Corrosion, pipe failure and natural force damages account for more than nine out 10 leaks from oil and natural gas production well flowlines in Colorado, a draft audit by state regulators has revealed.

NGI's Shale Daily was provided a copy of a presentation of the audit by Mark Schlagenhauf, engineering integrity supervisor at the Colorado Oil and Gas Conservation Commission (COGCC). He leads the integrity group.

"I think most other states have rules on flowlines, but they may not have a dedicated group looking at spill prevention and auditing of flowlines as Colorado established recently," Schlagenhauf said.

COGCC's integrity group focuses on preventing spills, reducing volumes from spills and maintaining proactive integrity programs.

The initial audit involved 30 operators, 2,847 wells, 400-plus flowline inspections and 3,800 pressure tests in parts of the Denver-Julesburg (DJ), Piceance, and North Park basins. Nearly half (48%) of the flowline releases were caused by corrosion; 23% were due to pipe weld or joint failures, and 22% were caused by natural force damage.

"Statistics on flowlines are hard to come by as they are part of the overall spill statistics," Schlagenhauf said. "One of the things our group does is sort the flowline spill data as a subset of the overall spill data and then reviewing the root cause of the spills."

The draft report stresses the high participation rate among operators, use of advanced technology to pinpoint flowlines and confirm leaks, along with documenting and explaining pressure testing procedures on the pipelines, which for the most part have escaped regulation in producing basins.

COGCC created the engineering integrity unit, and the audit followed the lead of the state legislature, which sought a "risk-based strategy" for inspections and a subsequent third-party study of more than 1,600 spills during a 3.5 year period (2010 to August 2013). The audit found that nearly 80% of the leaks came from the production process.

Preventing spills and keeping ones that do occur small is the major focus of Schlagenhauf's group, which was formed in 2015.

The COGCC audit identifies improvements the group plans to seek going forward. Improvements include  developing more detailed root cause and preventative information on spill reports from operators and creating an electronic database for storing records on flowlines. The state staff wants more comprehensive documentation on flowline integrity efforts.

As part of the extension of the program, the COGCC unit this year and in 2018 plans to target proper flowline abandonment, something that hasn't happened in the past As a result, the state engineers plan to develop a priority list of orphan flowlines and line up a team of qualified contractors to begin dealing with abandoned pipelines through fiscal 2017-2018, starting in July.

Regarding the list of projects planned, Schlagenhauf said, "Our group will be working on the flowline portion, and other groups will handle the well abandonment and site reclamation."