Equitrans Midstream Corp. said corrosion was to blame for a natural gas storage well in Southwest Pennsylvania that leaked over 1 Bcf of natural gas into the atmosphere for more than 10 days last November.
Corrosion on the outside diameter of the top joint of the well and debris between its outer and inner casings that caused them to fail contributed to the leak, according to a root-cause analysis (RCA) submitted to the Pipeline and Hazardous Materials Safety Administration. A third-party completed the RCA at the Rager Mountain Storage facility in Cambria County’s Jackson Township, about 70 miles east of Pittsburgh.
The analysis found that wireline testing conducted in 2016 was inaccurate and failed to identify the corrosion. Equtrans’ practice of keeping a vent open to release gas from the space between the inner and outer casings likely exacerbated corrosion, the company said.
The RCA also determined that nearly 1.2 Bcf of natural gas was leaked before the well was plugged, most of it was lost to the atmosphere.
The well was drilled in 1965 to produce oil and gas before it was converted to storage. It is one of 10 operating storage wells at the facility, which has a capacity of 9 Bcf. Equitrans said it hasn’t determined whether the well will stay plugged or return to service.
The top joints on several other wells at the facility have since been replaced to limit corrosion. The company also said that existing wireline reports for more than 180 wells at other Equitrans storage fields in Appalachia have been reprocessed using an updated algorithm technology to ensure their accuracy.
