The Role of Reservoir Microflora in the Process of Oil Displacement

with Combined Physico-Chemical and Microbiological Method

L.I. Svarovskaya and L.K. Altunina

Institute of Petroleum Chemistry, Russian Academy of Sciences

3, Academichesky Ave., Tomsk, Russia

Abstract

A combined physico-chemical and microbiological method has been developed to enhance oil recovery. The method has been developed taking into account both oil properties and microbiological characteristics of the formation waters in White Tiger oil field. Total number of microflora in the formation water exceeded 2107 cell/cm3. The solution of IKhN-KA system applied as a stimulating substrate increased the number of microflora by 5-6 orders. Due to active enzyme system microorganisms were capable to affect oil fixed on the porous rock. The contact of microorganisms with oil was accompanied with hydrocarbon destruction and with the accumulation of metabolism products. As a result rheological properties of oil were changed. During 10 days of microflora cultivation in contact with oil total biodestruction of n-alkanes in oil recovered from White Tiger oil field ranged from 76 to 81%. Filtration properties and oil-displacing capacity were studied using core reservoir models at 120C and at a pressure of 4 MPa under the conditions simulating those observed in White Tiger oil field. Porous volume of the model was 108.2 cm3, gas permeability averaged 0.712 D, core length - 26 cm. Oil displacement efficiency amounted to 57.4%. Using a combined physico-chemical and microbiological method one increased oil displacement efficiency by 14.2%.