Nearshore seabed drilling

Abstract

Disclosed is a subsea vertical drilling rig having a drill assembly and a vertical feed system, the drill assembly being 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, the vertical feed system being configured to vertically advance the drill assembly, the riser pipe being provided with at least one rack extending along at least a portion of the length of the riser pipe, and the vertical feed system including a motor coupled to a pinion, the pinion being arranged to engage the rack to advance the drill assembly.

Description

[Technical field]

[0001]

[0001] The present invention relates to a subsea vertical drilling machine and associated methods for subsea drilling, in particular for installing and embedding piles or casings in the seabed to form marine foundations. The present invention is particularly suited to offshore applications, for example for forming foundation piles for wind energy facilities. [Background technology]

[0002]

[0002] Interest in renewable energy systems has led to the application of various marine energy resources, such as offshore wind farms. As the field of offshore wind farms develops, a desire to move to locations further from the coast and with greater ocean depths is recognized.

[0003]

[0003] To achieve this, energy installations such as wind turbines must have stable foundations in and / or fixed to the seabed. Development towards increasing water depths and distances from the shore brings challenges in forming foundations. At the same time, the impacts of drilling and piling in the seabed on the marine environment, for example noise and vibrations causing disturbance to marine life, must be limited.

[0004]

[0004] "Bauer Maritime Technologies", Copyright BAUER Maschinen GmbH 1.2016, and "Seabed Drilling for Marine Energy", available for download from http: / / www.bauer-renewables.co.uk / export / shared / documents / pdf / bst / print / 905_042_2_Seabed-Drilling-for-Marine-Energy.pdf, show various systems for seabed drilling.

[0005]

[0005] http: / / www.tms.nl / documents / news-items / subsea-pile-drilling-tool.xml?lang=en describes a subsea pile drilling tool for relief drilling of jacket piles.

[0006]

[0006] However, they have limited production rates and push down capabilities and do not provide sufficient drilling depth potential in a variety of different ground conditions such as rock, etc. Furthermore, these drilling tools generally require a casing that is clamped to the drilling tool during the drilling operation, and the casing is either already installed in the earth or is embedded in the earth during the drilling operation. Summary of the Invention [Problem to be solved by the invention]

[0007] SUMMARY OF THE PRESENT EMBODIMENT It is an object of the present invention to provide an offshore drilling machine having increased drilling speeds.

[0008] It is a further object of the present invention to provide an offshore drilling machine which increases the production rate of setting and embedding piles or shafts into the seabed.

[0009] It is a further object of the present invention to provide an offshore drilling machine which allows for greater drilling depths in greater water depths. [Means for solving the problem]

[0010]

[0010] At least some of these objects are achieved by a subsea drilling machine according to claim 1, a subsea drilling machine according to claim 11 and / or a subsea drilling machine according to claim 14.

[0011]

[0011] Embodiments of the invention are set forth in the dependent claims.

[0012] In a first aspect, a riser pipe having a first end, a second end, and a length extending between the first end and the second end; a drilling machine body including a drilling head coupled to a first end of the riser pipe; a drill assembly comprising: a feed system configured to advance the drill assembly in a first direction; The present invention provides an offshore drilling machine comprising: a riser pipe provided with at least one rack extending along at least a portion of the length of the riser pipe; and the feed system comprises a motor coupled to a pinion, the pinion being arranged to engage the rack to advance the drill assembly.

[0013]

[0013] The rack and pinion cooperate to allow for a nearly continuous advance of the drilling head into the seabed, and a nearly continuous retraction of the drilling head out of the seabed, without the need to interrupt the drilling operation to reset the system at the end of the stroke, or similar solutions. The rack and pinion system also allows for an increased down force of the drill onto the seabed, which allows for increased drilling speeds to be achieved.

[0014] The feed system allows for precise feed control of the drilling speed and the drilling force applied by the cutting face of the drilling head, allowing the excavator to be adapted to a variety of different ground conditions ranging from loose sand to firm clay and hard rock.

[0015] In an alternative solution, the cooperating rack and pinion can be replaced by a hydraulic system, as will be explained in more detail below with respect to the second aspect of the invention.

[0016]

[0016] As described above, the drilling machine body equipped with the drilling head is suspended from the riser pipe and driven by the riser pipe.

[0017]

[0017] With the drill assembly defined herein, the riser pipe receives, reacts to and / or transmits operational drilling torque, crown force and setback force. The riser pipe also reacts to environmental wave, wind and current loads. Torque from the drilling head is transmitted through the riser pipe to the feed system and further to the structure to which the feed system is secured, for example by clamping.

[0018] The rack preferably forms an integral part of the riser pipe.

[0019]

[0019] The length of the riser pipe and the extension of the rack along the riser pipe sets the drilling depth that can be achieved without interrupting operation, therefore the offshore drilling machine is referred to as a single pass system.

[0020]

[0020] The at least one rack preferably extends over substantially the entire length of the riser pipe, which makes it possible to maximise the digging depth permitted by the machine.

