Most remaining unproduced ANS oil reservoirs are shallow deposits with heavy/viscous oil. These heavy/viscous oil deposits are not possible to produce using primary oil recovery. Only a small percentage can be produced using waterflooding as a secondary oil recovery method. Even after waterflooding, a vast portion of these deposits remains in place. These oil deposits must be produced using tertiary recovery methods such as thermal methods, carbon dioxide (CO2) injection or microbial MEOR.
Results
Experiments were conducted to assess the compatibility of the surfactant-producing microbes selected for the MEOR tests to a nutrient medium (mixture of Bushnell Haas Broth, sucrose, and sodium chloride) and it was observed that the bacteria grew at 30 °C in the proposed nutrient medium. The first core was injected with the microbial formulation after initial waterflooding. The initial waterflood led to a residual oil saturation of 53.24 percent of the initial oil saturation. There was a week’s shut-in period after injection of the microbial formulation. The microbial formulation led to 7.04 percent EOR. A second core was injected with the microbial formulation without the waterflooding. That core is currently in a shut-in period.
Benefits
A significant volume of ANS oil deposits are made up of heavy/viscous oil. The results of this project could lead to increased production of oil from existing ANS fields, as well as the extension of production to viscous oil resources on ANS that are not currently being produced. If the technology can be commercially developed, it could provide business opportunities for the Alaskan industries involved.
Summary
The research focuses on coreflooding experiments and microbial characterization studies. The coreflooding experiments are being conducted to find out whether using MEOR will lead to any increase in the oil recovery. Two successful experimental runs have been performed on Berea core samples.
For the microbial characterization studies, Bacillus licheniformis was used as the biosurfactant producing agent. A sample of the bacteria was obtained from American Type Culture Collection (ATCC) and cultured in the Arctic Health Research Building at UAF. An effective microbial formulation was made using Bushnell Haas Broth as the nutrient media, along with sucrose as the carbon source.
Cloning and sequencing studies still need to be performed to assess the indigenous microbial community present in the oil.
