With the recent surge of so-called “shale fever” around the world, the future of the planet’s energy sector is once again connected to natural gas. But shale prospects should not obstruct the view of other (more realistic in the Ukrainian case, according to experts) gas alternatives. In particular, one should not overlook the methane extracted from coal deposits, which is found in greater abundance in Ukraine and around the world. Indeed, scientists believe that its production is much cheaper. Furthermore, industrial production of methane would help decrease risks of miners’ work. Candidate of geological and mineralogical sciences, honorary mineral resources explorer Bohdan LELYK (CJSC “Concern NADRA,” Kyiv) told The Day about other advantages of this little known gas alternative and its prospects in Ukraine.
What is coalbed methane? Does it constitute a real energy alternative to traditional natural gas?
“Mine methane, as an associated mineral resource, has been used for over half a century already. Americans began to view it as a separate mineral resource after the oil crisis of 1973. Since then, by means of introducing numerous measures encouraging the production of coalbed methane in the USA, mainly tax reductions and privileged loans, production has grown to levels in excess of 60 billion cubic meters of gas per year. According to the Oil Council and the Institute of Gas Industry, deposits of coalbed methane up to the depth of 900 meters in the USA are between 8.5 and 14 trillion cubic meters. Over 200 companies work in the field and over 20 thousand boreholes have been drilled. In recent years intensive works on methane removal have been carried out in Australia, China, Canada, India, Poland, Germany and England. At the beginning of the year Russia actively joined this process by means of pilot projects in the Kuznetsk Basin. The countries enumerated above, together with Ukraine, contain the ten biggest reserves in the world, with total deposits of coalbed methane estimated at 260 trillion cubic meters. This exceeds the world’s deposits of natural gas. Ukraine, however, has lacked the necessary ‘enthusiasm’ to go beyond the experimental phase.”
Why isn’t coalbed methane produced in industrial amounts already? What are its prospects in Ukraine?
“The main coalbed methane reserves in Ukraine are concentrated in the Donetsk and Lviv-Volhynian coal basins. Gas content in different kinds of coal, from gas coal to hard coal, varies within the limits of 5 to 30 cubic meters of gas per ton (a ton refers to the dry ash-free or burning mass of coal), with levels in anthracite reaching 35-40 cubic meters per one ton of coal. Apart from coal, gas is also available in sandstone and siltstone, with gas content of 3-5 cubic meters of gas per one cubic meter of rock. According to both foreign and domestic experts, the total resources of methane up to the depth of 1,800 meters exceed 12 trillion cubic meters. Taking into account the considerable methane potential concentrated in coal deposits, they are often called coal-gas deposits. However, methane production from coal-gas deposits employing traditional technologies used in the field of coal production is actually impossible due to a special association of methane with the maternal rock (coal), in contrast to deposits of natural gas. A coal bed which is not unloaded from rock pressure is a natural, poorly-penetrable system, which has mutually closed pores and is a gas-containing, poorly filtering environment. Due to peculiarities of methane association with the coal containing it, there are two main technological approaches to its removal, namely: real-time or prior degassing connected with the safety of a mine’s operation and preliminary degassing connected with prior preparations of layers to safe mines’ functioning. Positive but rare examples of conducting intensive degassing works and the use of coal methane use the first method. It has been used in the following mines: Zasiadko, Molodohvardiiska, Komsomolets Donbasu, Krasnoarmiiska Zakhidna No. 1, and Krasnolymanska. These mines can’t maintain high coal production rates without degassing. There gas is mainly used for own needs, primarily as a fuel for boiler rooms, for producing electric power, and filling vehicles with fuel.
“Yet current trends show that preliminary degassing of coal rock massifs is becoming the dominant method. It is done in advance, before the construction and beginning of a mine’s work. This is used around the world mainly to provide industrial production of methane and ensures the safety of the mines operations. This direction of methane production in Ukraine, as an alternative source of energy, is still at its experimental stage. Testing new technologies and using international experience is a requisite for developing the methane-coal field in Ukraine. A considerable contribution to testing and developing technologies of preliminary degassing in the recent decades was made by Ukrainian companies Public Industry ‘Center for alternative fuel kinds,’ LLC ‘Ecomethane’ and others.”
What are the results of these experiments?
“Five powerful hydro disruptions of coal deposits and embedded rocks were conducted using liquids based on American technology with a maximal use of domestic materials. The work took place in Krasnoarmiisk and the South-Donbas. This is just the first stage of technology testing. During the next stages it would be desirable to make hydro disruptions with liquid nitrogen and water, securing cracks with a propping agent. An analysis of the results indicates the objects’ high gas potential. Unfortunately, the process didn’t produce a high influx of gas. However, this is due to the peculiarity of our deposits construction (thin layers, low penetration), insignificant influence of the crack drainage area for an individual borehole, collector soiling in the process of borehole drilling and so on. The absence of attention and support of the work on the part of governmental structures, reflected in insufficient financing of works, crowns the Ukrainian approach to solving methane problems and explains why we are still in the experimental stage. The experience of the Ukrainian company CJSC ‘Concern NADRA’ is praiseworthy, especially their work in developing new technologies of preliminary degassing taking into consideration the peculiarity of the geological conditions of Ukrainian coal deposits. The company’s specialists in 2008 developed and patented a new unique ‘way of preliminary degassing of a thickness containing coal,’ based on the use of the gravitation effect of massif unloading. The essence of the method lies in burning out a low-capacity coal bed ranging between 0.2-0.5 meters (useless for the mine) and situated beneath the primary industrial thickness, by means of gasification before the mine begins its operations, and initiating gravitation unloading of the massif accompanied by increasing gas penetrability. Based on the results of the materials submitted for the contest ‘TOP-Energy Efficiency 2009,’ experts recognized the technology to be the best in the category ‘Scientific and technological breakthrough.’”
What is the “zest” of this technology?
“The method is rather simple. It was approved separately as a means of degassing unloaded massif in coal mines and conducting underground gasification, also in Ukrainian deposits. The essence of the method lies in connecting two technologies in space and time, conducting preliminary degassing of the entire productive massif containing gas (coal plus rocks), obtaining and recycling power gas from gasification and high-quality methane from degassing, and ensuring the safety of future operations. The advantage is that the degassing network made of boreholes is ‘long-life’: it works before the start of operations of the mine, during them, and after shutdown. The average expected debit from one degassing borehole is 10-15 cubic meters of gas per day. Hundreds of such boreholes should be drilled in one mine field. The expected recoupment for such projects with current gas prices is one-two years.
“It is evident that efficiently conducted preliminary degassing will help decrease power inputs for producing ‘displaced’ coal and increasing production of high-quality coke coal in gas-safe coal mines. It will also decrease Ukraine’s dependence on the import of coke coal and natural gas.”