[0021]

[0021] Preferably, the riser pipe is provided with a number of said racks, said racks being distributed along the circumference of said riser pipe, each rack extending along at least a part of the length of said riser pipe, and said feed system comprises a corresponding number of pinions or sets of pinions, each pinion or each set of pinions being arranged to cooperate with one rack. The racks preferably extend along substantially the entire length of the riser pipe and are distributed symmetrically along its circumference. Preferably, the riser pipe is provided with two, three or four racks. This allows a stable positioning and movement of the riser pipe relative to the feed system to be achieved.

[0022]

[0022] The vertical feed system may include multiple pinions per rack. By arranging multiple pinions to engage each rack, the forward movement may be more stable and / or reliable.

[0023] The vertical feed system may also be operated in reverse to retract the drill assembly at the end of the drilling operation when the desired hole depth has been reached, and may also be operated in reverse to partially retract the drilling head during operation, for example, when casing is installed and embedded in the seabed, as described in more detail below.

[0024]

[0024] The feed system is typically a vertical feed system, and said first direction is vertical. The offshore drilling machine can also be called a vertical drilling machine, since it is designed to excavate the ground or seabed substantially vertically. However, the drilling machine may also be arranged to excavate in directions other than vertical, for example to install racked piles in offshore or nearshore structures.

[0025]

[0025] The drilling head is provided with drill units and / or cutters which can be selected depending on the soil or ground conditions at the drilling site, thereby allowing the drilling head to be adapted to a variety of different ground conditions.

[0026]

[0026] The drilling head may include underreamers that, when actuated, extend radially outward from the drilling head to increase the cutting diameter of the subsea drilling machine. Actuation, e.g., power, of the underreamer is typically provided at the drilling head.

[0027]

[0027] The drilling head, in particular the drill unit and / or the cutter, may be driven locally by a subsea gearbox and motor located in the drilling machine body.

[0028]

[0028] The drilling head is preferably designed so that its diameter can be varied. The diameter typically ranges from 2 to 3.5 meters or more. In many applications a nominal or default diameter of 3 meters is used.

[0029]

[0029] The outer diameter of the drill body may also be adjustable to match the drilling diameter. For this purpose, the drill body may be equipped with adjustable and / or replaceable external skis, which can be set according to the drilling diameter to provide stability to the drill body during drill advancement.

[0030]

[0030] Hydraulic and / or electrical umbilical cabling or routing for providing control, power, and / or other services to components located in the excavator body may be located inside the riser pipe, thereby protecting these components from environmental and / or operating elements.

[0031]

[0031] The riser pipe is further preferably equipped at its second, or upper, end with a docking mechanism or docking station for coupling to a lifting tool for lifting the drill assembly into and out of the water.

[0032]

[0032] The riser pipe preferably comprises a plurality of riser pipe modules, each riser pipe module comprising at least one rack extending along its length, said riser pipe modules being coupled together such that at least one rack of different modules are substantially aligned with each other. This allows the length of the riser pipe to be set to substantially correspond to the length of the pile foundation. The riser pipe can be assembled such that its length corresponds to the length of the pile foundation. The modules are preferably bolted together to form a complete riser pipe prior to the drilling operation. This avoids the need for additional riser pipe modules or sections during the drilling operation. The length of the riser pipe modules or riser pipe sections is in the range of 5 to 15 metres, preferably 10 metres.

[0033]

[0033] The feed system may be coupled to a tube, also called an overshot tube, which may be configured to couple to a secondary entity, such as a drilling machine receiver of a template, and to substantially fix the feed system relative to the secondary entity. To this end, the tube may be provided with a collar, sometimes also called a landing interface. This allows the feed system to be clamped and / or otherwise fixedly coupled to a template, such as a subsea template, a conductor template and / or a pile gate, for driving into the seabed. The socket may be configured to clamp and fasten externally to the template for cased and open socket drilling, or internally to the pile for pile relief drilling. This allows the drilling and environmental loads to be transferred to the template or the relief drilled pile. This device may increase the rotary cutting speed, providing a high drilling production rate. It may increase the rotary torque, providing a high drilling force. It may achieve a high push down capacity for casing installation. This allows a higher production rate to be achieved than prior art systems.

[0034]

[0034] An overshot tube provides further protection for the drilling head before and / or after a drilling operation. The overshot surrounds the drilling head before and during insertion of the drill into the template. After the drilling operation, the drilling head can be retracted into the overshot tube before lifting the drill from the template and / or the sacrificial casing that was inserted into the seabed during the drilling operation.

[0035]

[0035] In some embodiments, the subsea drilling machine further preferably comprises a spoil removal system, the spoil removal system comprising a conduit extending through the drilling head and the riser pipe and a spoil discharge at the second end of the riser pipe. A solid spoil pipe is therefore provided inside the riser pipe and the drilling head and is protected by the riser pipe. The spoil pipe is configured to transport the spoil cuttings away from the drilling head and the drill cuttings provided thereon to the spoil discharge. The subsea drilling machine preferably comprises a pump, also called a dredge pump, arranged in the drilling machine body, in particular in or near the drilling head, the pump being configured to pump the spoil from the drilling head to the spoil discharge. This allows an increase in spoil removal capacity and therefore in the drilling speed, compared to air-lifted spoil removal systems.

[0036]

[0036] Alternatively, in other embodiments, the excavator may be configured to use air lift excavation removal.

