Toward improved monitoring and control of microbiologically influenced corrosion(MIC)

EPA Grant Number: X83242801
Title: Toward improved monitoring and control of microbiologically influenced corrosion (MIC)

Investigators: Kathleen E. Duncan (PI,, Bruce A. Roe, Kerry L. Sublette, Gary Jenneman.
Institutions: University of Oklahoma (KED, BAR), University of Tulsa (KLS), Conoco-Phillips (GJ).
EPA Project Officer: Bala Krishnan
Project Period: One Year (Dates TBA)
Project Amount: $98,139
Research Category:  Pipeline Corrosion Detection and Monitoring


Description: Biofilm bacterial communities from a bench-scale flow loop designed to provide a model system for the examination of pitting corrosion in pipelines will be assayed using PLFA and DNA-based molecular methods to determine which bacteria may be key members in corrosion-producing biofilms. A variety of samples from the field will be examined in order to test whether the proposed bacteria are broadly indicative of bacterial communities that produce pitting corrosion. Preliminary development of molecular probes to rapidly detect bacteria indicative of corrosion will be made.

Objective:  Better control of pitting corrosion by targeting biocide use to the specific bacterial communities that cause pitting corrosion; preliminary development of a method for rapid detection of bacteria indicative of pitting corrosion.

Approach:  Clone and sequence specific genes from biofilm bacterial communities that produce pitting corrosion on metal coupons in a bench-scale biofilm flow loop, compare to genes from biofilm bacterial communities that do not produce pitting corrosion in order to identify putative corrosion-producing bacteria, assay field samples from corroded and non-corroded pipelines and other sources to test the association between specific bacteria and corrosion inferred from the biofilm flow loop system, devise DNA sequence-based probes for preliminary tests to specifically and rapidly detect bacteria confirmed by the field samples to be indicative of pitting corrosion.

Expected Results: Identification of key members of corrosion-producing bacterial biofilms, preliminary development of molecular probes to detect these corrosion-indicator bacteria.

Key Words: pitting corrosion, sulfate-reducing bacteria, molecular probes

            Microbiologically influenced corrosion (MIC) is a significant source of pitting corrosion affecting oil and gas pipelines, wells, and a variety of surface structures. The cost of MIC to the oil and gas industry includes the loss of product due to leaks, cleanup costs for damage to the environment caused by leaking petroleum products, and the cost of biocides and other agents to prevent MIC. Monitoring bacteria for control of MIC has typically focused on sulfate-reducing bacteria (SRB). However, since SRB encompass a diverse group which vary considerably in their propensity to produce corrosion, the capacity to track particular types of SRB is desirable in order to target the application of biocides in an appropriate, cost-effective manner.  This proposal is designed to use molecular methods to 1. identify the SRB and other bacteria in a biofilm contributing significantly to corrosion, 2. identify SRB that are of little corrosive potential, and 3. develop and test targeted gene analysis methods to monitor systems vulnerable to MIC for the types of SRBs likely to cause corrosion. The biofilm communities used to develop this targeted monitoring system will be derived from a bench-scale biofilm flow loop located in the ConocoPhillips Research Center, inoculated from an enrichment culture derived from an oil field, similar to that reported by Jenneman, et al. 2004. Biofilm communities which produce much pitting corrosion on metal coupons will be compared to those which, after prolonged biocide treatment, produce markedly less corrosion. Multiple sets of primers will be used for PCR amplification of 16S rRNA genes and a gene essential for sulfate respiration, dissimulatory sulfite reductase (DSR), in order to increase the likelihood of detecting SRB of interest. The high-throughput technology and bioinformatics capacity of the Advanced Center for Genome Technology (OU) will be used to efficiently identify cloned sequences of interest. Field samples will be used to test primers and probes designed to be specific for bacterial sequences judged likely candidates for targeted gene monitoring.