Development and utilization progress of coalbed methane in Jincheng mining area

(Shanxi Jincheng Anthracite Mining Group Co., Ltd. Shanxi Jincheng 048006)

About the author: He Tiancai, born in 1963, male, Shanxi Jincheng, chief engineer of Shanxi Jincheng Coal Industry Group, doctoral student, engaged in coal and coalbed methane development.

After several years' development, the ground drainage amount of coalbed methane in Jincheng mining area has reached 30× 104m3, and the daily compressed coalbed methane has reached 10× 104m3, initially forming a certain production scale. At the same time, the production practice has proved that the ground drainage of coalbed methane can effectively reduce the gas pressure and gas content in coal seam. According to the current actual gas production calculation, the gas content within the control range of coalbed methane wells can be reduced by about 1m3 every year, so surface extraction of coalbed methane can reduce the outburst danger of mines, reduce the underground gas emission and promote the safety production of coal mines.

Keywords:: Jincheng CBM development and utilization progress

Development and utilization progress of coalbed methane in Jincheng coal mine

He Tiancai, Tian Yongdong

(Shanxi Jincheng Anthracite Mining Group Co., Ltd., Jincheng 048006)

After several years' development, the surface extraction project of coalbed methane in Jincheng Coal Mine has reached 300,000 m3/day, and the daily output of compressed coalbed methane is100,000 m3, which has formed a certain production scale. At the same time, the production practice proves that the ground drainage of coalbed methane can effectively reduce the gas content and pressure. According to the current gas production, within the control range of a coalbed methane well, the coal seam gas content 1 m3 can be reduced every year. Therefore, surface extraction of coalbed methane can reduce the impact risk of mine, reduce underground gas emission and improve coal safety production.

Keywords: Jincheng; CBM development; Utilization rate; progress

The development background and general situation of 1

Jincheng mining area is an important part of Jin Dong coal base in the national planned 13 large coal base, and it is also one of the first planned 19 coal mining areas in China. It is an important high-quality anthracite production base in China, and it is a rare coal under special state protection. The mining area is located in the southeast of Shanxi Province, south of Qinshui coalfield, with a planned area of 3753km2, geological reserves of 437.6x108t, and three planned mines 13. As the main developer of Jincheng mining area, Jincheng Coal Industry Group currently has 7 production mines and 1 mine under construction. In 2005, the approved production capacity was 3060× 104t/a, and the actual production of raw coal was 3006× 104t.

According to the evaluation reports of Chongqing Branch and Xi 'an Branch of the General Research Institute of Coal Science, the total amount of coalbed methane resources in the planning area of Jincheng Mining Area is 6000× 108m3, and that in Sihe Mine Field and Chengzhuang Mine Field is 530× 108m3. The average gas content in the eastern part of Sihe mine field is 9.03m3/t, and that in the western part is 16.6m3/t, and the highest gas content in the northern part is 28.7m3/t during the construction of ground drainage drilling. The highest gas content in the southwest of Chengzhuang mine field is 15.62m3/t, the coal seam permeability coefficient in mining area is generally 0.0239 ~ 2 13m2/mpa2 d, and the coal seam gas pressure is generally 0.2 ~ 2. 12mpa.

In 2005, the absolute gas emission of Chengzhuang Mine reached 239m3/min, and the relative gas emission was16.14m3/t. In 2005, the absolute gas emission of Sihe Mine reached 479m3/min, and the relative gas emission was 22.3m3/t, which was a high gas mine.

At present, the underground gas drainage in Sihe Mine and Chengzhuang Mine has been difficult to meet the needs of coal mine safety production, and it is necessary to reduce the mine gas emission through surface drainage.

