Living and Drilling at Cape Roberts
Travelling to Cape Roberts
Much of the equipment has been brought to Cape Roberts across the sea ice. Cargo trains are made up of the various sledges towing the equipment. A bulldozer will keep up front of the traveling cargo train and mark the route by flags every 100 metres keeping it clear and in good condition.
The cargo trains move along the sea ice very slowly but efficiently, using little fuel. Personnel (people) travel by Hagglunds taking 10 hours or by helicopter which only takes 50 minutes!
Fast Ice
(Pack ice on the other hand, floats and moves freely on the sea.)
Fast ice thickness
The thickness of fast ice in the southwestern Ross Sea varies from year to year.
Cold calm winters result in thicker ice because it is able to freeze without being disturbed by turbulent seas or winds. Relatively warm or windy winters means newly formed ice may break out several times before becoming fast and thickening.
The ice will be drilled and tested by the first team at the end of August when the first flights go down to Antarctica. They will decide whether it is thick enough or not for drilling to go ahead for the season. The fast ice needs to be somewhere between 1.5 - 2 metres thick to support the drilling rig.
Because the camp and drill rig are to be located on annual fast ice, all buildings including the drilling rig must be designed for rapid pull down and movement in case ice conditions deteriorate unexpectedly.
The Drill Sites
Three holes will be drilled from the 1.5 - 2 metre thick fast ice, in water 150 - 500 m deep and up to a depth of 700 metres. Originally it was planned to drill 4 holes.
Drilling will take place in 1996 and 1997, over a 40 day period beginning in early October.
By spring the sea ice should be thick enough to support the 55 tonnes of drilling rig and equipment.
The location of the site for drilling has been carefully thought about.
The following factors had to be taken into account:
The main Cape Roberts camp will be on fast sea ice close to Cape Roberts. This camp will be built to cater for up to 36 people.
Drill site camp
The camp at the drill site and the drilling system itself are designed so they can be moved within 48 hours. While it is considered very unlikely, it is conceivable that unusually warm conditions combined with a southerly storm could cause the fast ice to deteriorate, break up (especially near the margins) and drift off.
Inability to move quickly would result in loss of equipment (and very likely the project) and risk human life where they might want to rescue material under difficult conditions.
In addition, the limited drilling season make it important that the move from one site to another be carried out in minimum time.
Workers will live at the Support Camp and be transported by helicopter to the drill site each day for their 12 hour shift.
Buildings at the Drill Site
At the drill site there will be fourteen buildings:
The Drilling Platform
The drilling rig is sledged to its location and a hole 1 metre across is cut with a chainsaw in the ice. Through this hole is lowered the sea riser system which is cemented into the sea floor. Inside the sea riser is lowered a casing which is rotated into the sea floor about 20m and also cemented in.
The weight of the drilling rig and rod is supported by the sea ice. To reduce this weight, floats are attached to the casing to make it buoyant.
At the end of the drilling rod is a diamond drilling bit that bites into the rock.
Mud!
To make it easier to get the rock core out and to make the actual drilling work better a special mud is used Not just any mud but potassium chloride (KCl). The mud arrives at Cape Roberts in bags. It is mixed with water and some other chemicals and pumped down the drilling rod. The mud returns up the outside of the rod (inside the casing) along with the bits of solid from the drill bit.
The mud is filtered, monitored and other chemicals added depending on the needs at the time. For example ground walnut shells, baking soda and mica can be added to change the properties of the mud.
If the drilling rod strikes a pocket of hydrocarbons under pressure, the mud can be used to prevent the gas from escaping to the surface.
It is thought very unlikely that any hydrocarbons will be found as the rock strata is such that any hydrocarbons are likely to have been released long ago.
Use the following resources:
F
LEARNZ BLM 13, BLM 14, BLM 15, BLM 16 Cape Roberts person profilesF
LEARNZ BLM 17 Photos of Cape RobertsF
LEARNZ BLM 20 Sketch of Cape RobertsF
LEARNZ BLM 21 Cape Roberts Glossaryhttp://www.icair.iac.org.nz/science/roberts/