[0037]

[0037] In accordance with the above, the components of the drilling machine, i.e. the riser pipe, preferably made up of several sections or modules bolted together, the drilling machine body including the drilling head and the feed system, are assembled to form a single unit which can be lifted from the vessel by a crane, positioned against the template and lowered, and then removed from the crane. During the drilling operation, the crane is not required. This allows the vessel's crane to be available for other operations carried out on or from the vessel.

[0038]

[0038] The offshore drilling machine may further comprise one or more control units configured to control the operation of one or more of the feed system, the drilling machine, in particular the drilling head drive system, and / or the cuttings removal system. The control units may be configured to control the operation of one or more parts or components of the feed system, the drilling machine, and / or the cuttings removal system. This allows the offshore drilling machine, or at least a part thereof, to be configured for self-contained (semi-)autonomous operation.

[0039] According to a second aspect, a riser pipe having a first end, a second end, and a length extending between the first end and the second end; a drilling machine body including a drilling head coupled to a first end of the riser pipe; a drill assembly comprising: a feed system configured to advance the drill assembly in a first direction, a first feeding subsystem comprising a first set of hydraulic actuators arranged to guide movement of a first gripper along the first direction, the first gripper comprising a first gripping means for gripping and / or clamping a riser pipe during actuation of the first gripping means; a second feed subsystem comprising a second set of hydraulic actuators arranged to guide movement of a second gripper along the first direction, the second gripper comprising a second gripping means for gripping and / or clamping the riser pipe during actuation of the second gripping means; A feed system comprising: An offshore drilling machine comprising:

[0040]

[0040] The excavator feed system according to the second aspect forms an alternative to the excavator feed system of the first aspect and one or more racks provided on the riser pipe. The first and second gripping means may comprise bladder means, which may be hydraulically and / or pneumatically operable to grip or clamp the riser pipe with sufficient force to support the weight of the riser pipe and to apply a thrust force to advance the drill assembly into the earth or seabed.

[0041]

[0041] The drill assembly, in particular the drilling head, can be advanced substantially continuously by alternating between the first and second feed subsystems. While the first set of hydraulic actuators is operated to move the riser along a first direction via the first gripping means which is actuated to grip or clamp the riser, the second gripping means is deactivated so as not to grip or clamp the riser, and the second set of hydraulic actuators is set or reset to an initial state so as to be ready to operate when the first set of hydraulic actuators reach the end of their stroke or operating interval. When the first set of hydraulic actuators reach the end of their stroke, i.e. the end of their range of movement, the second gripping means is actuated, the first gripping means is deactuated, and the second set of hydraulic actuators is actuated, thereby continuing the advancement of the riser pipe. Thus, the drill assembly can be advanced substantially continuously by alternating between the first and second feed subsystems.

[0042]

[0042] The advantages described in relation to the first embodiment, which are achieved by means of a rack and pinion, can hereby alternatively be achieved, at least to a large extent, by using a hydraulic actuator.

[0043]

[0043] Various embodiments of the excavator of the first aspect can be applied to the excavator of the second aspect.

[0044] According to a third aspect, a riser pipe having a first end, a second end, and a length extending between the first end and the second end; a drilling machine body including a drilling head coupled to a first end of the riser pipe; a drill assembly comprising: a feed system configured to advance the drill assembly in a first direction; a cuttings removal system including a conduit extending through the drilling head and the riser pipe, and a cuttings discharge portion disposed at a second end of the riser pipe; An offshore drilling machine comprising: As described above with respect to the excavator excavation removal system according to the first aspect, the internal excavation removal system allows for efficient excavation removal and contributes to increased excavation speed.

[0045]

[0045] The excavator preferably includes a pump, also called a dredge pump, arranged within the excavator body, the pump being arranged to pump the soil from the excavation head to the soil discharge section.

[0046]

[0046] The offshore drilling machine of the third aspect may further comprise any one or more features and / or embodiments of the offshore drilling machine of the first aspect.

[0047]

[0047] The offshore drilling machines of the first, second and third aspects may each have corresponding features and / or embodiments, and their corresponding technical effects and advantages, as described above.

[0048] According to a fourth aspect, there is provided a method for drilling a hole in a seabed, the method comprising: providing a drill assembly comprising a riser pipe and a drilling body comprising a drilling head coupled to a first end of the riser pipe; providing a feed system configured to advance the drill in a first direction; assembling the drill assembly and the feed system to form a drilling machine; placing a template on the seabed comprising one or more drilling machine receivers; placing the excavator in one of the excavator receptacles; fixing the feed system relative to the template; operating the feed system while operating the drilling head to advance the drilling head into the seabed by substantially continuously moving the riser pipe relative to the feed system; retracting the drill from the borehole after a final depth of the vertical borehole is reached; Includes.

[0049]

[0049] The method according to the fourth aspect is preferably carried out using an offshore drilling machine according to the first or second aspect, whereby the technical effects and advantages as described above are achieved using this method.

[0050]

[0050] The step of advancing the drilling head is preferably performed by a rotating pinion engaging a rack extending along at least a portion of the length of the riser pipe. This may be performed by the offshore drilling machine of the first aspect.

