As terrestrial mineral resources become increasingly scarce, people naturally turn their attention to the oceans. The oceans cover a significant portion of Earth's surface. 2/3 , harboring abundant mineral resources. Globally, offshore oil production has reached a share of the total oil output of... 30% Right. China’s offshore oil industry has made significant progress, and the output of offshore oil can account for a substantial portion of the country’s total oil production. 11% The widely distributed oceanic metallic nodules, due to their rich content of... With you 、 Co 、 You Useful metals have long attracted people's attention, and our country has already begun exploring the eastern Pacific Ocean. C-C Area demarcation 15 The 10,000-square-kilometer exploration area has been approved by the United Nations. The seabed boasts abundant and diverse mineral resources. This article focuses on two particularly important resources: seafloor hydrothermal sulfides and natural gas hydrates.

　　Submarine hydrothermal sulfide deposits

　　1.1 Discover

　　1948 During a scientific expedition in mid-Red Sea, Sweden’s research vessel “Albatross” detected anomalies in water temperature and salinity. Subsequent detailed investigations at that location revealed the presence of polymetallic nodules. Research suggests that the formation of these polymetallic nodules is closely linked to seafloor spreading. In the late 1960s and early 1970s, as scientists began using underwater photography to study areas along mid-ocean ridges associated with seafloor spreading, they discovered a series of hydrothermal vents along the oceanic ridge and confirmed that polymetallic nodules were actively depositing and forming in those locations. 1972 Year, 1976 Year in the Galapagos Expansion Ridge and 1984 During the seabed heat flow surveys conducted in the Okinawa Trough over the years, significant heat flow anomalies have been detected. For instance, at certain stations in the Okinawa Trough, heat flow values have reached 200 Many MW/M2 This is more than three times the normal value of seafloor heat flow. Subsequent deep-diving surveys conducted in these areas have all confirmed the presence of seafloor hydrothermal sulfide deposits. Moreover, the discovery of seafloor hydrothermal sulfide deposits has largely depended on the maturation of human deep-diving technology. United States ALVIN Deep-submergence vehicle, French NAUTILE Deep-submergence vehicle, former Soviet Union MIR Deep-submergence vehicles and Japan's deep-sea exploration 2000 Number and Deep Sea 6500 All deep-sea submersibles have played a very important role in the investigation and study of hydrothermal activities on the seafloor and their associated hydrothermal sulfide mineral resources. From... 1963 In the year, the U.S. Discoverer discovered polymetallic nodules of hydrothermal origin in the Red Sea, to... 1979 Year Alvin The deep-sea submersible discovered growing hydrothermal black smokers on the East Pacific Rise. To date, the exploration and research of modern seafloor hydrothermal sulfide deposits have spanned more than half a century. Over the past half-century, scientists, through relentless efforts, have achieved remarkable discoveries and research results.

　　1.2 Distribution

　　As investigation activities continue to advance, the discovery of seafloor hydrothermal sulfide deposits has expanded from specific regions to mid-ocean ridges and from back-arc basins to intraplate volcanoes. Soon, it became clear that seafloor hydrothermal sulfide deposits represent a remarkably widespread geological phenomenon across the global ocean floor. It is now known that the three major tectonic settings in the oceans are: ( Mid-ocean ridge, intra-plate volcanoes, and back-arc basins ) Hydrothermal sulfide deposits are widely distributed. Although there is limited survey data available for regions of the ocean other than mid-ocean ridges, intraplate volcanoes, and back-arc basins, it is certain that areas characterized by tectonic activity in the ocean are the primary locations for the development of seafloor hydrothermal sulfides. To date, we have identified more than a hundred hydrothermal sulfide mineralization sites on the world’s seafloor. According to our research findings, modern seafloor hydrothermal sulfides are predominantly found near the axial valleys and volcanic craters of mid- and low-latitude mid-ocean ridges, typically at water depths of... 2600 The site is located in the higher-elevation portion of the spreading segment along the mid-ocean ridge, and the spreading rate is closely correlated with the distribution of hydrothermal vent areas.

