Determining gas hydrate reservoirs using well-logging data is necessary for gas hydrate resource assessment. Conventional well-logging data interpretation can be tedious and time-consuming. Machine learning models can automate the well-logging interpretation process, saving time and reducing the need for the expertise of trained engineers. In this research, gas hydrate-bearing sediments in Qilian mountain permafrost of the Qinghai-Tibet Plateau were investigated. An extreme gradient boosting (XGBoost) ensemble learning model was constructed to identify gas hydrate-bearing sediments, with its performance benchmarked against typical machine learning algorithms including random forest (RF), K-nearest neighbors (KNNs), and gradient boosting decision tree (GBDT). The XGBoost model achieved the highest precision (99.0%) in identifying the gas hydrate of minority class in permafrost regions, demonstrating significant improvements over RF, KNN, and GBDT models. Through dimensionality reduction and sensitivity analysis of well-logging parameters for gas hydrate-bearing layers, the optimal parameter combination for identification was determined as caliper, resistivity, and bulk density. The optimized identification model based on ensemble learning algorithms provides theoretical foundations and technical support for detecting gas hydrate reservoirs in permafrost regions.

ABSTRACT Accurate identification of gas‐hydrate‐bearing layers in permafrost regions is critical for gas‐hydrate exploration and development. Conventional well‐logging methods are often affected by lithology, pore structure, and other interfering factors, leading to complex and ambiguous responses that hinder precise evaluation of gas‐hydrate saturation. Machine learning models offer an automated approach to well‐logging interpretation, improving efficiency and reducing dependence on expert knowledge. In this study, four models—Light Gradient Boosting Machine (LightGBM), Extreme Gradient Boosting (XGBoost), support vector machine (SVM), and K ‐nearest neighbors ( K NN)—are optimized using the grey wolf optimizer (GWO) algorithm and subsequently compared. The results demonstrate that the GWO–LightGBM model achieves an overall identification accuracy of 97.14%. For the gas‐hydrate class (the positive class), it yields an F 1‐score of 84.82%. The proposed model significantly outperforms the other three comparison models. Furthermore, validation using independent well data and SHAP (SHapley Additive exPlanations) analysis confirms the excellent generalization ability and interpretability of the proposed model.

In gas hydrate exploration, well-logging interpretation plays a crucial role in characterizing reservoir properties and evaluating gas hydrate reserves. However, traditional methods often suffer from low identification accuracy and lithological ambiguity. To address these challenges, this study proposes a deep learning-based lithology identification approach that integrates Bayesian Optimization, Convolutional Neural Networks (CNN), and Long Short-Term Memory (LSTM) networks. Specifically, Bayesian Optimization is employed to fine-tune the hyperparameters of a hybrid CNN-LSTM model, thereby enhancing its performance. The optimized model is then applied to well-logging data for lithology identification, leveraging CNNs for spatial feature extraction and LSTMs for modeling sequential dependencies. The proposed BO-CNN-LSTM model attained a lithology identification accuracy of97.26% on the test setfor permafrost-associated gas hydrate-bearing sediments, demonstrating significant performance improvements over the non-optimized CNN-LSTM and all other benchmark models. This approach provides a robust and effective solution for lithology identification in gas hydrate-bearing permafrost areas.

The Qilian Mountain permafrost area located in the northern of Qinghai-Tibet Plateau is a favorable place for natural gas hydrate formation and enrichment, due to its well-developed fractures and abundant gas sources. Understanding the formation and distribution of multi-component gas hydrates in fractures is crucial in accurately evaluating the hydrate reservoir resources in this area. The hydrate formation experiments were carried out using the core samples drilled from hydrate-bearing sediments in Qilian Mountain permafrost area and the multi-component gas with similar composition to natural gas hydrates in Qilian Mountain permafrost area. The formation and distribution characteristics of multi-component gas hydrates in core samples were observed in situ by X-ray Computed Tomography (X-CT) under high pressure and low temperature conditions. Results show that hydrates are mainly formed and distributed in the fractures with good connectivity. The ratios of volume of hydrates formed in fractures to the volume of fractures are about 96.8% and 60.67% in two different core samples. This indicates that the fracture surface may act as a favorable reaction site for hydrate formation in core samples. Based on the field geological data and the experimental results, it is preliminarily estimated that the inventory of methane stored in the fractured gas hydrate in Qilian Mountain permafrost area is about 8.67×1013 m3, with a resource abundance of 8.67×108 m3/km2. This study demonstrates the great resource potential of fractured gas hydrate and also provides a new way to further understand the prospect of natural gas hydrate and other oil and gas resources in Qilian Mountain permafrost area.

