| Popis: |
Microbial plugging has been proposed as an effective low cost method of permeability reduction. To optimize the field implementation, better mechanistic and volumetric understanding of biofilm growth within a porous medium is needed. In particular, the engineering design hinges upon a quantitative relationship between amount of nutrient consumption, amount of growth, and degree of permeability reduction. As a first step toward such a relationship, a Pseudomonas aeruginosa culture was inoculated into columns of glass beads and Berea sandstone cores. A growth substrate with acetate as carbon and energy source was injected continuously. Growth substrate utilization and permeability changes were used to track growth, and post-experiment in situ staining of biomass provided visual evidence of colonization and growth. Growth was observed as grainy coatings but in a spatially complex and unpredictable manner. Permeability was reduced noticeably in each experiment, but replicate experiments exhibited different growth rates and ultimate growth-induced permeability reduction. The experiments demonstrated that microbial growth is effective for reducing flow in porous media. Obtaining a mechanistic interpretation of the behavior will require a better understanding of the variability in microbe growth at the grain scale. |
