Oil and natural gas resources According to the estimation in 1995, the world's offshore proven oil resources reserves are 37.9 billion tons and natural gas reserves are 39 trillion cubic meters. According to incomplete statistics, the oil and gas resources on the seabed account for about 1/3 of the global oil and gas reserves. It is predicted that in this century, submarine oil and gas development will extend from the shallow continental shelf to the sea area with a water depth of 1, meters.
most of the world's offshore oil exists on the continental shelf. According to estimates, the world's continental shelf area is about 3 million square kilometers, accounting for 8% of the world's ocean area. With regard to the reserves of offshore oil, due to the limitation of exploration data and calculation methods, the conclusions are also different. An estimate by the French petroleum research institute is that the limited reserves of global oil resources are 1, billion tons and the recoverable reserves are 3 billion tons. Among them, offshore oil reserves account for about 45%, and the recoverable reserves are 135 billion tons.
Semi-submersible platform (used for deep water exploitation)
The oil production on the continental shelf of the Persian Gulf entered large-scale exploitation earlier, and together with the offshore oil production on the nearby land, it supplied more than half of the world oil demand after the war. Beihai in northwest Europe is the second largest offshore oil producing area after Persian Gulf. The Gulf of Mexico between the United States and Mexico and the offshore of China, including the seabed of Nansha Islands, are recognized as the regions with the richest offshore oil in the world.
it is much more difficult to explore and exploit oil and natural gas in the ocean than on land. It is necessary to have some special technologies different from those on land, such as platform technology, drilling technology and oil and gas transportation technology.
The working platform includes fixed platform and mobile drilling platform. The mobile drilling platform overcomes the shortcomings that the fixed platform and firewood cannot be reused, and greatly increases the working depth. Mobile offshore oil drilling equipment has its own buoyancy structure, which can be towed by tugboats. Some also have their own power equipment and can sail by themselves. Mobile offshore drilling equipment includes: pedestal platform, jack-up platform, semi-submersible platform and drilling ship. Among them, semi-submersible platform is an advanced platform suitable for deep water operation at present, which can not only overcome the instability of drilling ship, but also work in deep water.
in order to March into deep-water oil development, we have researched and stabilized cheap deep-water platforms and deep-water gravity platforms. The push platform is tied with tight steel cables, and the working water is 6-9 meters deep. The latter two platforms are fixed platforms that stand upright from the seabed to the sea surface. Their main features are reducing the cross-section and other technologies to reduce the cost, and their working depth can reach 5-6 meters.
Exploitation of marine living resources
There are rich and diverse biological species in China sea area, with more than 2, species described and recorded. There are more than 1,5 species of marine fish, and more than 2 species have a large yield. The fishing ground covers an area of 2.8 million square kilometers, and the annual output of aquatic products reaches more than 28 million tons, ranking first in the world.
The species of marine life in China are much more than those of fresh water. Of the 3,82 species of fish recorded, the ocean accounts for 3,14. In addition, China also has various high-productivity marine ecosystems such as mangroves, coral reefs, upwelling, estuaries, bays and islands, which are extremely beneficial to the reproduction and growth of all kinds of marine life.
Economists predict that the 21st century will be the century of oceans. "Agriculture and animal husbandry of marine aquatic products production", "blue revolution plan" and "seawater agriculture" constitute the main direction of marine agriculture development in the future.
Farming and stockbreeding of marine aquatic products
is to transform the marine environment through human intervention, so as to create good environmental conditions for the growth and development of economic organisms, and at the same time, to transform the organisms themselves to improve their quality and output. Specifically, it is to establish nursery factories, farms and proliferation stations to carry out artificial nursery, breeding, proliferation and release, so that the ocean can become an agricultural pasture for fish, shrimp, shellfish and algae. China is now the largest mariculture country in the world. With the further development of marine biotechnology in breeding, seedling raising, disease prevention and product development, marine aquaculture will be transformed into a high-tech industry in the 21st century.
the blue revolution plan
focuses on the utilization of seawater in the depths of the ocean. In the depths of the ocean, the deep water temperature is only 8℃ ~ 9℃, and the nitrogen and phosphorus are 2 times and 15 times that of the surface seawater, which is extremely nutritious. When deep water is pumped up and there is enough sunshine, a new artificial ecosystem with doubled output will be formed. The temperature difference can be used to generate electricity or directly used in agricultural production. The United States and Japan have been carrying out this artificial upwelling experiment, which is considered to trigger a revolution in mariculture, so it is called the "blue revolution".
