BE1021281B1 - METHOD AND DEVICE FOR WATER JET CUTTING UNDERWATER STRUCTURES - Google Patents

Abstract

The present invention relates to a method for waterjet cutting underwater structures, comprising the steps of: (i) fixing a support frame with one or more cutting elements on an underwater structure; (ii) supplying water to said cutting elements through a water pipe; (iii) feeding an abrasive to said cutting elements through an abrasive line separate from said water line; (iv) generating a high pressure water jet in said cutting elements; and (v) cutting said underwater structure with said high pressure water jet. The present invention relates to a device for water jet cutting of underwater structures.

Description

METHOD AND DEVICE FOR WATER JET CUTTING

UNDERWATER STRUCTURES

TECHNICAL FIELD

The present invention relates to a method for cutting underwater structures by means of water jet and equipment for cutting such structures; and on equipment and auxiliary equipment for underwater cutting.

BACKGROUND

For the extraction of natural gas and / or oil at sea, drilling platforms are provided which are supported by supporting pillars and which are in contact with the natural reserves under the seabed via pipelines. More recently, wind farms with offshore wind turbines are provided, also supported by underwater structures.

When an oil or natural gas field has become unusable, the pipeline must be closed and both the supporting pillars and the pipeline must be removed. A number of systems have already been developed for this purpose according to the state of the art.

A first generation of snlj systems made use of divers for underwater grinding of the pipelines and support structures. However, such systems are very labor-intensive and in many cases entail high risks for the divers themselves due to the flammability of organic material on said pipelines and bearing pillars. Other solutions are band saws and diamond wire cutting.

A second generation of cutting systems embraces water jet cutting as a cutting technique. With such a technique, a high-pressure water jet is aimed at the structure to be cut. One of the most important advantages of such a technique is that the cutting is not accompanied by local heating, which reduces the risk of fire or explosion. Other advantages are the precise cut-off of the structures, whereby any remaining underwater structures can be used for further purposes.

For example, GB 228 8 350 discloses an aid for radially or diametrically cutting metal submarines and support structures for supporting an oil platform, where the cutting is performed under high pressure by abrasive particles suspended in a vector fluid, includes a body that can be immobilized within said conduits, and a rotating head provided with a nozzle for projecting a mixture of water and abrasives, a first inflatable positioning ring and a second inflatable positioning ring, each of the inflatable rings being toroidal and formed by an elastomeric membrane which sealed cavity. The invention can be used advantageously for cutting pipes and of the supporting structures of oil platforms. When the cutting is complete, the cutting tool and the cut tube are lifted upwards via a hoist.

The water jet cutting of underwater structures is done with a direct injection of an abrasive into the water stream, after which the slurry is pumped to one of the cutting heads and can therefore deliver pressures of the water jet between 700 bar and 1000 bar. One of the problems with known methods is the pressures achievable with the prior art equipment. By transferring the slurry through a pipe to the cutting head, a large pressure loss occurs over the pipe. However, it is desirable to use larger pressures and thereby increase the speed of cutting and / or to be able to cut through thicker structures.

Due to the large pressure loss, larger pressures must be exerted on the slurry, as a result of which the technical requirements regarding mechanical strength and abrasion resistance on the pipes are correspondingly high. Also, the energy loss associated with the pressure loss is high and should preferably be limited to improve the energy efficiency of the cutting operation. Other disadvantages are that the method according to the state of the art often still requires local intervention by one or more divers, as a result of which the safety of operators during the cutting operations involves considerable risks.

The present invention seeks to provide a solution for one or more of the aforementioned problems or shortcomings.

SUMMARY

To this end, the invention provides a method and device for water jet cutting of underwater structures according to claim 1.

In a first aspect, the present invention provides a method for water jet cutting of underwater structures in an aquatic environment, comprising the step of separately controlling water supply and abrasive supply through a water pipe (4) and an abrasive pipe (5) to one or more cutting elements, respectively (2), thereby obtaining a high pressure water jet (6).

This offers the advantage that water and the abrasive can be transported separately to the cutting head without causing a significant loss of pressure. As a result, higher pressures can be realized and the technical requirements regarding mechanical strength and abrasion resistance on the pipes are less high.

In a second aspect, the present invention provides a device for water jet cutting of underwater structures comprising a support set with one or more cutting elements, wherein each cutting element is provided with a mixing chamber comprising an inlet facility for water connectable to a water pipe and an inlet facility for abrasively connectable to a abrasive pipe, wherein said water pipe and said abrasive pipe are provided separately.

In a third aspect, the present invention provides a water jet cutting system for underwater structures comprising a device according to the second aspect of the invention, a platform, a cable for suspending said device on said platform, and a high pressure water pump.

