Modelling bacterial effects on mass transport in porous media

Todor Baychev, Simon Gregory, Momtchil Tomov, Christopher Boothman, Andrey Jivkov, Jonathan Lloyd

    Research output: Contribution to conferencePaperpeer-review

    Abstract

    Understanding and predicting fluid flow through porous media is of fundamental importance to the design and operation of a geological disposal facility. For example, bacterial colonisation in the vicinity of the facility could potentially introduce an additional barrier between the radioactive waste and biosphere, with reported cases of reduction of the hydraulic permeability of the media of up to 98% (Cunningham et al. 1991). In this work, we present results from a flow-through sandstone column experiment colonized by the bacterium Pseudomonas aeruginosa and discuss the effects on the permeability of the system. Results indicate that such systems are susceptible to perturbations and that it is possible to obtain fairly even biomass distribution throughout the core. The experiment duration was 2500 hours during which time the injection pressure increased nearly two orders of magnitude. In addition, we conducted two XCT scans of the Hollington sandstone at a range of resolutions and extracted the equivalent irregular pore network models. Based on these networks, we developed an approach for the identification of a small number of critical features, that if affected by bacterial colonisation, the permeability of the media could be affected dramatically. The modeling results show that if the size of the critical features is reduced to 25% of its original size, this could yield permeability reduction of up to 85%. The study demonstrates the key effect of the critical features to the hydraulic permeability and the potential for a small amount of biomass to influence mass transport in porous media significantly.
    Original languageEnglish
    Publication statusPublished - 20 Aug 2017

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