EP2562346B1 - Underwater drilling assembly and method for producing a borehole - Google Patents

Description

The invention relates to an underwater drilling arrangement for producing a well in a river bottom according to the preamble of claim 1. Furthermore, the invention relates to a method for creating a well in a river bottom according to the preamble of claim 11.

The underwater drilling assembly comprises a retractable platform for placing on the bottom of the water, a drill drive, which is mounted axially displaceable on the work platform, and a drill pipe with drill head, which is rotatably driven via the drill drive.

In the method for creating a hole in a body of water, a working platform of the underwater drilling assembly is lowered to the bottom of the river and placed with ground contact elements on the bottom of the water and a drill pipe with drill head via a drill drive, which is mounted on the platform, rotatably driven.

The underwater drilling arrangement and the drilling method are used in particular to create foundations or foundation piles in the river bottom, for example for anchoring offshore wind turbines, flow turbines of tidal power plants or oil and gas production facilities in the sea.

In known underwater drilling arrangements and methods for creating a well in a body of water, loosened cores are retrieved discontinuously from the wellbore. The corresponding drilling methods are therefore complicated and time-consuming.

US 2009/0218136 A1 describes apparatus and method having the features of the preamble of independent claims 1 and 11, used for sampling from a body of water. Drilled cuttings are flushed out of the wellbore in a riser pipe surrounding the drill pipe by means of a mud fluid and directed into a collection chamber. The heavier particles sediment in the chamber, while the lighter particles are discharged at an upper end of the chamber.

US 3,419,092 describes a drilling arrangement for a shallow water, in which the discharge of the cuttings takes place above the surface of the water.

US 2,669,431 discloses an underwater drilling assembly having a drill string disposed within a sleeve. A mud fluid is directed through the drill string and out of the wellbore along with removed cuttings outside of the drill string. About outlet channels, the flushing fluid is discharged with the cuttings laterally in a lower portion of a bell-shaped platform to the surrounding water.

CA 1 137 122 discloses a drilling device with a plate-shaped rotary drive and a horizontally movable cutting device which is connected via lifting rods with the rotary drive. A suction pump sucks up removed cuttings.

In US 4,744,698 a device for installing a silo at the bottom of a body of water is described.

US 4,255,068 describes a drilling method in which cuttings are discharged via a arranged in an annular space between the drill pipe and borehole wall pipe and a pump in the water.

From the US 4,770,255 a tiller is known for use underwater.

DE 21 54 231 describes a drilling assembly that operates according to the air lifting and / or purging method. A drilling rig is connected to a ground anchor and turns the ground anchor into the seabed.

The invention has for its object to provide an underwater drilling assembly and a method for creating a hole in a body of water, which allow a particularly economical creation of a subsea well.

The object is achieved by an underwater drilling assembly with the features of claim 1 and a method for creating a hole in a body of water with the features of claim 11. Preferred embodiments of the invention are specified in the dependent claims.

In the underwater drilling arrangement according to the invention, it is provided that a delivery channel is formed in the drill string, through which a delivery fluid can be conveyed upwards together with removed cuttings, and that a discharge opening for the delivery fluid is provided together with the removed cuttings, via which the delivery fluid can be discharged under water together with the removed cuttings above the drill drive.

In the method according to the invention, which can be carried out in particular with an underwater drilling arrangement according to the invention, it is provided that removed cuttings are conveyed upwards together with a delivery fluid through a delivery channel in the drill string and discharged underwater via a discharge opening above the drill drive.

A first aspect of the invention may be seen as providing a subsea well continuously wherein the excavated soil material is conveyed uphole from the wellbore via an induced fluid flow within the drill string. The drill pipe is designed for this purpose as a hollow drill pipe. In particular, the delivery fluid can be water from the water, in the base of which the bore is created.

A second basic idea of the invention is to convey the conveying fluid with the cuttings into an area above the drilling drive and in particular above the bottom of the river and to discharge it there into the surrounding water. The drill cuttings then sediment on the bottom of the water in the vicinity of the created borehole. The discharge opening is located in the water, above the drill drive.

A fundamental aspect of the underwater drilling assembly according to the invention and of the corresponding method therefore consists in not conveying the excavated soil material to the water surface and recovering it, but discharging it into the water itself.

The working platform of the underwater drilling arrangement can preferably be lowered onto the body of water via a cable from a carrier device, in particular from a ship or a floating platform. Via a so-called umbilical cord, the working platform is connected during operation to the supply of energy and / or fluid, for example a hydraulic fluid for driving the auger drive, to the ship or the floating platform. After creating the borehole, the platform can be raised again via the rope and removed from the bottom of the water. To lower and recover the work platform, a winch may be provided on the ship or the floating platform.

