First helicopter-based measurements of methane emissions on the Arabian Peninsula from the oil, gas and waste sector
The invisible gas methane is one of the most potent greenhouse gases after carbon dioxide and is currently focus of worldwide initiatives to combat global warming. As part of the International Methane Emissions Observatory (IMEO), an initiative of the United Nations Environment Programme (UNEP), scientists from the DLR Institute of Atmospheric Physics (DLR-IPA) carried out the first successful measurements of methane emissions from the oil, gas (O&G) and waste sectors in Oman in November and December 2023. In close cooperation with the Institute of Flight Guidance (IFF) at the Technical University of Braunschweig (TUBS), the HELiPOD probe, which is flown as a sling load on a rope under the helicopter, was used. This unique configuration was already successfully tested in similar measurements in Poland in 2022.
In Oman, the HELiPOD was equipped with in-situ trace gas instrumentation from DLR-IPA as part of the Methane-To-Go-Oman campaign to measure methane (CH4), carbon dioxide (CO2) and sulphur dioxide (SO2) in the vicinity of oil and gas industry facilities as well as landfills. These high-resolution measurement data can be used to calculate methane mass fluxes in order to efficiently quantify the strength of the various sources in a target area. The helicopter probe has proven to be extremely efficient for analysing trace gas emissions from point sources. Especially at local scales, the HELiPOD offers a number of advantages over conventional airborne measurement methods. Firstly, it has great manoeuvrability, with the option of significantly reducing the flight speed and carrying out low-altitude flights at short distances from the emission sources. Secondly, the flight costs are lower and no special flight permission is required.
With a helicopter of the Omani company Al Sharqiya Aviation (ASA), CH4 emissions from various facilities in three regions across Oman were analysed during 26 mission flights (~70 flight hours). Measurements were conducted both upstream and downstream of the facilities (horizontal distance ~1-3 km) and at several altitudes ranging from 50 m to ~2 km to accurately capture the spatial distribution of CH4 emissions. Different flight strategies were implemented for each of the 26 flights, depending on the wind situation at the investigated sites. A continuously running wind lidar operated by DLR-IPA recorded the current wind situation and supported the flight strategy planning at the three locations. During the flights, the HELiPOD mission monitor in the cockpit displayed the measurements online so that the mission scientist could successfully guide the helicopter through the invisible methane plumes. In order to calculate the CH4 mass flux from the facilities, these measurements are combined with high-resolution wind information from the HELiPOD. In addition, the airborne measurements in Oman were complemented by ground-based CH4 measurements carried out by a team of Polish scientists from the AGH University of Science and Technology in Krakow.
Under the Oil & Gas Methane Partnership 2.0 (OGMP 2.0), UNEP’s flagship O&G reporting and mitigation programme, companies in the O&G sector have committed to monitor and reduce their CH4 emissions. Currently, more than 120 companies have joined OGMP 2.0, operating in 70 countries around the world, one of which is Oman. Besides. After the O&G sector, the waste sector is currently the second largest emitter of methane and contributes to 15% of Oman's CH4 emissions. To date, however, no sector-specific, measurement-based studies on such emissions are available for Oman.
The comparison of our collected data (top-down approach) with the estimates of CH4 mass fluxes provided by the industry (bottom-up approach) should help the involved companies and the respective governments to prioritise their measures and policies to reduce CH4 emissions in the future.
This research has been funded in the framework of UNEP's International Methane Emissions Observatory (IMEO).
