Developing and calibrating a numerical model for Microbially Enhanced Coal-Bed Methane (MECBM) production
Mineralogy, Petrology and Geochemistry
Final Report Abstract
Microbially enhanced coal-bed methane (MECBM) is a technology that can increase gas production from coal. In order to be effective, it is necessary to understand the details of how nutrients (amendments) can stimulate the microbial activity. We can consider this as secondary biogenic generation of gas where different kinds of microbial communities are involved. They produce intermediate products like hydrogen, acetate and methyl groups, which are furtheron used by methanogenic species. The MECBM technology has a large economic potential since it can increase the amount of gas produced from existing infrastructures in coal-beds significantly, even though the amount of coal that can be converted is likely very low in the order of less than 1 %. This project focused on an in-depth understanding of the involved metabolic pathways and their kinetics. A ’food web’ was conceptually designed, the corresponding reaction equations were parameterized and calibrated with experimental data provided by external project partners at the Center for Biofilm Engineering (CBE) at the Montana State University in Bozeman. Another focus was put on the coupling of the reaction model obtained from the batch studies with a flow and transport model. The simulator DuMux (www.dumux.org) has been used as the platform for the implementations. DuMux is well established in solving single- and multiphase flow in porous media. For this project, we used a two-phase multi-component model, since besides the flow an aqueous phase to provide nutrients (amendments) it is important to consider the appearance of a gaseous phase due to the generation of methane. For the coupling of flow/transport and reactions, another set of experimental data was available from the partners at CBE Bozeman. The comparison of the experimental data with the model and the calibration efforts have revealed important insights into the mechanisms involved in flow and transport of amendments and into the importance of biofilm growth, detachment, and re-attachment. The project has furthermore produced results on parameter sensitivies which are valuable for designing further experimental studies in order to put the emphasis on the most sensitive parameters. Last but not least, the project has briefly addressed the field of computational efficiency, where there is clearly a demand for further research in order to address the field scale. The initial plan included also the elaboration of a perspective to address the field scale. Due to changes in the funding situation at the CBE Bozeman, this could not be addressed until now.
Publications
- Importance of specific substrate utilizationby microbes in microbially enhanced coal-bed methane production: A modelling study. International Journal of Coal Geology, 229:103567, 2020
S. Emmert, H. Class, K. J. Davis, and R. Gerlach
(See online at https://doi.org/10.1016/j.coal.2020.103567)
