Nearshore Subsea Drilling

Abstract

A subsea vertical drilling machine is disclosed, having: a drill assembly formed by: a riser pipe having a first end, a second end, and a length extending between the first and second ends; and a drilling machine body, including a drilling head, coupled to the first end of the riser pipe;
and a vertical feed system configured for advancing the drill assembly in a vertical direction.

The riser pipe is provided with at least one rack extending along at least a part of the length of the riser pipe, and the vertical feed system comprises a motor coupled to a pinion, the pinion arranged for engaging with the rack for advancing the drill assembly.

Claims

1. Subsea drilling machine comprising: a drill assembly comprising: a riser pipe having a first end, a second end, and a length extending between said first and second ends; and a drilling machine body coupled to the first end of said riser pipe, said drilling machine body comprising a drilling head; and a feed system configured for advancing said drill assembly in a first direction; wherein said riser pipe is provided with at least one rack extending along at least a part of the length of the riser pipe; and wherein said feed system comprises a motor coupled to a pinion, said pinion arranged for engaging with said rack for advancing said drill assembly in said first direction.

2. The subsea drilling machine according to claim 1, wherein said at least one rack extends over substantially the entire length of the riser pipe.

3. The subsea drilling machine according to claim 1, wherein said riser pipe is provided with a plurality of said racks, said racks distributed along a circumference of said riser pipe, each rack extending along at least a part of the length of the riser pipe, and wherein said feed system comprises a corresponding plurality of pinions or sets of pinions, each pinion or set of pinions arranged for cooperating with one rack.

4. The subsea drilling machine according to claim 1, wherein said feed system comprises a plurality of pinions for each rack.

5. The subsea drilling machine according to claim 1, wherein said feed system is a vertical feed system and said first direction is a vertical direction.

6. The subsea drilling machine according to claim 1, wherein said riser pipe comprises a plurality of riser pipe modules, each riser pipe module provided with at least one rack extending along its length; said riser pipe modules coupled to one another such that the at least one rack of the different modules are substantially aligned with one another.

7. The subsea drilling machine according to claim 1, wherein said feed system is coupled to a tube, said tube configured for coupling to a second entity such as a drilling machine receiving section of a template, and substantially fixating said feed system with respect to said second entity.

8. The subsea drilling machine according to claim 1, further comprising: a spoil removal system; said spoil removal system comprising a conduit extending through said drilling head and said riser pipe, and a spoil exhaust provided at the second end of said riser pipe.

9. The subsea drilling machine according to claim 8, further comprising a pump arranged in said drilling machine body, said pump arranged for pumping said spoil from said drilling head to said spoil exhaust.

10. The subsea drilling machine according to claim 1, wherein the drilling machine body further comprises a drilling head driving system for operating the drilling head.

11. The subsea drilling machine according to claim 1, further comprising a control unit configured for controlling operation of one or more of the feed system, the drilling machine, in particular the drilling head driving system, and/or the spoil removal system.

12. Subsea drilling machine comprising: a drill assembly comprising: a riser pipe having a first end, a second end, and a length extending between said first and second ends; and a drilling machine body coupled to the first end of said riser pipe, said drilling machine body comprising a drilling head; and a feed system configured for advancing said drill assembly in a first direction, wherein said feed system comprises: a first feed subsystem, comprising a first set of hydraulic actuators arranged to induce a movement of a first gripper along said first direction, said first gripper comprising first gripping means for gripping and/or clamping the riser pipe upon actuation of said first gripping means; and a second feed subsystem, comprising a second set of hydraulic actuators arranged to induce a movement of a second gripper along said first direction, said second gripper comprising second gripping means for gripping and/or clamping the riser pipe upon actuation of said second gripping means.

13. The subsea drilling machine according to claim 12, wherein said feed system is coupled to a tube, said tube configured for coupling to a second entity such as a drilling machine receiving section of a template, and substantially fixating said feed system with respect to said second entity.

14. The subsea drilling machine according to claim 12, further comprising: a spoil removal system; said spoil removal system comprising a conduit extending through said drilling head and said riser pipe, and a spoil exhaust provided at the second end of said riser pipe.

15. Subsea drilling machine comprising: a drill assembly comprising: a riser pipe having a first end, a second end, and a length extending between said first and second ends; and a drilling machine body coupled to the first end of said riser pipe, said drilling machine body comprising a drilling head; a feed system configured for advancing said drill assembly in a first direction; and a spoil removing system comprising a conduit extending through said drilling head and said riser pipe, and a spoil exhaust provided at the second end of said riser pipe.

