CN118083057A - Polar region drilling ship with single-point mooring auxiliary power positioning function - Google Patents

Abstract

The invention relates to a polar drilling ship with single-point mooring auxiliary power positioning, which relates to the field of polar drilling ships, wherein a ship body is provided with a round moon pool which penetrates up and down, the radius of the lower half part of the round moon pool is larger than that of the upper half part of the round moon pool, the lower part of the round moon pool is provided with a space for accommodating a pontoon, the bottom of the pontoon is connected with a plurality of anchor chains, and the pontoon can be connected with a bearing with the ship body so as to enable the ship body to rotate around the circle center of the pontoon. Half of the propeller of the dynamic positioning system is replaced by the single-point mooring system, so that half of fuel oil can be saved theoretically compared with the existing dynamic positioning polar drilling ship; the single-point mooring system can automatically optimize the minimum load heading angle through the weathervaning effect, so that the positioning capability of the ship in the polar ice load environment is improved.

Description

Polar region drilling ship with single-point mooring auxiliary power positioning function

Technical Field

The invention relates to the field of ship type of polar drilling vessels, in particular to a polar drilling vessel positioned by single-point mooring auxiliary power.

Background

Arctic oceans possess abundant oil and gas resources, ascertaining oil and gas reserves to be about 13% and 30% worldwide. As sea ice ablates, arctic ocean oil and gas development is becoming increasingly realistic. With the gradual rise of the polar region gas temperature, the polar region environment conditions become milder, and meanwhile, the progress of the ocean engineering equipment technology also provides more possibilities for polar region oil gas resource development, so the polar region oil gas resource development is also gradually focused on worldwide.

The polar region is close to low temperature, ice and snow coverage, fragile ecological environment, difficult logistics replenishment, difficult rescue and the like, and once an accident occurs to a working ship in the polar region sea, serious consequences are very easy to cause, so that the polar region oil and gas resource development needs the support of highly safe and reliable equipment. The polar drilling ship is the most important equipment for polar mineral resource development and oil and gas resource development, and is used as a key link in polar oil and gas development, namely, the support of the polar drilling equipment is not separated from the resource exploration and development. The first polar ice ultra-deep water drilling ship in the world is "Stena DRILLMAX ICE" built by the company Stena in sweden, three stars, korea, which is suitable for PC-4 grade ice and can operate in a low temperature environment of-30 ℃. The drilling ship is provided with a DP 3-level dynamic positioning system and 6 high-power full-rotation propellers, wherein 3 propellers are arranged at the head part of the ship body, and the other 3 propellers are arranged at the tail part of the ship body, so that huge propelling force is provided for the ship, the ship is enough to resist the effect of wind, wave, current and ice load on the polar region, and the ship position is maintained.

The main function of the drilling ship is exploration drilling operation performed on the sea, the exploration drilling operation has very strict requirements on the positioning capability of the ship body, and the drilling operation can be normally performed only if the ship position and the heading of the ship body meet certain requirements. For polar drilling vessels, the positioning requirements are higher than those of traditional drilling vessels, because the polar environment is severe and the ecological environment is fragile, and the polar drilling vessels can cause great loss once accidents occur. In addition, the polar drilling ship is subjected to the effects of ice load besides the conventional environmental loads such as wind, waves and currents, so that the ship body is offset, the stress condition is more complex, and the positioning difficulty is also higher.

Therefore, when the polar drilling ship works, the ship is ensured to keep the ship position right above the wellhead and the horizontal position deviation is controlled, so that the deflection angle of the marine riser between the polar drilling ship and the underwater wellhead is reduced, the drilling operation safety is ensured, and a positioning system with extremely high safety is required to provide positioning capability for the ship. The 'Stena DRILLMAX ICE' polar region drilling ship is characterized in that 6 propellers are continuously distributed to provide restoring force required by positioning for the ship through a DP3 power positioning system, and the positioning mode has the advantages of flexible operation, higher positioning precision, but also has the defects that in the operation process, 6 propellers are required to be continuously operated in all weather, and the oil consumption is higher.

