Gas hydrate accumulations in high-altitude permafrost settings remain notoriously difficult to characterize seismically, yet they hold significant resource potential This study addresses key technical challenges in seismic exploration for gas hydrates in the permafrost of the Tso Co area, Qiangtang Basin, Tibetan Plateau, including low signal-to-noise ratio, complex static corrections, and difficult structural imaging. An integrated acquisition, processing, and interpretation workflow was developed to provide a high-precision seismic detection system suited to plateau permafrost conditions. A wide-line high-density geometry, combined with a low-frequency vibrator source with a sweep frequency of 1.5–96 Hz and point-receiver technology, enhanced low-frequency penetration and raw-data fidelity. Data processing used pseudo-three-dimensional wide-line tomographic static correction and global-optimization residual static correction to resolve high-frequency static distortions through iterative refinement. A multi-domain, stepwise, amplitude-preserving denoising workflow effectively suppressed high-energy noise, including surface waves and linear interference. Refined velocity modeling based on the Dip Moveout velocity field and finite-difference time migration achieved accurate positioning of complex structures. High-quality seismic profiles reveal alternating depression-uplift structural frameworks and major fault systems. The base of the permafrost layer shows a low-frequency, high-amplitude reflection of 10–35 Hz, with varying thickness (30–140 m). Ultra-low-frequency (5 Hz) relative impedance highlights permafrost distribution and indicates hydrate potential zones concentrated along faults, demonstrating structural control on gas migration. Low-frequency amplitude anomalies provide a reliable regional indicator for hydrate exploration.

Underwater images captured by Remotely Operated Vehicles are critical for marine research, ocean engineering, and national defense, but challenges such as blurriness and color distortion necessitate advanced enhancement techniques. To address these issues, this paper presents the CUG-UIEF algorithm, an underwater image enhancement framework leveraging edge feature attention fusion. The method comprises three modules: 1) an Attention-Guided Edge Feature Fusion Module that extracts edge information via edge operators and enhances object detail through multi-scale feature integration with channel-cross attention to resolve edge blurring; 2) a Spatial Information Enhancement Module that employs spatial-cross attention to capture spatial interrelationships and improve semantic representation, mitigating low signal-to-noise ratio; and 3) Multi-Dimensional Perception Optimization integrating perceptual, structural, and anomaly optimizations to address detail blurring and low contrast. Experimental results demonstrate that CUG-UIEF achieves an average peak signal-to-noise ratio of 24.49 dB, an 8.41% improvement over six mainstream algorithms, and a structural similarity index of 0.92, a 1.09% increase. These findings highlight the model’s effectiveness in balancing edge preservation, spatial semantics, and perceptual quality, offering promising applications in marine science and related fields.

Natural gas hydrates are a promising and environmentally sustainable energy resource, but their commercial production remains challenging. External heating is crucial for improving production efficiency. In this study, we employed a self-developed simulator (IGG-hydrate) to compare the thermal performance of three key heating methods: electric heating (EH), steam injection (SI), and hot water injection (WI). Quantitative indicators, including heating and depressurization thresholds, were introduced to assess the effectiveness of each method. The results demonstrate that external heating significantly facilitates hydrate dissociation, with electric heating and steam injection showing comparable gas production rates and early-stage efficiency. However, both electric heating and steam injection methods can cause localized overheating near injection wells, leading to energy inefficiency. In contrast, hot water injection achieves a more uniform temperature distribution and a broader heating range, while avoiding excessive temperature rise. However, it also reduces depressurization efficiency and increases subsidence near the wells. To optimize performance, we propose a steam-water alternating injection strategy: steam is injected initially for rapid dissociation near the wells, followed by hot water injection to extend the heating range and maintain thermal efficiency with the same equipment.