The drill pipe is passed through the drill drive. Thus, the production fluid can be conveyed with the cuttings through the drill drive up and into the water. The drill drive can be designed in particular as a turntable which surrounds the drill pipe.

For ejecting the cuttings at a certain height above the auger drive a discharge line is arranged above the auger drive. The ejection line is fluidly connected to the conveying channel of the rotatable drill string and opens above the bottom of the river and preferably in a predetermined minimum height above the platform into the water. Preferably, the ejection line is rotationally coupled via a rotary coupling from the rotatable drill pipe. For a uniform discharge of the cuttings independent of the rotational movement of the drill string, it is preferred that the discharge line is mounted on the platform. The ejection line is designed as a rigid line extending from the drill drive upwards.

According to the invention, it is preferred that the drill drive can be lowered along the working platform into the borehole. In order to enable ejection of the cuttings well above the bottom of the riverbed even when lowered into the borehole drill drive and drill pipe, it is advantageous that the discharge line is designed to be telescopic. During the drilling process, the discharge line can thus be extended upward in order to eject the cuttings above the bottom of the river and / or above the working platform.

In a further preferred embodiment of the invention it is provided that the ejection line has a manifold, which deflects the conveying fluid with the removed cuttings for ejection at a relative to the drill string, in particular laterally offset position in a lateral direction. The discharge opening is in this case preferably laterally offset next to the borehole to be created, so that the removed cuttings can be ejected laterally next to the working platform.

According to the invention, it is particularly preferred for the ejection line to be rotatably mounted in a specific direction relative to the drill string and / or the drill drive and / or the work platform for targeted discharge of the drill rig, and in particular to be rotatable as a function of a water flow. Preferably, a flow lug is connected to the ejection line which rotates the ejection line in response to the flow of water. In this way it can be achieved that the cuttings are always discharged in a desired direction, in particular in the direction of a stream of water and not against them. This can be prevented that the cuttings after discharge flows back towards the platform and this damaged.

A backflow or undesired penetration of foreign bodies into the delivery channel can be prevented by arranging a non-return flap in the area of the discharge opening.

Furthermore, it is preferred according to the invention that for generating an upward flow in the conveying channel along the drill pipe a supply channel for a compressed gas is provided, from which the compressed gas can be fed to the conveyor channel. The pressurized gas can be injected from the supply channel into the delivery channel via supply openings or injection nozzles in order to cause an upward flow there. The compressed gas can also be introduced directly into the drill head, from which it flows into the delivery channel. The compressed gas generates in the delivery channel a three-phase mixture of liquid conveying fluid, gas and cuttings, which has a lower density than the drill pipe surrounding water in the wellbore. As a result, an upward flow is generated in the delivery channel.

For supplying pressurized gas in the feed channel provided on the drill string, it is preferred that a supply line is provided which connects the feed channel to a feed unit at the water surface of the water body, in particular a compressor. The supply line for the compressed gas can be arranged in particular in the so-called umbilical cord, which contains power lines for driving the auger drive.

Another possibility for generating an upward flow in the delivery channel is that a pump, in particular a suction pump and / or a jet pump, is arranged. The pump can be arranged, for example, above the drill drive in the area of the work platform. In the case of a suction pump, the conveying fluid flows through the pump together with the cuttings. In particular, the jet pump can also be arranged in the region of the drill head, in particular in this, and supplied with propellant via a guided along the drill string fuel line. The delivery fluid may be supplied to the delivery channel either via the delivery channel or via the annulus between the drill string and the borehole edge.

The drill string is designed as a double tube in which the delivery channel and a feed channel for the delivery fluid and / or a compressed gas are formed. Preferably, the feed channel extends annularly around a central conveyor channel.

For sucking off the dissolved cuttings, it is preferred that the boring head has a suction chamber which is fluidically connected to the delivery channel and the supply channel. The suction arises here by the upward flow in the delivery channel. Preferably, the suction chamber has a downwardly directed opening, which is preferably located in the region of a drilling tool of the drill head. This allows the cuttings are removed immediately after its release from the bottom hole.

