Speaker
Description
The injection of gases such as CO2 and H2 into deep geological formations is a key strategy for carbon sequestration and energy storage. However, the success of these operations depends on our ability to monitor and predict the microbial response to such perturbations. Indigenous microorganisms can trigger biochemical reactions leading to gas conversion, reservoir souring, or bioclogging. Investigating these processes requires tools capable of mimicking the extreme conditions of the deep subsurface (i.e. high pressure, salinity) while providing high-resolution data on metabolic activities.
To address this, we developed optically transparent high-pressure multiscale reactors that allow for the monitoring of autotrophic microbial growth via in situ and ex situ characterization. The primary advantage of this technology is the ability to maintain the system at pressure (up to 100 bar) throughout the entire process, avoiding decompression biases and enabling also direct optical access (UV-Vis).
In the first part of this study, we established a laboratory-scale baseline using the model methanogenic strain Methanothermococcus thermolithotrophicus. We investigated the impact of H2/CO2 partial pressures and hydrodynamic conditions (i.e. stirred vs. unstirred) on methane production. Results demonstrated that unstirred conditions favor biofilm formation, which significantly extends the range of gas partial pressures under which the strain remains metabolically active. This underlines the critical role of spatial organization and mass transfer in hydrogenotrophic processes.
In the second part, we applied this methodology to a real case study using brine samples from depleted gas reservoirs (potential UHS sites). Through metagenomic analysis, we characterized the indigenous community and enriched a hydrogenotrophic co-culture including sulfate-reducing bacteria. High-pressure millifluidic and microfluidic cultivations revealed a metabolic symbiosis within this co-culture, where hydrogen consumption and microbial resilience are governed by the interplay between pressure and local physical constraints.
Overall, combining model strains and real reservoir co-cultures demonstrates that hydrogenotrophic activities are not only governed by thermodynamics but are strongly influenced by the local physical environment. This dual approach using multiscale reactors offers a direct method to evaluate biogeochemical risks, such as gas loss and souring, by capturing microbial behavior under representative reservoir conditions.
| Country | FRANCE |
|---|---|
| Acceptance of the Terms & Conditions | Click here to agree |