Currently, the positioning modes adopted by floating platforms can be divided into two types, one is the dynamic positioning mode mentioned above, and the other is the anchoring positioning mode. The dynamic positioning means that the thrust and direction of the thruster are regulated to resist the environmental force so as to automatically control the position and heading of the ship. The anchoring positioning is realized by throwing a positioning anchor on the seabed or presetting a positioning pile, connecting the ship with the anchor or the positioning pile on the seabed by utilizing a plurality of anchor chains, pretensioning, and providing restoring force for overcoming the deflection of the ship by the anchor chains. According to the number of the anchor chains fastened on the ship, the anchor chains can be divided into two types of multi-point mooring and single-point mooring. Generally, in the range of 1500 meters, the anchoring positioning system has better economy, and after the water depth exceeds 1500 meters, the use cost of anchoring positioning can be greatly increased. Conventional drillships typically employ dynamic positioning, which provides greater dispatch flexibility for the drillship, such as the aforementioned "Stena DRILLMAX ICE" polar drillship, as well as a few drillships employing moored positioning, which mainly highlights the operational economics of the drillship.

The polar drilling vessel will face different characteristics than conventional drilling vessels operating in non-polar sea areas when operating in polar sea areas. When the traditional drilling ship works in the non-polar sea area, the received environmental load is mainly wind, wave, current and other environmental loads, the wind speed, wave height, flow speed and other environmental factors are usually predictable, and the wind, wave and current environmental loads received by the ship in a plurality of days in the future can be predicted in advance through weather forecast or ocean current monitoring, so that the positioning performance during the operation is evaluated. If the environmental load is too large and exceeds the positioning capability of the drilling ship, avoidance can be performed in advance.

However, in the case of a drilling ship operating in the polar sea, the load applied is not only wind, wave and current load, but also ice load, so that the polar drilling ship faces a large difference. Compared with the predictability of wind, wave and flow loads, the prediction difficulty of the ice load is larger, the probability of encountering a large iceberg or a large ice block suddenly and accidentally is far larger than that of encountering typhoons in the non-polar sea area, and the reaction time of the polar drilling ship is shorter; and secondly, after wind, wave and current loads are superimposed on the ice load, the total load born by the polar drilling ship is higher than that of a conventional drilling ship, the restoring force requirement on a positioning system is higher, and if a dynamic positioning system is adopted, more power and fuel oil are consumed, so that the economical efficiency is poor.

In summary, if the power positioning system is adopted by the polar drilling ship, a large amount of fuel oil is consumed during operation positioning, and if the ice load is large, the ship positioning can be difficult to be performed by the power positioning system; if the anchoring positioning system is adopted, the conventional anchoring positioning system is difficult to release in time to cause collision between the polar drilling ship and the iceberg, so that accidents are caused; even if the anchoring system is released in time, the polar drilling vessel loses positioning capability after the releasing, and drifts everywhere under the ice load effect of the polar sea area, great potential safety hazards exist.

Disclosure of Invention

The purpose of the invention is that: the polar drilling ship with the single-point mooring auxiliary power positioning has economy and flexibility, so that fuel oil is saved, the positioning capacity of the ship in a polar ice load environment is improved, the positioning capacity of the polar drilling ship in the ice load environment is improved by a more economical means, and meanwhile, the polar drilling ship has the capacity of rapidly releasing and avoiding ice mountains.

In order to achieve the above purpose, the technical scheme of the invention provides a polar drilling ship with single-point mooring auxiliary power positioning, wherein a ship body is provided with a round moon pool which penetrates up and down, the radius of the lower half part of the round moon pool is larger than that of the upper half part of the round moon pool, the lower part of the round moon pool is provided with a space for accommodating a pontoon, the bottom of the pontoon is connected with a plurality of anchor chains, and the pontoon can be connected with a bearing with the ship body so that the ship body can rotate around the circle center of the pontoon.

