A ROTATING CUTTING HEAD AND CUTTING SYSTEM AS WELL AS A METHOD OF CUTTING A HOLLOW, LONGITUDINAL OBJECT FROM WITHIN

Field of the Invention

The present invention relates to a rotating cutting head that expels cutting fluid from at least two nozzles at a surface to be cut, in particular a rotating cutting head for use in a pipe. The rotating cutting head is used as part of a cutting tool in a cutting system.

Background

Known cutting heads have a single nozzle to project cutting fluid at a surface to be cut.

To achieve a more efficient cut some devices use a larger nozzle however this requires a larger amount of cutting fluid which increases cost.

Alternatively multiple separate cutting heads can be used to achieve an increase in the number of nozzles for expelling cutting fluid, however this increases the number of separate supply hoses required which is not always viable predominantly due to space constraints in a pipe and on support holding equipment, which may for example be a sea going vessel.

Furthermore, many current devices have a single nozzle and a single supply hose which means that there are several potential failure points. This is undesirable if there is no backup should a failure occur.

Failures are typically difficult to repair on site as accessing components parts may be difficult. This is because for example a cutting head assembly may have to be removed, and pipes disconnected. This operation takes time to complete and therefore can lead to significant delays. The invention has been developed to overcome problems, such as described herein or otherwise present in existing cutting heads. Accordingly, it may be an object of the present invention to overcome one or more problems associated with the prior art, such as described herein.

US patent US 10525569 (Linde) discloses a water-abrasive cutting system with a cutting head and a fixing device for fitting the cutting head to a wall to be cut.

European patent application EP 1199136 (Linde) discloses a method for filling a pressurised container and device for producing a jet of slurry.

US patent US 1018114 (Linde) discloses a water-abrasive suspension cutting facility with at least one high-pressure source which provides a carrier fluid at high pressure, with at least one exit nozzle with a high-pressure conduit connecting the high-pressure source to the exit nozzle.

Summary of the Invention

According to a first aspect of the present invention there is provided a rotating cutting head. The cutting head may be rotatable about an axis of rotation. The cutting head may be configured to rotate about the axis of rotation. The cutting head, in use, may rotate about the axis of rotation. The axis of rotation may be parallel to a longitudinal axis of the cutting head and/or a tool comprising the cutting head. The axis of rotation may be colinear with the longitudinal axis of the cutting head and/or the tool comprising the cutting head. Additionally, or alternatively, the axis of rotation may be parallel to, optionally colinear with, a longitudinal axis of an object or item to be cut. The object or item to be cut may comprise a longitudinal object or item. The object or item to be cut may comprise a hollow object or item. The rotating cutting head may be configured to cut the hollow object or item from within. The object or item to be cut may comprise a hollow cylindrical item or object, such as one or more of: a pipe, casing, liner, or the like. The object or item to be cut may comprise a wellbore object or item, such as a downhole object or item. The object or item to be cut may be located downhole, such as within a wellbore. The wellbore may comprise a hydrocarbon wellbore. The cutting head may comprise a pipecutting head. The pipe-cutting head may be configured to cut pipe-shaped objects or items, such as pipes, casings, piles, or other hollow objects or items.

The cutting head may comprise at least two nozzles. The cutting head may be rotatable to rotate the at least two nozzles. The cutting head may be configured to rotate the at least two nozzles around or about the axis of rotation. The at least two nozzles may be directed laterally relative to the axis of rotation. For example, in at least some examples the nozzles may be directed laterally outwardly from the central axis of rotation. The nozzles may be directed orthogonally to the axis of rotation, such as perpendicular to the axis of rotation. The nozzles may be directed radially outwards, relative to the axis of rotation.

The rotating cutting head may comprise a housing with the at least two nozzles supported therein. The nozzles may be connected to a single line feed by a flow splitter. The at least two nozzles may be each arranged in the housing to each direct a cutting fluid from a separate location on the cutting head. Accordingly, in at least one example, there is provided a rotating cutting head comprising a housing with at least two nozzles supported therein, the nozzles being connected to a single line feed by a flow splitter, wherein the at least two nozzles are each arranged in the housing to each direct a cutting fluid from a separate location on the cutting head.

