Gas hydrate occurrences and their relation to host sediment properties: Results from Second Ulleung Basin Gas Hydrate Drilling Expedition, East Sea

Bahk, Jang-Jun; Kim, D.-H.; Chun, Jong-Hwa; Son, Byeong-Kook; Kim, J.-H.; Ryu, Byungki; Torres, Marta E; Riedel, Michael; Schultheiss, Peter

doi:10.1016/j.marpetgeo.2013.05.006

Cited by 77 publications

(42 citation statements)

References 24 publications

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“…Expansion cracks in the recovered conventional cores were also observed, which can indicate the presence of gas and/or gas hydrate in the core (e.g., Kvenvolden and Lorenson 2001;Riedel et al 2006b). Bahk et al (2013a) defined the types of gas hydrates as "pore-filling" occurring sand layers, and "fracture-filling" in veins and nodules or "disseminated" type in mud without apparent lithologic controls. In addition, "porefilling" hydrates in diatomaceous mud were also found where gas hydrate occupies sediment layers dominated by diatom frustules.…”

Section: Summary Of Drilling Expeditionsmentioning

confidence: 99%

“…Results from UBGH2 core studies along with the analysis of similar samples from UBGH1 have contributed greatly to our understanding of lithologic controls on marine gas hydrate occurrences. Bahk et al (2013a) further examine the occurrence of gas hydratebearing sands at the Sites UBGH2-2_2 and UBGH2-6.…”

Section: Summary Of Drilling Expeditionsmentioning

confidence: 99%

“…Only few sand layers with gas hydrate were recovered during the two drilling expeditions within the Ulleung Basin Bahk et al 2013a, b). Resource assessments type studies were subsequently conducted using the drilling data combined with 2D and 3D seismic data (Kim et al , 2017 in smaller subregions of the basin.…”

Section: Resource Assessments Production Test Model and Geotechnicamentioning

confidence: 99%

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Gas hydrates in the Ulleung Basin, East Sea of Korea

Ryu¹,

Riedel²

2017

Terr. Atmos. Ocean. Sci.

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To develop gas hydrates as a potential energy source, geophysical surveys and geological studies of gas hydrates in the Ulleung Basin, East Sea off the east coast of Korea have been carried out since 1997. Bottom-simulating reflector (BSR), initially used indicator for the potential presence of gas hydrates was first identified on seismic data acquired in 1998. Based on the early results of preliminary R&D project, 12367 km of 2D multichannel reflection seismic lines, 38 piston cores, and multi-beam echo-sounder data were collected from 2000 to 2004. The cores showed high amounts of total organic carbon and high residual hydrocarbon gas levels. Gas composition and isotope ratios define it as of primarily biogenic origin. In addition to the BSRs that are widespread across the basin, numerous chimney structures were found in seismic data. These features indicate a high potential of the Ulleung Basin to host significant amounts of gas hydrate. Dedicated geophysical surveys, geological and experimental studies were carried out culminating in two deep drilling expeditions, completed in 2007 and 2010. Sediment coring (including pressure coring), and a comprehensive well log program complements the regional studies and were used for a resource assessment. Two targets for a future test-production are currently proposed: pore-filling gas hydrate in sand-dominated sediments and massive occurrences of gas hydrate within chimney-like structures. An environmental impact study has been launched to evaluate any potential risks to production.

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Section: Summary Of Drilling Expeditionsmentioning

confidence: 99%

Section: Summary Of Drilling Expeditionsmentioning

confidence: 99%

Section: Resource Assessments Production Test Model and Geotechnicamentioning

confidence: 99%

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Gas hydrates in the Ulleung Basin, East Sea of Korea

Ryu¹,

Riedel²

2017

Terr. Atmos. Ocean. Sci.

