A Pore Level Study of MIOR Displacement Mechanisms in Glass Micromodels Using Rhodococcus sp. 094

Abstract

Micromodel experiments have been executed in order to have better insight into the displacement mechanisms allowing Rhodococcus sp. 094 to increase oil recovery. Changes caused by the bacteria in the fluid interfaces and pore walls have been recorded and are presented. The previously suspected mechanisms are further confirmed by the results, but a much better insight into the details of how the process occurs has been obtained and a theory for this process is developed. Introduction Previous publications by the authors1, 2 have already stated the effectiveness of Rhodococcus sp. 094 to increase oil recoveries from Berea cores with pure hydrocarbons (dodecane) consistently with an additional 4 %1 and at the most favorable conditions with up to 9%2. The mechanisms suspected for the additional recovery have been: Selective plugging, interfacial tension (IFT) reduction3, and changes in wettability. In those publications, the work has focused on standard reservoir lab measurements, especially Berea corefloodings and interfacial tension and wettability measurements. Glass micro model experiments can complement very well these experiments, by providing a look into the process as it unfolds in the pore space. Even though the glass micromodels used have limitations from the larger pore size deriving from the fabrication process limitations, and from the homogenous and two dimensional geometry of the flow, they can still be an invaluable tool for understanding complex mechanisms, testing hypotheses and qualitatively provide a guide of the changes occurring in the pore space with different EOR methods. It was also possible to estimate the saturation by using image analysis software, which has made it possible to plot the enhanced oil recovery vs. the capillary desaturation curve (CDC). A total of ten experiments where brine and brine with either the surfactant producing or the non-surfactant producing variant of the Rhodococcus sp. 094 bacterium are presented. The results obtained in the micromodel flooding are analyzed in conjunction with the results from coreflooding experiments, and in this way a much better understanding of the mechanisms emerges, and a hypothesis can be proposed. By designing new experiments to test this hypothesis, it can be confirmed, improved or disproved.

Fundamental Study of Pore Scale Mechanisms in Microbial Improved Oil Recovery Processes

“…The mass creation leads to blockage of the pores where the oil phase is present. This result is consistent with results reported by Crescente et al (2008) and Kowalewski et al (2005). As observed through Fig.…”

“…It is observed that the contact angle is lower in the dynamic system compared with the static system. Crescente et al (2008) conduct a number of experiments in Berea sandstone to build the capillary desaturation curve (CDC) using the SPB cells and increasing rates. The CDC curve shows that if the capillary number, a parameter defined as a dimensionless ratio of viscous to capillary forces, is less than 3 × 10 −5 , the residual oil saturation (S or ) is 30 %.…”

“…However, as the SPB cells grow around the droplets, and form a biofilm, which in some cases get attached to the surfaces of the micromodel. Therefore a third phase is formed, which mainly contains of bacterial cells and viscous material of polymeric stabilizer (Bredholt et al 1998;Crescente et al 2005Crescente et al , 2008, and can change the flow pattern in the models. In our experiments, solid remnants of the growth are observed in the micromodel as shown in Fig.…”

Enhanced recovery of Bonny light crude oil from unconsolidated porous media by two Pseudomonas species

“…Biosurfactants are able to lower the interfacial tension (IFT) that is responsible for trapping oil in the reservoir. This reduction in IFT will lead to tremendous hydrocarbon mobilization and recovery from porous matrix (Austad and Taugbol, 1995;Green and Wilhite, 1998;Crescente et al, 2008;de Gusmao et al, 2010).…”