Accelerated Biomethanation of Sequestered Carbon Dioxide and Paraffin in Coal Beds

The objectives of this research are to enhance and accelerate the in situ bioconversion of sequestered carbon dioxide, a greenhouse gas, into methane in the presence of hydrogen-rich coal macerals and paraffin. Methanogens require a source of hydrogen and an electron acceptor such as carbon dioxide in order to generate methane. The abundance of hydrogen coupled with sequestered carbon dioxide in the presence of the appropriate microbes is expected to accelerate the in situ bioconversion process while simultaneously removing pore-plugging paraffin and increasing gas production rates and ultimate recovery. The primary objectives of the research are to develop the inocula and consortia that will accelerate the in situ biomethanation of the sequestered greenhouse gases in the presence of hydrogen-rich coal macerals and paraffin, and to identify areas that have the highest potential for successful application of this technology. Carbon dioxide, an undesirable greenhouse gas, will be converted into methane, an environmentally friendly energy source. The accelerated biomethanation technology can be expanded to sandstone and carbonate natural gas reservoirs where paraffin removal will increase production rates and ultimate recovery. The Phase I research focused on developing cultures of paraffin-degrading anaerobic microorganisms. Inocula were isolated from paraffin samples gathered from production equipment and from water samples collected from coal beds that contained emulsified paraffin. Enrichments of the microbes isolated during Phase I were prepared; these enrichments were capable of degrading the paraffin samples in real time. Additionally, an assessment of the degradation pathways was established, and a preliminary model for the accelerated in situ bioconversion of carbon dioxide into methane was developed. The primary factors affecting biodegradation of paraffin include (1) coal properties, (2) microbial population dynamics, (3) hydrogeology, and (4) reservoir conditions. Phase II research will collect additional microbes and paraffin samples from coal seams. Microbial enrichments will be prepared from coal and paraffin samples to evaluate paraffin degradation and methane generation from carbon dioxide mixed with the samples. The participating microbes will be isolated and characterized, and an optimum mix culture will be developed. Continued laboratory experiments will be designed to evaluate factors affecting biomethanation potential (from paraffin) and technology economics. Industry stakeholders will be identified and contacted for the Phase III Field Tests. Commercial Applications and other Benefits as described by the awardee: Accelerating the in situ bioconversion of sequestered carbon dioxide will reduce the risk of global warming and provide a reliable source of environmentally clean energy, thereby reducing the dependency on foreign energy supplies. Accelerated biomethanation may be applied to coalbed methane, sandstone, and carbonate reservoirs, resulting in higher production rates that prolong the life of some gas fields and increase the ultimate recovery. Microbial genomes identified during this research additionally may have useful applications in biomedical or other fields.