The rotating cutting head may comprise a housing with at least two nozzles arranged in at least one block. The nozzles may be connected to at least one line feed by a flow splitting means. The at least two nozzles may be each arranged in the at least one block each to direct a cutting fluid from a separate location on the cutting head. Each nozzle may located in an angled channel. The (respective) angled channel may be defined in the at least one block. The nozzles may be operative to direct cutting fluid at an angle corresponding to that of each angled channel. The angle may be defined with respect to an axis (e.g. longitudinal axis, of the head, tool and/or object to be cut; and/or the axis of rotation). The channel may comprise a conduit. Accordingly, in at least one example, there is provided at least one example of a rotating cutting head comprising: a housing with at least two nozzles arranged in at least one block, the nozzles are connected to at least one line feed by a flow splitting means, the at least two nozzles are each arranged in the at least one block each to direct a cutting fluid from a separate location on the cutting head; wherein each nozzle is located in an angled channel, defined in the at least one block, and the nozzles are operative to direct cutting fluid at an angle corresponding to that of each angled channel.

In preferred embodiments the nozzles are connected to a single line feed by the flow splitting means. It is appreciated that in some embodiments two or more separate line feeds may be provided to direct flow to the two or more nozzles arranged in one or more blocks.

In this way a cut can be achieved when the cutting head is inserted into a pipe, such as a conductor pile, multi-string well or large diameter wind turbine pile, and rotated whilst cutting fluid is pumped through the nozzles that are directed at a surface to be cut. This allows for the pipe, which may include one or more pipes (concentric or eccentric) within the main conductor pipe, to be cut in situ. For example, a multi-string production well may be cut during decommissioning so that it can be removed. It is appreciated that the pipes to be cut may be subsea pipes or land based.

In a first embodiment at least two nozzles are arranged in a block with an inlet for receiving the cutting fluid from the single line feed. The inlet connects to the flow splitting means that is arranged within the, or each, block which has a separate conduit leading to each nozzle.

In this way the flow splitting means is integrated with the block so that a single feed is fed to the block through an inlet and the feed is split by the flow splitting means within the block to direct flow of cutting fluid to each nozzle, so that cutting fluid is expelled from each nozzle towards the surface to be cut. In a second alternative embodiment two or more blocks are arranged in the housing of the cutting head, wherein a first nozzle is arranged in a first block having a first inlet for receiving the cutting fluid, and a second nozzle is arranged in a second block having a second inlet for receiving the cutting fluid. The flow splitting means is connected to each inlet to enable flow of cutting fluid from the single line feed to be distributed to each nozzle. Each inlet leads via a conduit to the nozzle.

In both the first and second embodiments the single line feed is received to a proximal surface of the cutting head in use and cutting is performed from a substantially distal end of the cutting head. In this way the single feed is received in substantially the same orientation as the longitudinal axis of the pipe being cut.

In the second embodiment the flow splitting means is external to the block and is connected to an upper (proximal) face of the cutting head.

In a third embodiment a first flow splitting means diverts a single feed to two or more blocks, and the two or more blocks may each have two or more nozzles fed by secondary flow splitting means, which may be arranged in the blocks.

Having a single line feed and a flow splitting means enables more than one nozzle to be fed from the same single line feed. This removes the requirement for using multiple cutting heads with separate line feeds to each. Advantageously this enables the cutting head to be inserted into narrower bore pipes and around restrictive bends and corners.

Additionally it is possible to reduce size of the nozzles and/or the block and maintain pressure by adjusting the diameter for the internal bore of the nozzle. For example if a nozzle is shortened to accommodate cutting within a smaller pipe or to accommodate more nozzles in a cutting head, the internal diameter of the nozzle, through which cutting fluid flows, may be reduced and pressure increased. This configuration can increase cutting efficiency, for example by enabling an increase of pressure from 1000 bar to 2500 bar which may further reduce cutting time and amount of cutting fluid required.

It is appreciated that the flow splitting means enables the diversion of flow from a single feed to two more different conduits. For example, the flow splitting means may be a component part connected to a single feed so that the flow splitting means is external of the block(s), or the flow spitting means may comprise channels (conduits) within a component part such as the block which receives a flow from a single line feed so that the flow splitting means is within the block.

In some embodiments a single line feed is connected to the flow splitting means by a swivel joint. This allows the cutting head to rotate independently of the single line feed.

Preferably the body of the flow splitting means is made from a strong, durable material such as stainless steel, which has high strength and is relatively easy to manufacture. The flow splitting means has one inlet port and two or more outlet ports. The number of outlet ports corresponds to the number of inlets or to the number of nozzles.

