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BP has review team looking at Prudhoe Bay maintenance Company insulating a component of the surface safety valves which has been failing in recent winter tests By Kristen Nelson PNA Editor-in-Chief
BP Exploration (Alaska) Inc. employees have raised concerns about maintenance at Prudhoe Bay — with the company and with outside groups — and BP has established a review team to take a look at what is going on.
Neil McCleary, BP Exploration (Alaska)’s greater Prudhoe Bay business unit leader, told PNA July 17 that the review team is expected to take six to seven weeks to look at Prudhoe Bay maintenance issues.
The review team is headed by Chris Phillips, head of BP’s Shared Services Technical organization in Alaska, and started work the second week of July. McCleary said the review process will include conversations with employees, reviewing documents and data and looking at facilities in the field. Chris Phillips has been a BP employee in Alaska for about 20 years, McCleary said, has held a variety of jobs and knows Prudhoe very, very well.
The team includes operators from the North Slope — from both the historic eastern and western operating areas, experts from BP’s upstream technology group in Houston and from outside the company. Dave Norton, a former Alaska Oil and Gas Conservation Commissioner, is one of the outside members of the review team, McCleary said.
McCleary emphasized that it is an outside review team: “There’s nobody from greater Prudhoe Bay line management on that group” and BP is looking at the review team to give the company “a very clear picture of what is the state of play at Prudhoe Bay,” he said. Operations and maintenance across the field Prudhoe Bay has been “essentially two oil fields for 22 or 23 years,” said BP Exploration (Alaska) spokesman Ronnie Chappell. “And this is a review that is looking at operations and maintenance practices across the entire field.” In addition to assessing the condition of the facilities and the effectiveness of the maintenance programs as they exist in both the historic eastern and western areas, Chappell said, the review will also be identifying best practices and figuring out how to better integrate the operation across “this whole historic boundary,” ensuring that best practices are spread from one part of the field to the other.Employees have concerns McCleary said BP takes employee concerns seriously. “We want to get to the bottom of the questions… find a resolution and move forward.”
The problem with surface safety valves was brought to BP’s attention by employees, McCleary said.
“Our employees brought this problem to us, but they also brought the concern outside of BP as well, so one of the issues we’re working on is to ensure that we have a clean process for handling employees’ concerns in terms of the company — an open and free communication.”
The surface safety valve on a wellhead is designed to respond to large changes in pressure and shut in the well. BP is required by the state to test these valves and report results of the tests (see related Alaska Oil and Gas Conservation Commission story on page A1).
The surface safety valves are held open by positive pressure through a hydraulic system, McCleary said. If a break occurs in the flow line leading from the well, the surface safety valve is supposed to detect low pressure and shut the well in.
Positive pressure keeps the valve open, allowing the well to flow, but the natural status of the valves is closed, McCleary said.
“So if something in the system fails and they lose hydraulic pressure they close. ... If they lose electrical power they will close. If they are triggered at the control panel by the operator in the well house they will close. And so their tendency is always to want to close and they’re held open by positive pressure.”
And because Prudhoe Bay is a mature field, only about half of the wells will flow to the surface unassisted, McCleary said. Reservoir pressure has been depleted because of the normal maturing of the field, and “about half the wells will just die from their own hydrostatic head if we turn off the gas lift. Which is one of the processes that occurs in the event of an incident — you turn off the gas lift system and then the wells choke themselves off.” Two valve components tested Two components on the valves are tested, Chappell said, “and something that we were aware of as early as 1999 was that we were having problems with pressure sensor freeze ups. We had high component failure rates during the cold winter months,” he said.
BP designed an insulating box to go over the pressure sensors to keep them from freezing, and the company began installing them around the field. Chappell said BP has acknowledged “that that program could have been better and more efficient” if guided by long-term data to help identify problem wells.
“But,” he said, “that process has been accelerated and we’re confident that we will have that problem licked by the time the weather begins to get cold.”
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