Identifying Components of Brackish Water in Spectral Emissions of Flare Flames in North Dakota, Saskatchewan, and Ecuador

Abstract:

Entrainment of brackish water aerosols into oil and gas sector flare systems is potentially an important driver of flare emissions. However, the frequency with which this may occur at upstream production sites is poorly understood. This study reports an advanced analysis of field measurement data that includes spectral emission signatures from gas flares in three different oil and gas production regions of the world: North Dakota, Saskatchewan, and Ecuador. Using portable plano-convex lens systems to focus light into a pair of broad (~400-1100 nm) and narrow bandwidth (~400-600 nm) Ocean Insight modular spectrometers, acquired signals were processed to identify characteristic atomic emission signatures of sodium (~589 nm) and potassium (~764 nm). Species in the measured spectra were positively identified using statistical methods that compare measured to theoretical emission signatures. Results were analyzed in the context of minimum detection limits for Na and K, determined via experiments in Carleton University’s Flare Facility in which controlled amounts of NaCl and KCl solutions were aerosolized and injected into lab-scale flares burning multicomponent flare gas compositions typical of the upstream energy sector. Parameters such as nominal droplet size, solution concentration, mass injection rate, flare gas composition, and flare flame length were considered. Among flares at 81 unique upstream production sites in North Dakota and Southern Saskatchewan measured during a field campaign in November 2019, preliminary results showed ~58% had strong sodium peaks, a further ~12% had low intensity or inconclusive sodium peaks, and 30% had no detectable sodium peaks. This suggests that entrainment of sodium containing aerosols into flares at upstream sites may be common. Further measurements from a campaign in the Amazon region of Ecuador in February 2020 initially found strong sodium emission signatures at 2 of 14 sites suggesting that this occurrence is not unique to production in North America. Currently underway is the implementation of a robust peak identification algorithm and further investigation into any potential links between occurrence of aerosol entrainment and identifiable site characteristics such as drilling, completion dates, and flared volumes.