　　1.3 Potential huge resources

　　From 1978 Since the discovery of massive sulfides at the East Pacific Rise, the issue of hydrothermal mineralization has received sufficient attention in modern research on seafloor hydrothermal activity. By... 1993 The year has been delineated in the world's seabed. 139 At hydrothermal mineralization sites, several of which contain resource quantities exceeding one million tons. For example, the massive sulfide deposits on the Explorer Ridge of the Northeast Pacific Ocean Ridge have diameters reaching— 200 Rice, height is 10 Rice, reserves greater than 1.5 Mt, North Juan de Fuca Ridge 7 Hydrothermal accumulation body, diameter 400 Rice, tall 60 Rice, with estimated resource volumes exceeding per site. 1.0Mt Red Sea Atlantis II The estimated reserves of hydrothermal metals in the deep-sea abyss are 94.0 Mt, Mid-Atlantic Ridge TAG Diameter of a sulfide deposit in a hydrothermal activity zone 250 Rice, tall 50 M, the estimated reserves of massive sulfides are 5.0Mt In addition, according to survey and research on the black and white chimney structures in the Lau Basin of the western Pacific Ocean, their reserves—whether in terms of size or sulfide content—are no less than those of the Mid-Atlantic Ridge. TAG Hydrothermal zone. Plus stretching along... 4 Kilometers long, 200 In a strip several meters wide, there are hundreds of manganese chimneys, with typical thicknesses. 4.5 Calculated in centimeters, the estimated resource amount exceeds 10.0Mt It is evident that the global reserves of hydrothermal mineral resources on the seafloor are truly substantial, and the prospects for resource development are highly promising.

　　1.4 Our country's research

　　As early as 1985 As early as this year, Chinese scholars proposed a multi-factor theory of hydrothermal mineralization and paid attention to the role of subsurface hydrothermal fluids at mid-ocean ridges. Fe 、 With you the role in the precipitation of sulfides. However, during this period, China’s research in this area was limited to theoretical studies and participation in overseas surveys and research projects through international cooperation. 1988 Year and 1990 In the middle of the year, Germany and the United States collaborated to conduct two surveys of hydrothermal sulfides in the Mariana Trench using Germany’s research vessel, the Sonne. 1993 In that year, the Institute of Oceanology, Chinese Academy of Sciences, conducted a cruise to survey hydrothermal deposits in the Okinawa Trough using the vessel “Science No. 1” for the first time, and at... 1994 Year 3 The team once again assembled to conduct an on-site investigation of hydrothermal sulfides in the Okinawa Trough. 1998 This past year, China’s “Dayang No. 1” vessel conducted its first experimental survey of deep-sea hydrothermal mineral deposits in the Mariana Trench. In just over a decade, China has achieved remarkable results in the exploration of deep-sea hydrothermal mineral resources. For example, we have found exceptionally high concentrations of gold and silver in hydrothermal samples from the Okinawa Trough.

　　Natural gas hydrate

　　The foundation of economic growth in modern society is the possession and utilization of energy. Today, the world’s energy… 80% From fossil fuels ---- Coal, oil, and natural gas—along with economic development and population growth, humanity’s demand for resources has been increasing year by year. According to our conventional fossil fuel theories and exploration findings, humanity is soon going to face a shortage of non-renewable fossil fuel resources. Therefore, it is imperative to find new alternative energy sources. ( Also known as follow-up ) Addressing resource shortages and sustaining economic growth is a critical challenge that China—and indeed, all countries around the world—faces jointly. Since natural gas hydrates were widely discovered in seabed sediments last century, they have drawn intense attention from the scientific community due to their extensive distribution, enormous reserves, and high energy content, and are considered promising as a potential future energy source. 21 The next-generation energy sources to succeed conventional oil and gas resources, which are nearing depletion in this century. ” The latest research findings by Japanese scientists indicate that Japan’s proven reserves of natural gas hydrates can sustain the country even after oil and natural gas resources are depleted. 140 year. This result is sufficient to draw our serious attention to the study of natural gas hydrates. It can be anticipated that... 21 In the 21st century, gas hydrates—considering solely from an energy perspective—will play a very important role.

　　2.1 Stable occurrence and distribution

　　Natural gas hydrates are gas-in-water clathrates. ( Generally methane. ) The cage-like structure resembles ice in appearance. Water molecules form a cage-like framework, with a gas molecule occupying the center. Many gas molecules are of an appropriate size to fit into this cage-like framework and form hydrates—for example, carbon dioxide, hydrogen sulfide, and certain low-carbon hydrocarbons. Generally speaking, when the cage-like framework is filled with carbon dioxide, it’s called a carbon dioxide hydrate; if it’s filled with methane, it’s called a methane hydrate. Research indicates that natural gas hydrates form under specific temperature conditions. - They are formed and remain stable only under pressure conditions. Gas hydrates primarily form in environments characterized by low temperatures and high pressures. The temperature range typically falls within... -10℃—30℃ , the corresponding pressure range is 1-100MPa If the temperature rises, the corresponding pressure must also rise. For example, in... 0℃ as long as the stress condition is greater than 3MPa gas hydrates can then form, and when the temperature rises to... 20℃ At that time, the pressure must be greater than. 20MPa Only gas hydrates can form and remain stable.

