KR20130139931A - Ice worthy jack-up drilling unit - Google Patents

Abstract

The present invention relates to a jack up rig suitable for ice that can extend the excavation season in shallow water polar seas or ice-prone positions. The rig according to the invention will work like a normal jack up rig when the hull is jacked out of the water in the open ice. However, in the presence of ice, the legs are held in place by cans embedded in the seabed to resist lateral movement of the rig, and the hull descends into the water to form an ice defense structure. The hull is specially shaped to have an ice bending surface for deflecting and crushing the ice that comes into contact with the hull when in the ice defense structure.

Description

ICE WORTHY JACK-UP DRILLING UNIT}

FIELD OF THE INVENTION The present invention relates to mobile offshore rigs called "jack-up" rigs or rigs, typically used in shallow water of less than 400 feet, for example, for drilling hydrocarbons. .

In the endless exploration of hydrocarbons, many oil and gas reservoirs have been discovered over the last one hundred fifty years. Many technologies have been developed to find new leisure and resources, and most of the world is scoured for new discoveries. A large amount of resources that have not yet been discovered remain in easy-to-access places and residential areas and are unlikely to be discovered in the future. Instead, new large stockpiles are being found in hard-to-reach areas.

One promising area is the polar ocean. However, the polar regions are distant and cold, where ice on the water causes considerable difficulties in drilling and producing hydrocarbons. Over the years, in general, it was considered that six unprofitable rigs had to be excavated in order to find one profitable well. If this is actually the case, we must hope that the cost of drilling an unprofitable drilling well is not expensive. However, in the polar regions, there are few cheap ones.

Currently, in shallow waters of cold regions, such as polar regions, jack-up or mobile marine rigs (MODUs) can be used for about 45 to 90 days in the summer season in a short open state. Predicting when the excavation season begins and ends is a game of luck, and determining when it can safely tow jack-up to the excavation position and initiate excavation involves a lot of effort. Once excavation commences, there is considerable urgency to complete the excavation well to avoid having to separate and withdraw if ice suddenly emerges. Even during the few weeks of open ice, ice floes pose a serious risk to jack-up excavation rigs when the excavation rig is on site and the legs of the jack-up excavation rig are exposed and very susceptible to damage.

Jack-up rigs are mobile self-lifting offshore drilling and rehabilitation platforms equipped with legs configured to descend to the bottom of the sea and then lift the hull out of the water. Typically, jack-up rigs include excavation and / or repair equipment, leg-jacking systems, crew quarters, unloading facilities, storage areas for large quantities of material and liquid materials, helicopter marinas and other related facilities. Includes equipment.

Jack-up rigs are designed to be pulled up to the excavation point and jacked up out of the water, whereby the sea wave affects only the legs with a fairly small cross-sectional area, so that the sea wave moves largely with respect to the jack-up rig. Allow it to pass without giving. However, the legs of the jack-up league have little protection against colliding collisions, and a significant size of ice can cause structural damage to one or more legs and / or push the rig out of position. If this type of event occurs before the excavation operation is interrupted and the excavation well is adequately secured, there is a potential for hydrocarbon leakage. For regulators and the public, this type of risk can never be tolerated in the oil and gas industry.

Therefore, if you decide to dig a potentially lucrative drilling well during this short season, you will need to carry a very large gravity-based production system or similar structure to provide a long process for drilling and producing hydrocarbons. Can be installed. These gravity-based structures are very large and very expensive, but are built to withstand ice year-round.

In particular, the present invention relates to a jack-up rig comprising a floating hull with a relatively flat deck on top, which is suitable for ice for drilling hydrocarbons in potentially iced environments in marine areas. The floating hull is formed along its lower portion and extends around the periphery of the hull, with ice bending shapes extending from the hull region near the deck height and extending downward near the bottom of the hull. It further includes an ice deflecting portion extending around the periphery of the bottom of the hull to guide it around the hull and not below the hull. The rig includes at least three legs disposed within the periphery of the bottom of the hull, the legs being lifted from the seabed and also extending to the seabed and partially extending the hull out of the water so that the rig can be towed in shallow water. Arranged to extend further to lift off or completely. The jack up device is designed to lift the legs off the seabed so that the ice-compatible jack-up rig floats by the hull's buoyancy, and pushes the legs down to the seabed so that when the ice floes threaten the rig, the hull is out of water. It is associated with each leg to partially push it up and push it out of the water when there is no ice.