Seawater agriculture
refers to directly irrigating crops with seawater and developing saline-alkali land, desert and wasteland along the coast. The "Blue Revolution Plan" is to expand mariculture from offshore to ocean. "Seawater agriculture" is to force land plants to "go to sea", which is a fundamental difference from land agriculture based on fresh water and soil. In order to obtain seawater-tolerant plants, human beings are making arduous explorations. Besides screening and cross breeding, they also adopt cell engineering and genetic engineering breeding. These studies are still going on. At present, wheat, barley and tomatoes which can be irrigated by seawater have been obtained by traditional methods such as variety screening and hybridization.
exploitation of seawater resources
The seawater used in coastal industries has reached more than 9% in developed countries. If China can also vigorously promote the utilization of seawater, it can greatly alleviate the water shortage problem in coastal cities.
Direct utilization of seawater
The direct utilization of seawater has many aspects and large water consumption, which plays an important role in alleviating the water shortage in coastal cities. In developed countries, seawater cooling is widely used in coastal electric power, metallurgy, chemical industry, petroleum, coal, building materials, textiles, ships, food, medicine and other industrial fields. Japan and Europe are about 3 billion cubic meters every year. At present, China only has more than 1 billion cubic meters. If seawater is actively used as cooling water, washing water, diluting water, etc. in industry, and residents' toilet flushing water (about 35% of residents' domestic water consumption) is developed, it will play an important role in alleviating the water shortage problem in coastal cities.
The technologies of seawater direct utilization include: seawater direct cooling technology, which has been used for 8 years and is the mainstream of industrial application at present; Seawater circulating cooling technology is still in the research stage in China; Seawater washing and other technologies. Important technologies related to the direct utilization of seawater include corrosion-resistant materials, anti-corrosion coatings, cathodic protection, anti-biological adhesion, anti-leakage, sterilization, cooling tower technology and so on.
seawater desalination
After more than half a century's development, seawater desalination technology has matured. The main desalination methods are:
Multistage Flash (MSF). The single machine capacity can reach 45-57, m3/d. The operating temperature, water production ratio and stage are 12℃, 1 and 4 respectively. Multi-stage flash evaporation consumes 4 ~ 5 kWh/m3 fresh water in addition to a certain amount of heating steam, which is used for seawater circulation and fluid transportation.
LT-MDE technology was developed in 1975 on the basis of multi-effect, and has made great progress in recent 1 years. A single device can produce 2 cubic meters of fresh water every day. The evaporation temperature is lower than 8 degrees, and the effect number is generally about 12. The water production ratio is greater than 1. In addition to the heating steam, the low-temperature multi-effect consumes 1.8 kWh/m3 of energy for fluid transportation.
The reverse osmosis (SWRO)RO cornea and module technology is quite mature, the desalination rate of the module can reach 99.5%, and the energy consumption is 3 ~ 4 kWh/m3 of fresh water. SWRO technology has the advantages of low investment in equipment, low energy consumption, high efficiency and mature technology. It has accumulated 3 years of experience and is the most competitive.
