In 2018, China's coalbed methane production was 5.4 billion cubic meters, and China's oil production was about 2 billion cubic meters, which dominated. Coalbed methane, also known as “coal mine gas”, is mainly composed of methane and is unconventional natural gas. China's coalbed methane resources are abundant, and its reserves rank third in the world, second only to Russia and Canada. According to the survey, the total reserves of coalbed methane with a depth of less than 2,000 meters is about 37 trillion cubic meters, which is roughly equivalent to the amount of conventional gas resources on land, and the recoverable reserves exceed 12 trillion cubic meters.
Since the 1980s, China has gradually carried out preliminary evaluations in more than 30 coalbed methane target areas. In 2006, it entered the scale development stage and has achieved scale development. In 2018, China's coalbed methane production reached 5.4 billion cubic meters, of which China Petroleum The output is about 2 billion cubic meters, which is dominant.
At present, nearly 20 domestic and foreign companies including the three major oil companies are conducting CBM exploration and development work in China. Nearly 10 universities and 8 specialized research institutions are engaged in coalbed methane exploration and development theory and technology research and development. Relevant departments have successively issued a series of preferential policies to support the development of coalbed methane, including price concessions, tax incentives, development subsidies, etc., to encourage industrial development. For example, the central government subsidizes 0.3 yuan per cubic meter of coalbed methane (purified).
Liu Honglin, a second-level expert at the China Petroleum Exploration and Development Research Institute, said that China started high-level coalbed methane development in 2006. High-order coal seams have high permeability and gas content, and gas saturation is low. The first batch of 100 vertical well tests in the year determined the well spacing developed in the future, and predicted the output of the whole area and the output of single wells. The pilot test two to three years of drainage and gas production achieved stable production, and the next step was to establish 2 billion cubic meters. The production capacity laid the foundation.
In view of the different geological characteristics of coal seams in different regions, China's coalbed methane development is gradually advanced. Firstly, the development of high-rank coalbed methane in the Qinshui Basin has the characteristics of high coal rank, low permeability and high gas content. Subsequently, the coal seam gas phase in the Baode area of Jincheng and Erdos Basin has been successfully developed. The Baode area is medium and low rank coal, and the development zone thereafter. The block extends to Hancheng in the southern part of the Ordos Basin and to the southern part of the Sichuan Basin.
At present, China's coalbed methane development is 800 meters. The shallow medium-high coal exploration and development technology is basically mature, basically solving the engineering and technical problems encountered. The next step is to develop deep coalbed methane, that is, 1500 meters deep or even 2000 meters, 2500 meters deep. Coalbed methane, deep coalbed methane resources are very large, and the depth of 800 meters to 2500 meters in the middle and deep layers accounts for 2/3 of China's resources. The deep formation pressure is high and the permeability is lower, which leads to the difficulty of desorption of coal seams. It is also difficult to reduce the pressure of the drainage. It is necessary to develop new drilling technology, fracturing drainage technology, etc. The deep technology is still immature, which is the challenge we face. Now we are solving this problem.
