Application of Bacillus spp. in Pilot Test of Microbial Huff and Puff to Improve Heavy Oil Recovery

Abstract

Microbial metabolic products, such as biosurfactants, bioemulsifiers, acids, solvents, and biogases, are useful for reducing the viscosity of heavy oils and enhancing oil recovery. Two heavy oil viscosity-reducing microorganisms, namely, SH-2 and SH-3, were selected from produced water which were collected from high-temperature reservoirs by enrichment culture technique. The screened bacteria produce biosurfactants and biogases that can biodegrade heavy crude oil components. The screened bacteria combined with indigenous bacteria were applied in a pilot test of microbial huff and puff. Temperature, porosity, and permeability of the reservoir were 50 °C, 14.32%, and 22 mD, respectively. After microbial treatment, the 50 °C degassing for crude oil viscosity of the produced oil was decreased from 750 to 634 mPa•s. Moreover, wax and resin−asphaltene contents of produced oil were reduced by 12.3% and 16.9%, respectively. The average oil production was improved from 2.2 to 3.5 t/day after microbial treatment. The production remained stable without the chemical viscosity reducer for 54 days. The analysis of bacterial community structure indicated that the number of bacteria species increased and that the microbial diversity was highly abundant. However, harmful microorganisms for microbe-enhanced oil recovery, such as sulfate-reducing bacteria, are inhibited during the progress of microbial huff and puff.

Microbially enhanced heavy oil recovery through biodegradation using fungal extracellular enzymes from Aspergillus spp.

“…E4 had greater viscosity reduction efficiency (66.33%) than E2 (53.87%). Previous studies have shown that some bacterial strains (e.g., Bacillus subtilis, B. licheniformis, and Geobacillus stearothermophilus) reduce heavy oil viscosity by 15.47-40.06% under aerobic and aerobic conditions [26,27]. Compared with these bacteria, the fungal enzyme preparations exhibited markedly higher abilities to decrease heavy oil viscosity in the current study.…”

Microbial enhanced heavy oil recovery through biodegradation using fungal extracellular enzymes from Aspergillus spp.

“…The two fungal enzyme preparations with a nal concentration of 4% (w/v) were able to reduce the viscosity of heavy oil from 29,700 to 13,700 (E2) and 10,000 (E4) mPa s. This result showed that E4 had greater viscosity reduction e ciency (66.33%) than E2 (53.87%). Other studies have shown that some bacterial strains (e.g., Bacillus subtilis, B. licheniformis, and Geobacillus stearothermophilus) reduce heavy oil viscosity by 15.47-40.06% under aerobic and aerobic conditions [26,27]. Compared to these bacteria, the fungal enzyme preparations tested in the current study exhibited markedly higher abilities to reduce heavy oil viscosity.…”

“…The degradation e ciency of different heavy oil fractions by bacterial consortia was reported to be 10.57-23.68% for alkanes, 6.03-20.62% for aromatics, and 3.63-16.90% for resins and asphaltenes [10,26,27]. By comparison, the fungal enzyme preparations from our Aspergillus cultures had higher abilities to degrade saturates, while the aromatic and resin fractions of heavy oil were relatively increased after enzymatic degradation.…”

Biodegradation of heavy oil by fungal extracellular enzymes fromAspergillusspp. shows potential to enhance oil recovery

“…The degradation efficiency of different heavy oil fractions by bacterial consortia was reported to be 10.57%–23.68% for alkanes, 6.03%–20.62% for aromatics, and 3.63%–16.90% for resins and asphaltenes 11,29,30 . By comparison, the crude enzyme extracts from our Aspergillus cultures had higher abilities to degrade saturates (decreased by 16.27%–27.61%), while the aromatic and resin fractions of heavy oil were relatively increased (decreased by 30.85%–64.89% and 2.45%–40.49%, respectively) after treatment.…”