A national assessment of underground natural gas storage: identifying wells with designs likely vulnerable to a single-point-of-failure

Abstract

The leak of processed natural gas (PNG) from October 2015 to February 2016 from the Aliso Canyon storage facility, near Los Angeles, California, was the largest single accidental release of greenhouse gases in US history. The Interagency Task Force on Natural Gas Storage Safety and California regulators recently recommended operators phase out single-point-of-failure (SPF) well designs. Here, we develop a national dataset of UGS well activity in the continental US to assess regulatory data availability and uncertainty, and to assess the prevalence of certain well design deficiencies including single-point-of-failure designs. We identified 14 138 active UGS wells associated with 317 active UGS facilities in 29 states using regulatory and company data. Statelevel wellbore datasets contained numerous reporting inconsistencies that limited data concatenation. We identified 2715 active UGS wells across 160 facilities that, like the failed well at Aliso Canyon, predated the storage facility, and therefore were not originally designed for gas storage. The majority (88%) of these repurposed wells are located in OH, MI, PA, NY, and WV. Repurposed wells have a median age of 74 years, and the 2694 repurposed wells constructed prior to 1979 are particularly likely to exhibit design-related deficiencies. An estimated 210 active repurposed wells were constructed before 1917-before cement zonal isolation methods were utilized. These wells are located in OH, PA, NY, and WV and represent the highest priority related to potential design deficiencies that could lead to containment loss. This national baseline assessment identifies regulatory data uncertainties, highlights a potentially widespread vulnerability of the natural gas supply chain, and can aid in prioritization and oversight for high-risk wells and facilities.

Characterization of Historical Methane Occurrence Frequencies from U.S. Underground Natural Gas Storage Facilities with Implications for Risk Management, Operations, and Regulatory Policy

“…Michanowicz et al. () documented a total of 14,138 injection and withdrawal wells in the United States (as of 2016) having a wide range of ages and years of operation, although more than 17,000 wells have been suggested (Folga et al., ; Joint Industry Task Force, ). Moreover, the total number of occurrences includes those having a wide range of severities and consequences, from minor nuisance occurrences through catastrophic occurrences (such as some of those noted in the IFR).…”

“…Porous‐rock storage thus represents some 91% of UGS facilities in the United States, with solution‐mined salt caverns comprising the remainder. Approximately 14,138 injection and withdrawal wells service UGS facilities in the United States, with 88% in depleted oil‐and‐gas fields, 11% in aquifers, and 1% in salt caverns (Michanowicz et al., ).…”

Methane emissions from underground gas storage in California

“…During the Aliso Canyon blowout, estimated emission rates from AVIRIS-C were consistent with those obtained by Scientific Aviation. Michanowicz et al (2017) identified 160 UGS facilities that use wells that were not designed for gas storage, like the well that failed at Aliso Canyon, suggesting the possibility for future blowouts. Airborne imaging of methane plumes offers the potential to quantify methane emissions while locating primary and secondary emission sources, as demonstrated in this study for Aliso Canyon.…”

Population allocation at the housing unit level: estimates around underground natural gas storage wells in PA, OH, NY, WV, MI, and CA

“…We used previously published data on UGS facilities and wells from Michanowicz [26]. Well counts included all active wells connected to active UGS facilities from the April 2016 Energy Information Administration-191 M Monthly Underground Gas Storage Report [31].…”

“…First, UGS wells are geographically dispersed across 32 U.S. states. Recent obsolescence issues identified at UGS facilities (e.g., single-point-of-failure well designs) have placed new scrutiny on the hazards they may pose to nearby populations [26–28]. Second, the Interagency Task Force on Natural Gas Storage Safety, which was formed after the 2015 Aliso Canyon leak, recommended that “stakeholders should collect and analyze data on the proximity of UGS facilities to population centers to help better quantify some of the risk factors” [27].…”