　　Based on the stable pressure range within which natural gas hydrates can stably exist, it is readily inferred that natural gas hydrates are primarily found in cold, terrestrial regions near the poles and in deep-sea sediments under high pressure. Currently, they have been identified in major oceans and inland seas around the world. 80 There are numerous prospective areas for natural gas hydrates, several of which have already been confirmed through seabed drilling, such as offshore Peru, the eastern and western waters of the United States, and the waters near Japan.

　　2.2 Potential huge energy

　　According to the data, the land area is... 27% , the area of the marine territory 90% Natural gas hydrates are widely distributed. Moreover, the vast majority of naturally occurring gas hydrates to date are methane hydrates. Methane hydrates act as traps for methane gas; under one atmospheric pressure, the decomposition of a unit volume of methane hydrate can yield: 160 Volumetric methane gas. Therefore, at a depth of approximately 2000 Shallow sedimentary gas hydrates in the seabed harbor vast quantities of methane. The carbon content of methane hydrates is twice that of all other fossil fuels. The energy flux of these methane hydrates... ( The volume of methane per unit volume of rock under standard conditions. ) It is another unconventional gas source. ( Such as coal seams, black shales, and deep aquifers. ) Energy flux of the 10 times, which is the conventional natural gas energy flux. 2-5 Twice as much. Its reserves are roughly equivalent to the combined total of coal and conventional oil and natural gas. 3 times. According to data from U.S. geologists, the total resource volume of modern natural gas hydrates is 1 × 10¹⁸ m³ , according to 28 Materials from the Geological Congress indicate that the resource volume of natural gas hydrates could reach... 28 × 10¹³ m³ 。

　　It is evident that natural gas hydrates have extremely abundant reserves. Some scientists have confidently pointed out that natural gas hydrates will be... 21 An important energy source of the century.

　　2.3 Research on Natural Gas Hydrates Abroad

　　80 Over the past decades, countries including Russia, the United States, Japan, Canada, Germany, the Netherlands, and India have attached great importance to the exploration and development of marine gas hydrates, and have successively formulated long-term development plans and implementation strategies from the strategic perspective of resource reserves. It should be noted that... 90 Research on natural gas hydrates has only begun to flourish in recent years. The United States 1995 Year in ODP The first 164 During the voyage, three exploration wells were first deployed on the Blake Ridge, and for the first time, gas hydrate samples were systematically obtained. 1995–1999 Japan has basically completed the offshore geophysical survey of natural gas hydrates in the Nankai Trough. 3000 The exploration well in Mi has revealed natural gas hydrate deposits within the accretion wedge. In 1998 Year 5 The U.S. Senate Resources Committee unanimously approved it in June. “ Research and Resource Development Program for Submarine Natural Gas Hydrates ” This century's Ocean Drilling Program (ODP21) Identifying the formation mechanisms of seabed gas hydrates will also be one of the primary academic objectives. In response to its current energy shortage, India... 1996–2000 In recent years, a special research program has been established to explore seabed gas hydrate resources, with plans to invest... 5600 Millions of U.S. dollars are being allocated to conduct research and survey activities in the Bay of Bengal and the Arabian Sea.

　　Near 10 In recent years, substantial progress has been made in research on the formation conditions, distribution patterns, formation mechanisms, environmental impacts, exploration technologies, development processes, economic evaluations, and environmental protection of seabed gas hydrates.

　　2.4 Research on Gas Hydrates in China’s Marginal Seas

　　In recent years, domestic institutions have convened seminars focused on natural gas hydrates, emphasizing the significance of conducting research on natural gas hydrates in China. They have also taken the lead in funding offshore surveys for natural gas hydrates in the South China Sea. Currently, several major science and technology projects in China—such as projects funded by the National Natural Science Foundation— ODP Project, 973 Project, S863 Projects and other initiatives have all listed the study of natural gas hydrates as a key research area.

　　The East China Sea and its adjacent waters not only boast rich geological features but also abundant oil and natural gas resources. Since the 1960s, exploration activities in this region have focused on tectonic evolution and mineral resource assessment. ( Oil and gas ) Geological and geophysical surveys conducted primarily for evaluation purposes have accumulated a wealth of data valuable for the study of gas hydrates. This data includes geological sampling data, seabed temperature data, crustal heat flow data, geothermal gradient data, refraction seismic data, multi-channel seismic data, and well-log data. The data indicate that in China’s marginal seas... ( East China Sea, South China Sea, and waters east of Taiwan ) Some regions have the water depth and seabed temperature conditions necessary for the stable existence of natural gas hydrates. ODP184 Drilling results from the cruise in the South China Sea revealed chemical anomalies associated with gas hydrates, which were identified on multiple seismic profiles along the northern continental margin of the South China Sea. BSR An obvious [feature] was also found on the seismic survey profile deployed in the South China Sea specifically for natural gas hydrate research. BSR The research and exploration of natural gas hydrates in China’s East China Sea and adjacent waters are continuing to advance.