Quantitative Assessment of Airborne LiDAR Technology for Methane Source Measurement and Comparison with Parallel Tracer Release and OGI Camera Survey Data

Abstract:

A field study to evaluate a plane mounted scanning LiDAR technology developed by Bridger Photonics Ltd was conducted by the Carleton University’s Energy and Emission’s Research Lab (EERL) in partnership with BC Oil and Gas Research and Innovation Society (BC OGRIS) as part of an aerial methane emission survey of oil and gas infrastructure in Northern British Columbia in September 2019. In parallel with aerial measurements by Bridger Photonics Ltd. at 167 sites, EERL simultaneously deployed a ground team consisting of 5 trucks with mobile methane tracer release equipment and 11 tripod mounted ultrasonic wind sensors to independently evaluate the lower detection limits and measurement uncertainty of the Bridger’s LiDAR technology. All tracer releases were performed in a true blinded fashion such that Bridger Photonics Ltd. had no knowledge that releases occurred until after all data processing was complete. This allowed for a truly objective assessment of both the ability to detect unknown sources (i.e. sensitivity limits) and accuracy of emissions quantification.

As a secondary objective. quantified emission rates from non-tracer sources measured during the aerial survey were compared to results of a camera based optical gas imaging (OGI) survey conducted at the same site locations in 2018. Overall methane emissions at these sites were found to be significantly higher (as much as 18x) by the aerial survey. This suggests that while OGI surveys, a standard method for leak detection and repair (LDAR) programs, may find tens of thousands of small leaks across the oil and gas sector, these camera-based surveys may not be well suited to identifying and quantifying large methane sources (e.g. tanks, unlit flares) that have the potential to dominated overall emissions. An ongoing analysis to understanding this discrepancy between the two surveys has revealed insights into emission source types and emission distributions that are crucial to developing accurate inventories, developing and updating methane regulations, and assessing industry reporting and compliance