Audio magnetotelluric (AMT) is an effective exploration method to study the electrical structure of strata based on the electrical differences of rocks. The gas hydrate in the permafrost has the characteristic of high resistivity, which is different from the surrounding rock electrically. The AMT method can be used for the exploration and evaluation of gas hydrate in the permafrost. Based on the actual geological characteristics of gas hydrate reservoir in the Qilian Mountain permafrost, the geoelectric model of gas hydrate reservoir is established by combining with resistivity logging. The application range of AMT method for gas hydrate reservoir detection and the optimal acquisition parameter setting scheme were simulated by using finite element method and nonlinear conjugate gradient method. When porosity of gas hydrate reservoir is less than 5%, gas hydrate saturation is greater than 70%, occurrence scale is less than 50 m, or burial depth is greater than 500 m, AMT technique cannot identify and delineate the favorable gas hydrate reservoir. Survey line should be more than twice the length of probable occurrence scale, while tripling the length will make the best result. The number of stations should be no less than 6, and 11 stations are optimal. At the high frequency section (10 similar to 1000 Hz), there should be no less than 3 frequency points, 4 being the best number. The research results could provide important reference for gas hydrate reservoir electrical prospecting in the Qilian Mountain permafrost.

Global warming and the response to it have become a topic of concern in today 's society and are also a research focus in the global scientific community. As the world's third pole, the global warming amplifier, and the starting region of China 's climate change, the Qinghai-Tibet Plateau is extremely sensitive to climate change. The permafrost on the Qinghai-Tibet Plateau is rich in natural gas hydrates (NGHs) resources. Under the background of global warming, whether the NGHs will be disassociated and enter the atmosphere as the air temperature rises has become a major concern of both the public and the scientific community. Given this, this study reviewed the trend of global warming and accordingly summarized the characteristics of the temperature increase in the Qinghai-Tibet Plateau. Based on this as well as the distribution characteristics of the NGHs in the permafrost on the Qinghai-Tibet Plateau, this study investigated the changes in the response of the NGHs to global warming, aiming to clarify the impacts of global warming on the NGHs in the permafrost of the plateau. A noticeable response to global warming has been observed in the Qinghai-Tibet Plateau. Over the past decades, the increase in the mean annual air temperature of the plateau was increasingly high and more recently. Specifically, the mean annual air temperature of the plateau changed at a rate of approximately 0.308?0.420°C/10a and increased by approximately 1.54?2.10°C in the past decades. Moreover, the annual mean ground temperature of the shallow permafrost on the plateau increased by approximately 1.155?1.575°C and the permafrost area decreased by approximately 0.34×106 km2 from about 1.4×106 km2 to 1.06×106 km2 in the past decades. As indicated by simulated calculation results, the thickness of the NGH-bearing permafrost on the Qinghai-Tibet Plateau has decreased by 29?39 m in the past 50 years, with the equivalent of (1.69?2.27)×1010?(1.12?1.51)×1012 m3 of methane (CH4) being released due to NGHs dissociation. It is predicted that the thickness of the NGH-bearing permafrost will decrease by 23 m and 27 m, and dissociated and released NGHs will be the equivalent of (1.34?88.8)×1010 m3 and (1.57?104)×1010 m3 of CH4, respectively by 2030 and 2050. Considering the positive feedback mechanism of NGHs on global warming and the fact that CH4 has a higher greenhouse effect than carbon dioxide, the NGHs in the permafrost on the Qinghai-Tibet Plateau will emit more CH4 into the atmosphere, which is an important trend of NGHs under the background of global warming. Therefore, the NGHs are destructive as a time bomb and may lead to a waste of efforts that mankind has made in carbon emission reduction and carbon neutrality. Accordingly, this study suggests that human beings should make more efforts to conduct the exploration and exploitation of the NGHs in the permafrost of the Qinghai-Tibet Plateau, accelerate research on the techniques and equipment for NGHs extraction, storage, and transportation, and exploit the permafrost-associated NGHs while thawing them. The purpose is to reduce carbon emissions into the atmosphere and mitigate the atmospheric greenhouse effect, thus contributing to the global goal of peak carbon dioxide emissions and carbon neutrality.