[0051] Alternatively, the step of advancing the drill assembly may be performed by alternating operation of a first feeding subsystem and a second feeding system, one of the first feeding subsystem and the second feeding subsystem being operated to advance the drill assembly while the other of the first feeding subsystem and the second feeding subsystem is reset. This may be performed by the offshore drilling machine of the second aspect.

[0052] The method comprises: and placing a casing substantially surrounding an excavator body prior to the step of placing the excavator in one of the excavator receptacles. It may further include.

[0053]

[0053] The drilling machine according to the invention does not require a casing or a cased hole to advance the drilling head into the earth, so the length of the casing does not have to correspond to the drilling depth. The length of the casing can be selected to stabilize the borehole during the drilling operation and during subsequent operations such as the introduction of piles into the borehole. For this reason, a casing length corresponding to the depth of the unstable layer of the earth or seabed may be sufficient. If left in the hole after the drilling operation, the casing may be called a sacrificial casing.

[0054]

[0054] The casing may be clamped or fixed to the excavator body, preferably by means of a clamping unit, for example in the form of a bladder, provided on the excavator body, which can be inflated / deflated to clamp / loosen the casing relative to the excavator body.

[0055]

[0055] The casing may be placed on the drilling machine by lowering the drill assembly over the casing, so that the drilling machine body enters the casing. Once a specified relationship between the casing and the drilling machine body is achieved, the clamping unit may be actuated to temporarily clamp the casing against the drilling machine body. The casing and drilling machine may be lowered simultaneously to the seabed. The casing and drilling machine may be advanced simultaneously, at least to a particular depth, and deposited on the seabed as a unit.

[0056]

[0056] In embodiments in which the drill assembly is provided with an overshot tube as described above with reference to the first aspect, the casing is preferably positioned between the overshot tube and the drill body so as to be substantially completely located between the overshot tube and the drill body when the drill is lowered into the water.

[0057]

[0057] The casing may suitably be advanced into the seabed together with the drill assembly.

[0058]

[0058] The position of the drill head relative to the outer end of the casing can be set according to the ground conditions at the drilling site. This makes the drilling machine according to the invention suitable for a wide range of different ground conditions. If necessary, the position of the drill head relative to the casing can be adjusted during the drilling operation.

[0059]

[0059] During the step of advancing the drill assembly into the seabed, the drilling head may protrude in front of the casing. This is advantageous when drilling rock. By protruding the drilling head from the casing, the drilling head moves in front of the casing so that the casing can be advanced into the hole formed by the movement of the drilling head. This allows the casing to be advanced into the earth together with the drilling head in the rocky area.

[0060]

[0060] Alternatively, the drilling head may be located within the casing during the step of advancing the drill assembly into the seabed. This is advantageous when drilling unstable formations such as sand and / or clay layers. Operating the drill head inside the casing contributes to a stable drilling operation during drilling of sand and / or clay.

[0061]

[0061] The method may include advancing the drilling head further into the earth when the casing has been inserted into the seabed to a casing depth, which may be set as described above to cover unstable formations at the drill location and stabilize the wellbore.

[0062]

[0062] The step of advancing the drilling head may include the step of advancing and operating an underreaming cutter of the drilling head, for example, to drill at a diameter equal to or greater than the outer diameter of the casing.

[0063]

[0063] The method may further include the step of removing the cuttings through a cuttings return pipe disposed within the drilling machine body and the riser pipe, and discharging the cuttings at a cuttings discharge section disposed at a second end of the riser pipe.

[0064]

[0064] The retracting step may preferably be performed by operating the feed system in reverse.

[0065]

[0065] The feed system may also be operated in reverse during part of the drilling operation, for example if a boulder or the like is struck while advancing the drill assembly. In such a situation, advancement of the drill assembly may be interrupted and the drill assembly then reset or repositioned before continuing advancement of the drill assembly.

[0066]

[0066] As described above, when advancing the drill assembly with the casing, the feed system may be operated in reverse, for example to adjust the position and / or orientation of the casing, before resuming advancement of the drill assembly and casing.

[0067]

[0067] The above-described method may preferably be performed semi-autonomously. One or more of the steps described herein above may be performed (semi-)autonomously or automatically.

[0068]

[0068] The subsea drilling machine described herein, also referred to as a vertical subsea drilling machine, may be advantageously applied in pile drilling and driving to form foundations for offshore energy installations, such as, for example, offshore wind farms, etc. It is equally applicable to other types of marine energy installations, such as, for example, tidal turbines.

[0069] It is expected that the excavator described herein will be used in water depths of 50 to 100 metres, for example 70 metres, and with an excavation depth of up to 50 metres, however it may also be used in water depths of up to 200 metres.

[0070]

[0070] As described above, the drilling machine provides open socket drilling, cased socket drilling, and pile relief drilling.

[0071]

[0071] A single pass drilling system is achieved by a riser pipe assembled to match the drilling depth and equipped with a rack which cooperates with a pinion of the vertical feed system.

[0072]

[0072] As described herein above, the excavator may be configured to operate in a self-contained, semi-autonomous manner.

