Mechanisms of flow-chemistry-biology coupling and enhanced caprock integrity in CO2 geological sequestration based on the synergistic effect of nanoparticles and methanogens.

01.07.2022 - 30.06.2025

Dr. -Ing Ke Li

The underground bio-methanation (UBM) converts the injected H2 and CO2 into renewable CH4 and H2O through methanogens in the CO2 geological sequestration reactors, which combines H2 storage, CO2 emission reduction and the production and storage of renewable CH4 to achieve a sustainable energy supply system. Currently, fundamental and technical studies of UBM are still insufficient in many aspects such as bacterial colonization, and the gas/ bacteria leakage during the UBM process is one of the major environmental concerns. The German team in TU Clausthal has started basic studies of UBM. As its long-standing partner, the Chinese team in Southwest Petroleum University has found that silicon dioxide nanoparticles (SNPs) added in the injected gas stream and the resulting biofilm formed by underground bacteria growth can improve caprock's sealability and stability. Thus, a cooperated project “Mechanisms of flow-chemistry-biology coupling and enhanced caprock integrity in CO2 geological sequestration based on the synergistic effect of nanoparticles and methanogens” was initiated. Tu-Clausthal utilizes particle image velocimetry technology to clarify the growth and heterogeneous migration mechanism of methanogens with SNPs. Then the corresponding model coupling multiphase flow, chemistry and biology will be established through the bilateral teams. On this basis, the Chinese team will evaluate the compaction effect of SNPs and biofilm on caprock through applying their technologies of dynamic capillary pressure evaluation and rock mechanical properties evaluation. Then the model describing the synergistic effect of SNPs and methanogens on caprock integrity will be established by mutual work. Finally, a coordinated optimization method for UBM and enhancement of caprock integrity will be formed, thus providing a scientific contribution to carbon neutrality and energy transition in China and Germany. In addition, this project will involve more young and female scientists, deepen the international cooperation level of the Sino-German teams, and build an internationally leading Sino-German CO2 Geosequestration and Conversion Joint Research and Development Platform.