Preferably, the bottom of the ship body is provided with telescopic thrusters around the bottom of the round moon pool.

Preferably, the ship body adopts an icebreaking type bow, and the included angle between the bow appearance and the ice plane is not more than 30 degrees.

Preferably, the circular moon pool is located at the hull centerline of not more than one third of the ship length in the ship length direction from the icebreaking bow.

Preferably, the tail area of the ship body is provided with a pod type full-rotation propeller.

Preferably, the inner wall of the pontoon is an inclined plane, and forms a trumpet-shaped channel after being connected with the round moon pool, and the pontoon can be rapidly released.

Preferably, the pontoon adopts split type design to make it form an annular pontoon through hydraulic locking mechanism, hydraulic locking mechanism releases the time the pontoon can decompose into a plurality of small-size pontoon structure.

Preferably, a derrick is arranged above the round moon pool, the derrick can be used for lowering a marine riser string concentrically arranged with the round moon pool and the pontoon, and the anchor chains are distributed on the periphery of the marine riser string.

Preferably, a drill rod yard and a drill rod catwalk are arranged on one side of the derrick along the ship length direction, and the drill rod catwalk can convey drill rods to the derrick; the derrick is provided with a riser yard, a riser catwalk and a riser gantry crane along the other side of the ship length direction, and the riser catwalk and the riser gantry crane can convey a riser to the derrick.

Preferably, an insulating layer is arranged on the periphery of the derrick.

Compared with the prior power positioning polar drilling ship, the technical scheme provided by the invention has the following technical effects:

The polar drilling ship with single-point mooring auxiliary power positioning can replace a half of a propeller of a power positioning system through a single-point mooring system, and can save half of fuel oil theoretically compared with the existing power positioning polar drilling ship; the single-point mooring system can automatically optimize the minimum load heading angle through the weathervaning effect, so that the positioning capability of the ship in the polar ice load environment is improved; the single point mooring system can increase the positioning restoring force by increasing the diameter of the anchor chain, and compared with the increase of the power of the propeller, the positioning capability of the polar drilling ship in the ice load environment can be improved by a more economical means; the single-point pontoon adopts a split design, so that the single-point pontoon can be smoothly and quickly released under normal working conditions and emergency working conditions, and the safety of the polar drilling ship in the iceberg collision risk is ensured; after the power positioning system is released, the power positioning system can be put into positioning and used under full load again, so that the polar region drilling ship is shifted to avoid icebergs, and the positioning redundancy is better.

Drawings

FIG. 1 is a schematic side view of a polar drilling vessel with single point mooring auxiliary power positioning according to the present invention;

FIG. 2 is a schematic diagram of the working principle of conventional release of a single point mooring auxiliary power positioning polar drilling vessel;

FIG. 3 is a schematic diagram of the working principle of emergency release of the polar drilling vessel positioned by single point mooring auxiliary power;

Fig. 4 is a schematic plan view of a buoy in a single point mooring auxiliary power positioning polar drilling vessel of the present invention.

Reference numerals: 1. an icebreaking bow; 2. a round moon pool; 3. a pontoon; 4. an anchor chain; 5. a bearing; 6. a drill floor; 7. a derrick; 8. a lifting system; 9. blowout preventer; 10. a drill rod storage yard; 11. drill pipe catwalk; 12. a carrying crane; 13. a riser yard; 14. riser catwalk; 15. a riser gantry crane; 16. a heat preservation layer; 17. a front telescopic propeller; 18. a rear telescopic propeller; 19. nacelle type full-rotation propeller; 20. a living building; 21. a helicopter deck; 22. a working room; 23. a crane; 24. an oil testing equipment area; 25. a combustion arm; 26. a nacelle; 27. a fuel tank; 28. a mud cabin; 29. a fresh water cabin; 30. a hydraulic locking mechanism; 31. a first partial pontoon; 32. a first portion of the anchor chain; 33. a second partial pontoon; 34. a second portion of the anchor chain; 35. a third partial pontoon; 36. a third portion of the anchor chain; 37. a riser string.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