The present invention also relates to a method for excavating a drilling well in water where ice is likely to form. The method comprises a relatively flat deck provided at the top, an ice bend shape formed along the bottom and extending from the hull area near the deck height and extending downward near the bottom of the hull, and guides the ice around the hull rather than under the hull. Providing a floating hull with ice deflectors extending around the periphery of the bottom of the hull. At least three legs are disposed in the perimeter of the hull bottom. If the ice does not threaten the rig while the rig is excavating the rig at the excavation point, the foot at the bottom of the leg touches the sea floor and lifts the hull completely out of the water. Is jacked down. The hull descends further into the water to become an ice defense structure, whereby the ice bending shape extends above and below the sea level, thereby bending the ice hitting the rig to submerge the ice under the water and apply the bending force to break the ice. To allow ice to flow past the rig.

DETAILED DESCRIPTION Referring to the following detailed description in conjunction with the accompanying drawings, the present invention and its advantages will be more fully understood.
1 is an elevational view of a first embodiment of the present invention showing a state in which an excavation rig is floating in water and can be towed to an excavation well excavation point.
FIG. 2A is an elevational view of a first embodiment of the present invention showing the excavation rig jacked up out of the water for open ice excavation through the door pool. FIG.
FIG. 2B is an elevational view of the first embodiment of the present invention showing a cantilevered derrick positioned to dig above the edge of the deck and the rig rig jacked up out of the water for conventional open ice excavation.
3 is an elevational view of a first embodiment of the present invention showing a state in which the excavation rig is partially lowered into the sea but is still supported by the leg and is a defensive structure for excavation in a potentially iced environment.
FIG. 4A is an enlarged partial elevation view of one end of the first embodiment of the present invention shown in FIG. 3, showing a state in which ice is moving relative to the rig. FIG.
4b is a partially enlarged view of a second embodiment of a hull structure;
4C is an enlarged partial view of a third embodiment of the hull structure.
4d is a partially enlarged view of a fourth embodiment of a hull structure;
5A is a plan view of a first embodiment of the present invention in which a cantilevered derrick is positioned to dig through a door pool;
5B is a plan view of the first embodiment of the present invention in which the cantilevered derrick is positioned to dig above the edge of the deck.
6 is a plan view of a fifth embodiment of the present invention.

Returning to the detailed description of the preferred arrangement or arrangements of the invention, it is to be understood that the features and concepts of the invention may be presented in other arrangements, and the scope of the invention is not limited to the disclosed or illustrated embodiments. Will be. It is intended that the scope of the invention be limited only by the following claims.

As shown in FIG. 1, a jack-up excavation rig suitable for ice is indicated generically by arrow 10. In FIG. 1, the jack-up excavation rig 10 has a hull 20 floating in the sea and a raised arrangement of trusses with the majority of the length of the legs 25 extending over the deck 21 of the hull 20. It is shown having legs 25 in the form. The leg can be triangular or square in shape when viewed from above, including long vertical posts at the corners and many crossing members connected to the vertical posts to form a strong and relatively lightweight truss structure. Above deck 21 is an oil well 30 which is used to dig a drilling well in a conventional manner. The excavation rig does not show conventional auxiliary equipment for drilling excavation wells. In the configuration shown in FIG. 1, the jack-up rig 10 can be towed from one exploration site to another exploration site and to and from the land base for maintenance and other land missions.

When the jack-up rig 10 has been towed to a generally shallow water excavation point, the leg 25 has a foot 26 at the bottom of the leg 25 as shown in FIGS. 2A and 2B. It descends through the opening 27 of the hull 20 until it reaches the sea bottom 15. In a preferred embodiment, the foot 26 is connected to the spud can 28 to secure the rig 10 to the seabed. When the foot 26 touches the seabed 15, the hull 20 is lifted out of the water as jacking rigs inside the opening 27 push the leg 25 downward. When the hull 20 is completely jacked up out of the water, any wave action and rip will break more easily through the legs 25 as compared to the effect of the wave on a large buoyancy body such as the hull 20. As shown in FIGS. 2A and 2B, a drilling rig excavation operation can typically be initiated when there is no ice in the area. The configuration shown in FIG. 2A is a configuration for excavation in a case where there is a possibility of ice during excavation. 2B is a configuration for excavation in the case where the threat of ice is not expected in the excavation operation. For example, when excavating a first rig in an open ice, ice will not be a major threat if it begins to dig a rig late in the working time window. Thus, when ice begins to form at sea level 12, in conventional jack-up rigs, the ice floes contact leg 25 and damage the leg or simply push jack-up rig 10 away from the excavation point. This is of considerable interest and such leagues are typically off the excavation point until the end of the open season.