Both submarine landslides and submarine canyons can transfer large amounts of terrigenous quantities from the continental shelf to the deep sea. In some cases, they can have a close relationship to their spatial distribution, formation and evolution. Submarine landslides on the shelf–slope can provide early depressions for submarine canyons, representing the early stage of submarine canyons. The continuous downcutting process during the evolution of submarine canyons can steepen the gradient of the canyon sidewalls, which can lead to the occurrence of submarine landslides. However, the role of submarine canyons in the initiation of slope failure has been overlooked. In this study, high-resolution multibeam bathymetry data, submarine image data and 2-D seismic data were used to investigate two adjacent submarine landslides developed on the northern slope of the Xisha Trough and the spatiotemporal relationship of these landslides to the Central Canyon. We identified a steep downslope between the submarine landslides and the Central Canyon. The Central Canyon formation age was much earlier than those of the submarine landslides. The Central Canyon is filled with modern submarine landslide deposits. The characteristics of the multiple failure scarps indicate retrogressive failure of the submarine landslides. We suggest that the submarine landslides developed on the northern slope of the Xisha Trough Basin have finally been captured by the Central Canyon. We determined that the emptying of sediments at the end of the northern slope of the Xisha Trough Basin caused by the development of the Central Canyon caused the end of the northern slope of the Xisha Trough Basin to lose support, which may have affected the slope stability and could have even played a role in the initiation of submarine landslides. Consequently, the slope area along the Central Canyon may be susceptible to slope instability and slope failure processes.

截至目前,只有中国和日本实施了海域天然气水合物的试采,了解日本的海域水合物试采中遇到的问题及其对问题的分析情况,有助于中国下一步的水合物研究和开发工作.为了深入认识日本于2013年和2017年在日本海域南海海槽分别实施的两次试采,介绍了两次试采的部署实施情况及实际产气情况,梳理了日本对两次试采中出现的问题及其针对问题的分析研究成果,对比了两次试采中3口生产井的产气情况.发现日本两次试采都没有解决实际产气与预测结果存在差异的问题,认为加强对水合物储层特征和物理特性的认识是解决上述问题的关键;另外,水合物的生产是一个综合的过程,防砂、压降过程、排水等互相影响,在解决这些问题时应综合考虑,并应寻找稳产需要的各项生产参数的平衡点.

Natural gas hydrates (NGHs) are globally recognized as an important type of strategic alternative energy due to their high combustion efficiency, cleanness, and large amounts of resources. The NGHs reservoirs in the South China Sea (SCS) mainly consist of clayey silts. NGHs reservoirs of this type boast the largest distribution range and the highest percentage of resources among NGHs reservoirs in the world. However, they are more difficult to exploit than sandy reservoirs. The China Geological Survey successfully carried out two NGHs production tests in the Shenhu Area in the northern SCS in 2017 and 2020, setting multiple world records, such as the longest gas production time, the highest total gas production, and the highest average daily gas production, as well as achieving a series of innovative theoretical results. As suggested by the in-depth research on the two production tests, key factors that restrict the gas production efficiency of hydrate dissociation include reservoir structure characterization, hydrate phase transition, multiphase seepage and permeability enhancement, and the simulation and regulation of production capacity, among which the hydrate phase transition and seepage mechanism are crucial. Study results reveal that the hydrate phase transition in the SCS is characterized by low dissociation temperature, is prone to produce secondary hydrates in the reservoirs, and is a complex process under the combined effects of the seepage, stress, temperature, and chemical fields. The multiphase seepage is controlled by multiple factors such as the physical properties of unconsolidated reservoirs, the hydrate phase transition, and exploitation methods and is characterized by strong methane adsorption, abrupt changes in absolute permeability, and the weak flow capacity of gas. To ensure the long-term, stable, and efficient NGHs exploitation in the SCS, it is necessary to further enhance the reservoir seepage capacity and increase gas production through secondary reservoir stimulation based on initial reservoir stimulation. With the constant progress in the NGHs industrialization, great efforts should be made to tackle the difficulties, such as determining the micro-change in temperature and pressure, the response mechanisms of material-energy exchange, the methods for efficient NGHs dissociation, and the boundary conditions for the formation of secondary hydrates in the large-scale, long-term gas production.

针对QK-3井取得的曲色组泥页岩、油页岩以及液态油苗进行了有机地球化学特征分析,探讨曲色组烃源岩与液态油苗的亲缘性.研究表明:QK-3井曲色组泥岩及油页岩达一般—好烃源岩标准,有机质类型多为Ⅰ及Ⅱ1型,处于成熟阶段;油页岩、油苗样品生物标志物对比表明,二者形成环境及成熟度特征较为接近,具有很好的可比性,在曲色组中发现的油苗与该组烃源岩有着较好的亲缘关系,油苗源于曲色组油页岩等烃源岩.综合烃源岩有机地球化学特征及曲色组分布范围与沉积厚度认为,下侏罗统曲色组泥质烃源岩的生烃能力属于较好级别,是研究区内最主要的烃源岩,具有较好的勘探潜力.

