This study presents a novel top-down approach to quantify diffuse methane (CH4) emissions at oil
and gas well sites. It uses an unmanned aerial vehicle (UAV) equipped with a scanning-sampling
tunable diode laser absorption spectroscopy (TDLAS) CH4measurement instrument. By integrating
the top-down emission rate retrieval algorithm (TERRA) and adopting concentric circular sampling,
the method aims to overcome the limitations of traditional ground-based measurements. The UAV
system was deployed at 11 oil and gas sites in the Changqing Oilfield. The results show that the
average CH4emission rate detected by the UAV is 1.425 kg/h (excluding non-detected samples),
which is larger than the 1.061 kg/h obtained from ground-based onsite direct measurement.
emissions.