In a fourth aspect, the present invention provides a use of a method according to the first aspect of the invention, for abrasive cutting of oil and / or gas pipes, bearing pillars of drilling platforms, under water.

DESCRIPTION OF THE FIGURES

The explicit characteristics, advantages and objectives of the present invention will further become apparent to those skilled in the art of the invention after reading the following detailed description of the embodiment of the invention and of the figures included herein. To that end, the figures should further illustrate the invention, without thereby limiting the scope of the invention.

Figures 1 to 4 represent a simplified representation of possible embodiments of the method and device according to the present invention.

Figure 1 is a schematic representation of an embodiment of the present invention in which one or more cutting elements (2) are fixed on the outside of an underwater structure (3), wherein water and abrasively are supplied in separate pipes.

Figure 2 is a schematic representation of an embodiment of the present invention in which one or more cutting elements (2) are fixed on the inside of an underwater structure (3) and in which water and abrasively are supplied in separate pipes.

Figure 3 is a schematic representation of an embodiment in which a water jet (6) is directed at said underwater structure (3) at an angle (10) between 0 ° and 75 ° with respect to the plane of the support frame (1).

Figure 4 is a schematic representation of an embodiment in which a water jet (6) is directed at said underwater structure (3) at an angle (11) between 0 ° and 85 ° with respect to the radial.

DETAILED DESCRIPTION OF THE INVENTION

Unless defined otherwise, all terms used in the description of the invention, including technical and scientific terms, have the meaning as generally understood by those skilled in the art of the invention. For a better assessment of the description of the invention, the following terms are explicitly explained. "A", "de" and "het" in this document refer to both the singular and the plural unless the context clearly assumes otherwise. For example, "a segment" means one or more than one segment.

When "about" or "round" is used in this document for a measurable quantity, a parameter, a duration or moment, and the like, variations are meant of +/- 20% or less, preferably +/- 10% or less, more preferably +/- 5% or less, even more preferably +/- 1% or less, and even more preferably +/- 0.1% or less than and of the quoted value, insofar as such variations of are applicable in the described invention. However, it must be understood here that the value of the quantity at which the term "about" or "round" is used is itself specifically disclosed.

The terms "include", "comprising", "consist of", "consisting of", "provided with", "contain", "containing", "include", "including", "contents", "contents" are synonyms and are inclusive or open terms indicating the presence of what follows, and which do not preclude or preclude the presence of other components, features, elements, members, steps, known from or described in the prior art.

The citation of numerical intervals by the end points includes all integers, fractions and / or real numbers between the end points, including these end points.

The term "water jet cutting" refers to a cutting technique in which a high pressure water jet is used to cut an object. The technique involves generating a water jet with a diameter between 0.1 mm and 0.3 mm and high speeds between 100 m / s and 1000 m / s when used in an air atmosphere. To this end, water under high pressure is led through an opening in a hard material, said hard material usually being a ruby, a diamond or an artificial diamond. Subsequently, the high-speed water jet, optionally, mixed with abrasive and finally passed through a valve with a specific diameter. The diameter of said valve determines the final diameter of the water jet, the pressure and the speed of the water jet. As used in the present invention, the term "water jet cutting" preferably refers to "abrasive water jet cutting", "water jet cutting with abrasive" or "abrasive cutting".

The term "underwater structure" refers to any natural or artificial structure that is partially or completely submerged in water. Preferably, the water jet cutting of underwater structures refers to the cutting of a structure in an aquatic environment by means of a water jet. Underwater structures which can be cut advantageously according to the method of the present invention are, for example, but not limited to pipelines of offshore natural gas or oil fields, supporting pillars of offshore drilling platforms and supporting pillars of offshore wind farms.

The term "cutting element" is to be understood as a synonym for "cutting head" and refers to an element comprising a water inlet, usually a hard material with an opening for centering said water jet and a valve or outlet opening for determining the diameter of the thereby water jet obtained. The inlet opening is preferably suitable for being connected to a water pipe that can be connected to a high-pressure water pump. Preferably, said cutting head is also provided with a mixing chamber arranged between the inlet opening and the outlet opening, said mixing chamber being suitable for connection to an abrasive line for supplying an abrasive.

The term "carrier" is to be understood as a synonym for "frame", "frame", "frame" or "skeleton" and refers to a structure suitable for supporting one or more cutting elements. of a guide mechanism along which said cutting elements can be moved, for example by means of a drive with a hydraulic motor, Preferably said support frame is provided with one or more fixing elements, said fixing elements being comprised of one or more friction elements and / or one or more clamping elements The shape of said support frame preferably corresponds to the shape of the underwater structure to be cut.

