Paraffin Control in Oil Wells Using Anaerobic Microorganisms (2 Year Project)
EPA Grant Number: X83-2428-01Description: Paraffins that form waxy deposits upon removal from reservoirs have been implicated in numerous oil field problems leading to reductions in oil recovery. The concept of microbial paraffin control measures has much to recommend it in offering substantial cost and safety advantages over more traditional practices such as hot oiling. Recently, it has been documented that microorganisms enriched from a variety of hydrocarbon-impacted environments are capable of degrading long-chain alkanes under anaerobic conditions, a phenomenon which can have important oil field implications. In oil reservoirs, anaerobic conditions usually prevail but the nutrient content of production water and salinity conditions can vary considerably. The application of microbial cultures with scientifically documented ability to biodegrade paraffins under the prevailing ambient conditions can be of great use to treat wax accumulations and improve the success rate of biological paraffin treatment.
Objective: To determine the feasibility of using anaerobic microbial inocula to effectively treat paraffin deposition in reservoirs and on oil production equipment.
Approach: We will test anaerobic inocula enriched from hydrocarbon-impacted areas already known to degrade waxy alkanes up to 40 carbons in length. Further, anaerobic inocula will be enriched from active oil reservoir production wells from Oklahoma fields using paraffin-rich oil or wax fractions thereof as the carbon source. All incubations will be carried out over a range of brine and nutrient concentrations as well as temperatures in order to achieve a balance between simulating reservoir conditions and optimizing for maximum paraffin decomposition. Paraffin-degrading activities will be assessed by monitoring for anaerobic electron accepting processes and alterations in wax profiles will be determined by high temperature gas chromatography. Changes in the physical characteristics of treated waxy oils will also be assayed by using wax deposition (cold-finger) and wax appearance temperature (via differential scanning calorimetry) tests.
Expected Results: We expect to successfully enrich for a variety of anaerobic populations capable of biodegrading and/or biotransforming high molecular weight paraffins that may be used in paraffin-laden reservoirs. Once anaerobic enrichment cultures capable of biodegrading problematic paraffins are established, they will continue to be scaled-up for eventual use in field trials.
Key Words: paraffin treatment, anaerobe, biodegradation, oil field reservoir
Funding is sought to determine the feasibility of using anaerobic microbial inocula to effectively treat paraffin deposition in reservoirs and on oil production equipment. Paraffins that form waxy deposits upon removal from reservoirs have been implicated in numerous oil field problems leading to reductions in oil recovery. Commercial microbial products sold to treat paraffins are marketed as beneficial mixtures of facultative anaerobic bacteria that “crack” paraffins resulting in a less viscous oily product with improved handling characteristics. However, despite widespread use of such products in domestic oil production facilities, little more than anecdotal evidence attests to their efficacy. Thus, in a previous IPEC-funded research project, we sought to provide the scientific basis to determine whether the purchase of commercial paraffin-treating microbial formulations represented a wise expenditure. Although we assayed for a variety of chemical, physical, and biological parameters, we found little evidence of paraffin alteration when existing commercial microbial formulations were added to waxy oils under either aerobic or anaerobic conditions at above and below the cloud points of the oils examined.
Despite these results, the concept of microbial paraffin control measures has much to recommend it in offering substantial cost and safety advantages over more traditional practices such as hot oiling. Recently, it has been documented that microorganisms enriched from a variety of hydrocarbon-impacted environments are capable of degrading long-chain alkanes under anaerobic conditions, a phenomenon which can have important oil field implications. In oil reservoirs, anaerobic conditions usually prevail but the nutrient content of production water and salinity conditions can vary considerably. The application of microbial cultures with scientifically documented ability to biodegrade paraffins under the prevailing ambient conditions can be of great use to treat wax accumulations and improve the success rate of biological paraffin treatment. Thus, we propose to study the feasibility of using anaerobic microbial cultures to biodegrade waxy paraffins in oil reservoirs. Minimally, we will test anaerobic inocula enriched from hydrocarbon-impacted areas already known to degrade waxy alkanes up to 40 carbons in length. Further, anaerobic inocula will be enriched from active oil reservoir production wells from Oklahoma fields using paraffin-rich oil or wax fractions thereof as the carbon source. All incubations will be carried out over a range of brine and nutrient concentrations as well as temperatures in order to achieve a balance between simulating reservoir conditions and optimizing for maximum paraffin decomposition. Paraffin-degrading activities will be assessed by monitoring for anaerobic electron accepting processes and alterations in wax profiles will be determined by high temperature gas chromatography. Changes in the physical characteristics of treated waxy oils will also be assayed by using wax deposition (cold-finger) and wax appearance temperature (via differential scanning calorimetry) tests. Once anaerobic enrichment cultures capable of biodegrading problematic paraffins are established, they will continue to be scaled-up for eventual use in field trials.