16. The subsea drilling machine according to claim 15, further comprising a pump arranged in said drilling machine body, said pump arranged for pumping said spoil from said drilling head to said spoil exhaust.

17. A method for drilling a hole in seabed, said method comprising the steps of: providing a drill assembly comprising a riser pipe and a drilling machine body coupled to the first end of said riser pipe, said drilling machine body comprising a drilling head; providing a feed system configured for advancing said drill assembly in a first direction; assembling said drill assembly with said feed system to form a drilling machine; arranging a template onto the seabed, said template comprising one or more drilling machine receiving sections; arranging said drilling machine in one of said drilling machine receiving sections; fixating said feed system with respect to said template; advancing said drill assembly into said seabed by operating said feed system, by substantially continuously moving said riser pipe with respect to said feed system, while operating said drilling head; and retracting said drill assembly from said vertical bore hole after having reached a final depth of said bore hole.

18. The method according to claim 17, wherein said advancing said drill assembly is performed by a rotating pinion engaging with a rack extending along at least a part of a length of said riser pipe.

19. The method according to claim 17, wherein said advancing said drill assembly is performed by alternatingly operating a first feed subsystem and a second feed system; wherein one of the first and second feed subsystem is operated to advance the drill assembly while the other one of the first and second feed subsystem is reset.

20. The method according to claim 17, further comprising the step of: prior to said step of arranging said drilling machine in one of said drilling machine receiving sections, arranging a casing substantially around said drilling machine body.

21. The method according to claim 20, wherein said casing is advanced into the seabed together with said drill assembly.

22. The method according to claim 20, wherein during said step of advancing the drill assembly into the seabed, said drilling head protrudes ahead of the casing.

23. The method according to claim 20, wherein during said step of advancing the drill assembly into the seabed, said drilling head is arranged within said casing.

24. The method according to claim 20, comprising, when the casing has been inserted into the seabed to a casing depth, further advancing said drilling head into said ground.

25. The method according to claim 20, further comprising the step of: removing spoil via a spoil return pipe arranged within said drilling machine body and said riser pipe, and discharging said spoil at spoil discharge arranged at a second end of said riser pipe.

26. The method according to claim 17, wherein said retracting is performed by operating said vertical feed system in reverse.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0102] Further features and advantages of the invention will become apparent from the description of the invention by way of non-limiting and non-exclusive embodiments. These embodiments are not to be construed as limiting the scope of protection. The person skilled in the art will realize that other alternatives and equivalent embodiments of the invention can be conceived and reduced to practice without departing from the scope of the present invention. Embodiments of the invention will be described with reference to the figures of the accompanying drawings, in which like or same reference symbols denote like, same or corresponding parts, and in which:

[0103] FIG. 1 shows a schematic illustration of off-shore wind energy installations;

[0104] FIG. 2a shows a perspective view of a subsea drilling machine according to an embodiment;

[0105] FIG. 2b shows a schematic cross section of FIG. 2a;

[0106] FIG. 3a shows a detail of a portion of the drilling machine shown in FIG. 2a;

[0107] FIG. 3b shows a schematic cross section of FIG. 3a, showing a detail of the feed system according to an embodiment;

[0108] FIG. 4 shows a detail of a drilling head according to an embodiment;

[0109] FIG. 5 shows a schematic illustration of a subsea drilling machine according to an alternative embodiment;

[0110] FIG. 6a schematically illustrates a seabed template arranged on the seabed;

[0111] FIG. 6b illustrates a section of the seabed template, with a subsea drilling machine according to embodiments arranged therein;

[0112] FIG. 7a illustrates mounting of a casing onto the drilling machine body; and

[0113] FIGS. 7b to 7d schematically illustrate the feed process of the drilling machine according to embodiments of the invention.

DESCRIPTION OF EMBODIMENTS

[0114] FIG. 1 schematically shows energy installations in the form of a wind mill 1, mounted in, or anchored to, the seabed via a foundation 2. FIG. 1 shows different types of foundations 2, all comprising a pile 4 drilled into and formed in the seabed 6. The wind mill is located in sea, at a water depth dl, the pile 4 having a drilling depth d2. As described above, there is a growing interest of locating sea based wind mills at still deeper waters, leading to various challenges, including drilling at larger water depths and reaching larger drilling depths, even at poor ground conditions. The present invention provides a subsea drilling machine for drilling with high drilling, or production, rates at a water depth of typically about 70 to 100 meters, or even up to 200 meters.