The embodiment of the invention discloses a polar drilling ship with single point mooring auxiliary power positioning, and fig. 1 is a side view of the polar drilling ship in an example. According to the requirements of different polar region operation sea areas and operation capacity indexes, the main scale of the polar region drilling ship can be adjusted to be 180-240 meters in ship length, the profile width can be adjusted to be 30-42 meters, the profile depth can be adjusted to be 14-17 meters, the designed displacement can be adjusted to be 5-10 ten thousand tons, the operation water depth of the marine riser is 1000-3000 meters, and the maximum drilling depth is 5000-12000 meters.

As shown in fig. 1, the polar drilling ship adopts an ice breaking type bow 1, the ice breaking type bow 1 has a reversed concave shape, an included angle between the ice breaking type bow 1 and an ice plane is not more than 30 degrees, and when the polar drilling ship moves from the bow to the polar drilling ship, the ice breaking type bow 1 can break ice cubes and then discharge the ice cubes to two sides of the ship so as to ensure a good ice breaking effect.

A circular moon pool 2 is arranged at the position which is not more than one third of the ship length away from the bow 1 of the icebreaking ship, and the circular moon pool 2 penetrates through the deck and the bottom of the ship and is connected with the bottom sea water. The round moon pool 2 is of a variable cross section, the radius of the upper half part is not smaller than 5m, and the radius of the lower half part is larger than that of the upper half part. The lower part of the round moon pool 2 can accommodate a circular pontoon 3, the inside of the pontoon 3 is provided with a cavity, and the sinking and floating of the pontoon 3 can be controlled by discharging or discharging seawater into the cavity inside the pontoon 3. The bottom of the pontoon 3 is connected with a plurality of anchor chains 4, the anchor chains 4 can be fixed on the seabed by means of anchoring or positioning piles, and the anchor chains 4 apply a pretension obliquely downwards to the pontoon 3.

When the pontoon 3 is installed, seawater is firstly discharged into the cavity inside the pontoon 3, and the pontoon 3 will sink under the pretension of the anchor chain 4. Then when the polar drilling vessel is positioned right above the pontoon 3, the pontoon 3 is embedded into the lower half part of the circular moon pool 2 under the buoyancy by discharging the seawater in the pontoon 3. The inner wall of the pontoon 3 is an inclined plane, and forms a flared channel after being connected with the round moon pool 2. After the pontoon 3 is in place, the pontoon 3 is fixed through the hydraulic locking device and the bearing 5 on the polar drilling vessel, the load of the pontoon 3 after locking can be transferred to the ship body through the bearing, and the relative rotation movement around the concentric axis can be generated between the pontoon 3 and the polar drilling vessel, namely the ship body can rotate around the circle center of the pontoon 3, thereby forming a single-point mooring system with 'wind vane effect'. When the pontoon 3 is released, the reverse operation of the above operation is performed.

A drill floor 6 and a derrick 7 are arranged right above the round moon pool 2, and the center of the derrick 7 is overlapped with the center of the round moon pool 2 and the pontoon 3 in the vertical direction. The lifting system 8 is arranged at the top of the derrick 7, and pipe column connection can be carried out in the derrick 7 through the lifting system 8, so that underwater operation equipment such as a blowout preventer 9 is lowered to the underwater and the seabed through the internal channels of the round moon pool 2 and the pontoon 3, and underwater drilling operation is carried out. The drill floor 6 mainly provides a base and working operation space for the derrick 7.

