Search finds super-emitters of methane and hydrocarbons

Certain oil and natural gas sites are known super-emitters of methane and hydrocarbons. Now, using helicopters and infrared cameras, researchers have better characterized these sites and pinpointed the major source of their emissions: leakage from field storage tanks and their hatches (Environ. Sci. Technol. 2016, DOI: 10.1021/acs.est.6b00705). These leaks could be easily controlled with the appropriate equipment, the researchers say.

Methane is a powerful greenhouse gas, 25 times more potent than carbon dioxide over a 100-year time span, according to the Environmental Protection Agency. Controlling methane emissions is critical to curbing climate change. About 30% of U.S. methane emissions come from the oil and gas sector, according to the EPA.

In the new study, a team headed by scientists at the Environmental Defense Fund, a nonprofit advocacy group, hired a firm to survey more than 8,000 oil and gas well pads in seven regions of the U.S., using helicopters equipped with IR gas-imaging instruments to detect methane and hydrocarbon leakage. These IR cameras can detect gas plumes emanating from individual pieces of equipment at the facilities, such as tanks and pipes.

By matching IR-observed gas plumes at field sites with IR images of controlled releases of known size and duration, the scientists were able to determine leak rate and the exact location of leaking equipment at the well pads. They found that more than 90% of some 500 detected leakage sources were the tanks that hold, separate, and further process oil and natural gas in the field, as well as hatches allowing access to the tanks. Tanks are a somewhat surprising source, notes David R. Lyon, lead study author. In the past, he adds, more attention fell on leakage from other stages of the process, such as drilling, production, transmission, and distribution.

“Most of the tank sites had control devices that appear to be not working, ineffective, or undersized,” notes Lyon. He recommends more frequent inspections and a greater emphasis on eliminating tank emissions.