In the heart of China’s Southern Junggar Basin, a region rich in coalbed methane (CBM) but plagued by low-quality reserves and challenging production conditions, a groundbreaking study offers a beacon of hope for the energy sector. Led by Xianbo Su from the School of Resources and Environment at Henan Polytechnic University, the research published in Meitan Xuebao (Journal of Coal Science and Engineering) presents a novel approach to enhance CBM production and quality through in-situ microbial processes.
The Southern Junggar Basin is a critical CBM resource area, but its potential is hampered by high volumes of carbon dioxide (CO2) and hydrogen sulfide (H2S), which not only compromise production safety but also significantly reduce the quality of the extracted gas. “The high CO2 and H2S content in the CBM of this region poses a significant challenge to maintaining stable production and ensuring the quality of the extracted gas,” Su explained. “There is an urgent need for a technology that can increase the production of CBM resources within the control range of a single well and address the issue of these acidic gases.”
The study introduces a key technology for in-situ microbial-mediated enhancement of CBM quality and production. The fundamental concept is to utilize the coal reservoir as an anaerobic fermentation site, with the coal and CO2 present in the reservoir serving as fermentation substrates. This approach aims to achieve in-situ suppression of H2S while enabling the biomethanation of CO2.
Physical simulations of CO2 microbial methanogenesis showed promising results. Cumulative methane production by hydrogenotrophic methanogens increased with rising reservoir temperatures, reaching a peak of 8.5 cubic meters per ton at 55°C. At this temperature, the abundance of key enzymes involved in glycolysis, pyruvate metabolism, and the TCA cycle was significantly higher, enhancing both CO2 conversion efficiency.
Moreover, in an anaerobic fermentation system without CO2 and with added biological inhibitors, biomethane production reached 4.5 cubic meters per ton, slightly higher than that of the control group. Notably, the gaseous H2S volume fraction was reduced by 88.8% compared to the control group. From the ninth day to the end of gas production during the anaerobic fermentation, the H2S volume fraction remained zero, achieving in-situ inhibition of H2S.
The implications of this research for the energy sector are profound. By addressing the issues of low-quality CBM and high volumes of acidic gases, this technology has the potential to significantly enhance the economic viability of CBM extraction in the Southern Junggar Basin and similar regions. The ability to increase methane production and suppress H2S generation in situ could lead to more stable and higher-quality gas production, reducing operational costs and environmental impacts.
Su’s work, published in Meitan Xuebao, which translates to the Journal of Coal Science and Engineering, highlights the necessity and feasibility of this technology. The study underscores the potential to enhance CBM production, facilitate in-situ microbial conversion of CO2, and inhibit H2S generation. The key challenges identified include cultivating efficient microbial communities, developing bio-fracturing fluids for in-situ H2S suppression, and establishing effective evaluation methods for enhancing CBM quality.
As the energy sector continues to seek sustainable and efficient solutions, this research offers a promising avenue for improving the development and utilization of CBM resources. The technology’s potential to enhance production and quality could pave the way for more robust and environmentally friendly CBM extraction practices, contributing to both national energy security and carbon neutrality goals. The future of CBM development in regions like the Southern Junggar Basin may well be shaped by the innovative approaches pioneered by Su and his team, offering a glimpse into a more sustainable energy landscape.
