Point Sensor Networks Struggle to Detect and Quantify Short Controlled Releases at Oil and Gas Sites

Abstract

This study evaluated multiple commercially available continuous monitoring (CM) point sensor network (PSN) solutions under single-blind controlled release testing conducted at operational upstream and midstream oil and natural gas (O&G) sites. During releases, PSNs reported site-level emission rate estimates of 0 kg/h between 38 and 86% of the time. When non-zero site-level emission rate estimates were provided, no linear correlation between the release rate and the reported emission rate estimate was observed. The average, aggregated across all PSN solutions during releases, shows 5% of the mixing ratio readings at downwind sensors were greater than the site’s baseline plus two standard deviations. Four of seven total PSN solutions tested during this field campaign provided site-level emission rate estimates with the site average relative error ranging from −100% to 24% for solution D, −100% to −43% for solution E, −25% for solution F (solution F was only at one site), and −99% to 430% for solution G, with an overall average of −29% across all sites and solutions. Of all the individual site-level emission rate estimates, only 11% were within ±2.5 kg/h of the study team’s best estimate of site-level emissions at the time of the releases.

Estimation and Applications of Uncertainty in Methane Emissions Quantification Technologies: A Bayesian Approach

“…The external validation indeed shows that for some technologies (truck-based TDLAS, airborne NIR HSI), the measurement error in the first campaign data behaves differently than predicted by the model fitted to the second campaign data. A similar result was reported recently by Day et al, who found that the detection probability and measurement accuracy of fixed sensor systems were significantly lower when installed at upstream oil and gas facilities compared to dedicated testing facilities. This finding highlights the important role played by latent environmental factors in quantification uncertainty.…”

Comparing Continuous Methane Monitoring Technologies for High-Volume Emissions: A Single-Blind Controlled Release Study

“…Note that in a study that more closely mimics real-world conditions, Day et al observed a significant deterioration in detection performance compared to the more controlled setup at METEC. 41 This comparison highlights the difficulty that continuous monitors face in accurate detection, particularly when moving from controlled environments to more complex, real-world scenarios. Our work concentrates on measuring the capacity for detecting and quantifying high-volume emission events from a single point source.…”

“…23,42 Our study, which complements the METEC findings, offers additional insights on large-source emission detection and quantification. 23,41,42 While METEC had anonymized participant data, we directly connected the results to individual teams. Furthermore, while METEC's experiments focus on multiple smaller methane leaks (<25 kg/hr) from a wide range of possible sources, our work encompasses larger emissions from a single source (<1600 kg/hr).…”

“…Furthermore, while METEC’s experiments focus on multiple smaller methane leaks (<25 kg/hr) from a wide range of possible sources, our work encompasses larger emissions from a single source (<1600 kg/hr). Note that in a study that more closely mimics real-world conditions, Day et al observed a significant deterioration in detection performance compared to the more controlled setup at METEC . This comparison highlights the difficulty that continuous monitors face in accurate detection, particularly when moving from controlled environments to more complex, real-world scenarios.…”

“…Continuous monitoring solutions evaluate emissions over an extended period and have been proposed as an option for improving emission inventories. , For this reason, we focused on evaluating quantification by comparing Stanford’s daily average emission rate to those reported by continuous monitors. Higher time resolution quantification estimates from these systems are generally noisy and difficult to interpret, as shown in Figure 18 in SI 2.2.…”