Grantee Research Project Results
2006 Progress Report: Paraffin Control in Oil Wells Using Anaerobic Microorganisms
EPA Grant Number: X832428C002Subproject: this is subproject number 002 , established and managed by the Center Director under grant X832428
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: HSRC (1989) - Northeast HSRC
Center Director: Sidhu, Sukh S.
Title: Paraffin Control in Oil Wells Using Anaerobic Microorganisms
Investigators: Suflita, Joseph , Gieg, Lisa M.
Institution: University of Oklahoma
EPA Project Officer: Aja, Hayley
Project Period: October 15, 2006 through October 14, 2007
Project Period Covered by this Report: October 15, 2006 through October 14, 2007
Project Amount: Refer to main center abstract for funding details.
RFA: Integrated Petroleum Environmental Consortium (IPEC) (1999) RFA Text | Recipients Lists
Research Category: Targeted Research
Objective:
Paraffins that form waxy deposits upon removal from reservoirs have been implicated in numerous oil field problems leading to reductions in oil recovery. In oil reservoirs, anaerobic conditions usually predominate. Thus the addition of anaerobic microbial populations that can definitively biodegrade paraffins under such conditions may be of great use to treat wax accumulations. Our aim is to evaluate the feasibility of using anaerobic microbial consortia to biodegrade waxy hydrocarbons in order to ameliorate paraffin accumulations in oil reservoirs.
Progress Summary:
For this project, we have been cultivating microbial populations from a variety of sources for the potential to degrade and treat waxy paraffins under anaerobic conditions. Enrichment cultures derived from hydrocarbon-contaminated marine sediments in San Diego Bay have shown enhanced levels of sulfate reduction when C28, C40, or C50 is provided as the paraffinic substrate relative to substrate-free controls (Figure 1). These cultures continue to be transferred and cultivated for potential paraffin-treating activity. The paraffin-utilizing enrichments are also able to utilize alkanes as low as C6 (hexane) based on sulfate reduction measurements. Molecular analyses were used to help identify the organisms in these enrichments responsible for anaerobic paraffin decay. Denaturing gradient gel electrophoresis (DGGE) analysis, cloning, and sequencing of the 16S rDNA (~1500 bp) amplified from the enrichments were used to assess the diversity and identity of the requisite bacteria. A comparison of the 16S rDNA clone library from the C28, C40, and C50-degrading enrichment cultures revealed close affinity to several known hydrocarbon-degrading sulfate-reducing members of the delta proteobacteria (Figure 2).
Figure 1.
Figure 2.
Enrichments set up from other marine sediments under methanogenic conditions (e.g., no added electron acceptor) have also shown enhanced levels of methane production relative to controls. This effect was most dramatically observed when C28 was supplied as the sole paraffin source, but some enhanced methane levels were also measured when C40, C50, or a commerically-available high molecular weight waxy mixture, Polywax (~ C30 to C100, Polywax 655, Supelco) was supplied as the paraffin substrate. These enrichments also continue to be cultivated as potential paraffin-treatment cultures. Experiments are in the planning phases to incubate the cultures with fully deuterated C28 in order to help with the identification of metabolites that may be produced during anaerobic paraffin degradation.
We have also established incubations using anaerobic sediments from a freshwater, hydrocarbon-impacted aquifer to determine the ability of the microbial population to utilize Polywax under sulfate-reducing and methanogenic conditions. These sediments are already known to degrade alkanes in oils up to C34 in length under anaerobic conditions (Townsend et al., 2003, Environ. Sci. Technol. 37: 5213-5218). Further, we established parallel incubations using a sediment-free, oil-degrading methanogenic population enriched from the same site as an inoculum. Incubations were amended with ANS oil (from Alaska’s North Slope), Polywax, or a mixture of ANS oil and Polywax. Over the course of approximately 7 months, we observed enhanced levels sulfate reduction over substrate-free controls when the enrichments were established in the presence of all three substrates. This was observed for incubations containing sediments as well as for those containing the sediment-free oil-degrading inoculum. When the cultures were re-amended with sulfate, sulfate reduction continued relative to the substrate-free controls, attesting to the ability of the enrichments to use a wide range of paraffins under sulfate-reducing conditions. In contrast, no enhanced levels of methane production from the added Polywax were observed in the methanogenic incubations.
Future Activities:
Enrichment and monitoring of the above-described cultures for the ability to degrade waxy paraffins under anaerobic conditions will continue. Experiments will be conducted to determine the nutritional requirements of some of the enrichment cultures to improve growth and deduce salinity tolerance. In the next phase of the project, enrichments will be challenged with field paraffins and paraffinic oils. Some cultures will also be established under more thermophilic conditions using field samples such as oil production waters. The concentration of paraffins will be assessed in addition to measures of electron-accepting processes.
Supplemental Keywords:
paraffin treatment, anaerobe, biodegradation, oil field reservoir,Progress and Final Reports:
Original AbstractMain Center Abstract and Reports:
X832428 HSRC (1989) - Northeast HSRC Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
X832428C001 Effective Stormwater and Sediment Control During Pipeline Construction Using a New Filter Fence Concept
X832428C002 Paraffin Control in Oil Wells Using Anaerobic Microorganisms
X832428C003 Fiber Rolls as a Tool for Re-Vegetation of Oil-Brine Contaminated Watersheds
The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.