In a first advantageous embodiment, said underwater structure is a solid cylinder such as, for example, but not limited to, a concrete supporting pillar, and said support frame is round and the inside diameter of said support frame is corresponding to the outside diameter of said underwater structure. In the aforementioned case, said one or more cutting elements are preferably directed partly or completely toward the center of said underwater structure. Still in the aforementioned case, said support frame is optionally comprised of two or more parts which can pivot relative to each other and which in the closed state form a substantially closing whole and thus can be positioned around a cylindrical underwater structure.

In a second advantageous embodiment, said underwater structure is a hollow cylinder such as, for example, but not limited to, a stainless steel pipeline, and said support frame is round and the outer diameter of said support frame is corresponding to the inner diameter of said underwater structure. In the latter case, said one or more cutting elements are preferably partially or completely directed away from the center of said underwater structure.

The term "water" preferably refers to freshwater, saltwater or seawater, but may also refer to any other fluid that is suitable for entrapping an abrasive in a cutting element.

The term "water pipe" is to be understood as a preferably flexible pipe suitable for conducting water. More preferably, said water pipe is suitable for conducting water under high pressure, such as, for example, a pressure between 10 bar and 500 bar, more preferably between 100 bar and 250 bar.

The term "abrasive" is to be understood as an "abrasive" or "abrasive" and refers to a granular material with preferably a grain size of 0.001 mm to 0.1 mm and a high hardness. Preferably, said abrasive is selected from the group comprising non-synthetic or naturally occurring abrasives such as, for example, but not limited to, quartz, corundum, emery, garnet or garnet sand, natural diamond; and synthetic abrasives, such as, for example, but not limited to, silicon carbide, chromium (III) oxide, adamantane-boron nitride, and synthetic diamonds.

The term "high pressure water jet" is to be understood as a synonym for "ultra high pressure water jet" and refers to a water jet with a pressure higher than 1000 bar, preferably with a pressure higher than 1500 bar, more preferably with a pressure higher than 2000 bar and even more preferably with a pressure higher than 3000 bar.

In a first aspect, the present invention provides a method for water jet cutting of underwater structures in an aquatic environment, comprising the step of separately controlling water supply and abrasive supply through a water pipe (4) and an abrasive pipe (5) to one or more cutting elements, respectively (2), thereby obtaining a high pressure water jet (6).

In a preferred embodiment, the present invention provides a method according to the first aspect of the invention, comprising the steps of: i. fixing a support set (1) with one or more cutting elements (2) on an underwater structure (3); ii. supplying water to said cutting elements (2) through a water pipe (4); iii. supplying an abrasive to said cutting elements (2) through an abrasive line (5), separate from said water line (4); iv. generating a high pressure water jet (6) in said cutting elements (2); and v. cutting said underwater structure (3) with said high pressure water jet (6).

This offers the advantage that water and the abrasive can be transported separately to the cutting head without causing a significant loss of pressure during the transport of water and abrasively to the local location on said underwater structure where the cutting operation is to be carried out. As a result, relatively higher pressures can be realized and the technical requirements regarding mechanical strength and abrasion resistance on the pipes are less high. Because higher pressures such as, for example, ultra-high pressures can be realized, the cutting speed can be considerably increased, so that the time for deploying the equipment is correspondingly reduced. Additional advantages are that the method according to the present invention does not require local intervention by one or more divers, whereby the safety of operators during the cutting operations is considerably promoted. Provided that use is made of automation and control possibilities as known, for example, according to the state of the art, said method can be finished semi-or preferably fully automatically. As a result, the operational deployment of technically trained operators is additionally limited, which increases the deployability of the equipment.

Figure 1 is a schematic representation of an embodiment of the present invention in which one or more cutting elements (2) are fixed on the outside of an underwater structure (3) and in which water and abrasively are supplied in separate pipes.

Figure 2 is a schematic representation of an embodiment of the present invention in which one or more cutting elements (2) are fixed on the inside of an underwater structure (3) and in which water and abrasively are supplied in separate pipes.

In a preferred embodiment, the present invention provides a method according to the first aspect of the invention, wherein said high pressure water jet (6) is provided with a pressure between 1000 bar and 15000 bar.

In a preferred embodiment, the present invention provides a method according to the first aspect of the invention, wherein said high pressure water jet (6) is provided with a pressure between 2000 bar and 10000 bar.

In a more preferred embodiment, said high-pressure water jet is provided with a pressure between 4000 bar and 8000 bar, more preferably between 5000 bar and 6000 bar.

