Colorado oil and natural gas regulators said 428 natural gas well flowlines tested by operators in the state -- a miniscule number overall -- failed integrity tests conducted in the wake of a fatal home explosion in Weld County earlier this year.
State investigators linked an April explosion in Firestone to a severed flowline from an Anadarko Petroleum Corp. well that was sited about 170 feet from the home. Two men were killed and the wife of one man was critically injured. Gas seeped into the home through a French drain and sump pit, investigators said.
Anadarko and other Front Range producers voluntarily began testing flowlines following the explosion. Gov. John Hickenlooper subsequently ordered a revamp of regulations, still underway, and ordered all operators to test their systems.
The Colorado Oil and Gas Conservation Commission (COGCC) issued a notice to operators (NTO) that required operators to inventory flowlines and then do integrity, or pressure tests.
The initial inventory identified more than 120,000 flowline segments within 1,000 feet of building units, COGCC said. Of all the segments identified, “107,297 of those lines passed an integrity test or were abandoned.”
However, 428 of the flowlines did not pass the integrity tests, and the COGCC is tracking the follow-up work on those lines. Staff also is working with operators to determine the status of the remaining 13,090 flowline segments that are not reconciled.
"While it is possible these lines were not tested, it is also possible the data submitted was simply incomplete or in error, or that the flowline segment was previously capped, shut-in, abandoned, or was not within the scope of the NTO," staff said in its report.
A COGCC spokesperson said the integrity test failures included a wide array of causes from faulty valves and flanges to loose fittings, as well as pinhole leaks from corrosion.
"We would prefer the number of failed tests be zero, but considering the volume of flowline segments under review, it represents 0.35% of the lines covered by the order," he said, adding that operators are required to conduct pressure tests annually.
The findings in the COGCC data "are the very reason why we ordered the review,” Hickenlooper said. “Given the number of flowlines in the state, this is a relatively small figure, however, each failure requires our attention."
Because the NTO required operators initially to submit data without pressure testing and provide the state with weekly updates, staff said, “ This resulted in many duplicate reports being contained in raw unfiltered data presented on the COGCC website.”
The lines that failed pressure tests were grouped into four categories: shut-in awaiting repair/replacement (47%); scheduled for abandonment or abandoned (39%); repaired/replaced (5%), and no clear action plan from operator (9%).
The Colorado Oil and Gas Association noted that the flowline pass rate for pressure testing was better than 99%, and "most notably, none of the leaks were of a size that would have required them being reported to regulators," a spokesperson told NGI's Shale Daily.
Colorado Concern CEO Mike Kopp, who oversees the business executive alliance, said the tragedy in Firestone had a "swift, serious and comprehensive response.” The subsequent review has turned up an "extremely low failure rate," surprising activists who he said had used the tragedy "to push for a complete shutdown of oil and gas permitting."