Microbial processes that produce solid-phase minerals could be judiciously applied to modify rock porosity with subsequent alteration and improvement of floodwater sweep in petroleum reservoirs. However, there has been little investigation of the application of this to enhanced oil recovery (EOR). We investigate a unique approach of altering reservoir petrology through the biogenesis of authigenic rock minerals. This process is mediated by anaerobic chemolithotrophic nitrate-dependent Fe(II)-oxidizing microorganisms that precipitate iron minerals from the metabolism of soluble ferrous iron (Fe2+) coupled to the reduction of nitrate. This mineral biogenesis can result in pore restriction and reduced pore throat diameter, improving water flood efficiency. Advantageously, and unlike biomass plugs, these biominerals are not susceptible to pressure or thermal degradation. Furthermore, they do not require continual substrate addition for maintenance.
Zhu, H. & Coates, J. D. Applicability of anaerobic nitrate-dependent Fe(II) oxidation to Microbial Enhanced Oil Recovery (MEOR). Environ Sci Technol (2013). Link to paper: ncbi.nlm.gov/pubmed