China has been attaching great importance to research on natural gas hydrate resources. Since the mid-1990s, China has experienced three stages of resource prediction, investigation, and test production. Until now, five hydrate accumulations have been discovered by drilling and sampling in the Shenhu, Dongsha, Qiongdongnan Basins, and offshore Taiwan of the South China Sea and in the Muli area of Qilian Mountain, and seven hydrates have been inferred by various indicators, including geology, geophysics and geochemistry in the South China Sea, the East China Sea, and the Qinghai-Tibet Plateau. According to the hydrate stability zone, the natural gas hydrate resources in the South China Sea are estimated to be 64.6 x 10(12) m(3), those in the East China Sea are similar to 28.5 x 10(12) m(3), and those in the terrestrial permafrost are similar to 38 x 10(12) m(3). The total amount of the natural gas hydrates in China reaches up to 131.1 x 10(12) m(3), which is twice the amount of China's conventional natural gas resources. China has successfully conducted the five field test production of gas hydrates in the Muli permafrost region of Qilian Mountain and in Shenhu area of the South China Sea since 2011, in particular first using horizontal well technologies to exploit hydrates that occurred in the fine-grained reservoirs. It is expected that commercial production from the hydrate reservoir will come true in the 2030s.

基于天然气水合物钻探试验井QK-8井的调查成果,以雀莫错地区发现的高烃类气体显示为线索,从影响高山冻土区天然气水合物成藏的关键地质因素出发,系统分析了影响天然气水合物成藏的冻土厚度、烃源岩特征、储集空间、疏导系统、矿物特征及盖层条件等地质因素,明确了该区天然气水合物成藏潜力.结果显示:雀莫错地区冻土厚度较大(约100 m);上三叠统主力烃源岩整体表现为有机质丰度高,为Ⅱ2型干酪根,成熟度较高(Ro为1.3％ ～1.5％);储集空间以缝洞型储层为主,裂隙、孔隙型次之;具备有效的运移通道和良好的区域盖层,同时多层段发育方解石和黄铁矿等天然气水合物伴生矿物.综合分析认为,雀莫错地区具有一定的天然气水合物成藏潜力,是下一步天然气水合物含油气系统综合能源资源调查的主要方向.

The major historical events not only impact the global pattern in society, politics and economy, but also exsert profound effect over science and technology. Based on researches about the development of theories and technoloy in marine geology during and after the major historical events, such as the past four technological revolutions and World War Ⅰ and Ⅱ, we first divided the development history of the world marine geological survey into 5 periods (emergence period, initial period, development period, mature period and upgrade period). We reviewed the objectives, characteristics and main achievements in the field of marine geological surveys in different periods in the history. Then, we summarized the law of development in world marine geological survey and discussed about the enlightenment. In the end, we put forward our suggestions on the development of China's marine geology in light of its current scientific, political and economic situation.

崖州湾宁远河河口区位于海南岛南侧,是以陆源为主、沉积环境相对简单的小型河流入海沉积区.分别在宁远河中游、下游、河流两侧海岸带以及近岸300余米的滩坝处,采集了5根重力柱状样、55个底质沉积物样品,通过粒度分析和同位素测试,对研究区近代沉积物沉积环境、空间展布规律和水动力演化规律进行了详细探讨.结果发现,研究区主要以河流三角洲沉积为主,在空间上,根据沉积物粒度和分选将研究区划分为五类沉积环境分区;在时间上,近百年来不同地区的水动力变化有所区别,入海口附近区域水体动荡随时间变化频繁;而河道上游附近区域水体条件变化小,形成明显的沉积旋回.

In this study, systematic soil methane cycle geochemical monitoring was carried out in a typical gas hydrate region in the Qinghai-Tibet Plateau. Soil gas samples were collected for hydrocarbon components and carbon isotope analysis. Meanwhile, soil-methane fluxes from the upper active layer (20–30 cm) were monitored during six months of one year. The results of this research provide evidence of a new source of methane emission from wetland soils in permafrost regions: gas hydrate release. Sites with large methane emissions were found using flux monitoring, the characteristics of thermogenic methane were identified using carbon isotope tracing, and the relationship between emission by soils and effusion from gas hydrates was determined through correlation analyses of soil-adsorbed hydrocarbons. Seasonal variation of methane emissions are also discussed by considering the emission of bacterial methane, thermogenic methane, and the absorption of methane from the soil active layer. These comprehensive findings provide valuable information for carbon cycle research of wetlands in permafrost regions.