Development and utilization of coalbed methane in Jincheng mining area

As an associated resource of coal, coalbed methane (gas) not only poses the greatest threat to coal mine production safety and miners' life safety, but also is a harmful gas with strong greenhouse effect. In order to effectively alleviate the harm of gas to coal mines and miners, effectively reduce the gas content in coal seams from the source, and build intrinsically safe mines, Jincheng Coal Industry Group has always adhered to the guiding ideology of "serving for safe production, improving the quality of life of residents, and realizing industrialized operation" for many years, and has continuously explored new ways of gas control, development and utilization with the working principle of "combining underground and underground drainage, and combining drainage and utilization", and achieved good economic, social and environmental benefits.

2. 1 CBM surface drainage

Pre-drainage of ground drilling mainly refers to pre-drainage before mine construction or coal seam mining. It is not limited by space or time. Large-scale well groups can be laid on the ground five years in advance, 65,438+00 years or longer, and large-scale drainage can be carried out, which can not only improve the drainage effect, but also form an industrial scale. Ground drilling can realize long-term stable drainage before, during and after mining, and can also play a role in geological exploration.

Since 1992, Jincheng Coal Industry Group has successively built seven coalbed methane wells in panzhuang, taking the lead in carrying out the pilot work of ground pre-drainage of coalbed methane in China. After more than ten years of production test and technical research, we have basically mastered a set of technologies such as surface extraction drilling, fracturing, drainage and gathering and transportation of anthracite in coalbed methane wells. Since 2003, Jincheng Coal Industry Group began to carry out large-scale surface drainage of coalbed methane in Sihe Mine and Chengzhuang Mine. By the end of 2005, it had formed a well group scale of 150 coalbed methane wells in Sihe Mining Area, becoming the largest surface drainage well group in China at present, with an annual drainage capacity of 1.2× 108 m3.

Up to now, Jincheng Coal Industry Group has completed more than 300 coalbed methane wells, and 200 coalbed methane wells are basically equipped with drainage conditions. The annual drainage capacity of surface coalbed methane reaches 1.5× 108m3, of which 1 10 coalbed methane wells are put into production to produce gas, with a daily gas production of 30× 104m3. With the gradual expansion of the scale of coalbed methane well groups, the surface coalbed methane production is also increasing. In the first half of 2006, the amount of surface coalbed methane extraction in Jinmei Group was close to 4000× 104m3.

Coalbed methane (gas) is also a clean and efficient energy source, and our government encourages its development and utilization. Therefore, Jincheng Coal Industry Group has not only built the largest surface drainage well group of coalbed methane in China at present, but also established a perfect utilization system of coalbed methane. At the end of 2005, panzhuang CBM compression station was expanded in two phases, with a daily processing capacity of 16× 104m3, and it is also the largest CBM compression station in China at present. After being compressed, panzhuang coalbed methane is continuously transported to Jincheng, Changzhi, Taiyuan, Zhengzhou, Jiaozuo, Kaifeng and other cities, and is widely used in civil, industrial, public, power generation, automobile fuel and other industries. In addition, panzhuang's coalbed methane has also begun to be supplied to the surrounding rural residents, making them bid farewell to the history of using coal for generations and use clean natural gas.

In 2005, Jincheng Coal Industry Group transported 870× 104m3 by tanker, and used 68.88× 104m3 locally. In the whole year, the total utilization rate of ground-extracted coalbed methane reached 939.88× 104m3, and the extraction utilization rate was 46.9%. With the increase of gasoline price and domestic energy demand, the intention of surrounding cities to buy coalbed methane is also increasing. In the first half of 2006 alone, Jincheng Coal Industry Group transported more than 1.400× 1.04 m3 by tanker.

With the continuous improvement of surface extraction capacity of coalbed methane, in order to make full use of surface extraction of coalbed methane, Jinmei Group has increased the investment and construction of coalbed methane utilization projects. At present, two new coal-bed methane compression stations with daily processing capacity of 20× 104m3 are being built, which are expected to be put into operation by the end of 2006. The "Lizhuang-Jincheng-Mining Area" coalbed methane gas pipeline is also under construction. It is estimated that the pipeline will be laid before the end of 2006, and the final annual throughput of the pipeline will reach 9× 108m3. After the completion of these projects, the coalbed methane in Sihe mining area and its vicinity will be effectively utilized.