Since the flow of cutting fluid from the single line feed through each conduit of the flow splitting means is subjected to increased wear by erosion caused by the cutting fluid passing through it, in some embodiments a sacrificial liner may be provided to protect the internal surface of the flow splitting means.

The liner is intended to at least protect the joint where the single line feed and flow splitting means join and may also extend through at least part of each conduit split from the main feed. The liner helps to reduce wear to the parts of the flow splitting means so that the flow splitting means can remain in use for longer. The sacrificial liner can be replaced when excessively worn so that the flow splitting means remains effective and operational. The sacrificial liner may be made from a wear resistant material such as from a ceramic material.

The liner may be replaced after a pre-set number of hours, and/or the liner may be replaced when excessive wear is detected.

In some embodiments the flow splitting means includes a control mechanism so that flow through the flow splitting means can be altered. The control mechanism may comprise valves associated with the inlet to the flow splitting means and/or one or more of the outlets. In this way flow of cutting fluid can be controlled at the cutting head. For example, for a cutting head with two nozzles, it may be possible to close one of the outlets on the flow splitting means so that only one nozzle is operative. This allows cutting to only be carried out by one nozzle. It is appreciated that the control mechanism may also permit operation of the nozzles in predefined sequences, such as alternating nozzle activation to reflect the cutting require and/or the material being cut and/or taking into account the surrounding environment.

Shutting off flow through the flow splitting means may also assist with cleaning or unblocking of nozzles that are in a system with an air entrainment mechanism as air may continue to be forced through without cutting fluid to help with removing residue in the nozzles.

In some embodiments it may also be possible to adjust flow rate by means of the one or more valves, thereby providing a fine adjustment for some cutting situations.

Preferably the valves are remotely control by the main controller. A command signal sent by the controller may open, close or adjust each valve opening. In some embodiments the sacrificial liner may be formed from layers of strong durable material and when a pre-set number of layers have worn the liner is changed. For example a user may carry out a visual inspection of the liner.

In another embodiment a wear sensor may be arranged on the sacrificial liner to monitor wear and once wear beyond a pre-set level is detected the sacrificial liner is replaced.

In some preferred embodiments the block has a second inlet that receives an air feed that is in communication with the nozzle to assist with flow and deployment of cutting fluid from the nozzle. This forms an air entrainment system that acts to aerate the cutting fluid for more effective and consistent cutting. The second inlet leads to the angled channel in which the nozzle is arranged, so that pressurised air is forced from the nozzle.

The air entrainment system may be adjusted, for example by changing tolerance of parts of the nozzle assembly, such as the baffle or aerator plate.

Each nozzle is located in an angled channel defined in the block and the nozzles are operative to direct cutting fluid at an angle corresponding to that of each angled channel. The channel is angled with respect to the longitudinal axis of the pipe to be cut so that cutting fluid is directed to a surface to be cut, such as a pipe, across a minimal distance thereby improving accuracy of cutting.

As the channels are angled there is no need for bolted wedges which are commonly used in existing cutting heads as a means to tilt the nozzles. Advantageously this reduces the number of component parts that form the nozzle assembly and means that the whole block containing one or more nozzles, can be easily removed for repair or replacement.

Preferably the angled channel is orientated to reduce the angle of elbows of the conduit that feeds cutting fluid from the inlet on the block to the nozzle. Advantageously this reduces wear and risk of failure, thereby prolonging life of the conduit elbow.

The angled channel is ideally located at an obtuse angle with respect to the longitudinal axis of the tool assembly in use, and in particular in relation to the angle of the inlet that receives cutting fluid. Preferably the angled channel is at an obtuse angle of between 91 degrees and 180 degrees with respect to a longitudinal axis of the tool assembly in use, thereby ensuring that the angle of the elbow of the conduit is greater than 90 degrees. More preferably the angled channel is at 96 degrees with respect to a longitudinal axis of the tool assembly in use.

It is appreciated that the conduit through which cutting fluid flows from the inlet for the cutting fluid to the nozzle may be sized to correspond to the nozzle in use, the cutting fluid being use and/or to accommodate different cutting styles.

The elbow of the conduit is provided at different obtuse angles depending on the angle of the angled channel. For example, the conduit may be flexible and arranged in blocks with different angled channels depending on use, so that a conduit elbow angle varies depending upon the angle of a channel.

