Title of article :
Thermal state and concentration of gas hydrate and free gas of Coyhaique, Chilean Margin (44°30′ S)
Author/Authors :
Vargas-Cordero، نويسنده , , I. and Tinivella، نويسنده , , U. and Accaino، نويسنده , , Nabeel F. and Loreto، نويسنده , , M.F. and Fanucci، نويسنده , , F.، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2010
Pages :
9
From page :
1148
To page :
1156
Abstract :
In the last decades gas hydrate occurrence along the Chilean continental margin has been well documented. In order to better define the seismic character of the hydrate-bearing sediments, we performed a detailed velocity analysis by using the pre-stack depth migration on part of multichannel reflection seismic line RC2901-734 located offshore Coyhaique. locity model shows a hydrate bearing layer above the BSR, with high velocity (1700–2200 m s−1) and maximum thickness of 250 m and a free gas bearing layer below the BSR, characterized by low velocity (1250–1400 m s−1). A weak reflector at about 70 m below the BSR marks the base of the second layer. wing the BSR depth, the seafloor depth, and the sea bottom temperature, the geothermal gradient was estimated. The resulting gradient varies from 35 to 95 °C km−1, with highest values at the structural high, and the lowest values located in the accretionary prism and in the fore arc basin. er to quantify the amount of gas phase, the velocity model was converted into a gas-phase concentration model by using a theoretical approach. The results indicate that highest concentrations of gas hydrates, up to 23% of the total volume, are located in the fore-arc basin, and that highest concentration of free gas, up to 3% of the total volume, are located at the structural high, which may be considered as a natural trap for migrating fluids. Average concentrations are equal to 12% and 1% of total volume for gas hydrate and free gas, respectively.
Keywords :
BSR , Gas hydrate , Seismic Velocity , Gas-phase concentration , Chilean margin , Pre-stack depth migration , CIG analysis
Journal title :
Marine and Petroleum Geology
Serial Year :
2010
Journal title :
Marine and Petroleum Geology
Record number :
2251986
Link To Document :
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