturation determines hydrate saturation profile. The model is validated against field data from a hydrate-bearing sand unit in Mt. Elbert.

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“…Recent insights from pressure cores where hydrate stability conditions within the sediment during core recovery are maintained have shown that in fine-grained sediments (typical for shallow marine sediments in the Arctic) hydrate readily forms as fracture-filled near-vertical veins with average hydrate saturations of 20-30 % (Rees et al 2011). These veins can vary considerably in thickness (<0.5 mm up to 6 mm) and be fibrous in nature with veins showing terminal forking and branching.…”

Section: Hydrate In Fine-grained Sedimentsmentioning

confidence: 99%

Submarine Mass Movements and their Consequences

2016

Advances in Natural and Technological Hazards Research

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The structure of methane gas hydrate bearing sediments from the Krishna–Godavari Basin as seen from Micro-CT scanning

Cited by 82 publications

References 39 publications

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

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

Effect of Relative Permeability Characteristics and Gas/Water Flow on Gas-Hydrate Saturation Distribution

Submarine Mass Movements and their Consequences

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