Assessing the Performance of Continuous Methane Monitoring Systems at Midstream Compressor Stations

Continuous Monitoring Systems (CMS) are a promising technology to detect and quantify intermittent and high-volume methane emissions across the oil and gas supply chain. This is particularly salient at midstream compressor stations where the contribution of short duration emission events to total emissions make survey type technologies less suitable to develop accurate measurement informed inventories. In this work, we report on the first concurrent and long-term test of five CMS technologies to detect, localize, and quantify methane emission from two major types of midstream compressor stations found in the US – a turbine-only station and an engine-only station. We find that CMS technologies can distinguish between different operational states of the compressor only under conditions of low background methane emissions. Combining known events at these facilities with in-situ controlled releases, we observe that all CMS technologies generally struggle in identifying short duration or low-emission rate (relative to baseline) events. Critically, we find that positive event detection, based on analysis of underlying methane signals, frequently did not translate to alerts sent to the operators. Deployment of CMS at midstream compressor stations must proceed with caution based on specific applications, site configuration, and the nature of baseline emissions.