[0073]

[0073] The drilling machine can be used in a variety of ground conditions, including unstable layers such as sand, and can install and embed foundation piles into the seabed with high stability. Cased boreholes can be installed and embedded into unstable layers and underlying rock masses using the machines and methods as described herein above.

[0074] Further features and advantages of the present invention will become apparent upon reading the description of the invention by non-limiting and non-exclusive embodiments. These embodiments should not be interpreted as limiting the scope of protection. Those skilled in the art will understand that other alternatives and equivalent embodiments of the invention can be devised and put into practice without departing from the scope of the invention. The embodiments of the present invention will be described with reference to the figures of the accompanying drawings, in which similar or identical reference symbols represent similar, identical or corresponding parts. [Brief description of the drawings]

[0075] [Figure 1] 1 is a schematic diagram of an offshore wind energy installation. [Figure 2a] FIG. 1 is a perspective view of an offshore drilling machine according to one embodiment. [Figure 2b] FIG. 2b is a schematic cross-sectional view of FIG. 2a. [Figure 3a] FIG. 2b shows a detail of a portion of the excavator shown in FIG. 2a. [Figure 3b] FIG. 3b is a cross-sectional view of FIG. 3a showing details of a feed system according to an embodiment. [Figure 4] FIG. 2 illustrates details of a drilling head according to one embodiment. [Diagram 5]1 is a schematic diagram of an offshore drilling machine according to an alternative embodiment; [Figure 6a] FIG. 2 is a schematic diagram of a subsea template disposed on the seabed; [Figure 6b] FIG. 2 illustrates a cross-section of a subsea template with a subsea drilling machine positioned thereon, according to an embodiment. [Figure 7a] FIG. 4 is a diagram showing the attachment of the casing to the excavator body. [Figure 7b] FIG. 2 illustrates a schematic diagram of a first step of an excavator feeding process according to an embodiment of the present invention. [Figure 7c] FIG. 13 illustrates a schematic diagram of a second step of the excavator feeding process according to an embodiment of the present invention. [Figure 7d] FIG. 13 is a schematic diagram illustrating a third step of the excavator feeding process according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0076]

[0086] In Fig. 1 an energy installation in the form of a wind turbine 1 attached to or fixed to the seabed via foundations 2 is shown diagrammatically. Fig. 1 shows different types of foundations 2, all of which comprise piles 4 embedded in and formed on the seabed 6. The wind turbines are located at a water depth d1 in the sea, the piles 4 having an excavation depth d2. As mentioned above, there is an increasing interest in locating offshore wind turbines in ever deeper waters, leading to various challenges including drilling at greater water depths and reaching greater drilling depths, even in poor ground conditions. The present invention provides a subsea drilling machine for drilling at high drilling or production rates, typically in water depths of about 70-100 meters, and even up to 200 meters.

[0077]

[0087] Figures 2a and 2b show an embodiment of a seabed drilling machine 8, also called a vertical seabed drilling machine, according to the present invention. Figure 2a shows a perspective view of the drilling machine 8 and Figure 2b shows a schematic cross-sectional view thereof. Although a vertical drilling machine is described herein, it will be appreciated that the same concepts can also be applied to drilling machines that drill in a direction inclined to the vertical.

[0078]

[0088] As is apparent from Figures 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 disposed at a lower end 16, also referred to as the first end, of the riser pipe 10. The riser pipe and the drilling machine body are assembled to form what is referred to herein as a drill assembly.

[0079]

[0089] At the upper end 18, also referred to as the second end, of the riser pipe 10, a cuttings discharge section 20 is provided which is connected to a cuttings pipe 48 disposed within the riser pipe. Furthermore, a docking station 22 for a lifting device is provided and / or coupled to the upper end 18 of the riser pipe.

[0080]

[0090] The drilling machine 8 further comprises a vertical feed system 24 arranged to guide movement of the riser pipe 10 to advance the drill assembly vertically relative to the vertical feed system, thereby advancing the drilling head into the seabed during drilling operations.

[0081]

[0091] 3a and 3b, the riser pipe 10 is provided with a number of racks 26 that extend along substantially the entire length of the riser pipe 10. The vertical feed system 24 includes a corresponding set of pinions 27 each driven by a motor 28. The pinions 27 engage the racks 26 to advance the drill assembly.

[0082]

[0092] 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 an associated motor 28, with 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 have been found to provide stable and accurate advancement of the drill assembly. Each set of pinions has four pinions associated with each rack. However, other numbers may be possible.

[0083]

[0093] The drilling machine body 12 is suspended from the riser pipe 10 and advanced into the seabed during drilling operations by a cooperating rack and pinion system, seen in detail in Figure 3b. The drilling machine body can be advanced substantially continuously by a rack 26 extending along the length of the riser pipe 10 and a pinion 27 engaging the rack 26. The drilling depth is primarily limited by the length of the riser pipe 10 and in particular the extension of the rack 26 thereon.

[0084]

[0094] As is evident from Figure 2b, the riser pipe 10 is made up of several riser pipe modules or sections 30 bolted together to form one riser pipe 10. The different modules 30 are oriented relative to each other such that the racks are aligned. This arrangement allows the length of the riser pipe 10 to be set according to the intended drilling depth d2. The modules are attached to each other before the start of the drilling operation.

