Being prepared for an oil spill response is like buying insurance — you hope that the worst will never happen but, if it does, you’d better be prepared.
And in the case of Shell’s proposed offshore drilling activities in the U.S. Beaufort Sea, those preparations have included the construction of the Nanuq, a 300-foot, ice-strengthened oil spill response vessel, and the chartering of the Arctic Endeavor, a 200-foot oil spill response barge. The company has also chartered a 500,000-barrel double-hulled tanker, to hold and carry away any oil that Shell might have to mop up as a result of an oil spill.
The idea is to have the oil spill response kit on the water, at the drill sites, ready to respond immediately to any emergency, Rick Fox, Shell’s asset manager for Alaska, told Petroleum News.
“Should it be a diesel transfer spill, should it be any kind of accident that we might have, we have a team ready to go,” Fox said. “We can deploy our equipment and begin recovering within 45 minutes.”
“We have a total of 24 vessels in the oil spill response program,” said Susan Moore, Shell’s Alaska operations manager. In addition to the three major vessels, there are 11 smaller boats, including mini-barges and boom towing vessels, mounted on the decks of the Nanuq and the Endeavor, she said.
Prevention firstHowever, the first line of defense against an oil spill is to prevent one happening. In that regard, an oil explorer’s biggest nightmare is the possibility of a blowout, in which crude oil under pressure spouts from an out-of-control well. But a blowout is a very rare occurrence nowadays, Fox said.
“There have been no blowouts in an Arctic environment that we have any record of,” Fox said.
But Fox emphasized that the rarity of blowouts does not lessen the need to be vigilant.
“We know what’s at stake here to the communities and to our own program,” Fox said.
The first line of defense against a blowout is the use of modern well logging technology that enables conditions at the bottom of the well to be monitored continuously while a well is being drilled, Fox said.
“We actually have the capability of detecting subtle changes in the formation as we go,” Fox said. “You are able to detect things that are indicators of pressure … as well as having the ability to control the direction of the drilling.”
Shell has established an operations center in which a team of experts will be able to continuously monitor the well conditions while drilling is in progress, and alert the drilling team to any potential problems. And, housed in a well cellar below the level of the seafloor, a modern six-valve blowout preventer would shut the well down immediately in the event of an unexpected surge of oil.
Were the containment provided by the blowout preventer to fail, Shell might have to drill a relief well into the out-of-control well, to plug the well up. The floating drilling vessel could reposition to drill that relief well, or Shell could bring in its second drilling vessel to drill a relief well, Fox said.
“We would not do any critical drilling when we didn’t have the capability of doing relief well drilling,” Fox said.
Ice monitoringThe other obvious scenario that could lead to an oil spill would be damage to the well piping following an oil strike. Such damage might occur, for example, if sea ice moved the drilling vessel while the vessel was connected to the well.
But Shell believes that it has effectively eliminated that possibility through its ice monitoring program and its critical operations curtailment plans. The rigs are designed to move off location when necessary and Shell has established procedures for determining when to curtail operations, before ice can cause any threat of damage.
“What’s key to that is being able to know what the ice is doing all of the time,” Fox said.
So, in addition to having icebreakers and ice management vessels stationed on site to protect the drillships and monitor ice movements, Shell has established an ice monitoring center in which images from ship-based radar and satellite-based radar combine to provide a continuous image of the sea ice cover and sea ice movement.
“So you have real time images of the ice and where it’s moving,” Moore said. “It’s a really neat piece of technology that’s been brought to bear here recently.”
Double coverageBut what if an oil spill were to occur?
Shell’s spill response strategy is based on the concept of a self-contained oil spill response capability on the water, next to each of its two Beaufort Sea drilling vessels. One response group would be based on the Nanuq while the other response group would be based on the Endeavor. Each of those groups would be independently capable of responding to a worst-case oil-spill scenario, said Jon Edmondson, Shell’s Alaska projects coordinator. And, were there to be a significant incident at one drill rig, the oil spill response vessel at the other rig would also move into action.
“In the event there was a major problem, we’d just shut down operations on the other rig and move all of the assets,” Edmondson said.
And, because Shell’s contingency plans don’t require all equipment to perform up to maximum capacity, the company believes that, overall, its response capability exceeds requirements by a factor of two to four. For example, four key skimmers in the spill response inventory could each meet the planning standard capacity when operating at just 20 percent of the equipment’s rated capacity, Moore said.
Variety of situationsThe technologies and tactical response plans that Shell has assembled cover the various types of spill response situations that could occur during a Beaufort Sea drilling season. Drilling operations would typically start in open water. But once the sea starts to freeze in the fall, ice can start building up quite rapidly, within typically a couple of weeks, Edmondson said.