2.2 CBM underground drainage

Although surface drainage of coalbed methane has many advantages, underground drainage is still the main means to solve mine ventilation and safe production. Therefore, while paying more attention to the surface drainage of coalbed methane, Jinmei Group has increased the intensity of underground drainage of coalbed methane, and adopted the combination of drilling and pumping in dense coal seams and mining and pumping in old goaf to increase the coverage and intensity of drainage. In 2005, Jinmei Group also introduced three thousand-meter drilling rigs from Australia for gas drainage in Sihe Mine and Chengzhuang Mine, and successfully constructed thousand-meter drilling holes in Sihe Mine.

In 2005, the total amount of underground gas drainage in Sihe Mine reached 10950× 104m3, and the average concentration of gas drainage was about 55%, which was mainly used for power generation, slime drying, boilers and civil use. In 2005, the actual gas utilization (nominal purity) of Sihe Mine reached 9065× 104m3, and the utilization rate of underground gas extraction reached 82.8%, of which the gas consumption of 1500MW gas power station was 4985× 104m3, and the gas consumption of slime drying was 52.6×/kloc. In 2005, the total amount of underground gas drainage in Chengzhuang Mine reached 5052× 104m3, which was mainly used for civil use and power generation. In 2005, the total utilization of coalbed methane in Jincheng Coal Industry Group reached 10004.88× 104m3, and the utilization rate was 55.6%, which was equivalent to reducing carbon dioxide emissions by about 150× 104t.

At present, the Asian Development Bank 12× 104kW coal-bed methane power station project was officially started in early 2006, and the first phase of the project is expected to be completed by the end of the year. By then, the gas discharged from Sihe Mine and its nearby mines will be fully utilized.

2.3 Clean Development Mechanism

Jincheng Coal Industry Group actively uses clean development mechanism to develop CDM projects while using tangible coalbed methane. The 12× 104kW coalbed methane power plant project loaned by the Asian Development Bank of Jinmei Group will use coalbed methane 1.8× 108m3 every year, which is equivalent to reducing carbon dioxide emissions by more than 2 million tons every year, which can greatly reduce mine gas wind emissions and protect the atmosphere and environment. In 2004, the carbon sink fund of the World Bank purchased 450× 104t( 10 year) emission reduction and 150× 104t option. The emission reduction purchase agreement was signed on February 1 2004, and the Japan Carbon Fund (Japan Carbon Fund)

3 Evaluation of the actual effect of ground pre-pumping of coalbed methane

Pre-pumping coalbed methane on the ground can reduce the gas content in the coal seam, release the gas pressure in advance, effectively control the gas disaster from the source, and promote mine safety production. In addition, coalbed methane drilling can also be used as a geological exploration hole, coalbed methane is a high-quality energy, and surface drainage of coalbed methane has good comprehensive benefits.

3. 1 Good effect, promoting safety.

According to the production data, by the end of June, 2006, the cumulative gas production of sihe CBM pre-pumping project100CBM wells exceeded 6000× 104m3. According to the average coal seam thickness of 6m and density 1.45 t/m3 in this area, the controlled coal reserves of these 100 CBM wells are about 9000× 6544. That is to say, after more than one year of drainage, the gas content per ton of coal seam within the control range of coalbed methane wells in this area has decreased by about 0.66m3 on average. At present, the total daily gas production of these 100 coalbed methane wells has reached 25× 104m3. According to this data, in the future, the gas content per ton of coal within the control range of the coalbed methane well group can be reduced by about 1m3 every year. In this way, after 7 ~ 8 years of ground pre-drainage, the gas content in each ton of coal seam in the drainage area can be reduced to below 8m3, which can achieve relatively safe conditions.

It is worth noting that the CBM wells constructed by Jinmei Group, SH-003, SH-075, SHX- 108, SHX-12, SHX-10/5 all have blowout phenomena in different degrees.