And a drill rod yard 10 and a drill rod catwalk 11 are arranged on one side of the derrick 7 along the ship length direction, the drill rod yard 10 mainly provides a loading space for drill rods, when the drill rods are required to be supplemented in drilling operation, the drill rods are conveyed in the derrick 7 through the drill rod catwalk 11, and after the drill rods are well connected in the derrick 7, the drill rods continue to drill downwards. On the other side of the derrick 7 in the ship length direction, there are arranged a storage area of the blowout preventer 9 and a handling hoist 12 of the blowout preventer 9, the handling hoist 12 being capable of handling the blowout preventer 9 between its storage area and the wellhead. The recovery of the drill pipe yard 10 would require the reverse of the above operation.

On one side of the transfer crane 12 along the captain, a riser yard 13, a riser catwalk 14, and a riser gantry 15 are arranged. When the drilling operation needs to supplement the marine riser, the marine riser gantry crane 15 uses the mechanical arm to extend downwards to the marine riser storage yard 13, picks up 1 marine riser from two ends and then places the marine riser on the marine riser catwalk 14, uses the sliding function of the marine riser catwalk 14 to convey the marine riser into the derrick 7, and continues to drill after the connection pipe is completed. Recovery of the riser yard 13 will require the reverse of the above operation.

The above-mentioned drill floor 6, derrick 7, lifting system 8, blowout preventer 9, drill pipe yard 10, drill pipe catwalk 11, handling hoist 12 of blowout preventer 9, riser yard 13, riser catwalk 14 and riser gantry 15 constitute the main parts of the polar drilling system. And the heat preservation layer 16 of the polar drilling system is arranged, and the heat preservation layer 16 can cover the polar drilling system and reserve enough space for material transportation. The heat-insulating layer 16 adopts a sandwich structure of steel structure, aluminum plate and heat-insulating material, and the heat-insulating material has good heat-insulating property, and can be one of rock wool, foam glass, polystyrene or vinyl polyurethane. Under the heat insulation effect of the heat preservation layer 16, the temperature rise of the internal temperature is not less than 20 ℃ compared with the temperature rise of the polar open environment, so that the internal operation space of the drilling ship is still kept at a more comfortable operation temperature under the polar low-temperature environment.

3 Nacelle type full-rotation propellers 19 are arranged at the tail of the ship body, and the nacelle type full-rotation propellers 19 can be used for power positioning and ice breaking navigation. The front part of the pontoon 3 is provided with 1 front telescopic propeller 17, the rear part of the pontoon 3 is provided with 2 rear telescopic propellers 18, and the 3 front telescopic propellers 17 and the rear telescopic propellers 18 are arranged in a shape of a Chinese character 'pin'. Under the sailing working condition, the front telescopic propeller 17 and the rear telescopic propeller 18 can be recycled to the inside of the main hull, the bottom of the ship is not exposed, and the sailing resistance is reduced; when the single-point mooring system auxiliary power positioning system works, the front telescopic propeller 17 and the rear telescopic propeller 18 are retracted into the main hull, so that the front telescopic propeller 17 and the rear telescopic propeller 18 are prevented from being scratched by the anchor chain 4; after the pontoon 3 is released, the front telescopic propeller 17 and the rear telescopic propeller 18 extend out of the main ship body and are matched with the 3 nacelle type full-rotation propeller 19 at the tail part to position the polar drilling ship.

A living building 20 is arranged at the bow position of the polar drilling ship, a comfortable living environment is mainly provided for operators in a polar low-temperature environment, a passage is arranged at the tail part of the living building 20, and the operators can enter a drilling operation area through a door on the heat preservation layer 16. A helicopter deck 21 is provided obliquely above the living building 20 for personnel transportation or replenishment in polar sea operation.

On one side of the insulation 16 in the direction of the ship's length, a working room 22 is arranged, which working room 22 is equipped with an insulation 16 similar to a drilling system, mainly providing a comfortable working space for drilling auxiliary operations. 2 cranes 23 are provided to provide handling for the workplace 22 and deck material transport. The tail of the polar drilling ship is provided with a tail oil testing equipment area 24, an insulating layer 16 similar to a drilling system is arranged on the periphery of the tail oil testing equipment area, and a carrying space is provided for oil testing equipment when oil testing operation is carried out in the polar sea area. In the oil test process, the generated combustible gas is combusted through the tail combustion arm 25, the combustion arm 25 can be suspended outside the ship through the selecting mechanism during operation, the influence of combustion heat on the polar drilling ship is reduced, and the combustion arm 25 is rotated and recovered until the ship body transversely rests at the tail of the ship when not in operation.

