Mapping methane sources and their emission rates using an aircraft

Abstract

Finding efficient and accurate ways to map and monitor methane sources is becoming a priority within government and industry, both for environmental applications and hydrocarbon exploration. For more than 10 years, Sander Geophysics and Shell have cooperated to develop airborne methods to detect and measure the enhanced methane concentrations associated with ground-level sources. The resulting data can be processed using a Markov chain Monte Carlo method (MCMC) to determine the locations and emission rates of the methane sources responsible. SGMethane is the name of Sander Geophysics' methane survey method, resulting from the collaboration with Shell. It consists of an optical gas sensor, an anemometer, a GPS, and an inertial navigation system, analogous to Shell's LightTouch method. A test survey was flown over two active waste landfill sites close to Ottawa, Ontario, Canada, and the modeled data corroborated the locations of the dumpsites. Several commercial surveys for environmental monitoring and hydrocarbon exploration have been flown in a wide variety of different countries and climates; these show that both systems can detect localized anomalous methane sources even in the presence of dense vegetation, such as a tropical rainforest.