[0115] FIGS. 2a and 2b show an embodiment of a subsea drilling machine 8, also referred to as vertical subsea drilling machine, according to the present invention. FIG. 2a shows a perspective view of the drilling machine 8, while FIG. 2b shows a schematic cross section thereof. Although herein a vertical drilling machine is described, it can be noted that the same concept can also be applied to a drilling machine drilling in a direction inclined with respect to the vertical direction.

[0116] As can be seen in FIGS. 2a, 2b, the drilling machine comprises a riser pipe 10 and a drilling machine body 12 comprising a drilling head 14. The drilling machine body 12 is arranged at a lower end 16, also referred to as first end, of the riser pipe 10. The riser pipe and the drilling machine body are assembled together, forming what is referred to herein as a drill assembly.

[0117] At an upper end 18, also referred to as second end, of the riser pipe 10, a spoil exhaust 20 is provided, which is connected to a spoil pipe 48 arranged within the riser pipe. Further, a docking station 22 for a lifting arrangement, is provided and/or coupled to the upper end 18 of the riser pipe.

[0118] The drilling machine 8 further comprises a vertical feed system 24, arranged for inducing a movement of the riser pipe 10 such as to advance the drill assembly in the vertical direction with respect to the vertical feed system. Thereby, the drilling head, is advanced into the seabed during drilling operation.

[0119] As can be seen in in more detail in FIGS. 3a and 3b, the riser pipe 10 is provided with a plurality of racks 26 extending along substantially the full length of the riser pipe 10. The vertical feed system 24 comprises a corresponding plurality of sets of pinions 27 each driven by a motor 28. The pinions 27 engages with the racks 26 such as to advance the drill assembly.

[0120] The racks 26 are symmetrically distributed around the circumference of the riser pipe. The vertical feed system 24 comprises a plurality of sets of pinions 27 and associated motors 28, each set of pinions associated with one of the racks 26. In the illustrated embodiment four racks and four sets of pinions are provided, which has been seen to provide a stable and accurate advancement of the drill assembly. The set of pinions comprises four pinions associated with each rack. However, other numbers may also be possible.

[0121] The drilling machine body 12 is suspended from the riser pipe 10, and advanced into the seabed during drilling operation, by means of the cooperating rack and pinion system, which can be seen in detail in FIG. 3b. By the racks 26, extending along the length of the riser pipe 10, and the pinions 27 engaging therewith, the drilling machine body can be advanced in a substantially continuous manner. The drilling depth is mainly limited to the length of the riser pipe 10, in particular to the extension of the racks 26 provided thereon.

[0122] As can be seen in FIG. 2b, the riser pipe 10 is made up of a plurality of riser pipe modules, or sections, 30, bolted together such as to form one riser pipe 10. The different modules 30 are oriented with respect to one another such that the racks are aligned. By this arrangement, the length of the riser pipe 10 can be set in accordance with the intended drilling depth d2. The modules are mounted together prior to the start of the drilling operation.

[0123] As shown in FIGS. 2a and 2b, the vertical feed system 24 is coupled to an overshot tube 32, provided with a collar 34 configured for coupling to a drilling machine receiving section of a template, as will be described further below. The collar 34 may also be referred to as a landing and locking collar. Thereby, the vertical feed system 24 can be substantially fixated with respect to the seabed template and/or the casing.

[0124] The drill assembly, comprising the riser pipe 10 and drilling machine body 12, may be assembled with the vertical feed system 24 and the overshot tube 32, such as to form a single drill. This single drill can be lifted, via the docket station 22, from the vessel and lowered into the sea, to be lowered onto a seabed template, as will be described further below. The overshot tube further acts for protecting the drilling head 14 prior to and/or after a drilling operation, in particular while lowering the drill assembly into the seabed template.

[0125] FIG. 4 shows a detail of the drilling head 14.

[0126] As can be seen in FIG. 4, the drilling head 14 comprises a plurality of cutters 38, also referred to as drill units, which form the cutting and/or excavating action during the drilling operation. The cutters are selected in accordance with the ground conditions at the drilling site. The drilling head 14 may further comprise a plurality of under-reamers 40, which may be activated to extend in the radial direction during drilling operations, increasing the drilling diameter.

[0127] A drill head driving system may be provided in the drilling machine body, for controlling and operating the drilling head, i.e., operating the cutters 38 and, if applicable, the under-reamer cutters 40.

[0128] The drilling machine may further comprise one or more control units (not shown) for controlling operation of one or more of the components of the drilling machine, in particular the feed system 24, the drilling machine body 12 including the drilling head 14, and/or the spoil removal system (described herein below). Thereby, the drilling machine may be configured for semi-autonomous operation.