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“…Bahk et al, 2014Bahk et al, , 2013Boswell et al, 2012;Collett et al, 2012;Malinverno et al, 2008;Torres et al, 2008;Uchida et al, 2009). Generally, in these systems the hydrate-host strata is both coarser grained and more well-sorted than the bounding bulk lithofacies.…”

Section: Hydrate Occurrence Versus Lithologic Parameters At Nghp-01 Smentioning

confidence: 99%

“…Field, modeling, and laboratory studies (Kneafsey et al, 2009;Lu et al, 2011;Malinverno, 2010;Shankar and Riedel, 2013;Torres et al, 2008) indicated that for the majority of marine systems, which are dominantly fine-grained with discrete, well-constrained porous and permeable layers, a general relationship exists between higher NGH saturations and grain size of the host sediment. However, studies of NGH accumulations both onshore Rose et al, 2011) and offshore (Bahk et al, 2011(Bahk et al, , 2014(Bahk et al, , 2013Collett et al, 2012;Torres et al, 2008) increasingly illustrate that hydrate distribution within the GHSZ does not always have a simple relationship with grain size.…”

Section: Introductionmentioning

confidence: 99%

Anomalous porosity preservation and preferential accumulation of gas hydrate in the Andaman accretionary wedge, NGHP-01 site 17A

Rose

Johnson

Torres

et al. 2014

Marine and Petroleum Geology

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a b s t r a c tIn addition to well established properties that control the presence or absence of the hydrate stability zone, such as pressure, temperature, and salinity, additional parameters appear to influence the concentration of gas hydrate in host sediments. The stratigraphic record at Site 17A in the Andaman Sea, eastern Indian Ocean, illustrates the need to better understand the role pore-scale phenomena play in the distribution and presence of marine gas hydrates in a variety of subsurface settings. In this paper we integrate field-generated datasets with newly acquired sedimentology, physical property, imaging and geochemical data with mineral saturation and ion activity products of key mineral phases such as amorphous silica and calcite, to document the presence and nature of secondary precipitates that contributed to anomalous porosity preservation at Site 17A in the Andaman Sea. This study demonstrates the importance of grain-scale subsurface heterogeneities in controlling the occurrence and distribution of concentrated gas hydrate accumulations in marine sediments, and document the importance that increased permeability and enhanced porosity play in supporting gas concentrations sufficient to support gas hydrate formation. The grain scale relationships between porosity, permeability, and gas hydrate saturation documented at Site 17A likely offer insights into what may control the occurrence and distribution of gas hydrate in other sedimentary settings.Published by Elsevier Ltd.

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The impact of lithologic heterogeneity and focused fluid flow upon gas hydrate distribution in marine sediments

et al. 2014

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Gas hydrate and free gas accumulation in heterogeneous marine sediment is simulated using a two-dimensional (2-D) numerical model that accounts for mass transfer over geological timescales. The model extends a previously documented one-dimensional (1-D) model such that lateral variations in permeability (k) become important. Various simulations quantitatively demonstrate how focused fluid flow through high-permeability zones affects local hydrate accumulation and saturation. Simulations that approximate a vertical fracture network isolated in a lower permeability shale (k fracture >> k shale ) show that focused fluid flow through the gas hydrate stability zone (GHSZ) produces higher saturations of gas hydrate (25-70%) and free gas (30-60%) within the fracture network compared to surrounding shale. Simulations with a dipping, high-permeability sand layer also result in elevated saturations of gas hydrate (60%) and free gas (40%) within the sand because of focused fluid flow through the GHSZ. Increased fluid flux, a deep methane source, or both together increase the effect of flow focusing upon hydrate and free gas distribution and enhance hydrate and free gas concentrations along the high-permeability zones. Permeability anisotropy, with a vertical to horizontal permeability ratio on the order of 10 À2, enhances transport of methane-charged fluid to high-permeability conduits. As a result, gas hydrate concentrations are enhanced within these high-permeability zones. The dip angle of these high-permeability structures affects hydrate distribution because the vertical component of fluid flux dominates focusing effects. Hydrate and free gas saturations can be characterized by a local Peclet number (localized, vertical, focused, and advective flux relative to diffusion) relative to the methane solubility gradient, somewhat analogous to such characterization in 1-D systems. Even in lithologically complex systems, local hydrate and free gas saturations might be characterized by basic parameters (local flux and diffusivity).

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Gas hydrate occurrences and their relation to host sediment properties: Results from Second Ulleung Basin Gas Hydrate Drilling Expedition, East Sea

Cited by 77 publications

References 24 publications

Gas hydrates in the Ulleung Basin, East Sea of Korea

Gas hydrates in the Ulleung Basin, East Sea of Korea

Anomalous porosity preservation and preferential accumulation of gas hydrate in the Andaman accretionary wedge, NGHP-01 site 17A

The impact of lithologic heterogeneity and focused fluid flow upon gas hydrate distribution in marine sediments

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