Keywords: methane emissions, continuous monitoring, fugitive
Summary:Methane emissions from the oil and gas industry are receiving intense scrutiny as part of the energy transition. A large portion of the methane emissions arise from events that are intermittent. Many different technologies have been proposed and demonstrated for detecting these emission events ranging from satellite-based screening to handheld inspections using an optical gas imaging camera. For most facilities, continuous monitoring using methane emissions detectors installed permanently at a site offers a cost-effective way to identify, quantify, and repair intermittent emissions. Due to the wide range of facility types and sizes, a one-size fits all model will not address all particular use cases. Here we describe two different continuous monitoring technologies that are capable of being economically deployed worldwide on a large scale to address facilities ranging from single well pads to large LNG processing sites. First is a continuous methane point sensor system, which is based on a small number of IoT-enabled, fixed-location methane sensors located at the boundaries of each facility. The detectors simultaneously collect data measuring methane concentrations and meteorological conditions, such as wind speed and direction. The data is then inverted to confirm the existence of a leak, its position, and the emissions rate. This simple system can be used to economically monitor smaller facilities such as well pads and gathering stations. Second is a methane LiDAR camera, which is a compact, high-sensitivity, low-power Tuneable Diode Lidar (TDLidar) gas detection system. It provides a long-range, high-sensitivity, high-speed quantitative imaging of gas plume shape and concentration. The images are then interpreted to provide quantitative measurements of leak position and emission rate. This system can be used to measure complex facilities with a minimal number of cameras installed due to its inherent long-range capability. Both systems have been deployed at a large outdoor test facility that can generate controlled releases of methane representative of emissions ranging from less than 1 kg/hr to over 15 kg/hr. The test release can be modified to imitate releases ranging from those that mimic loose joints to those that mimic open tank vents. The method thereby demonstrates both systems’ ability to accurately detect emissions less than 2 kg/hr with no false positives. These results confirm the robustness and high metrological performance of the systems as they are used to detect and quantify a wide range of potential leaks. However, there is still room for improvement, and the core sensor requirements needed to enable the next generation of systems to further lower the total cost of ownership while increasing their performance will also be described. The ability to rapidly identify oil and gas facilities emitting significant amounts of methane requires the deployment of a large-scale continuous monitoring system at all potential sites. When installed, as part of a complete solution for an emissions management system, continuous monitoring provides a vital method to cost-effectively monitor facilities.