It is of great importance for the estimation of reserve, distribution and feasibility of exploitation to study the formation dynamics of natural gas hydrate. Appropriate low temperature and high pressure are the two key parameters for the formation of natural gas hydrate besides gas supply and migration pathway. Meanwhile, the characteristics of the sediment and the existence of the Chloridionand Sulfate ions are also important for the formation of natural gas hydrate. To analyze correctly the formation of natural gas hydrate in some area, we should first obtain detailed historical data of geology, physics and mechanics by geological survey and then build the proper mathematical model. In this paper, summary on several areas has been first processed based on the enough relative data. Next the general and special characteristics of the formation in these areas have been discussed. Then the previous mathematical models for the formation dynamics of natural gas hydrate have been reviewed. The suggestions about the development of the mathematical model for the formation and the main parameter should be focused in the future exploration have been presented.

天然气水合物是21世纪最具潜力的新型洁净能源之一,同时也是目前尚未开发的储量巨大的一种新能源.全球天然气水合物蕴藏的天然气资源总量约为2.1×1016 m3,相当于全球已探明传统化石燃料碳总量的2倍,主要分布于世界深水海域和永久冻土带中.随着中国在南海神狐海域的试采取得圆满成功,天然气水合物资源的开发利用越来越多地受到世人的关注与重视,但如何安全、经济、高效开采这种新能源,仍需投入大量人力物力进一步开展研究工作.笔者从世界主要国家天然气水合物资源的勘查试采现状入手,分析其开发利用趋势,系统梳理存在问题,提出加快推进天然气水合物勘查试采产业化的启示.

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.

1.Objectives Southern Qinghai-northern Tibet permafrost region is a place having the most widespread and most developed permafrost in China with good mineralization conditions and prospecting potentials for gas hydrate （Zhu YH et al.,2011）.In 2011,China Geological Survey initiated a special national program entitled"Gas hydrate resource exploration and trial mining",

In recent years,the gas hydrate investigation in the permafrost region of China shows that the gas source condition is the key factor for controlling the breakthrough of gas hydrate exploration in the Qiangtang Basin.In order to further clarify the potential of gas hydrate accumulation in the Duck Lake area,the authors systematically analyzed such geological factors as permafrost,gas source,reservoir and structure based on the drilling results in recent years.The results show that there are good conditions of permafrost,geothermal gradient,gas source,reservoir,structure and water source in some areas,indicating that Duck Lake area has a certain gas hydrate accumulation potential.Finding sufficient hydrocarbon gas sources will be the main direction of the next gas hydrate investigation.In addition,the thickness of the gas hydrate stability zone (GHSZ) and the depth of bottom of GHSZ in the Duck Lake area were predicted by the data of the geothermal gradient and the gas composition obtained from the drilling and AMT results.Predictive results show that,when the methane is 85％,ethane is 9％ and propane is 6％,the thickness distribution of GHSZ is basically the same as that of the permafrost.The thickness of GHSZ is between 400m and 630m,and the depth of the bottom of GHSZ is between 400m and 680m.Where methane is 98％ and ethane is 2％,the thickness of GHSZ is sharply thinned,only 0～30m in most areas and only 150m thick in certain areas,and the depth of the deepest bottom of GHSZ is only 240m.Based on the results of gas logging,it is concluded that the Oligocene Suonahu Formation has more potential gas hydrate accumulation potential than the Upper Triassic Tumengela Formation in Duck Lake area,while Tumengela Formation has strong hydrocarbon generation and expulsion capability,which thus can be regarded as an important horizon for exploration of conventional oil and gas or shale gas.

A great amount of gas hydrates occurs in polar regions.They are dominated by the type of sand rich reservoir which is relatively easier to be put into exploration and commercial production.Therefore,gas hydrates in the polar region are regarded as a kind of important strategic energy sources of the world.In this paper,upon the distribution of gas hydrate,we made an assessment of gas hydrate resource,and reviewed the gas hydrate resource pyramid in the polar regions.Upon the information from the US,Canada and Russia on exploration and development of gas hydrate in the Arctic region,we made an introduction to and comparison of four kinds of extraction technology,and gas hydrate pilot production efficiency in polar and non-polar regions.According to the current international oil and gas prices,the energy structure of the world,research targets of gas hydrate in various countries and the current situation of gas hydrate exploration and development in China,we suggest China actively participating in the research and development of polar gas hydrate.