The jack-up excavation rig 10 suitable for ice is designed to resist ice floes by assuming a hull-in-water structure that defends the ice as shown in FIG. In FIG. 3, ice tends to mitigate waves and rough seas, so that sea level 12 appears less threatening, but the risk of the marine environment has only changed but not reduced. When the jack-up rig 10 suitable for ice takes on an underwater hull structure that defends the ice, the hull 20 descends into the water and contacts the water, but lowers until the hull 20 begins to float. It doesn't. Preferably, a significant portion of the weight of the rig 10 remains in the legs 25 to resist the pressure exerted by the ice to maintain the position of the rig 10 at the excavation point. As the rig 10 descends, an inwardly inclined ice-bending surface 41 blocks the sea surface 12 or extends from above the sea surface 12 into the water below the sea surface 12 so that the rig ( 10) come into contact with the ice floes that may approach it.

As best seen in FIG. 4A, the inclined ice bending surface 41 extends down from the shoulders 42 to the neckline 44, which shoulders have a significant distance above the bottom of the hull 20. As close to sea level as possible above deck 21. The neckline 44 may be very close to the bottom of the hull, or may be below the bottom of the hull, and is spaced inwardly from the shoulder 42 as a whole around the perimeter of the hull 20. Ice deflectors 45 extend downward at right angles from neckline 44 or at some small angle from vertical. If the ice deflector 45 is angled from vertical, it is desirable to angle it outward. Thus, as the ice floes as shown at 51 in FIG. 4A approach the rig 10, the ice bending surface 41 causes the leading edge of the ice floe 51 to submerge below sea level 12. . By the weight of the rig 10 a significant bending force is exerted on the ends of the ice floes in contact with the ice bending surface 41, and the buoyancy of water lifts the weight of the middle of the ice floes and the end of the ice floes 10 away from the rig 10. Since ice is less resistant to warpage than it is purely compressed, ice tends to break up into smaller, less damaging and less dangerous pieces of ice in large ice floes. For example, one may think that ice floes, which may be hundreds of feet or miles, may approach the rig 10. If the ice floes are crushed into pieces that are less than 20 feet long, preferably smaller, they can pass around the rig 10 at any rate.

In describing the ice bending surface, it should be noted that orientation is important. The ice bending surface is inclined downward from the shoulder 42. The ice bending surface is inclined upwardly outward from the neckline 44.

4B shows a first alternative shape of the hull with the ice deflector 145 slightly off-vertical (-10 °), with the ice bending surface 141 slightly entering from the shoulder 142 and shoulder 142. The hull area above) also has a surface inclined upwardly outward. 4C shows a second alternative shape with a convex ice bending surface 241, with the outwardly curved lip forming an ice deflector 245 for recoiling the ice. FIG. 4D shows a third alternative shape with a concave shaped ice bending surface 341 with an ice deflector 345 curved downward outward.

As the ice slides further down the ice bending surface 341, one can see a non-linear ice bending surface 341 that provides greater bending force. Outwardly angled ice deflectors 245 and 345 are shaped to prevent ice from sliding down the hull 20.

Ice has a significant compressive strength in the range of 4 to 12 MPa, but is usually much weaker in warping because it has a bending strength in the range of 0.3 to 0.5 MPa. As shown, the force of the ice floe 51 moving along the sea level 12 causes the leading edge to slide below the sea level 12 and the section 52 to be cut. If the ice floes 51 are broken into small fragments such as sections 52 and pieces 53, the small sections tend to float around the rig 10 without the impact or force of the large ice floes. It is preferable that the ice deflector 45 redirects the ice to flow around the side of the hull 20 without the ice being forced under the flat bottom of the hull 20. If very large ice is expected in the excavation position, the rig is arranged to extend even further down the bottom of the hull 20 and to extend downward at an angle steeper than the ice bending surface 41 to provide bending forces for the ice floes. It may be provided with an ice deflector 45 to increase. The neckline may or may not be at the bottom of the floating portion of the hull 20 such that the ice deflector 45 extends down from the flat bottom of the hull 20 or down to the flat bottom of the hull 20. It should be understood that it can be extended to It should also be understood that optionally, deck 21 may be installed eccentrically spaced above hull 20.