[0129] As shown in FIG. 2b the subsea drilling machine further comprises a spoil removal system, which comprises a spoil pipe 48 arranged internally within, and extending at least partly through, the drilling head 14, the drilling machine body 12, and the riser pipe 10. A dredge pump is arranged for suction of the drill cuttings, or spoil, into a spoil inlet 46 arranged in or close to the drilling head, pass it through the spoil pipe, to exhaust it via the spoil exhaust 20.

[0130] According to an alternative solution, the feed system, comprising pinions cooperating with racks provided on the riser pipe, described above with reference to FIGS. 2a, 2b, 3a and 3b, can be substituted with a hydraulic arrangement, which is illustrated in FIG. 5.

[0131] FIG. 5 shows a portion of a subsea drilling machine 108 including an alternative feed system based on hydraulic arrangements. The drilling machine 108 comprises a riser pipe 110, which does not have to be provided with racks. Other features of the drilling machine 108 are similar to those described above with reference to FIGS. 2a, 2b, 3a and 3b. The feed system 124, which in particular is a vertical feed system, comprises a first feed subsystem 126 and a second feed subsystem 128.

[0132] The first feed subsystem 126 comprises a first set of hydraulic actuators 130, or cylinders, arranged to induce a movement of a first gripper 132 along the vertical direction. The first gripper comprises first gripping means (not shown) for gripping and/or clamping the riser pipe 110 upon actuation of the first gripping means.

[0133] The second feed subsystem 128 comprises a second set of hydraulic actuators or cylinders 134 arranged to induce a movement of a second gripper 136 along the vertical direction. The second gripper 136 comprises second gripping means (not shown) for gripping and/or clamping the riser pipe upon actuation of the second gripping means.

[0134] The first and second gripping means may comprise hydraulically or pneumatically operated bladder means, for gripping or clamping the riser pipe, with a force sufficient for carrying the weight of the riser pipe and for applying a pushing force advancing the drill assembly into the ground or seabed.

[0135] While the first set of hydraulic actuators are operating such as to move the riser along the first direction, via the first gripping means activated to grip or clamp the riser, the second gripping means are in a deactivated state, such as to not grip or clamp the riser, and the second set of hydraulic actuators are set, or reset, in an initial state, such as to be ready for activation, when the first set of hydraulic actuators reach the end of their stroke, or actuation interval. When the first set of hydraulic actuators reach the end of their stroke, i.e., the end of their movement range, the second gripping means are actuated and the first gripping means deactivated, and the second set of hydraulic actuators are activated, thereby continuing the advancement of the riser pipe. Hence, by operating the first and second feed subsystems in an alternating manner, the drill assembly can be advanced in a substantially continuous manner.

[0136] The subsea drilling machine is configured to be used together with a template, such as a seabed template 50 shown in FIG. 6a, for mounting and/or holding it with respect to the seabed during drilling operation. The template 50 is generally lifted from a vessel and lowered onto the seabed, using a crane located on the vessel, and subsequently levelled, in a known manner.

[0137] The seabed template 50 comprises one or more drilling machine receiving sections 52 for receiving the drill assembly and the vertical feed system. When the drilling machine has been lowered into one of the sections 52, actuators 54 (shown in

[0138] FIG. 7b) provided on the template are activated to position and orient the drilling machine, in a manner as is known in the art. Once the drilling machine has been correctly positioned, the actuators of the template are deactivated, and the feed system 24 is fixated with respect to the template via the collar 34.

[0139] FIG. 6b schematically illustrates a drilling machine receiving section 52 of a seabed template, with a subsea drilling machine 8 arranged therein and having drilled some distance into the seabed 6. The collar 34 engages with the section 52 of the seabed template.

[0140] The operation of the subsea drilling machine and subsea drilling system, such as lowering the drilling machine toward the subsea template, coupling it to the subsea template, and operation of the drilling head, is typically operated from an operator console located on the vessel from which the drilling machine is deployed.

[0141] Further a machine monitoring system is provided, for monitoring and/or displaying various parameters associated with the operation of the subsea drilling machine. Such parameters may include drilling depth, drilling advancement rate, drilling advancement force, cutting face rotational speed, dredge pump pressure, machine diagnostics, etc. The machine monitoring system may comprise one or more control units, as mentioned above, configuring the drilling machine for autonomous or semi-autonomous operation.