The Qinghai-Tibet Plateau (also referred to as the Plateau) is the largest area bearing alpine permafrost region in the world and thus is endowed with great formation conditions and prospecting potential of natural gas hydrates (NGH). Up to now, one NGH accumulation, two inferred NGH accumulations, and a series of NGH-related anomalous indicators have been discovered in the Plateau, with NGH resources predicted to be up to 8.88×1012 m3. The NGH in the Qinghai-Tibet Plateau have complex gas components and are dominated by deep thermogenic gas. They occur in the Permian-Jurassic strata and are subject to thin permafrost and sensitive to environment. Furthermore, they are distinctly different from the NGH in the high-latitude permafrost in the arctic regions and are more different from marine NGH. The formation of the NGH in the Plateau obviously couples with the uplift and permafrost evolution of the Plateau in spatial-temporal terms. The permafrost and NGH in the Qilian Mountains and the main body of the Qinghai-Tibet Plateau possibly formed during 2.0–1.28 Ma BP and about 0.8 Ma BP, respectively. Under the context of global warming, the permafrost in the Qinghai-Tibet Plateau is continually degrading, which will lead to the changes in the stability of NGH. Therefore, The NGH of the Qinghai-Tibet Plateau can not be ignored in the study of the global climate change and ecological environment.

南祁连盆地木里坳陷部署的多个天然气水合物钻孔钻遇不同程度的水合物与油气显示伴生现象,指示该地区具有良好的油气勘探前景,有必要对已发现油气显示进行来源分析.由于水合物钻孔深度有限,针对DK-9孔4组油气显示样品,在开展现有烃源岩油源对比基础上,选取中侏罗统、上三叠统各5组代表性低熟烃源岩样品进行热模拟实验,模拟深部烃源岩生、排烃过程,将新生烃类再次与油气显示进行对比,进一步探究油气显示来源.结果显示,油气显示可分为两类(Ⅰ和Ⅱ),第Ⅰ类油气显示遭受生物降解作用,成熟度稍高,第Ⅱ类油气显示成熟度稍低;现有烃源岩主要分为三种类型(Ⅰ—Ⅲ),分别对应深度163.30～207.42 m、207.42～348.50 m、357.90～586.50 m.结合常规油源对比、热模拟实验与地质条件分析,最终推测第Ⅰ类油气显示主要与第Ⅰ类烃源岩同源;第Ⅱ类油气显示主要与第Ⅱ类烃源岩同源,此外可能还有第Ⅲ类烃源岩或更深层烃源岩的贡献,即其母质来源既与中侏罗统烃源岩有关又与上三叠统烃源岩有关.

通过开展南祁连盆地木里坳陷天然气水合物基础地质剖面调查工作,对石炭系、二叠系、三叠系、侏罗系共四套层系5条剖面的炭质泥岩、泥岩等样品进行了系统采样与分析,在此基础上深入研究四套层系的有机质丰度、有机质类型和有机质成熟度等地球化学特征,分析及对比各层系的有机地球化学指标,以探讨不同层系烃(气)源岩为天然气水合物提供的气源条件.结果表明:石炭系-二叠系有机质丰度偏低,TOC(总有机碳含量)普遍小于0.4％,为非和差烃源岩,有机质类型主要为Ⅱ型和Ⅲ型,有机质成熟度为过成熟,生烃能力较差,难以成为天然气水合物潜在气源岩.三叠系样品TOC值普遍大于1％,氯仿沥青"A"平均为0.89‰,以很好和好烃源岩为主,并含少量差和非烃源岩,有机质类型以Ⅲ型为主,含少量Ⅱ2型,镜质体反射率Ro值为0.74％～0.98％,整体上处于成熟阶段,生气能力较强,可作为天然气水合物主要潜在气源岩.侏罗系以很好、好和中等烃源岩为主,并含部分差烃源岩,有机质类型主要为Ⅱ型和Ⅲ型,Ro值为0.62％～0.97％,整体上处于成熟阶段,可作为天然气水合物次要潜在气源岩.

