February 12, 2018

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Safety of Underground Natural Gas Storage Facilities

Achieving compliance with the U.S. Department of Transportation's recent Pipeline and Hazardous Materials Safety Administration (PHMSA) Interim Final Rule (IFR) on the safety of underground natural gas storage facilities can be a challenging endeavor.

The United States has approximately 400 underground gas storage facilities, and 81% of those are depleted hydrocarbon reservoirs which have been adapted and reused for gas storage. Depleted aquifers and salt caverns make up the remaining 19%. Most storage facilities were drilled in the 1970s and earlier and were designed originally for oil production rather than the potentially higher pressures during the injection and production cycles used in gas storage operations.

In October 2015, the Aliso Canyon Well near Los Angeles developed a leak attributed to a failure in the well casing. This leak resulted in the release of an estimated 5.7 billion cubic feet of gas and the declaration of a state of emergency by the California Governor, Jerry Brown. This incident, along with several others associated with integrity management of gas storage facilities, brought about the issuance of the IFR (49 CFR Parts 191 and 192).

The IFR identifies the recommended procedures contained in the American Petroleum Institute (API) Recommended Practice (RP) 1170 "Design and Operation of Solution-mined Salt Caverns Used for Natural Gas Storage" and API RP 1171 "Functional Integrity of Natural Gas Storage in Depleted Hydrocarbon Reservoirs and Aquifer Reservoirs."

The following tasks are now recommended for an effective compliance program:

  • Gap analysis of current procedures against the mandated API RPs and recommend and develop procedures and processes to ensure compliance
  • Assessment of training programs to ensure competence
  • Desktop risk analysis and detailed site audits to determine risks and prioritize actions
  • Asset integrity, including the development of asset integrity programs, risk-based inspection, and fitness-for-service analysis.

Geosyntec has undertaken failure modes and effects analysis (FMEA) for a confidential storage operator following concerns raised regarding integrity of a well completed in the early 1980s. Subsequent to this, consequence analysis (ignition probability, fire, and explosion) was undertaken for a range of operating conditions. The likelihood of a blowout was also determined, and a quantitative risk assessment carried out. This analysis allowed the operator to determine the future operational modes of the business and develop necessary data elements needed for compliance.  In addition, we recently supported a client with asset integrity analysis during a litigation process following a major well blowout in the UK Continental Shelf.

More Information

If you would like further information, please contact Andrew Staszak at This email address is being protected from spambots. You need JavaScript enabled to view it..

Andrew Staszak has completed projects throughout the risk and technical safety industry, and has worked to develop new methods to meet the industry's changing needs. He has performed dispersion, toxic, dust, explosion, and fire hazard analysis using computational fluid dynamics techniques on a multitude of projects. He has worked on projects including LNG liquid and gaseous dispersion, and analysis of risks and hazards related to green energy projects. Andrew has experience in conducting analysis in the field, on numerous existing and future chemical, processing, manufacturing, and petroleum facilities on and off shore, as well as laboratory applications involving shock tube blast testing and design. Learn more about Andrew: https://www.linkedin.com/in/andrew-staszak-28116614/