2015 IR&D Annual Report

Online Monitoring System to Detect Microbial Induced Corrosion, 18-R8445

Principal Investigators
Todd Mintz
Amy De Los Santos
Spring Cabiness
Larry Miller

Inclusive Dates: 01/01/14 – 12/31/14

Figure 1: High-pressure flow system
Figure 1: High-pressure flow system
Figure 2: Raman spectra for sulfate-reducing bacteria D. Vulgaris and D. Sulfuricans
Figure 2: Raman spectra for sulfate-reducing bacteria D. Vulgaris and D. Sulfuricans

Background — Microbial-induced corrosion (MIC) is a phenomenon whereby microorganisms presence and activities result in the degradation of a material or component. In particular for the oil and gas industry, various bacteria have been linked to accelerated corrosion. Because of the detrimental effect that MIC can have on infrastructure, pipeline inspection methodologies to monitor this type of corrosion are required. However, current inspection methodologies are time consuming and costly. Thus, online detection systems for MIC are of great interest.

Approach — The objectives of the project are to develop a new in-situ technique to monitor MIC using surface enhanced Raman spectroscopy (SERS). Raman spectroscopy works via a coupling between incident laser light (visible, near infrared, or ultraviolet) with molecules at the surface of a material. Interactions between the laser light and surface molecules results in a shift in wave number of the incident beam that is characteristic of the surface molecules. By this method, the resulting Raman spectra can be used to discriminate between different bacteria strains. By depositing gold particles on the surface of the sample material, the Raman spectra intensity is enhanced (i.e. SERS). The approach to validating the SERS technique includes biological tests in an artificial growth medium, which are required for ideal growth of the bacteria being tested. The sensitivity of SERS compared to standard laboratory and field techniques was examined in this environment. Furthermore, SERS was also conducted in a high-pressure gas pipeline environment, as shown in Figure 1. The SERS results in the flow loop will be compared to the results obtained in the artificial growth medium.

Accomplishments — Use of SERS to distinguish between bacteria strains can offer an in-situ characterization tool to distinguish the types of bacteria that are growing in a media stream or gas pipeline. During this project, two types of sulfate-reducing bacteria in a biological growth media were grown. It was demonstrated that SERS could be used to distinguish a difference between the two strains, as shown in Figure 2. The work conducted showed that the growth of the two strains of bacteria used in this study was not affected by the deposited gold particles. Furthermore, the results also showed that SERS was able to distinguish bacterial growth on the surface of the samples prior to any visual indication of bacteria growth in the media. Finally, bacteria were grown in a flow loop at 1,000 psi and 38°C, and SERS measurements were made on test samples in this flow loop.

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