A particularly effective removal of the loosened Bohrguts of the borehole bottom can be achieved in that the feed channel has a lower outlet opening, which opens radially outward into the suction chamber and there generates a radially outward flow and in that the suction chamber has deflection means which a deflection produce the radially outward flow in a radially inward flow, the entrained cuttings entrained in the direction of the conveying channel. The drill head, in particular the suction chamber, for this purpose is preferably bell-shaped, so that the desired flow is established due to the bell-shaped profile of the suction chamber. The radially inwardly directed flow is, in particular, directly above the borehole bottom, so that the drilled cuttings are conveyed radially inwards into a central region of the boring head, in which the inlet of the conveying channel is located.

To guide the drill drive along the platform, the platform on a guide tube, along which the drill drive is guided axially movable. The guide tube is preferably adjustable in a receptacle of the platform and mounted fixed.

The guide tube thus assumes the function of a leader, along which the drill drive is movably guided. Furthermore, the arranged inside the guide tube and guided drilling drive is largely protected from external influences such as currents of the water.

To guide the drill drive, the guide tube preferably has a linear guide extending in the axial direction, which cooperates with a guide element of the drill drive.

Preferably, the guide tube is axially movable or rotatably mounted in the receptacle of the working platform, so that the guide tube moves during the creation of the bore, in particular lowered and raised or rotated. Furthermore, the guide tube can be fixed to the receptacle so that it is secured against rotational movement and / or axial movement relative to a base body of the working platform.

The fixed guide tube can serve as an abutment or support for the drill drive during operation of the drill drive. Furthermore, the guide tube can be tracked due to its adjustable mounting on the base body of the platform in the drilling direction to extend the leadership of the drill drive down. In particular, the guide tube itself, in particular rotating, are introduced into the body of water. For this purpose, a guide tube drive is provided. The drill drive can also be introduced along the guide tube into the water bottom or the borehole.

The entire work platform can be raised again after drilling and removed from the bottom of the water.

Fig. 1

eine Seitenansicht einer Unterwasser-Bohranordnung;

Fig. 2

eine Querschnittsansicht einer in einem Führungsrohr angeordneten Bohreinheit mit Bohrantrieb;

Fig. 3

eine in einem Führungsrohr nach unten verfahrene Bohreinheit.

The invention will be further described by means of preferred embodiments, which are illustrated in the attached schematic drawings. In the drawings shows:

Fig. 1

a side view of an underwater drilling assembly;

Fig. 2

a cross-sectional view of a guide tube arranged in a drilling unit with drill drive;

Fig. 3

a drilled in a guide tube down drilling unit.

Equivalent elements are identified in all figures with the same reference numerals.

Fig. 1 shows an underwater drilling assembly 10 according to the invention with a mountable on a body of water platform 20 and a mounted on the platform 20 and guided drill drive 50. The platform 20 includes a base body 30, which may also be referred to as a base frame, and a guide tube 22 for guiding the Drilling drive 50.

The base body 30 has a plurality of ground contact elements 32 for placement on the bottom of the water. The ground contact elements 32 are preferably designed to be adjustable, so that unevenness in the water bottom are compensated can and the platform 20 in the desired orientation, in particular horizontally, can be placed on the bottom of the water. The main body 30 further comprises a plurality of struts 34 and a central receptacle 36 for the guide tube 22. The guide tube 22 is adjustably mounted in the receptacle 36.

To rotate the guide tube 22 relative to the base body 30, a rotary drive 40 is provided on the base body 30 of the working platform 20. The rotary drive 40 comprises a hydraulically tensionable collet 42, which is rotatable by means of a horizontal cylinder 44. For applying a vertical force to the guide tube 22, an axial drive, in particular a vertical cylinder 46 is further provided.

The guide tube 22 has a cutter 28 with a plurality of cutting teeth at its lower end for easier insertion into the body of water. On the outer circumference of the cylindrical guide tube 22 a plurality of securing elements 23 for securing the guide tube 22 relative to the base body 30 are arranged.

Inside the guide tube 22 of the drill drive 50 is arranged, which can be introduced via a not shown rope in the guide tube 22. The drill drive 50, which can also be referred to as a rotary drive, drives a drill pipe 60, at the lower end of which a drill head 80 with drilling tools 82 is arranged, rotatingly. The drill drive 50 is mounted axially movable in the guide tube 22 and can be clamped in the guide tube 22. A conduit 12, which is referred to in particular as an umbilical cord, serves to supply the auger drive 50 with hydraulic fluid.