recently, a new seawater desalination device with low cost and high efficiency has been developed by Japan sindelayite company. Its outer surface is a porous cylinder made of stainless steel, and a tube made of 1 stainless steel sheets with an outer diameter of 156 mm and an inner diameter of 136 mm is installed inside. After this pipe is slowly twisted, scraggy layers will be formed inside and outside due to the displacement of stainless steel sheets, and nano-scale gaps will appear between layers. When in use, seawater is first put into a crystallization device, and then high-frequency voltage is applied for "processing". After a few tens of seconds, sodium ions and chloride ions in seawater will combine to form fine salt crystals, which will gradually grow into particles of about 1 micron. After these particles are agglomerated, salt particles with a diameter of several microns can be formed, which can be easily filtered out. Then, the seawater is put into the container of the stainless steel cylinder, and a certain pressure is applied, so that the salt particles will be blocked out of the tube, and the rest of the water immersed in the twisted tube under pressure is the fresh water to be obtained, with the salt concentration of about .67%, and the mineral content such as magnesium chloride is half that of normal seawater, making it an ideal drinking water.
The efficiency of the new device is three times that of the immersion membrane method, the utilization degree of seawater is as high as 95%, and the required electricity and maintenance costs are very low. The company has made a large device that can produce 2 liters of fresh water per minute.
the daily output of seawater desalination in the world has reached 27 million tons, and it is still rising at the rate of 1% ~ 3%. At present, the international market capacity of seawater desalination has reached more than 2 billion US dollars, mainly divided by the United States, Japan and other powerful countries, and it will be nearly 7 billion US dollars in the next 2 years, with huge market potential. At many international conferences on seawater desalination, the representatives of the third world countries urgently hope that China's seawater desalination technology can enter the international market and break the current monopoly pattern.
the combination with new energy sources such as nuclear energy is the trend of reducing the cost of seawater desalination and moving towards large scale. China Nuclear Industry Corporation has mastered the new technology of efficient utilization of low-grade nuclear fuel. It is estimated that if all the discarded low-grade nuclear fuels in the world are used, more than 3 low-temperature nuclear heating reactors with a capacity of 2, kilowatts can be built (China can build 1 existing waste materials). All this heat is used for seawater desalination, which can produce 24 million cubic meters of high-quality desalinated water every day and support more than 2 million people. The combination of nuclear energy technology and seawater desalination not only requires that the nuclear technology itself is mature, but also needs mature advanced distillation seawater desalination technology to match it, which can better show its technical and economic advantages. Seawater desalination technology is bound with China's nuclear industry to enter the international market, forming a nuclear desalination industry, which can realize the peaceful use of nuclear energy for the benefit of mankind. If China can occupy 1/5 of the nuclear energy desalination market, the sales output value of nuclear heating equipment will reach 15 billion yuan, and the sales output value of seawater desalination equipment will reach 48 billion yuan, forming an advantageous industry with independent intellectual property rights and international competitiveness in China.
seawater desalination plays an important role in promoting seawater utilization. Although the amount of desalinated seawater used by coastal industries is small, its nature is important. At present, the desalination of seawater in China can save about 4 million cubic meters of land water every year, which plays an important role in ensuring the needs of coastal industrial production and the domestic water consumption of residents. At present, the cost of seawater desalination is generally 4 to 5 yuan. If the cost of seawater desalination by cogeneration of thermoelectric water can be reduced below that of 4 yuan, if the comprehensive utilization of seawater is further developed and the concentrated seawater is used to extract chemical elements, the desalination cost will be reduced. At present, the cost of seawater desalination has been accepted by fresh water for islands and fresh water and pure water for coastal power plants.
