Burning combustible ice is the most magical energy source in the world. In people's impression, water and fire are never compatible. Water can extinguish fire, and fire can also devour water. The magic of combustible ice is that it can burn like a candle as a piece of ice solidified from water and a temperature below 0℃. In fact, it burns much more violently than candles.
1810, a scientist accidentally created combustible ice while doing an experiment. However, people at that time didn't know what this was, so they didn't care.
In 1934, American Hammer Schmidt discovered combustible ice in a blocked gas pipeline, which was the first time that combustible ice was discovered by humans.
In 1968, Soviet geologists discovered combustible ice in the biting permafrost of Mesoyaha, Siberia, and began development within the following decade. After the news came out, countries around the world began to study and explore this kind of burnable ice.
Combustible ice is not ice in the true sense. It just looks like ice. At the same time, it is called "combustible ice" due to its characteristic that it can burn when it encounters fire. Combustible ice is actually an ice-like crystalline substance formed by natural gas and water under high pressure and low temperature conditions.
The formation of combustible ice must meet three basic conditions: temperature, pressure and raw materials. First, combustible ice can be generated above 0°C, but it will decompose after exceeding 20°C. The seabed temperature is generally maintained at around 2~4℃.
Secondly, when combustible ice is at 0℃, it only takes 30 atmospheric pressure to generate. With the depth of the ocean, 30 atmospheric pressure is easy to ensure, and the greater the air pressure, the less easy it is to decompose hydrate .
Finally, organic matter on the seabed precipitates, and the abundant carbon is bioconverted to produce sufficient gas source. The seabed formation is a porous medium. Under the conditions of temperature, pressure and gas source, combustible ice crystals will be generated in the gaps of the medium.
Combustible ice is widely distributed in nature in the continents, slopes of islands, uplifts on the edges of active and passive continents, polar continental shelf, and deep water environments of the ocean and some inland lakes.
On Earth, about 27% of land is potential areas that can form combustible ice, and about 90% of the area in the ocean also belongs to such potential areas. In the seabed area alone, the distribution area of combustible ice reaches 40 million square kilometers, accounting for 1/4 of the total area of the earth's oceans. In 2011, as many as 116 combustible ice distribution areas have been discovered in the world, and the thickness and size of their ore layers are incomparable to conventional natural gas fields.
Scientists estimate that globally, the reserves of combustible ice are twice the existing reserves of natural gas and oil, which is enough for humans to use for more than 1,000 years.
my country's combustible ice reserves are considerable, ranking first in the world. According to preliminary forecasts, the amount of combustible ice resources in my country's sea area is about 80 billion tons of oil equivalent. The sea area located on the northern slope of South China Sea in my country is a combustible ice-rich area with a predicted reserve of about 19.4 billion cubic meters, which is quite rare. On land, my country's frozen soil areas also contain a large amount of combustible ice. In 2009, experts estimated that the combustible ice reserves of Qinghai-Tibet Plateau will reach 35 billion tons of oil equivalent.
Compared with traditional energy coal and petroleum, the biggest advantage of combustible ice is its low pollution and high calorific value. Scientific experimental data show that after combustible ice burns, only a small amount of carbon dioxide and water will be generated, which is much less polluted than coal, oil, etc., and the pollution to the environment is extremely low. However, it produces 10 times more heat than traditional energy sources, and 1 cubic meter of combustible ice can be converted into 164 cubic meter of natural gas and 0.8 cubic meter of water.
In the context of global energy resources and increasing environmental pollution, combustible ice, as a new energy source with abundant reserves, extremely high calorie value and extremely low pollution, can be exploited on a large scale by humans, it will inevitably change the global energy pattern.
However, at present, countries around the world, including our country, have not yet exploited and utilized combustible ice on a large scale. Why is this?
The main reason is that combustible ice is usually distributed in areas with harsh natural environments, such as the bottom of the ocean at a depth of hundreds or thousands of meters, and it is extremely difficult to mine. At present, countries around the world are very cautious about this. There are many methods for mining combustible ice, such as heat excitation mining method, reduced pressure mining method, chemical reagent injection mining method, CO2 replacement mining method and solid mining method. However, these methods are not technically and economically mature enough.
The mining of combustible ice will change the temperature and pressure conditions on which it relies, causing the decomposition of natural gas hydrate . During the mining of combustible ice, if the temperature and pressure conditions cannot be effectively controlled, a series of environmental problems may arise, such as the intensification of greenhouse effect , changes in marine ecology, and submarine collapse events.
For humans, there is still a long way to go to the large-scale mining of combustible ice. However, it is encouraging that my country has already been at the forefront of the world in the mining and utilization of combustible ice.
In 2017, my country's "Blue Whale One" carried out combustible ice trial operation in the South China Sea area. This operation has been continuously trial mining for 60 days, with a cumulative gas production of more than 300,000 cubic meters. It has achieved many major breakthrough results such as the longest continuous gas production time, the largest total gas production volume, the stable air flow, and the environmental safety, creating a world record of gas production time and total gas production volume.
In 2020, my country conducted the second round of combustible ice trial operation in the Shenhu Sea of the South China Sea. In one month of trial production, the total gas production reached 861,400 cubic meters, which is 2.8 times the total gas production in the first round of 60 days. The trial mining has conquered the core key technologies for drilling and mining of horizontal wells in deep-sea shallow and soft formations, achieved a significant increase in the scale of gas production, and laid a solid technical foundation for productive trial mining and commercial mining. my country has thus become the first country in the world to use horizontal well drilling and mining technology to test the natural gas hydrates in the sea area.
