Development of a microbial process for the recovery of petroleum oil from depleted reservoirs at 91–96 ℃

摘要

A consortium of bacteria growing at 91 ℃ and above (optimally at 96 ℃) was developed for the recovery of crude oil from declining/depleted oil reservoirs having temperature of more than 91 ℃. PCR-DGGESequencing analysis of 16S rRNA gene fragments of NJS-4 consortium revealed the presence of four strains identified as members of the genus Clostridium. The metabolites produced by NJS-4 consortium included volatile fatty acids, organic acids, surfactants, exopolysaccarides and CO_2, which reduced viscosity, emulsified crude oil and increased the pressure that facilitated displacement of emulsified oil towards the surface. NJS-4 enhanced oil recovery by 26.7% and 10.1% in sand pack trials and core flood studies respectively in optimized nutrient medium comprised of sucrose and sodium acetate as carbon/energy source and urea as nitrogen source (pH 7–9, 96 ℃, and 4% salinity). Nutrient medium for MEOR was constituted using commercial grade cheap nutrients to improve the economic viability of MEOR process.