[0085]

[0095] As shown in Figures 2a and 2b, the vertical feed system 24 is coupled to an overshot tube 32 with a collar 34 configured to couple to a drilling machine receiver of the template, as described further below. The collar 34 may also be referred to as a landing lock collar, which allows the vertical feed system 24 to be substantially fixed relative to the subsea template and / or casing.

[0086]

[0096] The drill assembly, including the riser pipe 10 and the drilling machine body 12, may be assembled with the vertical feed system 24 and the overshot tube 32 to form a single drill. The single drill may be lifted from the vessel via the docking station 22 and lowered into the sea for lowering onto a subsea template, as described further below. The overshot tube further serves to protect the drilling head 14 before and / or after a drilling operation, particularly during lowering of the drill assembly into the subsea template.

[0087]

[0097] FIG. 4 shows the drilling head 14 in detail.

[0088]

[0098] As is evident from Figure 4, the drilling head 14 includes a number of cutters 38, also referred to as drill units, which form a cutting and / or drilling action during a drilling operation. The cutters are selected according to the ground conditions at the drilling site. The drilling head 14 may further include a number of underreamers 40 which may be actuated to extend radially during the drilling operation to increase the drilling diameter.

[0089]

[0099] A drill head drive system may be provided on the drilling machine body for controlling and operating the drilling head, i.e., the cutter 38 and, if applicable, the under-ream cutter 40.

[0090]

[0100] The excavator may further comprise one or more control units (not shown) for controlling the operation of one or more of the excavator components, in particular the feed system 24, the excavator body 12 including the drilling head 14, and / or the excavation removal system (described later herein), such that the excavator may be configured for semi-autonomous operation.

[0091]

[0101] As shown in Figure 2b, the subsea drilling machine further comprises a cuttings removal system comprising a cuttings pipe 48 disposed within and extending at least partially through the drilling head 14, the drilling machine body 12, and the riser pipe 10. A dredge pump is arranged to draw drill cuttings or cuttings into a cuttings inlet 46 disposed in or near the drilling head and pass it through the cuttings pipe and discharge it via the cuttings discharge 20.

[0092]

[0102] According to an alternative solution, the feed system described above with reference to Figures 2a, 2b, 3a and 3b, comprising a pinion cooperating with a rack provided on the riser pipe, can be replaced by a hydraulic device as shown in Figure 5.

[0093]

[0103] Figure 5 shows a portion of a subsea drilling machine 108 including an alternative feeding system based on a hydraulic device. The drilling machine 108 includes a riser pipe 110 that does not need to include a rack. Other features of the drilling machine 108 are similar to those described above with reference to Figures 2a, 2b, 3a and 3b. The feeding system 124, which is specifically a vertical feeding system, includes a first feeding subsystem 126 and a second feeding subsystem 128.

[0094]

[0104] The first feed subsystem 126 comprises a first set of hydraulic actuators 130 or cylinders arranged to guide movement of a first gripper 132 along a vertical direction. The first gripper comprises a first gripping means (not shown) for gripping and / or clamping the riser pipe 110 during actuation of the first gripping means.

[0095]

[0105] The second feed subsystem 128 includes a second set of hydraulic actuators or cylinders 134 arranged to guide movement of a second gripper 136 along a vertical direction. The second gripper 136 includes a second gripping means (not shown) for gripping and / or clamping the riser pipe during actuation of the second gripping means.

[0096]

[0106] The first gripping means and the second gripping means may comprise hydraulically or pneumatically operated bladder means for gripping or clamping the riser pipe with sufficient force to support the weight of the riser pipe and apply a thrust to advance the drill assembly into the earth or seabed.

[0097]

[0107] While the first set of hydraulic actuators is operative to move the riser along a first direction via the first gripping means which is actuated to grip or clamp the riser, the second gripping means is deactivated so as not to grip or clamp the riser, and the second set of hydraulic actuators is set or reset to an initial state so as to be ready to operate when the first set of hydraulic actuators reach the end of their stroke or operating interval. When the first set of hydraulic actuators reach the end of their stroke, i.e. the end of their range of movement, the second gripping means is actuated, the first gripping means is deactuated, and the second set of hydraulic actuators is actuated, thereby continuing the advancement of the riser pipe. Thus, by alternating operation of the first and second feeding subsystems, the drill assembly can be advanced substantially continuously.

[0098]

[0108] The offshore drilling machine is configured to be used with a template, such as the offshore template 50 shown in Figure 6a, for mounting and / or holding it against the seabed during drilling operations. The template 50 is typically lifted from the vessel using a crane located on the vessel and lowered to the seabed, and then leveled in a known manner.

[0099]

[0109] The subsea template 50 includes one or more drilling machine receivers 52 for receiving the drill assembly and vertical feed system. Once the drilling machine is lowered into one of the receivers 52, an actuator 54 (shown in FIG. 7b) on the template is activated to position and orient the drilling machine in a manner known in the art. Once the drilling machine is correctly positioned, the template actuator is deactivated and the feed system 24 is secured relative to the template via collar 34.

[0100]

[0110] Figure 6b shows diagrammatically the drilling machine receiving portion 52 of the subsea template with the subsea drilling machine 8 positioned therein which has excavated some distance into the seabed 6. The collar 34 engages with the receiving portion 52 of the subsea template.

