作　　者： ; ; ;

机构地区： 中国科学院

出　　处： 《地球物理学报》 2005年第1期165-172,共8页

摘　　要： 冻土带是天然气水合物发育的两个重要地质环境之一 .青藏高原平均海拔在 4 0 0 0m以上 ,多年冻土面积约 1 4× 10 6 km2 .本文根据青藏高原冻土层厚度和地温梯度特征 ,运用天然气水合物的热力学稳定域预测方法 ,确定中低纬度高海拔区冻土带天然气水合物的产出特征 .青藏高原多年冻土带热成因和生物成因天然气水合物形成的热力学相平衡反映 ,水合物顶界埋深约 2 7～ 5 6 0m ,底界埋深约 77～ 2 0 70m .初步计算表明 ,青藏高原冻土带水合物天然气资源约 1 2× 10 1 1 ～ 2 4× 10 1 4m3.在冻土层越厚、冻土层及冻土层之下沉积层的地温梯度越小的地区 ,最有利于天然气水合物的发育 .气温的季节性变化对天然气水合物影响不大 .在全球气温快速上升的背景下 ,青藏高原天然气水合物将处于失稳状态 ,天然气水合物顶界下降、底界上升 ,与冻土带的退化相似 ,分布区逐渐缩小 ,最终将完全消失 . Permafrost is one of major geological environments for gas hydrate occurrences. Mean altitude is over 4000m and the permafrost area is about 1 4×10 6km 2 in Qinghai-Tibet Plateau. Based on the thickness of frozen layer and thermal gradient in Qinghai-Tibet Plateau permafrost, the occurrence and distribution of gas hydrate in the low-middle latitude and high altitude permafrost is predicted by using the thermodynamic method of natural gas hydrate stable temperature and pressure. The thermodynamic phase equilibrium of thermogenic and biogenic gas hydrate imply that gas hydrate is buried in depth from ～27 to ～2070m, and the resource potential of natural gases caged in hydrates are estimated as about 1 2×10 11 to 2 4×10 14m 3 in Qinghai-Tibet Plateau permafrost. Gas hydrate is propitious to occur where the frozen layer is thicker and thermal gradient is lower in the permafrost. Seasonal change of air temperature in Qinghai-Tibet Plateau affects only the uppermost sediments 10m and does not affect gas hydrate that is buried below 30m. Under the global warming, gas hydrate will be unstable and degrade in the permafrost. Its distribution area will be gradually reduced and finally disappear in Qinghai-Tibet Plateau permafrost.

关 键 词： 天然气水合物 中低纬度高原冻土带 青藏高原

领　　域： [天文地球] [天文地球]