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doi:10.2204/iodp.proc.302.106.2006

Expedition 302 experiment

As the MSP science operator for IODP, the European Science Operator, led by BGS, conducted Expedition 302. BGS contracted SPRS to provide the two support icebreakers, the Oden and the Sovetskiy Soyuz, fleet and ice management programs, logistics associated with these two vessels, and helicopter services and information technology (IT) for the entire fleet. BGS directly managed contracts associated with provision of the drillship Vidar Viking and drilling services provided by Seacore Ltd. Coring tools were supplied and operated by BGS. SPRS subcontracted ice management to AKAC Inc. because of this company’s ice experience in the Beaufort Sea and the Sakhalin region. The ice management strategy was to collect ice and weather data and combine into a single ice and risk analysis routine. Weather, ice drift predictions (from wind forecasts and ice drift “buoys”), ice maps prepared by hand from each of the ships and helicopter reconnaissance, and Radarsat images were compiled and analyzed by the ice manager. This analysis resulted in an ice alert report to the Fleet Manager that showed ice status with respect to T-time.

The Vidar Viking is a supply/anchor handling icebreaker, classed ICE-10, built in 2000 primarily to enable work in the Baltic Sea. Under Swedish flag, the ship is co-owned by B&N Viking Icebreaking and Offshore AS (Kristiansand, Norway). The Vidar Viking’s size (84 m × 18 m; 3.382 gross tonnage) and in particular its large deck space (603 m² with a large 40.2 m × 15.0 m fantail) made it particularly suitable as the drillship. A moonpool was installed to provide a pass through for the drill pipe midships during drilling operations, and a helicopter deck was installed at the stern. An ice-protective steel “skirt” was lowered in the moonpool while on site to protect the drill string from pieces of ice under the hull of the ship.

The Oden, owned by Svenskt Isbrytarkonsortium KB, is one of seven icebreakers operated by the Swedish Maritime Administration. The Oden, built in 1988, was designed for escort ice-breaking and for Arctic research operations. One of the most capable diesel electric icebreakers in the world (classed as DNV 1A1 and Icebreaker POLAR–20), the Oden has conducted many single-ship expeditions to the Arctic Ocean. The ship’s size (107.8 m × 31 m at its widest beam), scientific laboratory capabilities, and fuel capacity made it ideal for serving multiple capacities in the Expedition 302 fleet. In addition to the primary function, to protect the Vidar Viking during drilling operations, the Oden also served as the communication center for the fleet, was home to the fleet and ice management teams, served as the science center, carried the helicopter fleet, and supplied fuel to the Vidar Viking

The nuclear-powered icebreaker selected for Expedition 302 was the Sovetskiy Soyuz, which is Polar ice–classed and can break ice 2–3 m thick continuously at 3 kt. The ship is large (148 m × 30 m) and can carry more than 200 people. Built in 1989, the Sovetskiy Soyuz is owned by the Russian government and operated by the Murmansk Shipping Co. The Sovetskiy Soyuz had two primary functions: break ice for the fleet to transit quickly to the drill site area and provide the first protection against ice during drilling operations. To enable efficient communications among the icebreaker masters, two members of the ice management team were onboard the Sovetskiy Soyuz during operations.

Prior to meeting the Oden in the port of Tromsø, the Vidar Viking mobilized in Aberdeen (to install the drilling system) and Landskrona (to install the helicopter deck). The Oden conducted much of its mobilization in Göteborg before sailing north to the port of Tromsø. On 7 August 2004, the Oden sailed north from Tromsø, followed by the Vidar Viking on 8 August. The Oden and the Vidar Viking met the Sovetskiy Soyuz at the edge of the polar ice pack on 10 August at 81°30′N. Upon entering the ice pack, the three ships formed a convoy with the Sovetskiy Soyuz leading, followed by the Oden, and then the Vidar Viking (Fig. F3).

The fleet made faster time than expected, transiting to the primary drill site at an average speed of 5 kt. This speed was achieved because of the ice-breaking capability of the Sovetskiy Soyuz, Radarsat ice reconnaissance information, and by following another nuclear icebreaker (Yamal) track part of the way.

Upon arrival on 14 August (2350 h Universal Time Coordinated) at the primary drill site (87°34′N, 138°8.4′E), the ice management team began their first stationkeeping test. The site was covered in >9/10 ice, and the test began after the Oden’s captain gave the order to begin breaking ice. Although the concept for maintaining station had been discussed well in advance, the icebreaker masters were not able to develop the practices in advance. They relied on their experience in icebreaking to develop details first-hand, and after 1.5 days of experimenting with icebreaking directions and patterns, they were able to maintain the Vidar Viking within a watch circle of 50–75 m for drilling to proceed.

During this test it became clear that the drillship had to use manual positioning because the icebreaking could not achieve a clear pool of open water around the Vidar Viking for DP to operate properly. However, because the ice generally moved in one constant direction, the manual positioning primarily required that the officers on watch (two officers were always on watch at any one time) steered the bow so that the ship’s heading stayed in the upstream direction of the ice drift.

Once the stationkeeping test was successfully completed, the Fleet Manager gave the go-ahead for the drillship to begin operations. On 15 August 2004 at 1130 h, drilling operations began (Fig. F4). During the expedition, the time taken by various activities was logged and assigned to the following categories: drilling operations, waiting on ice, transit, and breakdown (Table T1).

Drilling operations, however, did not start with positive results. At the first site (Site M0001), the BHA was lost. The loss was first attributed to excessive vibration but was later linked to an error in applying the appropriate torque to a drill collar. After the loss of the BHA, the piston corer, which was needed to sample the upper ~100 meters below seafloor (mbsf), failed to recover core, and a high-pressure valve on the drill rig’s top drive cracked. After partially overcoming these problems, relatively routine core recovery began on 19 August at Site M0002.

Coring continued in a single hole (Hole M0002A) until 23 August with the drill pipe at a depth of 272 mbsf when the Fleet Manager suspended operations because of excessive ice pressure. After waiting for better ice conditions and rig floor repairs, coring continued on 25 August but was suspended again the next day because the piston core became stuck in the BHA and could not be recovered.

During the break-in drilling operations, the ice management team analyzed the long-term ice forecast using new reconnaissance data and recommended a move to a new site. Drilling operations continued on 28 August after relocating to the new site ~15 nmi away and conducting repairs on the rig floor.

Over the next 9 days, the fleet and ice management teams were able to maintain the position of the drillship over the final site (Site M0004), a record achievement. Drilling operations continued during this time period and were interrupted by drilling problems (some due to freezing equipment) and short periods of time waiting on ice as precautionary measures. Drilling operations officially ended on 5 September 2004. Target depths were achieved with an average 68% core recovery.

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