Top-down quantification of methane emissions from the oil, gas and waste sectors on the Arabian Peninsula using helicopter-borne observations

Methane (CH₄) emissions from the oil and gas (O&G) sector remain highly uncertain on the Arabian Peninsula, despite the region’s major contribution to global hydrocarbon production and increasing mitigation commitments. As the second most important greenhouse gas after carbon dioxide (CO₂), CH₄ is a key target of global climate initiatives due to its higher short-term global warming potential, enabling faster climate benefits from mitigation. In this context, UNEP’s International Methane Emissions Observatory (IMEO) aims to improve the accuracy of emission data from the oil and gas, waste, and coal sectors through targeted measurement studies to support mitigation activities.

In autumn 2023, airborne observations of CH₄ emissions from the O&G and waste sectors were performed for the first time on the Arabian Peninsula, namely in Oman, using the helicopter-towed probe HELiPOD. Equipped with instrumentation measuring the three-dimensional wind vector and in situ CH₄ (Picarro G2401-m and LI-7700), repeated upwind and downwind measurements were conducted at varying horizontal distances (~1–5 km) and altitudes (~35–3000 m) to capture inflow conditions and the horizontal and vertical dispersion of CH₄ plumes. Co-located mobile ground-based CH₄ measurements complemented the airborne probing, with both datasets combined within a mass-balance approach to quantify emissions.

Depending on the surveyed O&G emission source (point or clustered), calculated CH₄ emission rates span a wide range from <100 to several thousand kg h⁻¹, which is within the expected range for such installations. These differences reflect variations in production levels as well as stricter safety requirements and newer infrastructure at sour facilities, which generally exhibit lower emissions than sweet installations characterized by partly more aged infrastructure. Importantly, mobile ground-based measurements effectively revealed mitigation-relevant CH₄ sources such as leaks and maintenance-related emissions. However, in densely developed production areas with multiple operators, attributing individual leaks to specific companies and isolating sources within complex facility clusters remains challenging. To address this, a dedicated case study demonstrates the combined use of ground-based, airborne, and satellite measurements to disentangle emissions from a complex O&G facility cluster. This integrated approach was also applied to quantify CH₄ emissions from Omani landfills: a small landfill, probed by airborne observations, shows emissions up to ~100 kg h⁻¹, whereas the largest landfill, observed by satellite, can emit several tons of CH₄ per hour.

Our unique helicopter-borne measurements provide an independent verification tool bridging facility-scale observations, inventories, and satellite products, supporting operators and policymakers in translating CH₄ mitigation commitments into measurable and verifiable action. This research was funded within the framework of UNEP’s International Methane Emissions Observatory and forms part of the METHANE-To-Go (MTG) project series. Prior to the MTG-Oman project presented here, CH₄ emissions were investigated in Europe (e.g. MTG-Poland) and Central Africa (MTG-Africa).