In order to provide additional resistance to the force the bubbling can exert on the rig 10, the leg 26 of the legs may be arranged to connect to a can 28 installed on the seabed, whereby As it approaches 41, the leg 25 actually holds the hull 20 down, deflects the ice, and in extreme cases utilizes the foot 26 on the opposite side of the rig 10 as a lever or pivot. It can lift the near side of the rig 10 and resist the buoyancy of the ice floe that can push the rig to the side. The can at the seabed is known for other applications, and the foot 26 will include appropriate connectors for attachment and detachment to the can, if desired.

It should be understood that the transition from a conventional open excavation structure as shown in FIG. 2A to the underwater hull ice defense structure shown in FIG. 3 may require significant planning and compliance depending on the aspect of the excavation in progress at that time. . Some installations may accommodate a change in deck 21 height, while others may require separation or reconstruction to accommodate new heights from the seabed 15.

The jack-up excavation rig 10 suitable for ice is designed to work like a normal jack-up rig in the open ice, but after submerging in the water at the ice defensive position, the normal posture when the action of the waves becomes a problem Or designed to reacquire the structure. It is the shape of the hull 20 (as well as the strength of the hull) that provides ice bending and crushing capabilities.

Referring to FIG. 5, the hull 20 (as viewed from above) steers the crushed ice cubes, debris and sections around the periphery of the rig 10 regardless of the orientation of the rig 10 or the path of ice movement. It may have a circular or elliptical structure to provide a helpful shape. Ice tends to flow with wind and currents, and wind and currents do not tend to be linear, or some paths reflect the effects of both sea and air.

As shown in FIG. 6, the hull 20 has a multi-sided or multi-sided shape that offers the advantages of a circular or elliptical shape and can be less expensive to manufacture. The plates that make up the hull can be formed into flat plates, so that the overall structure comprises segments of flat material such as steel, which is less complicated. In view of changing the sea level up and down by tidal currents, storms and other effects, the ice-crushing surface 41 preferably extends at least about 5 meters above the water level or sea level 12. The height above sea level 12 accommodates ice floes comprising ridges that are considerably thicker or extend substantially above sea level 12. Since the height of the shoulders 42 is sufficiently above sea level 12, the tall ice floes are pressed downwards when contacting the rig 10. At the same time, the deck 21 at the top of the hull 20 should be far enough above the draft line so that no waves can sweep through the deck 21. Thus, deck 21 is preferably at least 7-8 m above sea level 12 and may be higher. Conversely, the neckline 42 is preferably at least 4-8 m below sea level 12 in order to adequately bend the ice floes and break them into more harmless debris. Accordingly, the hull 20 is preferably in the range of 5-16 m from the flat bottom to the deck 21, more preferably 8-16 m or 11-16 m.

The legs 25 and openings 27 through which they connect to the hull 20 are located in the periphery of the ice deflector 45, so that the rig 10 is sometimes referred to as an underwater hull structure, as shown in FIG. It should also be noted that when in the structure of the so-called ice-defense state, the ice floes cannot contact the legs. In addition, the rig 10 is of significant value to oil and gas companies because it does not have to deal with all the risks of ice floes. If the excavation rig 10 suitable for ice can extend the excavation season by as much as a month, this can increase productivity by 50% in some ice frequent areas, thus providing a very substantial cost savings for the industry. 50% longer drilling window allows drilling of two or three drill wells rather than one or two drill wells per year, significantly reducing costs and increasing oil and gas production .

Referring to FIGS. 5A and 5B, the derrick 30 is positioned to excavate through a door pool in the perimeter of the ice deflector 45 as shown in FIG. 5A, or in cantilevered form as shown in FIG. 5B. It may be arranged to dig above the face of the deck 21.

