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New Guidelines for Conducting Risk Assessments of Underground Storage Wells

A new set of guidelines has been released for conducting risk assessments of underground gas storage (UGS) wells that are subjected to periodic well entry.

These guidelines were developed by C-FER Technologies for The US Department of Transportation, Pipeline and Hazardous Materials Safety Administration (PHMSA) and are publicly available: Risk Assessment and Treatment of Wells

Webinar on the Demonstration Analyses in the Research Report

Part 2 of this two-part webinar series will provide an overview of the demonstration analyses described in the research report. These analyses serve to illustrate application of the quantitative risk assessment (QRA) process described in the guidelines.

The six UGS well configurations considered in the demonstration analyses were selected to include a range of representative UGS well completion configurations that are applicable to typical wells serving depleted hydrocarbon reservoirs and salt caverns. Risk levels were calculated for each well configuration under both normal operating conditions and during well entry. The QRA framework described in the guidelines was then followed to develop estimates of combined well operating and well entry risk for the purpose of safety and environmental risk evaluation.

In addition, the effect on risk of a set of well entry scenarios was analyzed and assessed over a range of evaluation periods. For each well configuration and entry scenario combination analyzed, the total environmental risk over the prescribed set of evaluation periods (or entry intervals) was compared to determine which combination of entry activities demonstrated a net reduction in overall environmental risk and which was associated with the lowest risk.

With reference to the above, the webinar will cover the following:

  • Overview of the reservoir and cavern well configurations analyzed,
  • Overview of the failure frequency and failure consequence estimation models used,
  • Summary of the risk estimates obtained for each well configuration, and
  • Findings of the risk evaluation process and well entry scenario analyses carried out.

The webinar will conclude with a summary of the high-level directional findings developed based on the demonstration analyses.


Interested in the recording of this webinar and part 1 covering the Overview of the Risk Assessment Guidelines described in the Report?

View the recordings of part 1 and part 2 of this webinar series and download the slide deck.