Natural gas hydrate, oil and gas were all found together in the Qilian Mountain permafrost area, northeast of Qinghai-Tibet Plateau, China. They are closely associated with each other in space, but whether they are in any genetic relations are unknown yet. In this paper, a hydrocarbon gas-generation series, gas-fluid migration series and hydrocarbon gas-accumulation series are analyzed to probe the spatial, temporal and genetic relationships among natural natural gas hydrate, oil and gas. The subsequent results show that natural gas hydrate, oil and gas actually form a natural gas hydrate-oil-gas system. Based on the Middle Jurassic and the Upper Triassic hydrocarbon gas-generation series, it is divided into four major sub-systems in the study area: (1) A conventional Upper Triassic gas-bearing sub-system with peak hydrocarbon gas-generation in the late Middle Jurassic; (2) a conventional Middle Jurassic oil-bearing sub-system with low to mature hydrocarbon gas-generation in the late Middle Jurassic; (3) a natural gas hydrate sub-system with main gas source from the Upper Triassic gas-bearing sub-system and minor gas source from the Middle Jurassic oil-bearing sub-system as well as little gas source from the Middle Jurassic coal-bed gas and the microbial gas; (4) a shallower gas sub-system with microbial alteration of the main gas source from the Upper Triassic gas-bearing sub-system. This natural gas hydrate-oil-gas system and its sub-systems are not only theoretical but also practical, and thus they will play an important role in the further exploration of natural gas hydrate, oil and gas, even other energy resources in the study area.

Alpine permafrost regions are important sources of biogenic CH4 and methanogens play an important role in the methane-producing process. The alpine permafrost on the Qinghai–Tibetan plateau comprises about one-sixth of China’s land area, and there are various types of alpine ecosystems. However, the methanogenic communities in the typical alpine ecosystems are poorly understood. In this study, the active layers and permafrost layers of the natural ecosystem of alpine grassland (DZ2-1) and alpine swamp meadow (DZ2-5) were selected to investigate the diversity and abundance of methanogenic communities. Methanobacterium (63.65%) are overwhelmingly dominant in the active layer of the alpine grassland (DZ2-1A). ZC-I cluster (26.13%), RC-I cluster (19.56%), and Methanobacterium (15.02%) are the dominant groups in the permafrost layer of the alpine grassland (DZ2-1P). Methanosaeta (32.92%), Fen cluster (29.59%), Methanosarcina (16.33%), and Methanobacterium (13.95%) are the dominant groups in the active layer of the alpine swamp meadow (DZ2-5A), whereas the Fen cluster (50.85%), ZC-I cluster (27.63%), and RC-I cluster (14.15%) are relatively abundant in the permafrost layer of the alpine swamp meadow (DZ2-5P). qPCR data showed that the abundance of methanogens was higher in the natural ecosystem of alpine swamp meadow than in alpine grassland. We found that the community characteristics of methanogens were related to environmental factors. Pearson correlation analyses indicated that the relative abundance of Methanobacterium had a significantly positive correlation with hydrogen concentration (P < 0.01), while the relative abundances of Methanosaeta and Methanosarcina were positively correlated with acetate concentration (P < 0.05). This study will help us to understand the methanogenic communities and their surrounding environments in alpine ecosystems.

水合物饱和度参数的准确计算对于水合物资源量的评价至关重要.本文提出利用超声波测井资料与等效介质模型相结合的方法,可有效评价祁连山冻土区孔隙型水合物储层水合物饱和度变化特征,并在典型孔隙型水合物钻孔DKXX-13进行了应用.基于等效介质理论的弹性波速度模型正演模拟的纵波速度相比基于双相介质理论的弹性波速度模型更加吻合实际测井纵波速度,可用于分析孔隙型水合物储层的纵波速度特征;通过正演模拟的纵波速度与实际测井纵波速度的对比,识别出X30.0～X30.2m、X30.3～X30.4m、X31.1～X31.6m、X31.7～X31.9m、X32.0～X32.2m井段存在水合物,水合物赋存井段地层的水合物饱和度变化范围为13.0％ ～85.0％,平均值为61.9％,与标准阿尔奇公式估算结果和现场岩芯测试结果基本一致.研究结果可为祁连山冻土区水合物地层测井评价与地震勘探提供理论依据和技术支撑.

本文综合木里地区已有地质、地震、钻井、测井资料,对冻土区天然气水合物储层进行了识别与预测.综合裂缝指示因子(the factor of fissure,FF)、有机质指示因子(the factor of carbon,FC)、钙质指示因子(the factor of calcareous matter,FCa)和水合物指示因子(the factor of gas hydrate,FH 、FHD)4种指示因子,形成了利用测井资料进行冻土区天然气水合物识别的方法;根据地震资料频谱分析计算能力系数,在能量系数剖面上,含天然气水合物层段能量系数表现为"高—低—高"的特征.测井资料水合物储层指示因子和地震资料能量系数在冻土区天然气水合物储层识别中的应用,为冻土区天然气水合物资源评价提供技术支撑.