This offers the advantage that the underwater structures to be cut can be cut with water jets with a sufficiently high energy impact. As a result, the cutting speed can be increased considerably.

In a preferred embodiment, the present invention provides a method according to the first aspect of the invention, wherein said underwater structure (3) is cylindrical and wherein said cutting elements (2) are moved over the circumference of said cylinder.

This offers the advantage that, during the cutting movement, said cutting elements can partially or completely cover the cross-section of said underwater structure. Preferably, said cutting elements are driven, for example hydraulically controlled, whereby movement of the cutting elements can take place during cutting. Preferably, said cutting elements are mounted on a guide system and said cutting elements are moved through successive positions on said guide system.

In a preferred embodiment, the present invention provides a method according to the first aspect of the invention, wherein said one or more cutting elements (2) are provided at a depth of at least 5 m below the water surface (7).

Preferably said cutting elements are provided at a depth of at least 10 m below the water surface, more preferably at least 20 m and even more preferably at a depth between 25 m and 250 m. Most preferably said cutting elements are provided at a depth of 25 m, 50 m, 75 m, 100 m, 150 m, 200 m or 250 m, or any depth in between. This offers the advantage that the method according to the present invention can cut structures at a depth below the water surface. Because water and abrasive according to the present invention are supplied separately to said cutting elements, the pressure loss during transport through the pipe is relatively limited, so that correspondingly high pressures can be realized at a certain depth.

In a preferred embodiment, the present invention provides a method according to the first aspect of the invention, wherein said support frame (1) is suspended via a cable (8) on a platform (9) and wherein said underwater structure (3) is at least after cutting partially lifted.

This offers the advantage that one or more cut-off parts of the underwater structure can be hoisted up onto a platform or onto a ship, or that said cut-off parts can be dragged by means of a ship to a collection point, for example to a collection point at sea or near a coast.

In a preferred embodiment, the present invention provides a method according to the first aspect of the invention, wherein said abrasive sand comprises, preferably garnet sand.

This offers the advantage that said abrasive is a natural abrasive, as a result of which no contamination of the natural environment occurs as a result of abrasive cutting with synthetic materials. Furthermore, said abrasive is inexpensive and widely available and the water-jet technique with said abrasive can be carried out with the aid of equipment according to the present invention carried out with materials known according to the prior art.

In a preferred embodiment, the present invention provides a method according to the first aspect of the invention, wherein said water jet is directed at said underwater structure (3) at an angle (10) between 0 ° and 75 ° with respect to the plane of the support frame (1).

This offers the advantage that said underwater structure can be cut off at an angle of 0 °, so that the remaining structure can serve as a support surface or support structure for further purposes. In another embodiment, said underwater structure is a pipe and said pipe is cut in a method according to the present invention, wherein said water jet intersects the wall of the pipe at an angle greater than 0 ° and preferably less than 75 °. As a result, the remaining structure is provided with a border on which the structure to be removed can temporarily rest and find balance. This prevents the structure to be removed from being dragged along with sea currents, for example.

Figure 3 is a schematic representation of an embodiment in which a water jet (6) is directed at said underwater structure (3) at an angle (10) between 0 ° and 75 ° with respect to the plane of the support frame (1).

In a preferred embodiment, the present invention provides a method according to the first aspect of the invention, wherein said water jet is directed at said underwater structure (3) at an angle (11) between 0 ° and 85 ° with respect to the radial.

Preferably, said water jet is directed at an angle greater than 0 ° with the radial. This offers the advantage that the center (14) of the underwater structure is not brought into contact with the water jet. Consequently, any structure (15) present in the center of the underwater structure is not cut by the water jet. This is particularly desirable when the center of the underwater structure is to be retained for further purposes, such as, for example, construction purposes.

Figure 4 is a schematic representation of an embodiment in which a water jet (6) is directed at said underwater structure (3) at an angle (11) between 0 ° and 85 ° with respect to the radial.

In a preferred embodiment, the present invention provides a method according to the first aspect of the invention, wherein said underwater structure (3) comprises a pipe and wherein said support frame (1) is fixed on said pipe by means of pipe clamps. This offers the advantage that the part of the pipe to be removed is clamped after being cut and can be lifted partially or completely.

In a preferred embodiment, the present invention provides a method according to the first aspect of the invention, wherein said underwater structure (3) is cylindrical and wherein said support frame (1) is fixed with cutting elements (2) around said cylindrical structure. Preferably, said support frame is comprised of two or more segments, which are hingedly movable relative to each other and can be connected to a whole which surrounds said cylindrical structure.