[0101]

[0111] Operation of the subsea drilling machine and subsea drilling system, such as lowering the drilling machine towards the subsea template, docking the drilling machine to the subsea template, and operation of the drilling head are typically operated from an operator console located on the vessel from which the drilling machine is deployed.

[0102]

[0112] Further provided is a machine monitoring system for monitoring and / or displaying various parameters associated with operation of the subsea drilling machine. Such parameters may include drilling depth, drilling advancement rate, drilling advancement force, cutting face rotation rate, dredge pump pressure, machine diagnostics, etc. The machine monitoring system may include one or more control units as described above that configure the drilling machine for autonomous or semi-autonomous operation.

[0103]

[0113] Figures 7a-7d show initial steps of a method for drilling a vertical hole or borehole in the seabed using the subsea drilling machine described above. Although described herein with reference to a drilling machine according to a first embodiment using feeding by a rack and pinion system, the following method is equally applicable to a drilling machine according to a second embodiment using a hydraulic feeding system. For ease of explanation, Figures 7b-7d show only one drilling machine receptacle 52. It will be appreciated by those skilled in the art that a subsea template may comprise one or more such receptacles 52.

[0104]

[0114] Figure 7a shows the placement of a casing 64 on the drilling machine body, which may be used as a sacrificial casing. As mentioned above, this casing may be embedded in the earth at the same time as the drilling head is advanced into the earth, particularly to a particular depth to stabilize unstable ground layers around the hole being drilled. Also, as mentioned above, the position of the drilling head relative to the outer end of the casing may be adjusted based on the ground conditions at the drilling site.

[0105]

[0115] As shown on the left hand side of Figure 7a, a drilling machine 8 with an overshot tube 32 is lowered over the casing 64. This operation is typically performed on board the vessel from which the drilling operation will be carried out.

[0106]

[0116] The central portion of Figure 7a shows the casing 64 substantially fully inserted between the excavator body 12 and the overshot tube 32. The casing is temporarily clamped or secured to the excavator body by a clamping unit, e.g. in the form of a bladder, provided on the excavator body.

[0107]

[0117] As shown on the left side of Figure 7a, after the casing has been attached and secured to the excavator body, the excavator, with the casing disposed thereon, can be lifted as one single unit for deployment into the water.

[0108]

[0118] The seabed template is placed on the seabed, as shown in Figure 6a, and is preferably horizontal to the seabed so as to provide a substantially vertical orientation of the central axis of the receiver 52. This allows holes or piles to be drilled substantially vertically, for example to form vertically oriented foundations.

[0109]

[0119] In a first step of the drilling operation, shown in Figure 7b, the drill machine 8 is lowered in a vertical direction 56 towards the drill machine receiver 52 so as to be positioned within the receiver 52. During and / or after lowering the drill into the receiver, actuators 54 provided on the seabed template may adjust the position and orientation of the drill, for example to place the drill in a central position in the receiver and orient the drill vertically.

[0110]

[0120] Although not shown in Figure 7b, the excavator may be provided with a casing 64 as described with reference to Figure 7a before being lowered into the excavator receiver 52. However, this may not be necessary in all applications and the following description applies regardless of whether such a casing is provided.

[0111]

[0121] Once properly positioned and oriented, the vertical feed system 24 is secured relative to the subsea template as described above.

[0112]

[0122] As shown in Figure 7c, during drilling operations, the drilling head 14, together with a casing 64, if applicable, is advanced vertically 56 into the seabed 6 by the rack and pinion system described above. During vertical advancement, the drilling head operates by rotating its drill unit in a rotational direction 58, for example to perform a drilling operation. Cuttings produced during drilling are removed via the cuttings removal system described above.

[0113]

[0123] As shown in FIG. 7d, drilling operations, and the advancement of the associated drilling head 14 to the seabed 6, can continue substantially continuously over a distance set by the length of the riser pipe 10 and the extension of the rack along the riser pipe.

[0114]

[0124] Once the intended drilling depth has been achieved and / or if required during the drilling operation, the drilling head 14 can be retracted from the borehole by reversing the vertical feed system, i.e. by driving the pinion in the opposite direction, such that retraction of the drilling head, and indeed the drill assembly, can also be performed substantially continuously.

[0115]

[0125] It will be apparent to those skilled in the art that the scope of the present invention is not limited to the above examples, and that several modifications and variations are possible without departing from the scope of the present invention as defined in the appended claims. Although the present invention has been illustrated and described in detail in the drawings and description, such illustration and description are to be considered as illustrative or exemplary only and not restrictive. The present invention is not limited to the disclosed embodiments, but includes any combination of the disclosed embodiments that may be advantageous.

[0116]

[0126] Variations to the disclosed embodiments can be understood and achieved by those skilled in the art in practicing the claimed invention, upon consideration of the drawings, the description and the appended claims. In this specification and claims, the word "comprise" does not exclude other elements, and the indefinite article "a" or "an" does not exclude a plurality. In fact, it should be interpreted to mean "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 advantageously used. Any reference signs in the claims should not be interpreted as limiting the scope of the invention. The features of the above-mentioned embodiments and aspects can be combined, unless such combination results in an obvious technical contradiction.