Finally, it should be noted that the description of any reference is not an admission that the reference, in particular, that the publication date may be after the priority date of the present application, is a prior art for the present invention. At the same time, each claim and all claims are incorporated into this description or the specification as additional embodiments of the invention.

Although the system and process disclosed herein have been described in detail, it should be understood that various modifications, substitutions and changes can be made without departing from the spirit and scope of the invention as defined by the following claims. Those skilled in the art will be able to learn the preferred embodiments and find other ways that do not exactly match those disclosed herein for practicing the invention. It is the intention of the inventors that modifications and equivalents to the present invention fall within the claims, while the detailed description, abstract and drawings should not be used as limiting the scope of the invention. In particular, the invention is to be construed broadly as the following claims and their equivalents.

Claims (12)

Jack-up rigs suitable for ice for drilling hydrocarbons in potentially ice-rich environments in marine areas,
A floating hull having a relatively flat deck provided at the top and an ice bend shape formed along the bottom and extending downward inward around the periphery of the hull, wherein the ice bend shape extends from the hull area near the deck height and near the bottom of the hull. Extending downward to, floating hull;
An ice deflector extending around the periphery of the bottom of the hull to guide the ice around the hull rather than below the hull;
At least three legs disposed within the periphery of the floating hull bottom, the legs being lifted from the seabed so that the rig can be towed in shallow water, and also extended to the seabed and to partially or completely lift the hull out of the water. Legs arranged to extend further; And
The jack-up rig suitable for ice lifts the legs off the seabed so that they can be floated by the hull's buoyancy, and when the legs are pushed to the bottom, the hull partially pushes the hull out of the water and there is no ice when the buoy threatens the league. A jack-up device associated with each leg to fully push it out of the water,
Jack-up League for Ice. The method of claim 1,
Further comprising a fixture associated with the foot of each leg to further resist the force the bubble can exert on the rig,
Jack-up League for Ice. 3. The method according to claim 1 or 2,
The ice bending surface slopes upwards and outwards from the neckline of small dimension to the shoulder of large dimension,
Jack-up League for Ice. The method according to any one of claims 1 to 3,
The ice bending surface extends at least 8 to 10 meters or more vertically,
Jack-up League for Ice. 5. The method of claim 4,
The angle of the ice bending surface is in the range from 30 to 60 ° from vertical
Jack-up League for Ice. 6. The method according to any one of claims 1 to 5,
The ice bending surface includes a plurality of relatively flat and inclined segments extending around the periphery of the rig,
Jack-up League for Ice. 7. The method according to any one of claims 1 to 6,
The ice bending surface is the reinforcement surface,
Jack-up League for Ice. It is a method for digging a drilling well in ice-prone water,
Providing a rig having a floating hull, the floating hull having a relatively flat deck provided thereon, and ice formed along the bottom thereof, extending from the hull area near the deck height and extending downward near the bottom of the hull. Providing a rig with a bent shape and an ice deflection extending around the periphery of the bottom of the hull to guide the ice around the hull rather than below the hull;
Providing at least three legs disposed within the perimeter of the hull bottom;
If the ice does not threaten the rig while the rig is drilling the rig at the excavation point, jacking down each leg in such a way that the foot at the bottom of the leg touches the sea floor and lifts the hull completely out of the water. ;
An ice deflection shape extends above and below sea level, bending the ice hitting the rig to submerge the ice under water and applying the bending force to break the ice so that the ice flows past the rig, allowing the hull to flow under water. Descending to; And
Excavating an excavation well from the rig,
A method for excavating excavation wells in icy water. The method of claim 8,
Securing the leg to the seabed to further resist the force of the ice floes,
A method for excavating excavation wells in icy water. 10. The method according to claim 8 or 9,
The ice bending surface extends from the shoulder to the neckline, and the step of lowering the hull into the water more particularly comprises lowering the hull into the water so that the neckline is at least 4 meters below sea level and the shoulder is at least 7 meters above sea level. Included,
A method for excavating excavation wells in icy water. 11. The method according to any one of claims 8 to 10,
When the risk of ice floes is reduced, further comprising raising the hull out of the water,
A method for excavating excavation wells in icy water. It is a method for digging a drilling well in ice-prone water,
Comprising the use of a rig according to any of the preceding claims.
A method for excavating excavation wells in icy water.

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