A national estimate of natural gas underground storage well blowout emissions

Abstract:

The 2015 Aliso Canyon storage well incident was the biggest natural gas leak event in US history and released ~0.1 MMT of methane (CH4), a potent greenhouse gas with a global warming potential 28-36 times of carbon dioxide in a 100-year horizon. Currently, there are over 14,000 active storage wells in the continental US, and recent studies suggested around 200 wells were constructed before the adoption of the cement zonal isolation method and might blowout in the same fashion as the Aliso Canyon accident. Most of such wells are in the eastern US. Historical data are particularly sparse for quantifying blowout emissions from underground storage wells. Although storage well emissions are estimated in the U.S. Environmental Protection Agency’s annual Greenhouse Gas Inventory (GHGI), the inventory does not include historical estimates on anomalous large emission events other than Aliso Canyon. A total of 135 storage well failure-related events were recorded across various federal/state agencies and oil & gas companies databases. We compiled the blowout accident reports and propose a method to estimate the leakage rates based on the storage field type (salt cavern, aquifer, and depleted oil/gas field). Findings from the study will help understand CH4 emissions from historic storage well blowout incidents, contribute to the data gaps in the national inventory, and provide more accurate data input to global models.