In open water, spill responders would use boom to channel the oil into skimmers that would recover the oil from the sea. The Shell response equipment inventory includes small boats that can deploy boom to corral the oil, and mini-barges for collecting the recovered oil.
But once the ice cover reaches a certain point, the ice itself would provide natural containment of spilled oil during cleanup operations, while shore-fast ice would protect the shoreline, Moore said.
In these more ice-laden conditions, rope mop skimmers could transfer oil out of the water without becoming clogged with floating ice, Moore said. State-of-the-art Lamor brush skimmers could also be deployed from the sides of the oil spill response vessels to remove the oil from the ice-laden waters.
At some point the ice cover would become too extensive for mechanical recovery of oil to continue. Any oil remaining in the sea would become trapped within the ice, Moore said. In the spring the oil would rapidly float to the surface through brine channels — the resulting oil pockets on the surface of the ice could then be burned off (because of the low temperatures, little degradation of the oil would occur during the winter), Moore said.
But would the techniques for oil recovery in icy conditions actually work? People have in the past expressed skepticism about the practicalities of oil spill response in ice-laden water, especially in broken ice conditions.
Fox said that he understands why people would think that cleaning up oil in icy conditions would be difficult. But the Shell team has thoroughly researched the issues involved, he said. And Shell is involved in a joint industry program of research into Arctic oil spill response, Edmondson said.
“We researched all the different technologies against different levels of broken ice and different conditions and put together a suite of answers for that,” Fox said.
For example, the Lamor skimmers that Shell would deploy from the two oil spill response vessels have been tested and proven in icy conditions, Moore said. In fact, this type of skimmer has seen successful action in icy water in actual spill responses by the Swedish coast guard, she said.
“They’ve performed really well,” Moore said.
In-situ burningBut, in addition to using mechanical oil recovery technologies, Shell sees the in-situ burning of spilled oil as a key spill response technique.
“That is a tried and tested technique too, which in many situations can have upwards of 85 percent to 95 percent removal efficiency,” Moore said. “… Burning is potentially a very viable option, even early in the season.”
The Shell spill response equipment inventory includes a new, patented type of water-cooled fire boom that can be used repeatedly to corral pools of oil for burning.
“We have the capacity to burn six times the worst case discharge planning standard,” Moore said.
Burning of the oil leaves a residue that represents 2 to 3 percent of the original oil volume, Edmondson said. That residue would congeal and sink — although it might be possible to capture the residue in nets, research has indicated that the residue would have minimal environmental impact, he said.
“It doesn’t look as if the long-term effects are significant,” Edmondson said.
Edmonson said that Shell would likely use in-situ burning in combination with mechanical oil recovery techniques.
“It gives you an awful lot of immediate disposal of crude prior to addressing the mechanical recovery,” Edmondson said. Workboats with boom might move some oil to a designated area for burning, while other components of the spill response fleet engage in mechanical recovery of oil, he said.
Experienced staffShell also believes that it has assembled an oil spill response team that is fully capable of responding to any incident.
“We’ve been able to tap into a lot of incredibly experienced people, both to design and operate the oil spill response program,” Moore said. “It’s something we’re really proud of.”
Al Allen, a 40-year oil spill response veteran, has been assisting Shell with its oil spill response strategy. Allen was the first manager of Absorb, the organization that later became Alaska Clean Seas, the North Slope oil spill response cooperative.
“So we’ve got an incredible amount of experience that he brought to the table to help design a system,” Moore said.
Shell has contracted with ASRC Energy Services to operate the offshore response arrangements, while Alaska Clean Seas will provide nearshore and shoreline spill response services. ACS also has a large inventory of oil spill response equipment that would become available to Shell in the event of a major incident. And ACS is providing its established techniques and tactics for responding to an oil spill in Arctic conditions.
The ASRC Energy Services team includes managers and supervisors with global and Alaska spill response experience, including experience in ice, Moore said. And about 38 percent of the oil spill response crew will consist of North Slope residents.
“Obviously they bring a lot of traditional knowledge to the table, and a lot experience of being in and around the ice,” Moore said.
In addition, Shell could muster village response teams, the North Slope response team and an auxiliary contractor response team for a sustained response. That would amount to an additional 300 or more people from Alaska, Moore said.
But the traditional knowledge of the North Slope residents is also factoring into some less obvious aspects of Shell’s spill response arrangements — Shell painted the Nanuq blue and white, the color scheme that the North Slope whalers said would minimize the impact on the whales, Fox said.
“That’s what the whalers told us to paint it,” Fox said.