Training a Neural Network Via Large-Eddy Simulation for Autonomous Location and Quantification of CH4 Leaks at Natural Gas Facilities

Abstract:

Fugitive methane (CH₄) leaks from oil and gas production fields are a potential significant source of atmospheric methane. US DOE’s ARPA-E MONITOR program is supporting research to locate and quantify fugitive methane leaks at natural gas facilities in order to achieve a 90% reduction in CH₄ emissions. LANL, Aeris and Rice University are developing an LDS (leak detection system) that employs a compact laser absorption methane sensor and sonic anemometer coupled to an artificial neural network (ANN)-based source attribution algorithm. LANL’s large-eddy simulation model, HIGRAD, provides high-fidelity simulated wind fields and turbulent CH₄ plume dispersion data for various scenarios used in training the ANN. Numerous inverse solution methodologies have been applied over the last decade to assessment of greenhouse gas emissions. ANN learning is well suited to problems in which the training and observed data are noisy, or correspond to complex sensor data as is typical of meteorological and sensor data over a site. ANNs have been shown to achieve higher accuracy with more efficiency than other inverse modeling approaches in studies at larger scales, in urban environments, over short time scales, and even at small spatial scales for efficient source localization of indoor airborne contaminants. Our ANN is intended to characterize fugitive leaks rapidly, given site-specific, real-time, wind and CH₄ concentration time-series data at multiple sensor locations, leading to a minimum time-to-detection and providing a first order improvement with respect to overall minimization of methane loss. Initial studies with the ANN on a variety of source location, sensor location, and meteorological condition scenarios are presented and discussed.