[0142] FIGS. 7a to 7d illustrate initial steps of a method for drilling a vertical hole, or bore, in a seabed using the subsea drilling machine described above. Although described herein with reference to the drilling machine according to the first embodiment, using feeding via a rack and pinion system, the below method can be analogously applied to the drilling machine according to the second embodiment, using a hydraulic feed system. For ease of illustration, FIGS. 7b-7d only show one drilling machine receiving section 52. It is understood by the skilled person, that the seabed template may comprise one or more such sections 52.

[0143] FIG. 7a shows the arrangement of a casing 64, which may be used as a sacrificial casing, onto the drilling machine body. As described above, this casing can be drilled into the ground simultaneously with the advancement of the drilling head into the ground, in particular to a certain depth such as to stabilize unstable ground layers surrounding the hole which is being drilled. As also described above, the position of the drilling head with respect to the outer end of the casing can be adjusted based on the ground conditions at the drilling location.

[0144] As shown to the left in FIG. 7a, the drilling machine 8, provided with an overshot tube 32, is lowered over the casing 64. This operation is generally performed on a vessel from which the drilling operation is to take place.

[0145] The middle portion of FIG. 7a shows the casing 64 substantially fully inserted in between the drilling machine body 12 and the overshot tube 32. The casing is, temporarily, clamped or fixated with respect to the drilling machine body by clamp units, for example in the form of bladders, provided on the drilling machine body.

[0146] As shown to the left in FIG. 7a, after the casing has been mounted and fixated to the drilling machine body, the drilling machine, with the casing arranged thereto, can be lifted as one single unit, for deployment into the water.

[0147] The seabed template, as shown in FIG. 6a, has been arranged on the seabed, and preferably levelled with respect thereto such as to provide a substantially vertical orientation of a central axis of the section 52. Thereby, the holes, or piles, can be drilled substantially vertical, e.g. such as to form vertically oriented foundations.

[0148] In a first step of a drilling operation, shown in FIG. 7b, the drilling machine 8 is lowered in a vertical direction 56 towards the drilling machine receiving section 52, in order to be positioned in the receiving section 52. During and/or after lowering the drill into the receiving section, its position and orientation can be adjusted, e.g. such as to set it at a center position of the receiving section and orient it in the vertical direction, by means of a actuators 54 provided in the seabed template.

[0149] Although not shown in FIG. 7b, the drilling machine may be provided with a casing 64 as described with reference to FIG. 7a prior to lowering it towards the drilling machine receiving section 52. However, this may not be necessary for all applications, and the following description applies independently of whether or not such casing is provided.

[0150] Once correctly positioned oriented, the vertical feed system 24 is fixated with respect to the seabed template, as described above.

[0151] As illustrated in FIG. 7c, during drilling operation, the drilling head 14, if applicable together with the casing 64, is advanced in the vertical direction 56 into the seabed 6, by means of the rack and pinion system described above. During the advancement in the vertical direction, the drilling head is operated, e.g. by its drill units being rotated in a rotational direction 58, such as to perform an excavating action. The spoil produced during drilling is removed via the spoil removal system described above.

[0152] As illustrated in FIG. 7d, the drilling operation, and associated advancement of the drilling head 14 into the seabed 6, can be continued, substantially continuously, for a distance as set by the length of the riser pipe 10 and the extension of the racks along the riser pipe.

[0153] Once the intended drilling depth has been achieved, and/or if necessitated during the drilling operation, the drilling head 14 can be retracted from the bore hole by operating the vertical feed system in reverse, i.e., by driving the pinions in a reverse direction. Thereby, also the retraction of the drilling head, and in fact the drill assembly, can be performed in a substantially continuous manner.

[0154] It will be clear to a person skilled in the art that the scope of the invention is not limited to the examples discussed in the foregoing, but that several amendments and modifications thereof are possible without deviating from the scope of the invention as defined in the attached claims. While the invention has been illustrated and described in detail in the figures and the description, such illustration and description are to be considered illustrative or exemplary only, and not restrictive. The present invention is not limited to the disclosed embodiments but comprises any combination of the disclosed embodiments that can come to an advantage.

[0155] Variations to the disclosed embodiments can be understood and effected by a person skilled in the art in practicing the claimed invention, from a study of the figures, the description and the attached claims. In the description and claims, the word “comprising” does not exclude other elements, and the indefinite article “a” or “an” does not exclude a plurality. In fact it is to be construed as meaning “at least one”. The mere fact that certain features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope of the invention. Features of the above described embodiments and aspects can be combined unless their combining results in evident technical conflicts.