The main hull afterbody is equipped with cabin 26, and cabin 26 divides into 3 regions through fire prevention and watertight bulkhead, and 6 diesel generating set average distribution is in 3 regions, and the single region of cabin 26 is on fire or is soaked, still can guarantee the diesel generating set normal work of 2 other regions, guarantees the power redundancy, satisfies DP-3 power location ability requirement. The nacelle 26 is provided with a fuel tank 27 along one side of the captain for fueling the diesel generator set. A mud pod 28 is provided alongside the circular moon pool 2 for delivering drilling mud to a riser string 37 in the region of the circular moon pool 2 for drilling operations. A fresh water cabin 29 is arranged in the main hull below the living building 20 to provide living water and drinking water for the cabin in the living building 20.

Fig. 2 illustrates the working principle of conventional release. When the polar drilling vessel monitors the movement of the iceberg to the polar drilling vessel, the polar drilling vessel needs to recover the subsea equipment blowout preventer 9 to the deck through the riser string 37, and the buoy 3 is lowered under the gravity of the anchor chain 4 after loading the seawater. When the top of the pontoon 3 is sunk below the front telescopic propeller 17 and the rear telescopic propeller 18, the power positioning system shifts the polar drilling ship to other places, so that the collision of icebergs is avoided, and the safety of the ship is ensured. And after the safety is achieved, the tie-back is carried out again.

Fig. 3 shows the working principle of emergency release. When the polar drilling vessel monitors that the iceberg moves to the polar drilling vessel at a faster speed, the polar drilling vessel does not return the subsea equipment blowout preventer 9 to the deck as much as it is, and the tripping of the buoy 3 and the anchor chain 4 needs to be performed in a state where the subsea equipment blowout preventer 9 is suspended. As shown in fig. 4, the pontoon 3 is designed in a three-split manner, and the pontoon 3 is locked into a ring-shaped pontoon by a hydraulic locking mechanism 30. First, according to the conventional tripping process, the pontoon 3 is submerged below the front telescopic propeller 17 and the rear telescopic propeller 18, and the hydraulic locking mechanism 30 is released, so that the pontoon 3 is separated into a first partial pontoon 31 and a first partial anchor chain 34, a second partial pontoon 33 and a first partial anchor chain 34, and a third partial pontoon 35 and a third partial anchor chain 36, thereby tripping the riser string 37 from the pontoon 3, and finally completing the emergency tripping.

The invention adopts the auxiliary power positioning system of the single-point mooring system, namely, adopts two positioning modes of single-point mooring and power positioning on a polar drilling vessel to provide positioning capability for the vessel, has the economy of the single-point mooring positioning system and the flexibility of the power positioning system, and meets the requirements of polar drilling operation. The single-point mooring system has a quick release function, when the iceberg collision risk is met, the release can be quickly carried out, and the polar drilling ship is avoided through the dynamic positioning system; during normal operation, the single-point mooring system can replace a half-power positioning system propeller to achieve the purpose of saving oil consumption, and meanwhile, the single-point system and an accessory anchor chain 4 system of the single-point system do not influence the operation of underwater equipment such as a drilling riser, a blowout preventer 9 and the like, so that the safety of a ship drilling ship and the underwater equipment of the ship drilling ship is not influenced under the two modes of normal operation and emergency release of the single-point mooring system. Through implementation of the scheme, under the auxiliary action of the single-point mooring system, the polar drilling ship dynamic positioning system can have better positioning performance in the ice load environment with complex polar sea areas, and meanwhile, compared with the traditional non-auxiliary dynamic positioning system, the polar drilling ship dynamic positioning system has more oil consumption saving effect.