extraction and utilization of seawater chemicals
chemical extraction from seawater is a new industry with unlimited prospects. 3.5% minerals dissolved in seawater are great wealth given by nature to human beings. Many developed countries have gained great benefits in this regard. At present, there are potassium, magnesium, bromine, chlorine, sodium and sulfate in the extraction of chemical elements from seawater in China. However, except that sodium chloride is directly extracted from seawater, other elements are only extracted from underground brine and bittern in salt field. Moreover, the technological process of comprehensive utilization of resources is backward, and the quality of products is far from that of the international market, so technical update and equipment transformation are urgently needed. China is the largest producer of sea salt in the world, with an annual output of nearly 2 million tons; At present, China is still in the transition stage from saline-alkali industry to marine chemical industry. After the technical research in the Eighth Five-Year Plan and the Ninth Five-Year Plan, the industry of directly extracting chemicals from seawater is gradually taking shape in China. There is a huge amount of seawater in the world, with a volume of 1.37 billion cubic kilometers, or about 13.7 billion tons. Seawater itself is a treasure house of resources, and there are more than 8 kinds of metal and nonmetal elements dissolved in seawater. Generally, the elements in seawater are divided into two categories: the elements containing more than 1 mg per liter of seawater are called constant elements; Elements with a content below 1 mg are called trace elements. There are more than 6 kinds of trace elements in seawater, such as 25 billion tons of lithium (Li), which is one of the important materials in thermonuclear reaction and the raw material for making special alloys. Rubidium (Rb) has 18 billion tons, which can make photovoltaic cells and vacuum tubes; There are 8 billion tons of iodine (I), which can be used in medicine. The commonly used iodine wine is made of iodine.
Comprehensive seawater development technology
Compared with developed countries, there is a big gap in comprehensive extraction and utilization technology in China, but it has made great progress since the 199s, from the traditional "four kinds" of bittern chemicals (potassium chloride, magnesium chloride, sodium sulfate and bromine) to nearly 1 varieties now.
The projects that can be further developed include: developing new bromine extraction technology to improve the bromine utilization rate of existing above-ground brine resources, improve bromine quality, reduce energy consumption and cost, and actively developing efficient brominating agents and new flame retardants; Actively develop the technology of extracting potassium from seawater and brine by inorganic ion exchange. The success of this technology can transform old salt chemical enterprises and make up for the shortage of potassium resources on land in China. Actively develop new magnesium products with high technology content and high added value; Strengthen the research and development of uranium extraction technology from seawater; Strengthen the research and development of extracting other chemicals directly from seawater, and combine the combined production of water, electricity and heat with the comprehensive utilization of seawater.
ocean energy
ocean energy includes eight kinds: temperature difference energy, wave energy, tidal and tidal current energy, ocean current energy, salinity difference energy, offshore wind energy, marine biological energy and marine geothermal energy. These energies are renewable energy stored at sea, in the sea and under the sea, and belong to the category of new energy. The so-called "renewable" means that they can be replenished continuously and will never be exhausted. Unlike non-renewable energy sources such as coal and oil, their reserves are limited and they are mined a little less. People can convert these ocean energy into electric energy, mechanical energy or other forms of energy by various means for human use. Most of the ocean energy comes from solar radiation energy, and a smaller part comes from the gravitational force in the relative motion between celestial bodies (mainly the moon and the sun) and the earth. The ocean energy contained in seawater is very huge, and its theoretical reserves are hundreds or even thousands of times of the annual energy consumption of countries all over the world.
schematic diagram of French Langs tidal power station
schematic diagram of garland current power station
Ocean energy has some characteristics. First, it has huge reserves in the total ocean water body, while the energy per unit volume, unit area and unit length is small. That is to say, if you want to get great energy, you have to get it from a lot of seawater. Second, it is renewable. Ocean energy comes from the gravitational force between solar radiation energy and celestial bodies. As long as the sun, the moon and other celestial bodies exist with the earth, this energy will be regenerated and inexhaustible. Third, ocean energy can be divided into stable and unstable energy sources. The stable ones are temperature difference energy, salinity difference energy and ocean current energy. Unstable energy can be divided into two types: regular and irregular. There are tidal energy and tidal current energy which are unstable but change regularly. According to the changing law of tides and tidal currents, people compile daily and hourly tidal and tidal forecasts in various places to predict the tidal size and tidal current strength at various times in the future. Tidal power stations and tidal power stations can arrange power generation and operation according to the forecast table. What is unstable and irregular is wave energy. Fourth, ocean energy.