Qilian Mountain permafrost, with area about 10×104 km2, locates in the north of Qinghai‐Tibet plateau. It equips with perfect conditions and has great prospecting potential for gas hydrate. The Scientific Drilling Project of Gas Hydrate in Qilian Mountain permafrost, which locates in Juhugeng of Muri Coalfield, Tianjun County, Qinghai Province, has been implemented by China Geological Survey in 2008–2009. Four scientific drilling wells have been completed with a total footage of 2059.13 m. Samples of gas hydrate are collected separately from holes DK‐1, DK‐2 and DK‐3. Gas hydrate is hosted under permafrost zone in the 133–396 m interval. The sample is white crystal and easily burning. Anomaly low temperature has been identified by the infrared camera. The gas hydrate‐bearing cores strongly bubble in the water. Gas‐bubble and water‐drop are emitted from the hydrate‐bearing cores and then characteristic of honeycombed structure is left The typical spectrum curve of gas hydrate is detected using Raman spectrometry. Furthermore, the logging profile also indicates high electrical resistivity and sonic velocity. Gas hydrate in Qilian Mountain is characterized by a thinner permafrost zone, shallower buried depth, more complex gas component and coal‐bed methane origin etc.

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Based on gas composition and temperature measurements in the course of field drilling, the upper and lower depths of gas hydrate stability zone are calculated by modeling in the Muli permafrost, Qinghai, then the modeling results are compared with the drilling results. The modeling results show that the upper depth of gas hydrate stability zone is 148.8~122.7 m and the lower depth of gas hydrate stability zone is 324.6~354.8 m, with the thickness of gas hydrate stability zone of 175.8~232.2 m; the drilling results indicate that gas hydrate and its related indications occur at the interval of 133~396 m. These two types of results are comparable and thus are basically accordant, suggesting that the modeling can serve as a prediction of the upper and lower depths of gas hydrate stability zone. Gas composition, depth of permafrost, thermal gradients above and below the base of permafrost are sensitive factors affecting the upper and lower depths of gas hydrate stability zone in the Muli permafrost.

Natural gas hydrates were discovered in the Muli area of the Qinghai-Tibetan Plateau permafrost, which is an area of alpine permafrost in the midlatitudes. Resistivity models were employed to understand the distribution and accumulation mechanism of gas hydrates in the Muli area, as these models are suitable for use in detecting the presence and amount of pore-and fracture-filling gas hydrates in consolidated rocks, and geophysical logs were used to constrain gas hydrate saturation. The results show that resistivity logs are sensitive to gas hydrate saturation in consolidated rocks in the Muli area. Geophysical log analysis enabled the discovery of eleven pore-filling gas hydrate reservoirs (total thickness: 21.95 m) and nine fracture-filling gas hydrate reservoirs (total thickness: 90.55 m). It is hypothesized that gas accumulation is more likely to occur in fractures within mudstones due to good permeability and sealing properties and that fracture-filling gas hydrates are more likely to occur than pore-filling gas hydrates. Poor preservation conditions may thus be the key factor in the absence of gas hydrates in the eastern part of the study area. Evidence from geophysical logs shows that the upper boundary of the gas hydrate stability zone in the Muli area is at a depth of 133.25 m and that the lower boundary is deeper than 400 m. The results of this study are useful for further gas hydrate exploration in alpine permafrost at the midlatitudes.Key Points:• Resistivity logs are more sensitive to gas hydrate saturation than compressional-wave velocity logs in consolidated rocks of the Muli area • Resistivity models of pore-and fracture-filling gas hydrate reservoirs are used to detect gas hydrates in consolidated rocks • Gas hydrate accumulation in the Muli area is affected by faults, lithology, and the gas hydrate stability zoneSupporting Information:• Supporting Information S1