Methane Plume Mapping Over Offshore Oil and Gas platforms Using Sun Glint

Offshore oil and natural gas platforms are responsible for about 30% of global oil and natural gas production. Despite the large share of global production there is little known about the greenhouse gas emissions from these production facilities. Given the lack of direct measurements, studies that seek to understand the greenhouse gas contribution of offshore oil and gas platforms are incredibly important. The use of airborne imaging spectroscopy to map greenhouse gases from on shore oil and gas infrastructure has become a prominent method to quantify and attribute large individual emissions to their sources. However, until now, this method has not been used offshore due to the lack of consistent reflected radiance over water bodies. Here, we pioneer a method to map methane with imaging spectrometers over water by capturing the sun glint reflection from directly over offshore oil and gas platforms. In May 2021, the Global Airborne Observatory (GAO) platform, which is an aircraft equipped with a 432 band Visible Short-Wave InfraRed (VSWIR) imaging spectrometer and a bore sighted high resolution true color camera, surveyed 32 offshore platforms in the Gulf of Mexico. Of the platforms surveyed, 15 were found to have large methane plumes. The emissions rates from the platforms were between 57 and 2866 kg CH4 hr-1 and most of these plumes were observed on multiple days. The emissions from these platforms indicate a clear pattern of super emitter activity that is consistent with on shore oil and gas basins. These results demonstrate the feasibility of using targeted glint acquisitions to map point source methane plumes over offshore infrastructure and provide much needed insight into the emissions from these platforms. Figure 1: Methane plume observed from GAO with an estimated emission rate of 2510.4 ± 374.5 kg hr-1. The plume is overlaid on the GAO high resolution true color camera image.