Elastic properties of gas hydrate-bearing sediments
Elastic properties of gas hydrate-bearing sediments
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DOI：
10.1190/1.1444966
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发表时间：
2001-05-01
期刊：
影响因子：
3.3
通讯作者：
Collett, TS
中科院分区：
文献类型：
--
作者：
Lee, MW;Collett, TS
在加拿大西北部的 Mallik 2L-38 天然气水合物研究井中获得的井下测量的压缩波和剪切波速度表明，天然气水合物对含天然气水合物沉积物弹性特性的主要影响是作为孔隙填充成分。与胶结理论预测的高弹性速度相反，孔隙空间中的少量天然气水合物会显着增加弹性速度，沉积物孔隙空间中天然气水合物饱和度的速度增加很小。有效介质理论和加权方程都预测天然气水合物浓度导致的速度略有增加，类似于现场观测的速度；然而，加权方程更准确地描述了含有天然气水合物的沉积物的压缩波和剪切波速度。泊松比随着天然气水合物浓度的增加而减小，与泊松比随着沉积物孔隙度的减小而减小相似，含天然气水合物沉积物的泊松比大于0.33，表明该井场含天然气水合物沉积物具有松散性质。该地点含天然气水合物沉积物的地震特征可用于比较和评价北极其他含天然气水合物沉积物。
Downhole-measured compressional- and shear-wave velocities acquired in the Mallik 2L-38 gas hydrate research well, northwestern Canada, reveal that the dominant effect of gas hydrate on the elastic properties of gas hydrate-bearing sediments is as a pore-filling constituent. As opposed to high elastic velocities predicted from a cementation theory, whereby a small amount of gas hydrate in the pore space significantly increases the elastic velocities, the velocity increase from gas hydrate saturation in the sediment pore space is small. Both the effective medium theory and a weighted equation predict a slight increase of velocities from gas hydrate concentration, similar to the field-observed velocities; however, the weighted equation more accurately describes the compressional- and shear-wave velocities of gas hydrate-bearing sediments. A decrease of Poisson's ratio with an increase in the gas hydrate concentration is similar to a decrease of Poisson's ratio with a decrease in the sediment porosity Poisson's ratios greater than 0.33 for gas hydrate-bearing sediments imply the unconsolidated nature of gas hydrate-bearing sediments at this well site. The seismic characteristics of gas hydrate-bearing sediments at this site can be used to compare and evaluate other gas hydrate-bearing sediments in the Arctic.