The biopolymer produced by Rhizobium viscosum CECT 908 is a promising agent for application in Microbial Enhanced Oil Recovery

Polymer flooding is one of the most promising techniques used to increase the productivity of mature oil reservoirs. Polymers reduce the mobility ratio of the injected water relative to the crude oil, improving the displacement of the entrapped oil and consequently, increasing oil recovery. Biopolymers such as xanthan gum have emerged as environmentally friendly alternatives to the chemical polymers commonly employed by the oil industry. However, in order to seek more efficient biomolecules, alternative biopolymers must be studied. Here, the applicability of a biopolymer produced by Rhizobium viscosum CECT 908 in Microbial Enhanced Oil Recovery (MEOR) was evaluated. This biopolymer exhibited better rheological properties (including higher viscosity) when compared with xanthan gum. Its stability at high shear rates (up to 300 s-1), temperatures (up to 80?°C) and salinities (up to 200?g/L of NaCl) was also demonstrated. The biopolymer exhibited better performance than xanthan gum in oil recovery assays performed with a heavy crude oil, achieving 25.7?±?0.5% of additional recovery. Thus the R. viscosum CECT 908 biopolymer is a promising candidate for application in MEOR.This work was supported by PARTEX OIL AND GAS (Lisobon, Portugal). The authors acknowledge the Portuguese Foundation for Science and Technology (FCT) for financial support under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684). The authors also acknowledge financial support from BioTecNorte operation (NORTE-01-0145FEDER-000004) and the project MultiBiorefinery (POCI-01-0145FEDER-016403) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. Márcia R. Couto was supported by the doctoral Grant SFRH/BD/ 132998/2017 provided by FCT. Débora Ferreira is recipient of a fellowship (UMINHO/BD/21/2016) supported by a doctoral advanced training (call NORTE-69-2015-15) funded by the European Social Fund under the scope of Norte2020 - Programa Operacional Regional do Norte.E.J.Gudiñawassupported bythePost-Doctoral grant UMINHO/BPD/39/2015 from the project UID/BIO/04469/2013, funded by FCT.info:eu-repo/semantics/publishedVersio

Isolation and screening of Bacillus subtilis MJ01 for MEOR application: biosurfactant characterization, production optimization and wetting effect on carbonate surfaces

Abstract The bacterial strain MJ01 was isolated from stock tank water of one of the Iranian south oil field production facilities. The 16S rRNA gene of isolate, MJ01, showed 99% similarity to Bacillus subtilis. The results revealed that biosurfactant produced by this strain was lipopeptide-like surfactin based on FTIR analysis. Critical micelle concentration of produced surfactin in distilled water was 0.06 g/l. Wettability study showed that at zero salinity surfactin can change original oil-wet state to water-wet state, but in seawater salinity it cannot modify the wettability significantly. To utilize this biosurfactant in ex situ MEOR process, economical and reservoir engineering technical parameters were considered to introduce a new optimization strategy using the response surface methodology. Comparing the result of this optimization strategy with the previous optimization research works was shown that significant save in use of nutrients is possible by using this medium. Furthermore, using this method leads to less formation damage due to the incompatibility of injecting fluid and formation brine, and less formation damage due to the bioplugging