Maritime Innovation In Miniature
Stena DrillMAX
This is a model of Stena DrillMAX, one of the most technologically advanced deep water drill ships in the world, used to explore for oil and gas. Such offshore drilling requires exceptional levels of skill and enormously complex operating systems. Ships like this represent one of the greatest achievements in the history of maritime technology.
Stena DrillMAX was built for Stena Drilling by Samsung Heavy Industries and delivered in 2007, one of a series of four drillships designed to operate efficiently in the harshest environments on earth. To drill, a complex drilling assembly is lowered from the ship to the seabed by screwing sections of drillpipe together to then drill deep down into the earth below. She has a maximum drilling depth of 35,000 ft: just over six and a half miles.
To provide stability for this work and space for the equipment, the vessel is very wide with a breadth of 42 metres. The central mast tower contains a hoisting system to raise and lower the drilling equipment, a highly advanced fully hydraulic system that is unique to Stena drillships. There are two separate well centres, the main, and the auxiliary. The main well has a lifting capacity of 2 million lbs, the auxiliary of 1.2 million. The two well centres optimise efficiency of the drilling process.
Drillpipe is stored in the offset setback area. The bottom of the setback is only 5m above the hull of the vessel ensuring that the racked tubulars do not affect the stability of the vessel when sailing. All drilling operations are carried out through a ‘moon pool’ which allows access to the sea.
Once the well is drilled to a depth where hydrocarbons may be encountered, the Blow Out Preventer is lowered to the seafloor on joints of Riser. It is one of the most important pieces of equipment aboard. The Blow Out Preventer is the ultimate failsafe device, able to seal the well and even cut the drillstring, allowing the ship to move safely away in an emergency. 99 joints of riser are stored aft of the drillfloor, horizontally. They are picked up by the yellow riser gantry crane which lifts them up to the riser skate.
This then feeds the joint into the main well which orientates each from horizontal to vertical before running them through the rotary table. A key challenge when operating in deepwater is that the vessel must remain in exactly the same location above the well, several thousand meters below. The water depth Stena DrillMAX operates in can be up to 3,000 meters, so conventional mooring is not possible.
The solution is a computer-controlled dynamic positioning system formed of six azimuth thrusters underneath the vessel which rotate 360 degrees and constantly respond to shifting sea and weather conditions. The vessel uses three differential GPS systems to triangulate and maintain this position. The vessel is equipped with a variety of cranes and lifting equipment to move tubulars, well construction equipment and supplies from supply vessels which come alongside to support the ship.
Safety is considered in every aspect of this vessel’s design. There are three engine rooms onboard, with two engines in each. The engine rooms are separated into watertight sections, so the vessel can afford to lose an entire engine room and still be able to maintain position. There are six lifeboats four at the bow and two at the stern; as well as thirteen inflatable life rafts, and a fast rescue craft capable of 25 knots. There are two escape tunnels built either side in the hull allowing the crew to move in an emergency unencumbered from one end to the other. All the electrical and electronic systems near the drillfloor are explosion-proof.
There is accommodation for 180 people. The helideck allows for easy crew transfer via helicopter. The immense size of the vessel means that it can carry fuel, water, drilling chemicals and any other consumables on board in great quantities – reducing the amount of supply needed at sea and increasing its operational endurance. The vessel carries more than ten million spare parts to ensure continuous operations in the middle of any ocean in the world.
Able to relocate quickly and easily to any new location and setting new standards for drillship operational efficiency, Stena DrillMAX is an engineering marvel, and represents a key moment in the history of maritime innovation and humanity’s exploitation of fossil fuels.