A biotechnological process for enhancing oil recovery of 14 to 25° API oil contained in carbonate or sandstone rock systems with low permeability utilizes indigenous extremophile microorganisms (first culture) from the oil well, a second culture containing selected microorganisms and its metabolites (gases, acids, solvents and surfactants), to improve oil mobility. Under anaerobic conditions, such microorganisms are able to grow in temperatures from 60 to 95° C., at pressures from 7 to 154.6 kg/cm2 and NaCl content from 5,000 to 45,000 ppm. Injection of indigenous microorganisms and a second culture for metabolites production into the well improves oil recovery after closing the system for periods from 5 to 10 days. The biotechnical process includes biostimulation (indigenous microorganisms) and bioaugmetation (second culture) to increase oil recovery.