In a preferred embodiment, the present invention provides a method according to the first aspect of the invention, wherein said underwater structure (3) comprises a pipe and wherein said support frame (1) is fixed in said tube with cutting elements (2). Preferably, said support frame is fixed by means of two or more friction elements which are provided on the inner wall with said pipe.

In a second aspect, the present invention provides a device for water jet cutting of underwater structures comprising a support set (1) with one or more cutting elements (2), each cutting element (2) being provided with a mixing chamber comprising an inlet provision for water (12) ) connectable to a water pipe (4) and an inlet for abrasive (13) connectable to an abrasion pipe (5), said water pipe (4) and said abrasive pipe (5) being provided separately.

This offers the advantage that water and said abrasive can be guided separately to said cutting elements. Due to the separate transport of water and the abrasive mentioned, the pressure loss due to the transport is relatively smaller. As a result, it is possible to work more energetically and as a result higher pressures can be achieved for the resulting water jet.

In a third aspect, the present invention provides a system for water jet cutting of underwater structures comprising a device according to the second aspect of the invention, a cable (8), a platform (9), for suspending said device on said platform (9) ), and a high pressure water pump.

In an advantageous embodiment, a system as described in the preceding paragraph is used for carrying out a method according to the first aspect of the invention. Said platform can be made available at sea or can be available on a ship at sea at the height of the underwater structures to be cut. A device according to the second aspect of the invention can be fixed to said underwater structure via a cable, preferably suspended from a mechanically operated pulley. Said one or more cutting elements can be adjusted or remotely operated for cutting said underwater structure. An abrasive and water are guided in separate lines to said respective one or more cutting elements with the aid of one or more air pumps and one or more high-pressure water pumps, respectively.

In a fourth aspect, the present invention provides a use of a method according to the first aspect of the invention, for abrasive cutting of oil and / or gas pipes, bearing pillars of drilling platforms, under water.

Claims (15)

CONCLUSIONS A method for water jet cutting of underwater structures in an aquatic environment, comprising the step of separately controlling water supply and abrasive supply through a water pipe (4) and an abrasive pipe (5) to one or more cutting elements (2), thereby obtaining a high pressure water jet (6). The method of claim 1, comprising the steps of: i. fixing a support set (1) with one or more cutting elements (2) on an underwater structure (3); ii. supplying water to said cutting elements (2) through a water pipe (4); iii. supplying an abrasive to said cutting elements (2) through an abrasive line (5), separate from said water line (4); iv. generating a high pressure water jet (6) in said cutting elements (2); and v. cutting said underwater structure (3) with said high pressure water jet (6). Method according to claim 1 or 2, wherein said high-pressure water jet (6) is provided with a pressure between 1000 bar and 15000 bar. Method according to at least one of the preceding claims, wherein said underwater structure (3) is cylindrical and wherein said cutting elements (2) are moved over the circumference of said cylinder. Method according to at least one of the preceding claims, wherein said one or more cutting elements (2) are provided at a depth of at least 5 m below the water level (7). Method according to at least one of the preceding claims, wherein said support frame (1) is suspended via a cable (8) on a platform (9) and wherein said underwater structure (3) is at least partially lifted after cutting. Method according to at least one of the preceding claims, wherein said abrasive sand comprises, preferably garnet sand. Method according to at least one of the preceding claims, wherein said water jet is directed at said underwater structure (3) at an angle (10) between 0 ° and 75 ° with respect to the surface of the support frame (1). A method according to at least one of the preceding claims, wherein said water jet is directed at said underwater structure (3) at an angle (11) between 0 ° and 85 ° with respect to the radial. Method according to at least one of the preceding claims, wherein said underwater structure (3) comprises a pipe and wherein said support set (1) is fixed on said pipe by means of pipe clamps. A method according to at least one of the preceding claims 1 to 10, wherein said underwater structure (3) is cylindrical and wherein said support frame (1) is fixed with cutting elements (2) around said cylindrical structure. A method according to at least one of the preceding claims 1 to 10, wherein said underwater structure (3) comprises a pipe and wherein said support frame (1) is fixed with cutting elements (2) in said tube. Device for water jet cutting of underwater structures comprising a support set (1) with one or more cutting elements (2), each cutting element (2) being provided with a mixing chamber comprising an inlet provision for water (12) connectable to a water pipe (4) and an inlet arrangement for abrasive (13) connectable to an abrasive line (5), characterized in that said water line (4) and said abrasive line (5) are provided separately. A water jet cutting system for underwater structures comprising a device according to claim 13, a cable (8), a platform (9), for suspending said device on said platform (9), and a high pressure water pump. Use of a method according to at least one of claims 1 to 12, for abrasive cutting of oil and / or gas pipes, bearing pillars of drilling platforms, under water.