Alternatively the conduit is a substantially rigid component that is provided in a range of different angles/diameters/cross sections to accommodate use in different size blocks and/or blocks with different angled channels. For example the conduit may be an exchangeable part, (along with the nozzle assembly or parts of the nozzle assembly and the locking member), so that the cutting head can be selectively configured for a particular purpose, by changing parts rather than changing the entire cutting head.

It is an intention that the cut is not to be a straight cut, made at 90 degrees with respect to the surface to be cut, but is angled with respect to the surface being cut, so that the surface being cut retains some structural integrity until separation is intended. For example when cutting an item such as a platform jacket, this may have four skirt piles on each leg, with each skirt needing to be cut. By cutting each skirt at an angle, such as at 33 degrees with respect to the plane of the surface, the two cut parts remain in position even when cut because the two cut parts are interlocked by the angle of the cut and require separation by displacement of the first part from the second part, or vice versa. Advantageously this helps to prevent dislodgment of cut parts during cutting and irrespective of surrounding environmental conditions, such as sea conditions.

The presence of at least two nozzles (either two blocks each having at least one nozzle, or one block with two or more nozzle) means that cutting can be achieved at two or more locations simultaneously, or selectively wherein the nozzles are not operative simultaneously, but instead at different selected times, or for different selected durations.

Advantageously this means that a full rotation may not be required to achieve a cut, or that a reduced number of rotations are required to achieve a cut, or that two or more separate cut lines can be achieved simultaneously or selectively. Therefore the use of at least two nozzles enables cutting time to be reduced.

It is appreciated that some embodiments of the cutting head may include more than two nozzles depending on pipe diameter and the specific application.

By having two or more nozzles, and thereby multiple cutting points, it is possible to reduce size of the nozzles and/or the blocks to allow multiple nozzles to be installed within the housing of the cutting head (as explained above).

Advantageously, having more than one nozzle in the cutting head also provides redundancy in the cutting head, should any part of the nozzle or nozzle assembly fail or become clogged, thereby enabling cutting to continue without having to retrieve the tool assembly and change the cutting head. In a preferred embodiment the nozzles are equally spaced on an axis of symmetry which is defined in the housing. In this way cutting points are equally spaced, and this helps to balance the forces subjected to the cutting head when the nozzles are operative simultaneously.

The direction in which cutting fluid is expelled is determined by the angled channel which houses the nozzle.

In some embodiments a first nozzle may be set at a first radial angle determined by a first angled channel and a second nozzle may be set at a second radial angle determined by a second angled channel so that two or more cuts are made in different planes and therefore at different positions on the surface to be cut.

In preferred embodiments the block(s), and thereby the nozzles, are displaceable from the cutting head. In this way nozzles can be easily removed for cleaning or repair and parts such as the block, conduit, or nozzle, of the whole block assembly can be exchanged, for example when a different cutting angle is required a block with angled channels at the desired orientation(s) may be fitted.

In preferred embodiments a means for seating the blocks in the housing. Preferably the housing includes a recess in which the block is seated in use. The recess has an opening so that the blocks can be slid in and out from the housing. In preferred embodiments the recess is closed by a displaceable member that is locked in place to fix the block in position. The displaceable member may be a bar, or plate that has an attachment means to enable the member to be locked in place across the opening. For example the displaceable member may include apertures that correspond with threaded holes in the housing for receiving threaded bolts.

Preferably each nozzle is locked in the angled channel by a locking member. The locking member may be a hexagonal bolt or similar that is screw fitted, or twist locked to an external surface of the block about the angled channel. In this way component parts of the nozzle can be easily accessed when the locking member is removed, without requirement for the block holding the nozzle to be completely removed from the housing.

By having a locking member rather than a traditional machined shoulder the consumable parts of the nozzle, or the nozzle itself can be replaced quickly and easily without the need to remove the nozzle from the housing.

In a preferred embodiment the rotatable cutting head a centraliser arranged above the at least two nozzles. By having the centraliser above the cutting head in use, this prevents the centraliser from getting caught if cut pipe sections move out of axial alignment.

Preferably the centraliser is an annular ring projecting from an outer surface of the housing of the cutting head for centralising the cutting head within a tubular aperture such as a pipe. In this way the centraliser engages with the pipe rather than the housing.

In some embodiments a distal end of the cutting head is tapered to a point making insertion into the pipe (pile) easier.

