Abstract: Field Demonstration of the Ability of In-Situ Microorganisms in the Oil-Bearing Formations to Modify Waterflooding Profiles

BROWN, LEWIS R., ALEX A. VADIE, and JAMES O. STEPHENS

This paper will report on a field demonstration of the ability of in-situ indigenous microorganisms to reduce the flow of injection water in the more permeable zones thereby diverting flow to other areas of the reservoir, thus increasing the efficiency of the waterflooding operation. At the outset, a well was drilled and a core was obtained therefrom for core flood experiments to determine the schedule and amounts of nutrients to be employed in the field. The field demonstration involves injecting nutrients (KNO₃, NaH₂PO₄, and molasses) into four injector wells (test) and comparing the performance of the surrounding producer wells to the producers surrounding four untreated injector wells (control).

After two years of treatment, three new wells were drilled within the field and cores have shown the presence of injected nutrients (nitrate and phosphate ions) indicating their wide distribution in the reservoir. Electron microscopic examination of the cores has shown the presence of large numbers of bacteria suggesting that they are being stimulated to multiply by the added nutrients.

Two of the four test injectors wells are experiencing an increase in injection pressure and a decrease in fluids pumped indicating resistance probably caused by microbial growth in the reservoir. Based on improved oil production and/or Water:Oil Ratios, 8 of the 15 producing wells in the four test patterns are responding favorably while the producers in the four control patterns have continued their natural decline in performance.

AAPG Search and Discovery Article #90939©1997 AAPG Eastern Section and TSOP, Lexington, Kentucky