Gas Geochemical Features of the DK-8 Gas Hydrate Drilling Hole in the Permafrost of Qilian Mountain, and their Indicative Significance
详细信息
- 责任者：Lu Zhenquan (Institute of Mineral Resources ; CAGS ; Beijing 100037 ; China) ; Rao Zhu
- 刊名：Acta Geologica Sinica
- 出版年：2013
- 卷期：87(8)
- 关键词：天然气水合物 ; gas hydrates ; 祁连山 ; Qilian Mountains
- 页码：p.1167-1178
- 图表：6 illus., 4 tables, 32 refs.
- 分类号：1003
- issnNo：ISSN0001-5717
- isbnNo：CN11-1951/P
摘要
Gas component and methane carbon isotope were analyzed for the cores at different depths in DK-8 gas hydrate drilling hole in the Muli permafrost of the Qilian Mountain.Their changing features are correlated with the intervals of gas hydrate & anomalies and with spatial distribution in faults or fractures.Out study shows that these characteristics have indicative significance in gas hydrate occurrence and hydrocarbon migration.Gas contents (μl/kg) in the cores shows anomalies at depths of 149～167m,228～299m,321～338m and 360～380m,which are basically consistent with intervals of gas hydrate and its anomalies,suggesting that high values of gas content were caused by gas hydrate and its anomalies.Based on total volumetric percentage of hydrocarbon gases in core (vol%),carbon isotope of methane (δ13C1,‰PDB),and ratios of C1/ΣC1-5,C1/ΣC2-5,C1/ΣC2-3,C1/C2,C2/C3,C2/ΣC3-4,iC4/nC4 and iC5/nC5 from samples with different distance away from faults or fractures,it is suggested that hydrocarbon gases in cores with high values migrated mainly from deep sources and were closely related with faults or fractures.Deeper faults or fractures may serve as migration paths for hydrocarbon gases,and middle to shallower faults or fractures may provide accumulation space for gas hydrate.