In preferred embodiments the cutting head has at least one cutting sensor to monitor cutting and other related parameters during use, such as positional information and conditions such as presence of water, temperature etc. In this way the cutting system incorporates feedback received from one or more sensor that can be displayed at a control station to monitor collected data such as cut data, positional information, conditions and verification.

The at least one sensor may be a strain gauge to monitor variation of thrust and/or reaction force on the cutting head as cutting fluid is pumped through the nozzle. The level of thrust or reaction force detected will indicate when cutting is still in progress (higher level of thrust/reaction force), and when the cut is complete (lower level of thrust/reaction force). Typically a cutting sensor is arranged between two component parts to monitor forces during cutting. For example a digital feedback signal from a cutting sensor, that monitors actual cutting force, may be achieved by positioning one or more strain gauges or load cells between the external face of the block and a reactive surface (such as for example the housing) to record force of the nozzle against the housing.

In yet a further embodiment the cutting sensor(s) may be arranged under bolts that clamp the cutting head together, for example in the form of washers, monitoring the increased strain in the bolts securing the block within the cutting head.

As the jet of cutting fluid reacts against a pipe surface, there is a significant reaction force, translated through the component part, to the cutting sensor. As the pipe erodes away during cutting, the distance from the nozzle to the surface being cut gradually increases, and the thrust and reaction force decreases proportionally. As the jet of cutting fluid breaks though the outer surface of the pipe, a steep drop in thrust is detected which is indicative of a full cut. The data collected by the one or more cutting sensors enables variations in thrust and/or reaction force to be detected.

The readings obtained are preferably transmitted to a processor that uses computer implemented software to analyse the data received to enable a user to accurately monitor cutting for example, the depth of any cut and to identify when a cut is completed. The cutting head and processor define a cutting system in which activity of the cutting head is monitored. It is appreciated that the cutting head forms part of a tool that is inserted into and fitted with a pipe to be cut so that the cutting head is fixed in a desired position during cutting. Therefore the cutting system comprises the tool and at least one processor

Preferably the processor is remote from the cutting head, for example the processor is arranged at a control container. For example a control container may be provided at ground level or at sea/deck level to communicate with the cutting head within the pipe. Typically the processor is operatively connected to a controller that operates the rotatable cutting head, for example controlling rotation and ejection of cutting fluid.

In a preferred embodiment a slip ring as part of the system with conductive sliding electrical contacts, sealed inside an enclosure. This slip ring allows the signals from the sensors to be transmitted past the rotating portion of the assembly and up to the controller. For example the slip ring may be associated with the swivel joint that connects the main line feed to the flow splitting means.

It is appreciated that cutting sensor data may be analysed in real time based on the data collected and this commences at the initial ‘punch through’ the pipe which establishes a baseline data point. This data point can then be used as a datum for the duration of the cut to assist in calculating required duration of cutting. This is important as expected cut duration may vary when a pipe has been in situ of long periods of time which may have led to wear and/or degradation of the materials that is not immediately evident from external inspection.

In some embodiments two or more different types of cutting sensor may be used to analyse cutting. For example readings from a pressure sensor such as a strain gauge or load cell, may be combined with readings from a hydrophone and/or a water pressure sensor and/or a vibration sensor to obtain more comprehensive feedback readings and to provide redundancy should a cutting sensor fail.

In some embodiments where the pipe to be cut is submerged, the cutting head includes a liquid sensor, such as a dewatering sensor, to monitor the water level around the cutting head. This sensor determines if the cut is being made in air (still cutting through the pipe) or in water (has cut through the pipe).

In preferred embodiments cutting is automated based upon data received from all active sensors. For example the feedback from the sensors may be used to automatically trigger particular functional actions during operation to eliminate the risk of human error.

These functional actions that are initiated by feedback from sensors may include but are not limited to: flow of cutting fluid from a reservoir, pressure dependent upon a pump, presence of cutting media in the delivery flow, rotational speed of the cutting head, axial travel speed, direction, positional recall to ensure the most efficient and effective cut is achieved.

This enables the controller to operate the system in order to initiate cutting, control rotation speed of the cutting head and cease cutting when pre-set cutting conditions are not met. The controller issues command signals to initiate or cease cutting.

Initiation command signals may include the controller may automatically adjust flow rate, pressure, revolutions speed, ration of cutting fluid, such as garnet to water ratio in relation to sensor feedback, removing the need for a highly specialised operator.

Cease command signals may include transmission of command signal upon receipt of a signal, or combination of signals, from one or more cutting sensor that indicate an undesirable cutting condition.