Through the implementation of the invention, the single-point mooring system on the polar drilling vessel can replace the action of a half of the propeller of the dynamic positioning system, thereby greatly reducing the oil consumption level of the dynamic positioning system; the single-point mooring system can exert the 'weathervaning effect', and can help the ship body to find the minimum load bow angle on the premise of ensuring safety, thereby helping the ship to have better positioning performance under the condition of extremely complex ice load; the single-point mooring system is used as an auxiliary system of the dynamic positioning system, the targets of better positioning capability and lower oil consumption can be realized in normal operation, and meanwhile, the single-point mooring system and the dynamic positioning system are mutually standby, so that the redundancy of the positioning system of the polar region drilling ship can be improved.

Finally, it should be noted that: the foregoing description of the preferred embodiments of the present invention is not intended to be limiting, but rather, although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described, or equivalents may be substituted for elements thereof, and any modifications, equivalents, improvements or changes may be made without departing from the spirit and principles of the present invention.

Claims (10)

1. The utility model provides a polar region drilling ship of auxiliary power location of single-point mooring, its characterized in that, the hull is equipped with circular moon pool (2) about link up, the latter half radius of circular moon pool (2) is greater than the latter half radius, circular moon pool (2) lower part is equipped with the space that holds flotation pontoon (3), flotation pontoon (3) bottom is connected with a plurality of anchor chains (4), flotation pontoon (3) can with hull connection has bearing (5), so that the hull can wind the centre of a circle of flotation pontoon (3) makes rotary motion.

2. A polar drilling vessel with single point mooring assisted dynamic positioning according to claim 1, characterized in that the hull bottom is provided with telescopic thrusters around the bottom of the round moon pool (2).

3. A polar drilling vessel with single point mooring assisted dynamic positioning according to claim 2, characterized in that the hull employs an icebreaking bow (1) with a bow profile not exceeding 30 ° from the ice level.

4. A polar drilling vessel with single point mooring assisted dynamic positioning according to claim 3, characterized in that the circular moon pool (2) is located at the hull centre line of not more than one third of the ship's length in the ship's length direction from the ice breaking bow (1).

5. A single point moored auxiliary power positioned polar drilling vessel as defined in claim 4 wherein the hull aft region is provided with pod full swing thrusters (19).

6. The polar drilling vessel with single point mooring auxiliary power positioning according to claim 5, wherein the inner wall of the pontoon (3) is an inclined plane, and forms a trumpet-shaped channel after being connected with the round moon pool (2).

7. The polar drilling vessel with single point mooring auxiliary power positioning according to claim 6, wherein the pontoon (3) is of split design and is formed into an annular pontoon by a hydraulic locking mechanism (30), and the pontoon (3) can be separated into a plurality of small pontoon structures when the hydraulic locking mechanism (30) is released.

8. The polar drilling vessel with single point mooring auxiliary power positioning according to claim 1, wherein a derrick (7) is arranged above the round moon pool (2), the derrick (7) can be used for lowering a marine riser string (37) which is concentrically arranged with the round moon pool (2) and the pontoon (3), and the anchor chains (4) are distributed on the periphery of the marine riser string (37).

9. The polar drilling vessel with single point mooring auxiliary power positioning according to claim 8, wherein a drill pipe yard (10) and a drill pipe catwalk (11) are arranged on one side of the derrick (7) along the ship length direction, and the drill pipe catwalk (11) can convey drill pipes to the derrick (7); the derrick (7) is provided with a riser yard (13), a riser catwalk (14) and a riser gantry (15) along the other side of the ship length direction, and the riser catwalk (14) and the riser gantry (15) can convey a riser to the derrick (7).

10. The polar drilling vessel with single point mooring auxiliary power positioning according to claim 9, wherein the derrick (7) is peripherally provided with an insulation layer (16).