The present invention provides a microbial consortium containing three
hyperthermophilic, barophilic, acidogenic, anaerobic bacterial strains
for enhanced oil recovery from oil reservoirs where temperatures range
from 70.degree. C. to 90 C. The said microbial consortium is unique in
producing a variety of metabolic products mainly CO.sub.2, methane,
biosurfactant, volatile fatty acids and alcohols in the presence of
specially designed nutrient medium. These metabolic products increase
sweep efficiency of crude oil from oil bearing poles of rock formation.
The present invention also provides a process for enhancing the oil
recovery by in situ application of the said microbial consortium.