On an inner wall of the guide tube 22, a linear guide 24 is formed, along which the drill drive 50 is axially guided. The feed movement of the drill string 60 with the drill head 80 can be achieved in particular by gravity. To increase the load on the drill head 80 Auflastplatten 78 are arranged on the drill pipe 60 above the drill head 80, in particular on a drill collar 76 of the drill string 60, load plates 78. The load plates 78 include a central passageway for the drill pipe 60 and are particularly removably attached to the drill pipe 60. They extend largely over the entire cross section of the guide tube 22nd

In addition to the feed motion by gravity, a feed device, in particular a feed cylinder, be provided on the drill drive 50, which controls the load on the drill head 80.

The hollow drill string 60 includes a central delivery channel 62 and a supply channel 66 surrounding it annularly. The drill string 60 is rotationally driven by the drill driver 50 and passes axially through the drill bit 50. Above the drilling drive 50, a discharge line 68 with a discharge opening 69 is connected to the drill pipe 60 via a coupling device 70 and is connected fluidically to the delivery channel 62.

The ejection line 68 extends upwardly and may include a manifold, not shown, which deflects the conveying fluid with the drill cuttings laterally. The discharge opening 69 is in this case preferably arranged laterally of the working platform 20, so that the discharge of the cuttings takes place next to the working platform 20.

The flow in the delivery channel 62 can be generated in different ways. For example, an air lifting method may be used. For this purpose, a gas, for example compressed air, can be guided downwards via the feed channel 66 and introduced into the feed channel 62 via injection openings 64 or nozzles, so that the density of the conveying fluid in the feed channel 62 is reduced and an upwardly directed flow is created. The gas can be supplied via a feed line 58, in particular the umbilical cord 12, from the carrying device on the water surface.

Alternatively or additionally, the flow in the delivery channel 62 can also be generated by means of a pump. For example, a suction or displacement pump 74 may be disposed above the auger drive 50, as in FIGS FIGS. 2 and 3 indicated. The suction or displacement pump 74 sucks the conveying fluid in the conveying channel 62 and thus generates an upward flow in the conveying channel 62. The pump 74 conveys the conveying fluid together with the cuttings into the ejection line 68.

Alternatively or additionally, a jet pump 86 may be provided for generating the upward flow in the guide channel 62. The jet pump 86 may also be located above the auger drive 50 or, as in FIG Fig. 3 schematically indicated, in the region of the drill head 80, in particular within a suction chamber 84 of the drill head 80, which will be described in more detail below. The jet pump 86 is supplied via a non-illustrated propellant conduit with propellant.

The suction chamber 84 is fluidly connected to the supply channel 66 and the delivery channel 62. The feed channel 66 has an outlet opening at its lower end, via which a fluid, for example water or air, can be introduced into the suction chamber 84 in such a way that a flow is generated there which entrains the released cuttings radially inward. In a central region of the suction chamber 84, the dissolved cuttings are sucked up by the upward flow in the conveying channel 62.

In the following, a drilling method according to the invention for producing a bore in a body of water will be described.

First, the platform 20 including guide tube 22 by means of a rope, not shown, lowered by a arranged on the water surface support means, such as a floating platform or a ship, and placed on the bottom of the water. The platform 20 is then aligned and can be additionally attached to the ground.

After the work platform 20 is arranged in the desired orientation at the bottom of the water, a drilling unit with a drill drive 50, a drill pipe 60 and a drill head 80 is inserted into the guide tube 22. The drill string 60 is rotationally driven by the auger drive 50. As a result of the drilling progress, the drill drive 50 moves downwards along the guide tube 22. Once the drill drive 50 has reached the lower end of the guide tube 22, the guide tube 22 can be sunk along the borehole created, the drill drive 50 moves back toward the upper end of the guide tube 22. Subsequently, the drill drive 50 can again be moved along the guide tube 22 down, again soil material is removed. The drill drive 50 can thus be sunk in the guide tube 22 of the platform 20 in the created wellbore.

The removed soil material is conveyed upwards by a flow generated in the conveying channel 62, upwards and discharged via a discharge opening 69 into the water.

The upward flow in the delivery channel 62 can be generated in different ways. For example, a gas, in particular air, are blown into the delivery channel, so that the density of the delivery fluid in the delivery channel 62 is reduced and thus an upward flow is generated. Alternatively or additionally, it is possible to pump the delivery fluid in the delivery channel 62 upwards, which can be effected for example by a suction pump 74 or a jet pump 86. The pump can be supplied with hydraulic fluid or propellant by the so-called umbilical cord, which connects the underwater drilling assembly 10 with the support means provided on the surface of the water. The air which may optionally be introduced into the delivery channel 62 is preferably provided from above the water surface via the umbilical cord.

