In 2020, Canadian oil and gas producers will need to start measuring methane, and managing towards stringent caps. The regulations require measurement 3x annually at many sites, using EPA Method21 or Optical Gas Imaging (OGI) cameras. Producers have an opportunity in 2019 to develop and propose Alternative measurement and inspection programs that deliver the same reductions at lower measurement cost. These triage programs may depend on multiple measurement techniques. But which ones work? The service sector has not yet developed clear performance specifications across conditions. In the meantime, inter-comparative studies can provide insight.
This paper is a recent Australian effort that comprehensively compares different methane monitoring techniques (truck, stationary, imaging, tracer, etc). We’ve seen many of these inter-comparative “shootout” style experiments over the years, particularly for Carbon Capture and Storage monitoring technologies. In this area, the Australians are leaders. This study impressed us, because the experiments were made blind (in size and time) to the instrument operators. In other words, nobody knew what was coming, or what they should find. Good science.
Fig. 2. Boreal GasFinder2 UAV octocopter target with reflector payload near the gas release chamber. (Taken from the International Journal of Greenhouse Gas Control paper)
The results, however, were not a surprise. The most important take-home is written right in the abstract: “The majority of CH4 estimates were within 20% of the actual CH4 release rate (5.8 g/min).” Since the difference between the smallest and largest emissions in a typical oilfield often exceeds 100,000%, most of these techniques performed well relative to the variability onsite.
There is a lot of uncertainty and skepticism in oilfield circles around methane monitoring techniques. But, they’re far from magic. Many of the techniques (including those tested here) rely on decades-old foundational methods like gaussian dispersion. Uncertainty amongst O&G operators is related more to unfamiliarity than to actual measurement novelty.
The trick for Canadian operators will always be to use the right technique for the weather – whether -40, +40, snow, or smoke from forest fires.
Fig. 12. Column densities of methane derived from the spectral measurement using the Bruker HI90 at 20 g/min release rate at a distance of 100 m. The red box illustrates the region of methane recordings. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)