Claims

1. A subsea drilling machine (8) comprising a drill assembly and a feed system (24), The drill assembly includes: a riser pipe (10) having a first end (16), a second end (18), and a length extending between said first end (16) and said second end (18); a drilling machine body (12) including a drilling head (14) coupled to the first end (16) of the riser pipe (10); Equipped with the feed system (24) is configured to advance the drill assembly in a first direction; the riser pipe (10) is provided with at least one rack (26) extending along at least a portion of the length of the riser pipe (10); The offshore drilling machine (8), wherein the feed system (24) comprises a motor (28) coupled to a pinion (27), the pinion (27) being arranged to engage the rack (26) to advance the drill assembly in the first direction, the offshore drilling machine (8) further comprises a drillings removal system; the cuttings removal system comprises a conduit extending through the drilling head (14) and the riser pipe (10), and a cuttings discharge section provided at the second end (18) of the riser pipe (10). Subsea drilling rig (8).

2. The offshore drilling machine (8) of claim 1, wherein the at least one rack (26) extends substantially the entire length of the riser pipe (10).

3. 3. The offshore drilling machine (8) according to claim 1 or 2, wherein the riser pipe (10) is provided with a plurality of the racks (26), the racks (26) being distributed around the circumference of the riser pipe (10), each of the racks (26) extending along at least a portion of the length of the riser pipe (10), and the feed system (24) comprises a corresponding plurality of pinions (27) or a plurality of sets of pinions (27), each of the pinions (27) or the set of pinions (27) being arranged to cooperate with one of the racks (26).

4. said feed system (24) comprising a plurality of pinions (27) for each of said racks (26); and / or the feed system (24) being a vertical feed system (24) and the first direction being a vertical direction; A subsea drilling machine (8) according to any one of claims 1 to 3.

5. the riser pipe (10) comprises a plurality of riser pipe modules, each of the riser pipe modules comprising at least one rack (26) extending along a length of the riser pipe module; The offshore drilling machine (8) according to any one of claims 1 to 4, wherein the riser pipe modules are coupled to each other such that the at least one rack (26) of different riser pipe modules are substantially aligned with each other.

6. The subsea drilling machine (8) of any one of claims 1 to 5, wherein the feed system (24) is coupled to a tube configured to couple to a secondary entity, the tube being a drilling machine receptacle of a template, and to substantially fix the feed system (24) relative to the secondary entity.

7. The subsea drilling machine (8) of any one of claims 1 to 6, further comprising a pump disposed in the drilling machine body (12) and configured to pump drillings from the drilling head (14) to the drillings discharge section.

8. The subsea drilling machine (8) according to any one of claims 1 to 7, wherein the drilling machine body (12) further comprises a drilling head drive system for operating the drilling head (14).

9. The offshore drilling machine (8) of any one of claims 1 to 8, further comprising a control unit configured to control operation of one or more of the feed system (24), the drilling head drive system, and / or the drillings removal system.

10. 1. A method for drilling a hole in a seabed, comprising: providing a drill assembly comprising a riser pipe (10) and a drilling machine body (12) comprising a drilling head (14) coupled to a first end (16) of the riser pipe (10); providing a feed system (24) configured to advance the drill assembly in a first direction; assembling said drill assembly and said feed system (24) to form a drilling machine (8); placing a template on the seabed comprising one or more excavator receivers; placing said excavator (8) in one of said excavator receptacles; Fixing the feed system (24) relative to the template; operating the drilling head (14) while operating the feed system (24) to advance the drill assembly into the seabed by substantially continuously moving the riser pipe (10) relative to the feed system (24); retracting the drill assembly from the hole after a final depth of the vertically drilled hole is reached; A method comprising: the method further comprising removing the cuttings through a cuttings return pipe disposed within the excavator body (12) and the riser pipe (10) and discharging the cuttings at a cuttings discharge section disposed at a second end (18) of the riser pipe (10). method.

11. the step of advancing the drill assembly is performed by a rotating pinion (27) engaging a rack (26) extending along at least a portion of the length of the riser pipe (10); or the advancing step of the drill assembly is performed by alternating operation of a first feeding subsystem and a second feeding subsystem, one of the first feeding subsystem and the second feeding subsystem being operated to advance the drill assembly while the other of the first feeding subsystem and the second feeding subsystem is reset. The method of claim 10.

12. 12. The method according to claim 10 or 11, further comprising the step of placing a casing substantially surrounding the excavator body (12) prior to the step of placing the excavator (8) in one of the excavator receptacles.

13. The method of claim 12 , wherein the casing is advanced into the seabed with the drill assembly.

14. during the step of advancing the drill assembly into the seabed, the drilling head (14) projects forward of the casing; or During the step of advancing the drill assembly into the seabed, the drilling head (14) is disposed within the casing.

14. The method according to claim 12 or 13.

15. A method according to any one of claims 12 to 14, comprising advancing the drilling head (14) further into the earth when the casing is inserted into the seabed to a casing depth.

16. The method according to any one of claims 10 to 15, wherein the retracting step is performed by operating the feed system (24) in reverse.

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