|
BP reports to AOGCC on A-22 well; commission schedules hearing Company has implemented new testing and operating procedures, investigation team recommends evaluation of remote monitoring; failed casing will be sent for analysis Kristen Nelson PNA Editor-in-Chief
BP Exploration (Alaska) Inc. has provided the Alaska Oil and Gas Conservation Commission with a review of the Prudhoe Bay A-22 well explosion Aug. 16 which seriously injured a BP worker, including recommendations its investigation team made to BP management and action plans. The commission has scheduled a hearing for Nov. 14 on all of its orders on the Prudhoe Bay field.
BP said the A-22 well, drilled in 1982, had been shut-in for about six days prior to the incident due to facility issues. Production had been averaging 500 barrels of oil per day.
The well had been diagnosed with gas pressure communication between the production casing and surface casing annulus; no leaks at surface or down hole had been identified.
BP had added the well to its annulus pressure management program. Approval from the company’s well integrity group was given to initiate production with up to 2,000 psi outer annulus pressure on Aug. 15, and the well was put in production that evening.
Surface casing failed The 13-3/8 inch surface casing failed 17 feet below grade Aug. 16, some five hours after the well was put on production, and lift gas and fluid flowed up the 20 inch conductor by surface casing annulus, blowing gravel and boards up into the well house.
BP said the ignition source could have been a spark from flying debris or electrical equipment damaged by the blast. The subsequent fire was sustained by high-pressure gas-lift gas through a needle valve damaged by the blast. Well production was isolated with surface safety valve closure, the company said. The fire was extinguished within six hours and the well controlled within 24 hours.
BP recovering damaged pipe The team that BP formed to investigate recommended that wells that could not be maintained at or below 1,000 psi should be shut-in; 137 wells were shut-in Aug. 29.
BP Exploration (Alaska) spokesman Paul said told PNA Sept. 20 that as of Sept. 19, 26 of the 137 wells were on-line and producing; 21 additional wells were ready for production as soon as routine maintenance was completed at Gathering Center 2. The 90 wells not ready to come back into production accounted for 27,000 barrels per day of production.
Laird said BP is “in the process of recovering the damaged section of pipe from A-22 right now and expect to have that in hand sometime in the next week and then we’ll be sending it off for further analysis and that will help pinpoint the root cause of the explosion.”
The workover rig is on site, he said, and work began earlier in the week. He said BP does not have an estimate of how long it will take to reach a conclusion once the pipe has been recovered. Investigation team, hearing BP’s investigation team recommended a hazard review of the company’s well integrity program and implementation of appropriate improvements and BP told the commission that new testing and operating procedures have been implemented. Each of the 137 wells that could not be maintained at or below 1,000 psi was to “undergo testing to reconfirm the integrity of its surface casing” prior to being started up.
The investigation team said “monitoring resources are not adequate to monitor multi-well startups” and recommended that some type of remote monitoring be evaluated for wells with outer annulus pressures that exceed 1,000 psi.
The team also recommended review and update of startup, bleed-down and annular pressure procedures and field practices and said a database should be developed to record operator notes, annulus pressure readings and pressure bleed events.
A safety bulletin was issued Aug. 28 was to reflect what was learned from the A-22 incident. The team recommended training be developed for operators and supervisors on annulus pressure issues and a six-month progress review on the recommendations.
The commission said Sept. 20 that it has scheduled the hearing “to consider prescribing a rule to govern the operation of development wells within the Prudhoe Bay field with pressure communication or leakage in any casing, tubing or packer.” The commission will also accept written comments through Nov. 14.
| 