2:35 PM - 2:50 PM
[BGM02-04] A project of microbially enhanced coalbed methane by HRISE
Keywords:Lignite, Methane, Methanogenic archaea, Coalbed methane, Hydrogen peroxide, Organic acids
“Microbially enhanced coalbed methane (MECBM)” has been studied to facilitate the processes of biogenic methane generation in coal seams. Solubilization of the coal appears to be the critical pre-treatment, because it is likely the rate-limiting step of microbial methane generation. Surfactants, oxidants, acids, bases, and chelating agents have been used to solubilize coal for subsequent microbial processes. Among them, hydrogen peroxide (H2O2) is known to substantially solubilize lignite to produce low-molecular weight organic acids. Our laboratory has studied H2O2 as a solubilizing agent for in situ biogenic conversion of lignite seams into methane as a part of the “Subsurface Cultivation and Gasification (SCG)” project of HRISE. Until 2018, our experiments have demonstrated that H2O2 slowly reacted with lignite at low temperature (10℃), forming organic acids with the concentrations as high as those formed at room temperature (22℃), and that these organic acids were utilized by microbes in the lignite, forming biogenic methane.
With the collaboration of Mitsubishi Materials Corporation, three boreholes were constructed in 2019 in the Tempoku Coal field, northern Hokkaido, Japan. In 2020, H2O2 was injected in the lignite seam (8℃) through one of the wells, and the rapid formation of organic acids, such as formic acid (> 25 mg L-1) was observed. The isotopic composition of methane in the lignite seam changed shortly after the H2O2 injection, possibly indicating biogenic methane formation. In 2021, formic acid (1000 mg L-1) was injected in the same well to confirm the rapid methane formation in the lignite. We would like to present the outline of these field experiments.
With the collaboration of Mitsubishi Materials Corporation, three boreholes were constructed in 2019 in the Tempoku Coal field, northern Hokkaido, Japan. In 2020, H2O2 was injected in the lignite seam (8℃) through one of the wells, and the rapid formation of organic acids, such as formic acid (> 25 mg L-1) was observed. The isotopic composition of methane in the lignite seam changed shortly after the H2O2 injection, possibly indicating biogenic methane formation. In 2021, formic acid (1000 mg L-1) was injected in the same well to confirm the rapid methane formation in the lignite. We would like to present the outline of these field experiments.