Period Covered by Report: June 1, 2002 through August 31, 2002
Date of Report: January 14, 2003
EPA Agreement Number: R 827015-01-0
Title: Evaluation of Commercial, Microbial-Based Products to Treat Paraffin Deposition in Tank Bottoms and Oil Production Equipment
Investigators: L. M. Gieg, M. J. McInerney, and J. M. Suflita
Institution: University of Oklahoma
EPA Project Officer: Bala Krishnan
Project Period: June 1, 2002 through May 31, 2003
Project Amount: $149,999
Research Category:Wellbore Cleanout
Petroleum, bioremediation, microbiology
We aim to determine the mechanism(s) of action of commercially available, microbial formulations used to treat paraffin deposition in the oil field. Because there are many conflicting reports by producers on the efficacy of microbial treatments to remedy paraffin deposits, it is not known why microbial treatments work under some conditions but not others. Knowledge of the mechanism(s) used by microorganisms to remediate paraffin deposits is a critical first step to understanding how the application of microbial treatments for paraffin removal can be optimized in the oil field. The results of this study will benefit the domestic oil industry because understanding the mechanisms of action of these products will allow the independent producer to determine the conditions under which these products are likely to succeed and to determine if and when the purchase of microbial commercial paraffinic treatments represents a wise expenditure of investment dollars.
We met with Dr. Gary Jenneman and other individuals from Philips Petroleum (now Conoco-Phillips) to decide what types of oils we would use and to plan the initial experiments. One oil, designated Alaska Oil A, was chosen for our initial work. This oil was sent to the microbial formulation proprietor for testing. The microbial formulation proprietor will provide us with a microbial formulation suitable for use with this oil. We also investigated methods to analyze high molecular weight alkanes (up to 100 carbons in length). We purchased and installed the column for the gas chromatograph needed for this procedure. Testing of the procedure in currently underway.
A protocol for the preliminary screening process for this oil was developed. Replicate bottles with (test bottles) and without (control bottles) the microbial formulation will be incubated under aerobic and anaerobic conditions at two temperatures, room temperature and at 60°C. Each test incubation vessel will contain 85 mL of an artificial seawater medium, 10 mL of oil, and 5 mL of the microbial formulation. In the microbial-free controls, the incubation vessels contained 90 mL of medium and 10 mL of oil. The seawater medium used for aerobic and anaerobic incubations will be identical except that the anaerobic medium will contain a higher amount of bicarbonate for buffering with a 20% CO2 in N2, resazurin as a redox indicator, and a reductant (cysteine-sulfide). As per recommended protocol by the microbial formulation proprietor, the bottles will be incubated for 3 days under the appropriate conditions with slow end- over-end mixing. Duplicate bottles will also be incubated anaerobically at the two temperatures for a longer period of time, in case additional time was needed for microbial activity in the absence of oxygen.
After incubation, a portion of the oily layer from each bottle will be removed and analyzed for any changes in the wax appearance temperature (WAT). The WAT test measures the temperature at which paraffin crystals begin to form when an oil is cooled under controlled conditions. We have decided for the purposes of this research that a microbial paraffin treatment which lowers the WAT by a minimum of 5% over that of the parallel microbial-free controls is considered a successful treatment.