Gas Blowout at Californian Gas Well Caused Largest US Methane Release Ever
A gas blowout at a natural gas well in Aliso Canyon resulted in over 100,000 tons of methane being released into the atmosphere before the leaking well was plugged on the 11th of February, according to a study that was recently published in Science (Feb. 26, 2016). Results from the study show that it was the largest methane leak ever in the US. The study shows that at the height of the Aliso Canyon disaster, the amount of methane being released each day could have filled a balloon as big as the Rose Bowl. According to study co-author, Donald Blake, who has 30 years experience measuring air pollutant levels all over the world, and who collected ground-level air samples from Porter Ranch, a residential area in close proximity to the natural gas site, the levels of methane released as a result of the gas blowout were exceptionally high â€” higher than we've ever seen before. After analyzing the samples, the researchers found levels of several other potentially harmful substances that occur in natural gas, such as toluene, benzene and xylenes, to be higher than normal levels. Some of these VOCs are known to pose a health risk after long-term exposure. Because methane is such a potent greenhouse gas, this disaster will drastically reduce California's ability to keep within its annual GHG emission target this year, the researchers point out. "Our results show how failures of natural gas infrastructure can significantly impact greenhouse gas control efforts," said NOAA's Tom Ryerson, a lead scientist on the study. When the gas blowout occurred, Stephen Conley of Scientific Aviation together with his specially rigged out plane were assisting UC Davis with a California Energy Commission project looking for gas pipeline leaks. He was asked to fly over the area where the breached Southern California Gas Well Company well was sited. Conley partnered with Ryerson, A NOAA scientist who had previous experience using airborne chemical sampling techniques to assess oil spills following the Deepwater Horizon disaster in 2010 and the blowout on the Elgin oil rig in the North Sea in 2012, together with a specialist team of air quality researchers from the University of California Irvine, the University of Colorado Boulder, and the California Energy Commission. Conley said that when he took the first readings early in November, the measurements were so high that he initially thought his instruments were faulty. After rechecking his methane monitoring gear it soon became apparent that there was nothing wrong with the equipment; it was just a mammoth event. The measurements showed that ethane and methane were spewing into the atmosphere and drifting from the Aliso Canyon well to the heavily populated San Fernando Valley. Upon analysis, the researchers found that at the peak of the blowout, the rate of methane being emitted from the entire Los Angeles Basin was twice as high as normal, and was double that of the previous largest anthropomorphic methane source in the US â€” a coal mine in Alabama, making it the highest methane leak on record in the US. According to the report, the total emissions recorded over the 112-day event were the equivalent of a quarter of the total annual combined methane releases produced by all other sources in the Los Angeles Basin. And in terms of its climate impact, the methane released during the gas blowout is equivalent to the GHG emissions produced by more than 500,000 cars. Besides the environmental impact, the gas blowout also posed a health risk to residents, resulting in Gov. Jerry Brown declaring a state of emergency, and over 11,000 residents being evacuated. This mammoth methane leak has highlighted the wider problem of rogue emissions associated with natural gas production, pipelines, processing and gas storage infrastructure, both in the US and further afield. This study highlights the importance of sampling for accidental methane and other hazardous chemical releases, and in this case, particularly the importance of rapid-response aerial sampling to ensure time-critical, independent, detailed and accurate information is available. Determining information such as gas leakage rates, locations of gas plumes, and the composition of gas plumes, will assist officials with assessing the environmental impact (both in terms of air quality and climate) as well as the risk to public health, and also provide an indication of how effective leak control measures are. It is important that we get these measurements as soon as possible so that we can initiate the most appropriate response. "If we don't measure these things quickly, we won't have any idea what kind of response might be called for," Conley said.
Aliso Canyon leak well pad 4 - Image Credit: Earthworks, [CC BY 2.0] via Wikimedia Commons