我国是世界上既有海域水合物也有陆域水合物的少数几个国家之一.中国地质调查局高度重视陆域水合物调查研究,2016年正式设立"陆域天然气水合物资源勘查与试采工程",通过对我国重点冻土区开展地质、地球物理和钻探调查,研发有效的陆域水合物调查、钻探和资源评价技术,初步摸清资源家底,评价资源潜力.自2002年开始探索性调查以来,已在青海省发现木里天然气水合物产地1处、昆仑山垭口盆地和乌丽地区疑似产地2处及系列找矿线索,评价出南祁连盆地、羌塘盆地及漠河盆地三大成矿远景区、12个成矿区带,资源潜力巨大;在祁连山木里地区成功实施单直井和水平对接井试采,并取得了陆域天然气水合物成矿理论、勘采技术、环境调查和平台建设系列成果.以上成果有力推进了我国天然气水合物资源勘查试采进程,支撑国务院将天然气水合物设为第173个新矿种,初步形成"海陆并举、资环并重"的良好局面.

哈拉湖地区目前基本属于地质空白区,有关天然气水合物形成及分布的研究较少,尤其针对该地区天然气水合物储层研究与认识较为有限。青徳地2井（QH-2）位于南祁连盆地哈拉湖坳陷西部,为坳陷内首口天然气水合物调查深井,钻遇第四系、新近系—古近系和三叠系。以青徳地2井三叠系主要储集岩层段岩心为研究对象,通过岩石薄片观察以及孔隙度、渗透率、密度、铸体薄片等物性测试,结合测井资料开展哈拉湖坳陷储层特征研究,结果表明:青德地2井三叠系储层分布较广,厚度巨大,但储集性能整体较差,绝大部分属非常规储集层,且整体裂隙较不发育,较难形成类似木里地区固结岩层中的裂隙型水合物及孔隙型水合物,而该区冻土层下存在厚层第四系松散沉积物及裂隙相对发育的古近系—新近系,可为天然气水合物形成提供良好的储集空间。

通过对南祁连盆地哈拉湖坳陷天然气水合物科学钻探试验QH-1孔、QH-2孔不同层段内岩心顶空气中各烃类气体含量及甲烷碳同住素值的统计,对比研究了岩心中烃类气体组分含量随不同深度的变化特征,剖析了组分含量与岩性、裂隙或破碎带之间的对应关系,探讨烃类气体的成因,指出了烃类气体对岩性、裂隙或破碎带、天然气水合物异常的地质指示意义.结果 显示:顶空气高含量区间段对泥岩有一定的指示作用,岩心中一定深度范围内多处钻遇石膏晶体,石膏出露层段与顶空气高含量区间段较为吻合,烃类气体可能主要以吸附(游离)的方式被封存在泥岩中,石膏起到了一定的封堵作用;裂隙或破碎带内岩心顶空气组分含量相对较高,显示裂隙或破碎带对烃类气体的聚集有一定控制作用;与南祁连盆地木里地区相比,钻探区虽然达到了天然气水合物稳定带条件,但未能钻获到天然气水合物,推测气体浓度较低为原因之一;钻孔岩心顶空气中甲烷气体主要以热解成因为主,并含部分混合成因气.

羌塘北缘开心岭—乌丽冻土区沿隐伏断层发育多处冷泉含水溶解烷烃,采用水溶烃组分和甲烷的稳定碳、氢同位素特征对其成因开展了分析研究.结果表明,开心岭—乌丽冻土区水溶烃组分中甲烷含量比例高达99.83％ ～99.96％,同时伴随有少量乙烷、丙烷,另含微量的乙烯和丙烯.开心岭一带水溶烃甲烷 δ13 CPDB值介于-46.5‰ ～-55.1‰,δDVSMOW值为-281.0‰ ～-342.0‰;乌丽一带水溶烃甲烷 δ13 CPDB值介于-47.8‰ ～-58.9‰,δDVSMOW值为-339.0‰ ～-346.0‰,指示水溶烃甲烷为有机成因,但气源较复杂,利用 δ13 CCH4-δDCH4、δ13 C1-C1/(C2+C3)等成因图解判别,得出甲烷主要属微生物气,次之为热解成因气,混有少量原油伴生气.推断甲烷主要为有机质在微生物作用下分解的烃类气体或次生生物气,与晚二叠世那益雄组含煤烃源岩有关,气源条件暗示该地区冻土带200～500 m深度内有利于微生物成因气为主的甲烷天然气水合物形成.