Claims (11)

1. Underwater drilling arrangement for making a bore in a bed of a water body, with

   - a service platform (20) which can be lowered for placing on the bed of the water body,

   - a drill drive (50) which is mounted so that it can be axially displaced on the service platform (20), and

   - a drill rod (60) with drill head (80) which can be rotatably driven via the drill drive (50),

   characterized in that

   - the drill rod (60) being rotatably driven comprises a double pipe with a feeding channel (66) for feeding a conveying fluid and a central conveying channel (62), through which the conveying fluid can be conveyed upwards together with excavated drill cuttings, and the drill rod (60) is led through the drill drive (50),

   - the service platform (20) for guiding the drill drive (50) comprises a guide pipe (22), inside which the drill drive (50) is guided in a displaceable manner,

   - an ejection line (68) adapted as rigid line is connected to the drill rod (60) and fluidically connected with the conveying channel (62) above the drill drive (50) via a clutch element (70), and

   - the ejection line (68) extends upwards and a discharge opening (69) is provided, via which the conveying fluid can be discharged underwater together with the excavated drill cuttings above the drill drive (50) and above the service platform (20) with the guide pipe (22).
2. Underwater drilling arrangement according to claim 1,
   characterized in that
   the ejection line (68) is designed telescopically.
3. Underwater drilling arrangement according to claim 1 or 2,
   characterized in that
   the ejection line (68) has an elbow which deflects the conveying fluid with the excavated drill cuttings for ejection at a position offset relative to the drill rod (60) into a lateral direction.
4. Underwater drilling arrangement according to one of the claims 1 to 3,
   characterized in that
   the ejection line (68) is rotationally mounted relative to the drill rod (60) and/or the drill drive (50) and/or the service platform (20).
5. Underwater drilling arrangement according to one of the claims 1 to 4,
   characterized in that
   a non-return valve is arranged in the region of the discharge opening (69).
6. Underwater drilling arrangement according to one of the claims 1 to 5,
   characterized in that
   in order to generate an upwardly orientated flow in the conveying channel (62) along the drill rod (60) a feed channel (66) for a compressed gas is provided, from which the compressed gas can be fed to the conveying channel (62).
7. Underwater drilling arrangement according to one of the claims 1 to 6,
   characterized in that
   a feed line (58) is provided which connects the feed channel (66) to a conveying unit on the water surface of the water body, in particular to a compressor.
8. Underwater drilling arrangement according to one of the claims 1 to 7,
   characterized in that
   in order to generate an upwardly orientated flow in the conveying channel (62), a pump, in particular a suction pump (74) and/or a jet pump (86), is provided.
9. Underwater drilling arrangement according to one of the claims 1 to 8,
   characterized in that
   the drill head (80) comprises a suction chamber (84) which is fluidically connected to the conveying channel (62) and the feed channel (66).
10. Underwater drilling arrangement according to one of the claims 1 to 9, characterized in that

    - the feed channel (66) comprises a lower outlet opening which opens radially outwardly into the suction chamber (84) and produces a radially outwardly orientated flow there, and

    - the suction chamber (84) comprises deflection means which generate a deflection of the radially outwardly orientated flow into a radially inwardly orientated flow which carries along excavated drill cuttings in the direction of the conveying channel (62).
11. Method for making a bore in the bed of a water body with an underwater drilling arrangement, in particular according to one of the claims 1 to 10, wherein

    - a service platform (20) of the underwater drilling arrangement is lowered onto the bed of a water body and placed with bottom standing elements (32) on the bed of a water body, and

    - a drill rod (60) with drill head (80) is rotatably driven via a drill drive (50) which is mounted on the service platform (20),

    characterized in that

    - the drill rod (60) being rotatably driven comprises a double pipe, which is led through the drill drive (50),

    - a conveying fluid is led through a feeding channel (66) of the drill rod (60) and is conveyed upwards together with excavated drill cuttings through a conveying channel (62) in the drill rod (60),

    - a drilling unit comprising the drill drive (50), the drill rod (60), and the drill head (80), is led into a guide pipe (22) and is displaced downwards inside the guide pipe (22) for making the bore, and

    - the drill cuttings conveyed upwards through the guide pipe (22) together with the conveying fluid is discharged underwater via an ejection line (68) designed as rigid line which is connected to the drill rod (60) above the drill drive (50) via a clutching means (70) and extends upwards, and via a discharge opening (69) above the drill drive (50) and above the service platform (20) with the guide pipe (22).

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