An unusually high incidence of rig crews engaging blowout preventers to control wells on Alaska’s North Slope has drawn the attention of state oil and gas regulators.
Through the first half of the year, blowout preventers have been used 12 times, officials with the Alaska Oil and Gas Conservation Commission told Petroleum News.
Ten of these cases involved rigs working for BP. The other two were on rigs working for ConocoPhillips and Pioneer Natural Resources.
During all of 2009, Alaska drilling crews used blowout preventers 15 times, said Jim Regg, a petroleum engineer on the commission’s staff.
The higher usage rate so far in 2010 prompted regulators to ask BP representatives to visit the commission’s downtown Anchorage offices on June 21 to talk about it.
Cathy Foerster, a petroleum engineer who sits on the three-member commission, presided over the BP meeting. She said the purpose was to ask why BP rigs are engaging blowout preventers more often, and to make sure communication is open between field workers and the commission’s inspectors.
One concern was that BP was reporting blowout preventer engagements verbally, not in writing, Foerster said. Operators are required to notify regulators within 24 hours of activating a blowout preventer.
In each of the 12 cases, the blowout preventers worked and no oil was spilled, she said.
But using blowout preventers too often is a concern because they are the last line of defense in controlling a well, Foerster said. She likened them to a car’s airbag — you don’t want to routinely rely on it to get home safely.
After talking with the BP representatives, Foerster said she felt reassured.
“We’re satisfied with their answers,” she said. “We’re done with this.”
The Gulf calamityBecause of the Deepwater Horizon disaster in the Gulf of Mexico, many Americans are now all too familiar with an otherwise obscure piece of oilfield equipment known as the blowout preventer, or BOP.
The blowout preventer on BP’s Macondo exploratory well is believed to have failed, contributing to what has been a large and continuing oil spill.
BP operates Prudhoe Bay, the nation’s largest oil field, and so is the top contractor for drilling rigs in Alaska.
During congressional testimony on June 17, BP’s chief executive, Tony Hayward, seemed to indicate that the Gulf disaster had prompted changes with respect to blowout preventers and well control in Alaska and perhaps elsewhere.
U.S. Rep. Marsha Blackburn, a Tennessee Republican, asked Hayward if he had been briefed on “significant safety incidents” at BP’s Alaska production facilities.
Here’s more of the exchange:
Hayward: I have discussed those issues at the group operating risk committee.
Blackburn: As a result of these briefings, did you authorize any changes to BP policies and practices for dealing with the safety incidences?
Hayward: We took actions in Alaska to change both the organization and some of the processes.
Blackburn: Thank you. Since the Deepwater Horizon incident have you made changes and what are those? Will you submit those to us for the record?
Hayward: We have made changes to our testing procedures on BOPs. We’ve made changes to the intensity with which wellsite leaders are aware of well control procedures and a variety of other interventions that are predicated on what we have learnt from the incident so far. And as we learn more we will make more changes as we deem appropriate. And I’d be very happy to submit to you, congresswoman, the details of the changes that we’ve made.
Blackburn: Thank you.
Petroleum News asked BP’s Alaska spokesman, Steve Rinehart, to elaborate on Hayward’s comments, but he had not replied by press time.
Four events on Nabors rigThe AOGCC provided Petroleum News a summary of the 12 instances that rig operators activated blowout preventers on the North Slope.
The first engagement occurred on Jan. 26 and the most recent one on June 7.
None of the cases involved the drilling of an exploratory well. Rather, they predominantly involved workover activity or development drilling in the BP-operated Prudhoe Bay unit, the BP-operated Milne Point unit, the ConocoPhillips-operated Colville River unit, and Pioneer’s offshore Oooguruk field.
In half of the 10 BP cases, rigs were involved in workovers, doing jobs such as changing out electric submersible pumps.
Four BP cases involved the same drilling rig — the Nabors 4ES rig, the AOGCC summary shows. The Nabors 9ES rig activated its blowout preventer three times.
Blowout preventers sit at the top of the well and work by closing off pathways for fluids or natural gas to travel up to the surface, typically through an outer space called an annulus. The preventers don’t engage automatically; rather, rig operators must make a decision to trigger a BOP.
Foerster, the AOGCC commissioner, said rigs involved in workover operations can be especially prone to encountering conditions requiring activation of a blowout preventer. For example, she said, a gas “bubble” trapped at the bottom of a well can flow up when a rig pulls out tubing and packers — downhole devices that seal the wellbore.
Rig operators usually — and ideally — prevent dangerous upsurges by pumping heavy fluids such as drilling mud into the well.
State regulations require tests of blowout preventers every week or two, and AOGCC inspectors personally witness many of these tests, Foerster said.
The AOGCC summary indicates that blowout preventers used thus far in 2010 were tested between one and five days after the engagement.