Chiemezie Ilonze

Standardized controlled testing of emerging methane detection solutions is a critical step in demonstrating emissions mitigation equivalence between emerging solutions and existing regulatory-approved leak detection and repair methods, such as ground-based optical gas imaging (OGI) camera surveys, in the United States and Canada. In this study, 12 solutions─including four hand-held OGI cameras, hand-held NextGen solutions, and mobile solutions (automobile- and drone-based)─were evaluated using a single-blind controlled testing protocol at an outdoor facility designed to simulate emissions from a simplified onshore North American oil and gas production facility. Three solutions were retested 3 to 12 months after the initial assessment using the same protocol and facility to evaluate how performance changed over time. Results indicated that hand-held OGI cameras generally achieved better emission source localization accuracy as well as lower 90% probability of detection and false positive fraction compared to other solution categories. The false negative fractions of OGI cameras were comparable to those of hand-held NextGen solutions but generally lower than those of mobile solutions, which exhibited shorter survey durations relative to other categories of hand-held solutions. The performance of two of three solutions improved with repeat testing, highlighting the potential benefit of regular, comprehensive testing for the development of solutions. Overall, the study findings suggest that while several emerging survey solutions showed promising detection and localization capabilities, hand-held OGI cameras demonstrated higher efficacy in identifying and accurately localizing small emission sources.

Continuous Monitoring (CM) solutions have been identified as a method to address methane emissions at oil and gas (O&G) facilities, as these solutions can facilitate faster emission detection and repair compared to traditional survey methods. This study tested 13 CM solutions over 12 weeks using single-blind controlled testing. Controlled release rates ranged from 0.08 to 6.75 kg CH4/hr and lasted 18 minutes to 8 hours. Six solutions demonstrated 90 % method detection limits (DL90s) within the range of controlled releases, from 0.5 [0.3, 0.6] kg CH4/hr to 6.7 [5.9, 8.0] kg CH4/hr. Of the six solutions, four had False Positive (FP) rates between 7.8% and 14.0% (less than 15%), and four had False Negative rates (FN) of 8.0% to 34.1% (less than 50%). Compared with Ilonze et al., these results show retested solutions balancing method sensitivity with FP and FN rates. All scanning/imaging solutions had high localization (≥ 40%) precision and accuracy to the equipment unit. Eleven of the 13 solutions were tested for quantification. Single quantification estimates exhibited high relative quantification errors, outside the -90 % to 1000% range. The mean quantification error ranged from 33 [0.9, 66] %, 95% CI to 1326 [1003, 1648] %, 95 % CI for small emissions, between 0.1 and 1 kg CH4/hr, and from 3 [-20, 26] %, 95% CI to 3578 [-2832, 9988] %, 95% CI for larger emissions, greater than 1 kg CH4/hr. There were 3 and 9 solutions in the small and large emissions categories, respectively, that had less than 100% relative quantification error. Relative to previous studies, errors in quantification estimates decreased, as did FN and FP rates, with improved DL90s for two of the four retested solutions. These findings highlight that continuous, rigorous testing enhances solution performance, with notable improvements observed across multiple testing programs using the same test protocol.

Standardized controlled testing of advanced methane detection technologies (solutions) has been identified as a step in demonstrating the emissions mitigation equivalence between these solutions and existing regulatory-approved leak detection and repair methods (e.g., ground-based optical gas imaging [OGI] camera survey) in the US and Canada. In this study, 12 solutions consisting of 4 handheld OGI cameras, 4 advanced handheld systems, and 4 mobile (automobile- and drone-based) solutions were tested under a single-blind controlled testing protocol at different periods between 2021 and 2023 at an outdoor test facility that simulates emissions from a simple, onshore North American production oil and gas (O&G) facility. Three solutions were tested again 3–12 months after the first test, using the same test protocol and facility to assess how performance changed over time. Results showed that handheld OGI cameras had comparable or better performance in terms of lower 90% probability of detection (DL90), false positive and negative fractions, and higher equipment unit-level localization performance compared to other categories of solutions tested. Advanced handheld solutions had comparable performance with the OGI cameras across all metrics except false positive fraction (much higher), while mobile solutions generally had shorter survey durations compared to other solutions. For solutions that tested twice, the performance of 2 of 3 solutions generally improved, illustrating the benefit of regular, comprehensive testing in the development of solutions. The different value propositions inferred from the various categories of solutions tested suggest that mobile solutions can rapidly survey larger areas to inform more targeted, follow-up inspections with handheld solutions. While advanced handheld solutions can be as effective as OGI cameras, mobile solutions have some difficulties to overcome to make them directly comparable or need to have a different use case.

