Field Deployment of a Portable Optical Spectrometer for Methane Fugitive Emissions Monitoring on Oil and Gas Well Pads

• Published in: Sensors (Basel, Switzerland) Vol. 19; no. 12; p. 2707
• Main Authors: Zhang, Eric J, Teng, Chu C, van Kessel, Theodore G, Klein, Levente, Muralidhar, Ramachandran, Wysocki, Gerard, Green, William M J
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 16.06.2019; MDPI
• Subjects: absorption spectroscopy; angle-of-arrival; chemistry; diode laser; Diodes; ENGINEERING; fugitive emissions; Gaussian plume model; infrared; Infrared detectors; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; instruments & instrumentation; Lasers; Line of sight; Localization; Methane; natural gas; Optics; OTHER INSTRUMENTATION; Photonics; Pollution monitoring; Sensitivity analysis; Sensors; source estimation; Tunable lasers; VOCs; Volatile organic compounds; Wind speed; United States > US; natural gas; diode laser; Gaussian plume model; absorption spectroscopy; methane; angle-of-arrival; infrared; fugitive emissions; source estimation
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s19122707

We present field deployment results of a portable optical absorption spectrometer for localization and quantification of fugitive methane (CH ) emissions. Our near-infrared sensor targets the 2ν R(4) CH transition at 6057.1 cm (1651 nm) via line-scanned tunable diode-laser absorption spectroscopy (TDLAS), with Allan deviation analysis yielding a normalized 2.0 ppmv∙Hz sensitivity (4.5 × 10 Hz noise-equivalent absorption) over 5 cm open-path length. Controlled CH leak experiments are performed at the METEC CSU engineering facility, where concurrent deployment of our TDLAS and a customized volatile organic compound (VOC) sensor demonstrates good linear correlation (R = 0.74) over high-flow (>60 SCFH) CH releases spanning 4.4 h. In conjunction with simultaneous wind velocity measurements, the leak angle-of-arrival (AOA) is ascertained via correlation of CH concentration and wind angle, demonstrating the efficacy of single-sensor line-of-sight (LOS) determination of leak sources. Source magnitude estimation based on a Gaussian plume model is demonstrated, with good correspondence (R = 0.74) between calculated and measured release rates.