Geothermal modeling of the gas hydrate stability zone along the Krishna Godavari Basin

Shankar, Uma; Riedel, Michael; Sathe, A. V.

doi:10.1007/s11001-010-9089-6

Cited by 16 publications

(14 citation statements)

References 37 publications

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“…In order to map the distribution of the BGHSZ and understand changes in BSR occurrence and amplitude character across the 3D seismic data area, we used 1D thermal modelling to predict the BGHSZ as described by Shankar et al (2010). We assumed a hydrostatic pressure regime, uniform thermal conductivity (based on the little variation seen in the measurements during the NGHP expedition), and a uniform P-wave velocity structure with a gradual increase from seafloor to BSR depth.…”

Section: Methods and Datamentioning

confidence: 99%

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Documenting channel features associated with gas hydrates in the Krishna–Godavari Basin, offshore India

2011

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Section: Methods and Datamentioning

confidence: 99%

“…The base of the gas hydrate stability zone (BGHSZ) is highlighted by the black dashed line. during the India NGHP Expedition 01 Shankar et al, 2010).…”

Section: Methods and Datamentioning

confidence: 99%

Documenting channel features associated with gas hydrates in the Krishna–Godavari Basin, offshore India

2011

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“…But such bathymetric relief can cause large lateral temperature changes in short wavelengths due to topographic focusing of heat flow from depths (e.g., Kinoshita et al 2011), and might need correction as we wish to document in this work. Topographic focusing of heat flow occurs due to the fact that some heat from depth will transfer through the shortest path to the seafloor, causing higher heat flow in the submarine canyons; similarly defocusing effect will conversely lead to lower heat flow in ridges (e.g., Birch 1950;Turcotte and Schubert 1982;Shankar et al 2010). In this study, the effect of a poorly fitting curve on the phase boundary may be separated from that of larger-scale regional thermal structures due to the small footprint of the dataset used in this study.…”

Section: Introductionmentioning

confidence: 99%

Estimating the composition of gas hydrate using 3D seismic data from Penghu Canyon, offshore Taiwan

Sahoo¹,

Chi²,

Han³

et al. 2018

Terr. Atmos. Ocean. Sci.

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Direct measurements of gas composition by drilling at a few hundred meters below seafloor can be costly, and a remote sensing method may be preferable. The hydrate occurrence is seismically shown by a bottom-simulating reflection (BSR) which is generally indicative of the base of the hydrate stability zone. With a good temperature profile from the seafloor to the depth of the BSR, a near-correct hydrate phase diagram can be calculated, which can be directly related to the hydrate composition. However, in the areas with high topographic anomalies of seafloor, the temperature profile is usually poorly defined, with scattered data. Here we used a remote method to reduce such scattering. We derived gas composition of hydrate in stability zone and reduced the scattering by considering depth-dependent geothermal conductivity and topographic corrections. Using 3D seismic data at the Penghu canyon, offshore SW Taiwan, we corrected for topographic focusing through 3D numerical thermal modeling. A temperature profile was fitted with a depth-dependent geothermal gradient, considering the increasing thermal conductivity with depth. Using a pore-water salinity of 2%, we constructed a gas hydrate phase model composed of 99% methane and 1% ethane to derive a temperature depth profile consistent with the seafloor temperature from in-situ measurements, and geochemical analyses of the pore fluids. The high methane content suggests predominantly biogenic source. The derived regional geothermal gradient is 40°C km-1. This method can be applied to other comparable marine environment to better constrain the composition of gas hydrate from BSR in a seismic data, in absence of direct sampling.

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“…Among these conditions, the gas source must be sufficient, and the temperature and pressure are necessary conditions and root causes, which represents the possible scope for the existence of gas hydrate. Therefore, the influences of the 3 parameters on gas hydrate formation have become one of the topics of focus in the study of gas hydrate . The gas hydrate potential region is usually located in the high latitude regions of China, which has good gas hydrate formation conditions, and which are favorable for the development of a gas hydrate reservoir.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, the influences of the 3 parameters on gas hydrate formation have become one of the topics of focus in the study of gas hydrate. [14][15][16][17][18][19][20][21][22][23][24] The gas hydrate potential region is usually located in the high latitude regions of China, which has good gas hydrate formation conditions, and which are favorable for the development of a gas hydrate reservoir. However, the related work about temperature and pressure conditions for gas hydrate formation and accumulation in this area is scarce, and the understanding on the distribution range of GHSZ is still superficial.…”

Section: Introductionmentioning

confidence: 99%

A preliminary study of the gas hydrate stability zone in a gas hydrate potential region of China

Xiao

Zou

Yang

et al. 2019

Energy Science & Engineering

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Due to its significance for gas hydrate accumulation, the gas hydrate stability zone (GHSZ) is an essential condition for successful gas hydrate exploration and is usually controlled by three main factors: gas components, geothermal gradient, and permafrost thickness. Based on the core and conventional log data of gas hydrate potential region, the CSMHYD program was adopted to simulate the influences of above three factors on the thickness of the GHSZ. When the gas components of the gas hydrate were CH4, C2H6, and C3H8, with the CH4 percentage ranging from 50% to 100%, the average GHSZ thickness can reach 1000 m according to the forward simulation results. When the gas hydrate was composed of CH4 and one of C2H6, C3H8, H2S, and CO2, the influence order of the above four gases on the thickness of GHSZ is as follows: H2S ＞ C2H6 ＞ C3H8 ＞ CO2. Under the gas components of 90% CH4, 5% C2H6, and 5% C3H8, the thickness of GHSZ decreased rapidly as the geothermal gradient increased following an exponential relation with a correlation of 99.92% and increased slowly as permafrost thickness increased following a linear relation with a correlation of 99.9%. In addition, the thickness of a gas hydrate favorable reservoir was determined by comprehensive log methods as 500 m. We conclude that a reservoir within 500 m below the permafrost layer is favorable for gas hydrate reservoir formation.

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Geothermal modeling of the gas hydrate stability zone along the Krishna Godavari Basin

Cited by 16 publications

References 37 publications

Documenting channel features associated with gas hydrates in the Krishna–Godavari Basin, offshore India

Documenting channel features associated with gas hydrates in the Krishna–Godavari Basin, offshore India

Estimating the composition of gas hydrate using 3D seismic data from Penghu Canyon, offshore Taiwan

A preliminary study of the gas hydrate stability zone in a gas hydrate potential region of China

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