The Qilian Mountain permafrost is one of the key areas for the investigation and study of gas hydrates in China, and is also the only area where gas hydrate has been discovered in China's permafrost. Since gas hydrate sample was firstly recovered in 2008, the investigation and research work is gradually progressing toward breadth and depth. It has achieved series of achievements such as the breakthrough in point-to-face prospecting, the discovery of various energy sources such as oil and gas, and the success of trial production tests. Moreover, the basic theoretical understanding has been significantly improved. The various elements of gas hydrate system are described more comprehensively and deeply, especially the in-depth analysis of gas sources and structural conditions further enriches the connotation of gas hydrate petroleum system. The effective survey technology system including geological, geophysical, geochemical, and drilling was summarized. In the aspect of gas hydrate production test, the feasibility of the use of key technologies such as depressurization technology and control monitoring in diagenetic reservoirs was confirmed. It is proposed that horizontal well production technology will be one of the key scientific and technological research directions for increasing gas production in the future. For the environmental effects, mineralogical evidence that hydrates have changed or are changing in their steady state has been discovered, and the evolutionary pattern of the gas hydrate system caused by climate warming has been proposed, and the environmental impact has gradually emerged. Thus, gas hydrate not only has potential resource value as a new type of energy, but also is an unstable factor that can cause environmental effects. It is not difficult to predict that with the continuous warming of Qinghai-Tibetan Plateau, the study on the stability evaluation of gas hydrate reservoirs in permafrost will become an important aspect for environmental effects.

The heat flow values of northern Tibet were calculated based on three gas hydrate wells' temperature logs and core thermal conductivity analysis. Laboratory thermal conductivity test results were first calibrated by using associated core porosity and a 100% water-saturated model, then the arithmetic average thermal conductivity was determined from the corrected values, which were weighted by a factor proportional to the interval thickness. Geothermal gradients were from the linear regression analysis of the borehole temperature data, which was logged within 48 hours after TD. The shallow interval temperature data was filtered out to avoid the impact of ground temperature and permafrost. Two different geothermal gradients were derived from well A. A weighted average of the two zones for well A resulted in a heat flow value of 42.7 mW . m(2). Well B and well C only had one geothermal gradient. Heat flow values of 58.3 mW . m(2) and 70 mW . m(2) were calculated for well B and well C, respectively. Some factors, such as crustal faults, mantle upwelling and shear heat from overthrust terrains, may lead to higher heat flow values in the south of Bangong Co-Nujiang suture zone. Conversely, the heat flow value is relatively low in the north of the suture zone.

Gas hydrate saturation calculation is a complex problem in the evaluation of gas hydrate reservoirs in the Qilian Mountain permafrost. From observations of the actual rock samples and experimental results from scanning electron microscopy images, gas hydrate reservoirs contain some extent of laminated and dispersed clay that affects the resistivity response of formation rocks. In light of this situation, we need to consider the influence of clay content when we evaluate the saturation of gas hydrate reservoirs in the studied area. We establish two kinds of resistivity models according to the distribution of clay and obtain corresponding methods to evaluate the saturation of gas hydrates based on the effective medium theory (EMT). The results show that the clay content in the shaly sand reservoirs varies over a large range, from 3.0 to 45.0%, and the average value is 19.4% indicating a high clay content overall. The comparison between experimental resistivity and simulated results show that the models based on EMT can be used to characterize the resistivity of reservoirs with different clay distributions. In the DK-2 well, the mean value of gas hydrate saturation obtained by the EMT is 35.6%, whereas that estimated using the Archie equation is 9.5%. In the DK-3 well, similarly, the mean value of gas hydrate saturation obtained by the EMT is 34.4%, whereas that estimated using the Archie equation is 15.5%. The gas hydrate saturation obtained from the EMT is higher than that obtained from the Archie equation because the former takes into account not only the content but also the distribution of clay. The method based on EMT is more effective for identifying and estimating gas hydrate reservoirs in the Qilian Mountain permafrost.