Effect of Microbial Activities on the Viscosity of Heavy crude in Niger Delta Field

Abstract

Abstract This study focuses on the post-recovery effect of Nigerian heavy crude viscosity in microbial enhanced oil recovery process. The technique involves the injection of exogenous hydrocarbon-degrading microbes with the required nutrients to guarantee the bacteria isolates produce the needed metabolites such as biosurfactants, biopolymer, etc. In this study, thirty- seven hydrocarbon-degrading bacteria were isolated from a hydrocarbon-contaminated soil samples from Gio, Tai Local Government Area in Ogoniland. Three of the bacterial isolates were selected and screened for biopolymer and biosurfactant production using Sudan black solution, oil spreading test, emulsification index, and haemolytic assay. The selected microbes were identified as Bacillus sp, Klebsiella sp & Pseudomonas sp by biochemical analysis. The selected microbes were exposed to ranges of salinity, pH, temperature, nutrient sources, and inoculum concentration to determine their optimum performance in reservoir conditions. The result showed the optimum parameter range for the three microbes: pH 7- 8, a temperature within 25 - 400C and salinity within 0.5% - 5%. The best nitrogen source was peptone while the best carbon source for Bacillus sp was glucose and glycerol for Pseudomonas sp and Klebsiella sp respectively. These optimum parameters were employed in the formulation of the nutrient broth used for the core flooding experiment. The core flooding setup was locally fabricated and calibrated. Fourteen microbial samples of pure and consortium were injected with carbon and nitrogen sources. The result showed an additional recovery range between 18.33% to 29.09% of the pore volume. The post-recovery analysis showed drastic transformation (reduction in viscosity) of the heavy crude to light hydrocarbon components by an average of 20.33% with glucose and 97.27% with peptone.