青藏高原昆仑山垭口盆地发现天然气水合物赋存的证据

Evidence of natural gas hydrate in Kunlun Pass basin, Qinghai-Tibet Plateau, China

青藏高原多年冻土区是否存在天然气水合物一直是国内外广泛关注的问题,但一直没有确定的答案.通过钻探、地球物理测井以及气体地球化学研究,在昆仑山垭口盆地发现了天然气水合物赋存的证据.钻探发现250 m以下多个深度岩层存在大量气体释放异常,甲烷气体浓度为22%~32%,且具有天然气水合物分解间歇性释放的特征,这些气体释放层位具有显著的含天然气水合物特有的密度降低、侧向电阻率和声波波速的增大特征.同时多个深度上发现了与水合物分解产生甲烷密切相关的碳酸盐和黄铁矿等自生矿物.

The possible occurrence of natural gas hydrate in permafrost of the Qinghai-Tibet Plateau has significant potential impact on energy resources, climate change and the environment. New data from a scientific drilling project in the Kunlun Pass basin indicates the presence of natural gas hydrate in permafrost on the plateau at Kunlun Pass, Qinghai Province, China. A full suite of petrophysical logs was run in the borehole, and gas geochemistry was logged during drilling. Gas recovered from multi-layer strata below the depth of 250 m was characterized by intermittent gas peaks and methane concentration ranges from 22% to 32% during drilling. Petrophysical analysis indicates that these multi-layer strata are dominated by typical gas hydrate features including low density, high lateral resistivity, and high acoustic velocity. Corroborating petrographic evidence includes authigenic carbonate minerals and pyrite found in these strata, closely related with methane and expected as a product of gas hydrate dissociation.