3.2 Multi-purpose and low investment.

During the development of coalbed methane wells, a large number of detailed data on the depth and lithology of coal seams and their roof and floor, as well as detailed information on gas content and water abundance of coal seams can be obtained, which are also necessary information in the future coal mining process. Through the processing and utilization of these data, the utilization efficiency of data can be improved and the exploration investment can be saved, so the surface drilling of coalbed methane also plays the role of geological exploration hole.

The well spacing of coalbed methane wells is generally about 300 ~ 400 m, which is much smaller than that of common coal exploration holes, so the parameters obtained by drilling coalbed methane wells have relatively high accuracy. At present, Jinmei Group is sorting out the relevant data of coalbed methane well control area, and drawing more detailed contour map of coal seam floor and contour map of coal seam thickness on this basis, which will be applied to coal production in coal mines in this area soon. Figure 1 and Figure 2 are isoline maps of coal seam floor and gas content drawn by using the development data of coalbed methane wells, and the accuracy of these maps has been greatly improved.

Figure 1 Contour map of coal seam floor drawn according to drilling data

Isogram of gas content based on desorption and desorption data.

With the future coal mining, the ground pre-drainage holes of coalbed methane will also have the post-mining function, which can pump and drain mine gas at different stages of coal mining, thus prolonging the production cycle of gas wells, greatly improving the utilization rate of coalbed methane wells and truly realizing multi-purpose of one well.

3.3 High concentration and wide application.

Because of the relatively low concentration, underground gas can only be generated or burned on the spot, which has low utilization value and poor benefit. However, the methane concentration of coalbed methane extracted from the ground is usually higher than 95%, so it is more widely used and has higher utilization value. Ground drainage coalbed methane can be used not only for power generation and combustion, but also as automobile fuel. At present, the sales price of compressed coalbed methane for automobiles in Jincheng is 2.2 yuan /m3, which is much higher than that for power generation and combustion. In addition, coalbed methane can be transported to other cities by compression or liquefaction, so it has high utilization value and good benefit.

At present, most of the coalbed methane mined on the ground by Jinmei Group is transported to neighboring cities for utilization through compression. Up to now, panzhuang CBM compression station has compressed 2500× 104m3 CBM, which is well received by market users and has strong demand for purchase.

4 Development and utilization planning of coalbed methane in Jinmei Group

During the Eleventh Five-Year Plan period, Jincheng Coal Industry Group will closely focus on the overall development plan of Jincheng mining area and carry out large-scale coalbed methane drainage. Production mines will arrange ground drilling drainage 5 ~ 7 years or longer in advance to reduce the gas content in coal seam and release the gas pressure. Underground drainage mainly adopts a comprehensive drainage mode combining modular pre-drainage, dense borehole drainage in this coal seam, drainage while mining and drainage in old goaf, so as to increase the coverage and intensity of drainage, and finally form a combination of above-ground drainage and underground drainage. The mine to be developed will be pre-pumped on the ground from now on, and the gas content in the coal seam will be reduced to below 65438+1100m3/t when the new well is put into production through pre-pumping, which can not only effectively improve the safety and reliability of the new well and realize safe production, but also reduce the investment in mine ventilation system and roadway construction to a certain extent, thus reducing the investment in infrastructure construction of the new well.

It is estimated that by the end of the 11th Five-Year Plan, Jincheng Coal Industry Group will build 2,000 surface coal-bed methane extraction wells in existing high-gas mines and newly-built mines, further improve the underground gas extraction system and increase the intensity of gas extraction, so that the annual coal-bed methane extraction capacity above and below the well can reach 18× 108 m3. By then, Jinmei Group will fully realize the simultaneous extraction of coalbed methane, build an integrated production pattern of gas production and coal mining, and truly establish an intrinsically safe coal enterprise.

refer to

Lyna. In 2004, the theory and technology of gas drainage in soft and low permeability coal seams. Beijing: Coal Industry Press.

Lin Baiquan, Zhang Jianguo. Theory and technology of mine gas drainage. Xuzhou: China University of Mining and Technology.