The recent regulatory spotlight on continuous monitoring (CM) solutions and the rapid development of CM solutions have demanded the characterization of solution performance through regular, rigorous testing using consensus test protocols. This study is the second known implementation of such a protocol involving single-blind controlled testing of 9 CM solutions. Controlled releases of rates (6-7100 g) CH₄/h over durations (0.4-10.2 h) under a wind speed range of (0.7-9.9 m/s) were conducted for 11 weeks. Results showed that 4 solutions achieved method detection limits (DL90s) within the tested emission rate range, with all 4 solutions having both the lowest DL90s (3.9 [3.0, 5.5] kg CH₄/h to 6.2 [3.7, 16.7] kg CH₄/h) and false positive rates (6.9-13.2%), indicating efforts at balancing low sensitivity with a low false positive rate. These results are likely best-case scenario estimates since the test center represents a near-ideal upstream field natural gas operation condition. Quantification results showed wide individual estimate uncertainties, with emissions underestimation and overestimation by factors up to >14 and 42, respectively. Three solutions had >80% of their estimates within a quantification factor of 3 for controlled releases in the ranges of [0.1-1] kg CH₄/h and > 1 kg CH₄/h. Relative to the study by Bell et al., current solutions performance, as a group, generally improved, primarily due to solutions from the study by Bell et al. that were retested. This result highlights the importance of regular quality testing to the advancement of CM solutions for effective emissions mitigation.

Quantitative optical gas imaging (QOGI) system can provide rapid quantification of leaks detected by optical gas imaging (OGI) cameras across the oil and gas supply chain. A comprehensive evaluation of the QOGI system’s quantification capability is needed for successful adoption of the technology. This study conducted single-blind experiments to examine the quantification performance of the FLIR QL320 QOGI system under near-field conditions at a pseudo-realistic, outdoor, controlled testing facility that mimics upstream and midstream natural gas operations. The study collected 357 individual measurements across 26 controlled releases with rates between 2 slpm to 88 slpm of compressed natural gas (CNG). The majority (75%) of measurements were within a quantification factor of 3 (quantification error of -67% to 200%) with individual errors between -90% and 831% (i.e. within a factor of 10). Quantification error decreased with increasing controlled release rates. Performance improved when viewing gas plumes against a clear sky as background and at calm wind speed conditions relative to other scenarios. Quantification error varied substantially when the same controlled releases were quantified from different camera positions.

Recent regulatory spotlight on continuous monitoring (CM) solutions and the rapid development of CM solutions has demanded the characterization of solutions performance through regular, rigorous testing using consensus test protocols. This study is the second known implementation of such protocol involving single-blind controlled testing of 9 CM solutions. Controlled releases of rates (6 to 7100) g CH4/h over durations (0.4 to 10.2) hours under wind speed range of (0.7 to 9.9) m/s were conducted for 11 weeks. Results showed that 4 solutions achieved method detection limits (DL90s) within tested emission rate range with all 4 solutions having both the lowest DL90s (3.9 [3.0, 5.5] kg CH4/h to 6.2 [3.7, 16.7] kg CH4/h) and false positive rates (6.9% to 13.2%) indicating efforts at balancing low sensitivity with low false positive rate. Quantification results showed wide individual estimate uncertainties with emissions underestimation and overestimation by factors up to > 14 and 42 respectively. Three solutions had > 80% of their estimates within a quantification factor of 3 for controlled releases in the ranges of (0.1 – 1] kg CH4/h and >1 kg CH4/h. Relative to the study by Bell et al., current solutions performance, as a group, generally improved primarily due to solutions from the study by Bell et al. that retested. This result highlights the importance of regular, quality testing to the advancement of CM solutions for effective emissions mitigation.

Continuous emission monitoring (CM) solutions promise to detect large fugitive methane emissions in natural gas infrastructure sooner than traditional leak surveys, and quantification by CM solutions has been proposed as the foundation of measurement-based inventories. This study performed single-blind testing at a controlled release facility (release from 0.4 to 6400 g CH4/h) replicating conditions that were challenging but less complex than typical field conditions. Eleven solutions were tested, including point sensor networks and scanning/imaging solutions. Results indicated 90% probability of detection (POD) of 3-30 kg CH4/h; 6 of 11 solutions achieved POD >50%. False positive rates ranged from 0 to 79%. Six solutions estimated emission rates. For release rate of 0.1-1 kg/h, the solutions' mean relative errors ranged from -44% to +586% with single estimates between -97% and +2077%, with 4 solutions' upper uncertainty exceeding +900%. Above 1 kg/h, mean relative error was -40% to +93%, with two solutions within 20%, and single-estimate relative errors from -82% to +448%. The large variability in performance between CM solutions, coupled with highly uncertain detection, detection limit, and quantification results, indicate that the performance of individual CM solutions should be well understood before relying on results for internal emissions mitigation programs or regulatory reporting.