Additionally the system may also be functional to change position of the cutting head and thereby the nozzle in the pipe.

In some embodiments the tool of the cutting system may include a telescopic assembly that enables adjustment of the cutting head in the pipe. The telescopic assembly is always arranged above the cutting head in the pipe so that it is not necessary to move the whole tool in order to adjust position of the cutting head. This allows a castellated or non-linear cut to be performed. The advantages of preforming such a cut is to prevent cut pipes from dislocating until required; to enable the cutting of ‘windows’ in the side of the pipes for activities such as external visual inspection or introduction of other tools into the pipe; and to allow for easy resetting of the tool position, should tension be released during the initial cut.

In some embodiments the telescopic assembly comprises at least one sliding portion that is attached to, and moveable relative to, a fixed part of the tool, or non-moving part of the tool by means of at least one actuator. The at least one actuator may be a linear actuator, or a rotating gear or helix. The cutting head is arranged distally to the telescopic assembly. For example the telescopic assembly may have one or more actuator attached to a gripper that is fixed in the pipe. The sliding portion is then moveable relative to the gripper and parts of the tool below the telescopic assembly that include the cutting head move as the telescopic assembly is adjusted.

In a preferred embodiment the telescopic assembly has two sliding portions moveable relative to each other by at least one actuator. The at least one actuator may be a linear actuator, or a rotating gear or helix. In this way when one of the sliding portions are arranged between components of the tool, parts below the telescopic assembly are moveable up and down in the pipe, and parts above the telescopic assembly remain fixed in position.

For example a first sliding portion may be connected to a fixed part of the tool, such as a gripper and a second sliding portion may be connected to a swivel assembly that connects to the flow splitting means that is connected to the rotating cutting head. In this way movement of the second sliding portion relative to the first sliding portion causes movement of the flow splitting means and cutting head so that a position of the cutting head is adjustable by the at least one linear actuator so that the location of the cut is adjusted by movement of a sliding portion and there is no adjustment required to other components higher up in the pipe. The controller may be used to automate vertical control of the telescopic assembly in combination with controlling rotation. In a preferred embodiment the controller may be programmed to initiate pre-programmed patterns such as castellations, waves, zig zags, circles, squares windows etc. Thereby removing the requirement for specialist operator to manually initiate cutting.

The cutting system may additionally include a means for rotating the cutting head, such as one or more motor for driving one or more gear associated with the cutting head. For example, in a preferred embodiment the cutting system includes a drive gear for rotating the cutting head. Preferably the drive gear, such as central spur gear comprises at least one electric motor such as a stepper motor or servo motor for rotating a central spur gear connected to the cutting head.

In a preferred embodiment the cutting system includes at least three electric motors that are provided along the central spur gear. This arrangement provides rotational drive at different positions along the gear and redundancy should one motor fail.

It is appreciated that a drive gear may be provided on the outside of the motor, rather than centrally on the inside meaning that the drive gear is cut into the inside wall of the circumference of part of the tool.

Traditional cutting systems typically rely on a hydraulic system. The use of electric motors takes up less space making the system more compact than traditional systems due to the removal of a hydraulic motor, reduction gearbox, clutch, drive shafts and universal joints. This means that the size of an umbilical to the surface is significantly smaller by omitting the use of hydraulics, resulting in increased well clearances, ease of deployment, smaller topside equipment such as winches, and reduces risks associated with manual handling as the cutting fluid is able to pass the motor in a straight line instead of having a bend to fit around known systems that use hydraulics. Another advantage of using direct drive from the electric motors, rather than through a reduction gearbox from a hydraulic motor and driveshaft is that backlash is vastly reduced which therefore improves cut accuracy.

By using electric motors the environmental risk is significantly reduced as no hydraulic oil will be used.

The use of electric motors improves handling, storage and enables operation according to regulatory requirements with respect to the cut depth below the mudline of subsea wells due to the shortened tool length (cutting head and associated parts for the system). A system suitable for use at shallow depths below the mudline allows a cut to be performed as close to the surface of the mudline as possible, avoiding excessive stiction when the pipe stub is pulled from the ground.

In a preferred system with at least two electric motors, each of the electric motors is operational in use at a lower torque than full capacity, for example at 50% torque when all electric motors are operational, to provide redundancy at the same capacity, even if one electric motor fails. In a situation where a motor fails, the torque of an active motor is adjusted to compensate. Each motor preferably includes a means to adjust torque to reflect the number of active motors. It is appreciated that torque of each motor may be automatically adjusted by the controller in response to feedback from sensors monitoring the tool and in particular the cutting head during cutting.

