Enhanced Oil Recovery Using Indigenous Microbiome of High Temperature Oil Reservoirs.

Crude oil is a primary energy source used for economic expansion across the world. Secondary recovery processes employed by industries to recover oil from oil wells leave behind 70% of the oil trapped in marginal and deleted zones of reservoirs. To recover the oil from depleted zones, microbial enhanced oil recovery (MEOR) tertiary processes were introduced, which involve the production of metabolites from the indigenous microbiome. In this study, the indigenous microbiota was identified as Marinobacterium sp., Silvanigrella sp., Petrothermobacter sp., Pseudomonas sp., Bacillus sp., Nitrincola sp., Halomonas sp., Uncultured Roseovarius sp., and Phaeobacter. Further, the secondary metabolites such as volatile fatty acids (ethanol, acetone, and acetate), biomass, gases (CO2, CH4), and biosurfactants were estimated through gas chromatography and FTIR spectroscopy. Once stable microbial growth was attained in the baltch media, it was optimized through response surface methodology (RSM) to minimize the process cost. The optimized media with 9 g/L of molasses, 1.75 g/L of sodium bicarbonate, and 1.25 g/L of ammonium chloride showed a significant impact on metabolite production. Additionally, core flood studies to simulate field studies were performed that represented that TeriK-1 brought a significant increment of 18.9%, which makes it suitable for MEOR field implementation. This study is one of its kind where the indigenous thermophilic sp. was successfully established and is capable of producing the secondary metabolites that aid in the MEOR process.

Instigation of indigenous thermophilic bacterial consortia for enhanced oil recovery from high temperature oil reservoirs.

The purpose of the study involves the development of an anaerobic, thermophilic microbial consortium TERIK from the high temperature reservoir of Gujarat for enhance oil recovery. To isolate indigenous microbial consortia, anaerobic baltch media were prepared and inoculated with the formation water; incubated at 65°C for 10 days. Further, the microbial metabolites were analyzed by gas chromatography, FTIR and surface tension. The efficiency of isolated consortia towards enhancing oil recovery was analyzed through core flood assay. The novelty of studied consortia was that, it produces biomass (600 mg/l), bio-surfactant (325 mg/l), and volatile fatty acids (250 mg/l) at 65°C in the span of 10 days, that are adequate to alter the surface tension (70 to 34 mNm -1) and sweep efficiency of zones facilitating the displacement of oil. TERIK was identified as Clostridium sp. The FTIR spectra of biosurfactant indicate the presence of N-H stretch, amides and polysaccharide. A core flooding assay was designed to explore the potential of TERIK towards enhancing oil recovery. The results showed an effective reduction in permeability at residual oil saturation from 2.14 ± 0.1 to 1.39 ± 0.05 mD and 19% incremental oil recovery.

Evaluating the potential of indigenous methanogenic consortium for enhanced oil and gas recovery from high temperature depleted oil reservoir.

In past years, lots of research has been focused on the indigenous bacteria and their mechanisms, which help in enhanced oil recovery. Most of the oil wells in Indian subcontinent have temperature higher than 60 °C. Also, the role of methanogenic consortia from high temperature petroleum reservoir for enhanced oil recovery (EOR) has not been explored much. Hence, in the present study methanogens isolated from thermophilic oil wells (70 °C) were evaluated for enhanced oil recovery. Methane gas is produced by methanogens, which helps in oil recovery from depleted oil wells through reservoir re-pressurization and also can be recovered from reservoir along with crude oil as alternative energy source. Therefore, in this study indigenous methanogenic consortium (TERIL146) was enriched from high temperature oil reservoir showing (12 mmol/l) gas production along with other metabolites. Sequencing analysis revealed the presence of Methanothermobacter sp., Thermoanaerobacter sp., Gelria sp. and Thermotoga sp. in the consortium. Furthermore, the developed indigenous consortium TERIL146 showed 8.3% incremental oil recovery in sandpack assay. The present study demonstrates successful recovery of both oil and energy (gas) by the developed indigenous methanogenic consortium TERIL146 for potential application in thermophilic depleted oil wells of Indian subcontinent.

Laboratory Investigation of Indigenous Consortia TERIJ-188 for Incremental Oil Recovery.

Bacterial Profile modification is an efficient process which brings the alteration in permeability of the porous media of the reservoir by selective plugging which eventually recover the residual oil. It is an advantageous and feasible method for residual oil recovery from high permeability zones of the reservoir. In this study, indigenous bacterial consortia, TERIJ-188 was developed from Gujarat oil fields. TERIJ-188 was identified as Thermoanaerobacter sp., Thermoanaerobacter brockii, Thermoanaerobacter italicus, Thermoanaerobacter mathranii, Thermoanaerobacter thermocopriae. The novelty of consortia was that it produces biomass (850 mg l-1), bio-surfactant (500 mg l-1), and volatile fatty acids (495 mg l-1) at 70°C in the span of 10 days, which are adequate to alter the permeability and sweep efficiency of high permeability zones facilitating the displacement of oil. The biosurfactant was analyzed for its functional group by FTIR and NMR techniques which indicate the presence of C-N bond, aldehydes, triacylglycerols. TERIJ-188 showed an effective reduction in permeability at residual oil saturation from 28.3 to 11.3 mD and 19.2% incremental oil recovery in a core flood assay. Pathogenicity test suggested that TERIJ-188 is non-toxic, non-virulent and safe for field implementation.