ConocoPhillips is moving ahead with plans for exploration drilling in Alaska’s Chukchi Sea in the summer of 2014, Mike Faust, the company’s Chukchi Sea exploration project manager, told the National Marine Fisheries Service’s annual Arctic Open Water Meeting on March 7.
“Our goal is to drill one well,” Faust said, adding that, although it might be possible to drill two wells during the summer open water season, the drilling of one well would meet the company’s expectations.
ConocoPhillips’ drilling target is its Devil’s Paw prospect, a 200,000-acre structure about 120 miles west of the coastal village of Wainwright. Devil’s Paw was previously penetrated by the Klondike well, drilled by Shell in 1989. And although that well did not encounter commercial quantities of oil and gas, ConocoPhillips clearly views the prospect as holding promise for a major oil find — the Devil’s Paw feature is similar in size to the huge Kuparuk River field in the central North Slope, Faust said.
Jack-up rigFaust said that ConocoPhillips is contracting a brand-new, state-of-the-art jack-up rig from Noble Corp. for the drilling.
“They’re building six of them and we’re getting one of the rigs fresh out of the yard,” Faust said. “We’re not going to bring up a 30-year-old piece of equipment. We’re bringing up state-of-the art new stuff that is meant to work in the Arctic.”
The rig will have the latest features for safety and environmental protection, he said.
A jack-up rig is a floating structure that is towed into position at a drilling site, where tall legs are lowered into the water to the seafloor to lift the rig’s drilling platform above the sea surface, thus creating a rigid, fixed structure from which to drill. And because the bulk of the structure is above the water, the drilling operation transmits less sound into the sea than a similar operation in a floating drillship, Faust explained.
The new rig will be extremely strong; it is designed for use in the North Sea where wave heights can be significantly higher than anything seen in the Chukchi Sea, with the drilling platform typically 40 to 60 feet above the water, Faust said. And, while the rig is designed for use in water depths of 400 to 500 feet, the water at the Devil’s Paw drilling location will only be about 140 feet deep, he said.
One advantage of using a fixed jack-up platform for the drilling will be the ability to install a strong, heavy-duty steel riser pipe from the seafloor to the platform, rather than the more flexible type of pipe required for a floating drilling structure, Faust said. And that, in turn, enables the placement of the well’s blowout preventer on the platform, where it can be accessed easily, rather than in a mud-line well cellar on the seafloor.
As a further line of defense against a well blowout, should the surface blowout preventer fail, ConocoPhillips is placing a well capping device on the seafloor, to close off the well if necessary.
“That cap is in place before we start drilling the well and we drill through that,” Faust said.
Accommodating sea iceThe rig is not designed to operate in sea-ice conditions. But, although ConocoPhillips will use the rig at a time of year when sea at the drilling site should be clear of ice, there is the ever-present possibility of an unfavorable wind blowing ice floes into the area of the drilling operation.
To allow for the possibility of a threat from ice encroachment, ConocoPhillips has developed an ice alerts program, using satellite synthetic radar data showing sea-ice images that enable the plotting of sea-ice movements. This type of satellite technology can see through cloud, works in the darkness and images ice very effectively, Faust said.
Ice-alert circlesEssentially, the drilling team will plot three concentric ice-alert circles around the drilling location. Ice management vessels will investigate any ice that enters the outermost circle, about 50 kilometers from the drilling rig. If ice crosses the middle circle, no new drilling operations will start and the rig crew will begin preparations for a possible move from the drilling site. Once ice enters the inner circle, drilling operations will stop, the rig will jack down into the water and support vessels will tow the rig to safety, well away from the ice.
If the jack-up rig has to move off site, the well would be comprehensively sealed at the sea floor and the riser pipe removed, Faust told Petroleum News.
The diameters of the ice-alert circles may vary from day-to-day, and even within a day, depending on the observed speed of ice movement and the nature of the drilling operation being conducted — the longer the anticipated time taken to finish an operation, jack the rig down and tow it from the site, the larger the circles become.
If uninterrupted, the complete drilling of a single well, from rig-up to rig-down, should take about 40 days, 30 days of which would involve the actual drilling operations, Faust said. So, with the Chukchi Sea open water season lasting on average 100 to 120 days, there should be more than enough time to drill one well, with the possibility of a second well, he said.
Heavy-lift vesselConocoPhillips will use a heavy-lift vessel to transport the drilling rig from Singapore, hopefully all the way to the Chukchi Sea drilling site, Faust said. However, given the vagaries of the ice conditions, it may be necessary to stage the rig near the coast to the south, with tugs towing the rig into position once the ice has cleared, he said.
According to a Federal Register notice for an application for a marine mammal incidental harassment authorization that ConocoPhillips has submitted to the National Marine Fisheries Service vessels involved in the drilling operation will not arrive at the drill site until July 1 at the earliest, with drilling operations potentially taking place between July and October. A heavy-lift vessel will remove the jack-up rig from the drilling arena at the end of the drilling season, the notice says.
Staging locationThe Federal Register notice also says that the location where ConocoPhillips may stage the drilling rig at the beginning of the drilling season, should ice conditions prevent the heavy-lift vessel delivering the rig all the way to the Chukchi Sea drilling site, is six miles offshore the Chukchi Sea coast, about 20 miles south of the village of Kivalina.
This choice of staging area location was based on proximity to infrastructure and the likelihood of ice-free conditions at the time when staging might be required, the notice says.
It became evident during the open water meeting that some Kivalina residents, presumably concerned about potential disturbance to subsistence hunting, are less than enthusiastic about the idea of having a jack-up rig parked near their village.
“We’re certainly listening to that and tying that into our plans as much as we can,” Faust said, commenting that, depending on ice conditions, one option might be to keep the rig on the heavy-lift vessel, rather than stage it.
Support fleetConocoPhillips anticipates needing nine vessels to support the drilling operation, with three vessels providing oil spill response support and the other vessels performing multiple roles, Faust said. Other than when used for shipping supplies, the support vessels will remain within five-an-a-half miles of the drilling rig, he said.
Wainwright will act as a supply base for the operation, with personnel being transferred to and from the offshore by helicopter, and with a landing craft carrying perishable supplies to a supply vessel. After hearing worries about possible noise and disturbance in Wainwright, ConocoPhillips has built a road to an out-of-town helipad and is in discussion with people from the community about appropriate helicopter routes, Faust said. And, to minimize the number of crew changes required, the company is using a drilling rig with large crew quarters, he said.
Faust said that in working with local North Slope communities ConocoPhillips has been addressing concerns and taking advice based on traditional knowledge.
“Over the past four years the plan has changed pretty significantly, in many ways because of the feedback we’ve gotten in the communities and the kinds of observation that the hunters and whalers have told us about,” Faust said.