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Microbial Enhanced Oil Recovery: A Pore-Scale
Investigation of Interfacial and Microbial Interactions
Dorthe Wildenschild
School of Chemical, Biological, and Environmental Engineering
Oregon State University
Microbial Enhanced Oil Recovery (MEOR) is a
process where microorganisms are used for tertiary
oil recovery. Some bacteria can facilitate the
mobilization of oil through the production of
amphiphilic compounds called biosurfactants that
reduce the interfacial tension (IFT) between
immiscible phases. Additionally, most bacteria have
an inclination to colonize surfaces and form biofilm,
which can change a reservoir's wetting properties or
clog preferential flow paths
The work under this award uses fundamental
research approaches to evaluate MEOR technology,
specifically biofilm- and biosurfactant- facilitated oil
recovery are addressed.
The MEOR mechanisms of biosurfactant production and bioclogging were studied
within micromodels, using Shewanella oneidensis MR-1 that forms biofilm and
Bacillus mojavensis JF-2 that produces biosurfactant and forms biofilm. Micromodel
MEOR tests were visualized with a stereomicroscope to give insight into the
mechanisms allowing for increased oil recovery: Test (1) Extracted biosurfactant
from B. mojavensis JF-2, Test (2) S. oneidensis MR-1, & Test (3) B. mojavensis JF-2
Figure 1: Capillary desaturation curve for the abiotic recovery test in comparison to
residual oil saturations for the biosurfactant and JF-2 MEOR tests.
Table 1: MEOR test results for additional oil recovered,
original oil in place, and residual oil saturation.
Bioclogging was the most effective mechanism, in terms of AOR, compared to biosurfactant
flooding and when bioclogging and biosurfactant production occurred simultaneously AOR was
optimal (Table 1). Test 1 was ultimately explained by changes in capillary number where,
viscosity, pore velocity and interfacial tension were mutually effected (Figure 1). In the case of
biofilm formation ( Test 2 & 3, results are only for JF-2 since MR-1 biofilm was not thick enough
to provide sufficient contrast for image segmentation thus biofilm induced porosity change
could not be calculated) capillary number could not fully explain recovery (Figure 1) and it was
assumed that a change in pore morphology, due to biofilm formation was responsible for the
additional recovery.