Check out the technology behind the ANDRILL drill rig and how the ANDRILL team will drill through the ice shelf and down to the sediment at the sea floor.
The ANDRILL drilling system is based around a drilling rig constructed by UDR in Brisbane. This type of rig is commonly used in minerals drilling, but has been customized for ANDRILL scientific requirements and for Antarctic conditions.
- Reconfiguration of the main winch for a double line pull to deploy sea riser casing, which weighs up to 30 tons.
- Tide compensation to allow for up to 1.5 meters of vertical tidal movement of the ice shelf or sea-ce platform.
- Enclosure to provide a warm environment for workers and equipment on the drill floor.
- Separation of the rig hydraulic power pack (in an insulated container) and the drill mast and winches to provide the best heated location.
The entire system can be broken down into components allowing transport on sledges. The rig components can be airlifted. Some parts of the system, such as the drill platform and catwalk, have been designed and fabricated to incorporate sledge bases for ease of transportation across snow and ice.
Aside from the drill rig itself, other components of the drilling system include:
The drill platform, which supports and encloses the drill rig, and provides the location for the tide compensation system and the hot water drilling system.
The catwalk sledge & rod ramp, which provide the staging area for the sea riser and drill pipe as they go into and come out of the hole, and also where the core is first taken out of the core barrel.
The drill fluids (mud) system, which provides a fluid for cooling the drill bit and lifting drill cuttings from the base of the hole. Cuttings are removed from the fluid using a centrifuge and other systems, so that the cleaned fluid can be reused.
The cementing system, which can supply cement to anchor the sea riser to the sea floor, case the hole, to plug off the hole at the completion of drilling.
Power supply, which is in two parts: (1) the hydraulic systems, which supply the drill rig, and (2) the electrical system (two generators) supplying the drill fluids and other ancillary systems.
Hot Water Drilling system, which will make a hole through approximately 100 meters of shelf ice, and keep the hole open around the sea riser pipe to prevent any pressure from the ice shelf.
The drill platform
The jack-up drill platform was designed by Opus (Christchurch) and constructed by Goughs Engineering in Christchurch. The base of the platform is a 13-meter long sledge that can be towed across snow and ice in Antarctica. The platform jacks up three metres to allow space for tidal movement of the ice when the drill pipe is connected to the sea floor.
The catwalk sledge & rod ramp
Pegasus Engineering in Christchurch fabricated the Catwalk sledge and Rod Ramp. The catwalk sledge is 12.5 meters long. The rod ramp can be hauled into its location between the drill rig floor and the catwalk by using the winches on the drill rig. The catwalk and rod ramp can accommodate 3, 6 or 9-meter lengths of pipe.
Drill fluids (mud) system
Webster Drilling & Exploration of Porirua, New Zealand, refurbished equipment from the Cape Roberts Project (CRP) and incorporated new components to provide an improved system for the circulation of drilling fluids. The system incorporates a new sea water heating tank, four refurbished CRP mud tanks, a refurbished mud mixing "gun", two refurbished centrifugal pumps and drill cuttings removal equipment consisting of a new de-sander/de-silter cone(s) pump and the refurbished CRP centrifuge. The entire system is based on the use of sea water and environmentally acceptable additives to provide a fluid of a suitable viscosity and weight. Once cuttings have been removed, the 'mud' is returned to the system for reuse.
The fluid is pumped to the drill rig from the drill fluids system, which is housed in three ISO containers that are linked to the catwalk sledge. Waste heat from the boilers is ducted to the other parts of the system.
The cementing system
The cementing system is housed in a container adjacent to the catwalk along with some of the drill fluids equipment, and was also refurbished/built by Webster Drilling & Exploration. It incorporates a palletized batch cementing system consisting of cement mixing tank, hydraulic mixer and cement pump, and an electric/hydraulic power pack (reassembled from CRP hydraulic components) to power the cement system and mud tank agitators. The cement system can mix a batch of 6-700 liters of cement.
The power supply
The 315 horsepower hydraulic power pack for the Drilling Rig is housed in a container which sits next to the platform and is connected via several hydraulic hoses to the rig. The drillsite also has two generators for supply to the drill fluids and other auxillary systems. These have a combined capacity of 175kVA.
The Hot Water Drilling system
The Hot Water Drill system was designed and built in New Zealand, with hoses supplied by IVG in Italy, and consists of several major components:
- an initial surface water supply (melted snow on site);
- boilers to heat the low pressure primary heating circuit;
- a secondary high pressure circuit with heat exchangers and high pressure pump suitable for heated sea water;
- a high pressure pump suitable for heated water;
- a submersible pump for water recirculation; and
- flexible hoses, winches and jetting tools.
The Hot Water Drill System uses a succession of progressively larger tools to make the hole through the ice shelf. The first tool (the pilot lance) jets water down through a small nozzle, making a hole approximately 100 mm in diameter. The second tool is the reaming lance, which shoots water back up the hole to ream the hole out to as much as 600 mm as it is lowered. The third tool is the ring reamer, which can jet water upwards or downwards, or recirculate hot fluid inside the tool. The ring reamer is designed to keep the hole open while drilling is going on, and can run up and down the hole melting ice while the sea riser is in place.
The ropes and hoses are on winches controlled by a specially designed electronic system, which can control speed and monitor load changes on the tools.
- Mast height on Jack-up Platform: 20 meters
- 9 meter drill rod pull capacity
- Weight of drill rig and platform: 40 tons (total system weight: 90 tons)
- 315 horsepower diesel motor to power hydraulics
- Main winch capacity: 30 tons (double-line pull)
- Top Head Drive pull out capacity: 23 tons
- Core sizes: 83 mm, 61 mm & 45 mm diameter
- Drilling depth: to approx. 2000 meters
- Total cost of drilling system including drill pipe and ancillary equipment: approximately USD $3 million
- Drill site electrical generation capacity: two generators totaling 175 KVA
The drill rig and ancillary systems were tested on land in New Zealand in September-October 2005. This was followed by modifications and completion in Christchurch before shipping to Antarctica in January 2006.
The Hot Water Drill was tested on the McMurdo Ice Shelf in February 2006 and drilled through 97 m of ice creating a hole greater than 600 mm diameter.
New Zealand Expertise
The international scientific leaders of ANDRILL chose Antarctica New Zealand to be the Project Operator because of New Zealand experience in Antarctic drilling projects over the last 35 years. Expertise from Victoria University of Wellington and Webster Drilling & Exploration are contracted by Antarctica New Zealand to develop, test and operate the drilling system.
New Zealand has been involved with scientific drilling in Antarctica for over 35 years, and the selection of Antarctica New Zealand reflects the New Zealand expertise in the field. The most recent project was the Cape Roberts Project (CRP), which ran from 1995 to 2000, and involved scientists from Germany, Italy, The Netherlands, New Zealand, the UK and USA. CRP yielded exciting research results that expanded our understanding of climate history of the Antarctic ice sheet.
Earlier drilling projects included:
- Dry Valley Drilling Project (DVDP) (1972-75)
- McMurdo Sound Sediment and Tectonic Studies (MSSTS) (1979)
- Cenozoic Investigations in the Western Ross Sea (CIROS) (1984-86)
- Cape Roberts Project (CRP) (1995-2000)
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