Microbial Systems for Enhancement of Oil Recovery Used in Romanian Oil Fields

Abstract

Microbial Enhanced Oil Recovery (MEOR) as a new Enhanced Oil Recovery (EOR) technology became mainly after the petroleum crisis in 1973, an important goal of research and development. The right microbial systems involved by this technology play an important role for the applications success. In Romania an intensive R and D activity took place during two “generations” of MEOR field trials (1975-1982 and 1986-1992 respectively). The investigations were focussed on several types of bacterial inoculum, good production of acids, gases, solvents and biosurfactants on nutrient support based on molasses (2-4%). It was found that bacterial consortia represented by Adapted Mixed Enrichment Cultures (AMEC) are much more efficient than the pure or mixed pure cultures. Finally, it was established a simple methodology to obtain AMEC for any oil reservoir with temperature up to 55-60°C, salinity up to 70-100 g NaCl/1, porosity and permeability more than 20%, and 150-300 mD respectively. The AMEC inoculum is based mainly on sporogenic bacteria of Bacillus and Clostridium type and nonsporogenic bacteria of Gram-negative rods type belonging mainly to Pseudomonas and Enter obacteriaceae groups.