Preferably the system includes a means to automatically shutoff operation of cutting if a pre-set level of torque is detected by at least one of the motors in order to prevent damage. For example the system may include an automatic shutoff function that is activated by a shutoff mechanism when certain conditions are detected by one or more sensor. Preferably the system includes at least one electric motor that includes a position monitoring means to monitor rotational position of the cutting head that is driven by one or more gears. Preferably the position monitoring means is arranged on, or associated with, each motor. The position monitoring means can determine an arc through which cutting has occurred, a number of rotations or part rotations.

In preferred systems current drawn by each motor is monitored, and each motor is controllable to stop automatically if a maximum allowable torque is detected as being exceeded. This protects the cutting head from over-torque damage, should the head become jammed and removes the need for a mechanical clutch or shear pin, or similar weak link which may require recovering of the cutting head and associated system to deck for replacement or repair.

According to a further aspect, there is provided a cutting system comprising the cutting head of any other aspect, embodiment, example of claim. The system may comprise the cutting head and a controller. The controller may be for receiving and analysing signals received from at least one sensor.

According to a further aspect, there is provided a cutting tool comprising the cutting system and cutting head of any other aspect, embodiment, example of claim.

According to a further aspect there is provide a method of cutting. The method may comprise rotating a cutting head. The method may comprise rotating the cutting head about an axis of rotation. The method may comprise cutting a longitudinal object or item, such as a hollow object or item from within (e.g. selected from one or more of: a pipe, casing, liner, hollow pile or the like). The method may comprise a wellbore cutting operation. The method may comprise a downhole operation, such as within a wellbore. The method may comprise rotating the cutting head to rotate at least two nozzles. The method may comprise directing the at least two nozzles laterally relative to the axis of rotation. The method may comprise directing the at least two nozzles laterally outwardly from the central axis of rotation. The method may comprise directing the at least two nozzles orthogonally to the axis of rotation, such as perpendicular to the axis of rotation. The method may comprise directing the at least two nozzles radially outwards, relative to the axis of rotation. The method may comprise connecting the at least two nozzles to a single line feed by a flow splitter. The method may comprise directing a cutting fluid from a separate location on the cutting head.

Examples of the invention are providing in the following non-limiting clauses, which are not to be interpreted as the claims defining the scope of protection - with the claims being appended herein after the detailed description.

Clauses:

1. A rotating cutting head comprising: a housing with at least two nozzles supported therein, the nozzles are connected to a single line feed by a flow splitter, wherein the at least two nozzles are each arranged in the housing to each direct a cutting fluid from a separate location on the cutting head.

2. A rotating cutting head according to clause 1 wherein the at least two nozzles are arranged in a block with an inlet for receiving the cutting fluid from the single line feed, the inlet connects to the flow splitter arranged in the block which has a separate conduit leading to each nozzle.

3. A rotating cutting head according to clause 1 wherein a first nozzle is arranged in a first block having a first inlet for receiving the cutting fluid, and a second nozzle is arranged in a second block having a second inlet and the flow splitter connects to each inlet to enable flow of cutting fluid from the single line feed to each nozzle.

4. A rotating cutting head according to clause 2 or clause 3 wherein each nozzle is located in an angled channel defined in the block and the nozzles are operative to direct cutting fluid at an angle corresponding to that of each angled channel.

5. A rotating cutting head according to any preceding clause wherein the flow splitter has a sacrificial liner. 6. A rotating cutting head according to any preceding wherein the at least two nozzles are equally spaced on an axis of symmetry which is defined in the housing.

7. A rotating cutting head according to any preceding clause wherein the at least two nozzles operate simultaneously to expel cutting fluid at substantially identical cutting angles.

8. A rotating cutting head according to any preceding clause wherein the at least two nozzles operate simultaneously to expel cutting fluid at different cutting angles.

9. A rotating cutting head according to clause 2 or clause 3 wherein the block and associated nozzle(s) is/are displaceable from the cutting head.

10. A rotating cutting head according to clause 4 wherein the nozzle is locked in the angled channel by a locking member.

11. A rotating cutting head according to any preceding clause including a centraliser arranged above the nozzles.

12. A rotating cutting head according to clause 11 wherein the centraliser is an annular ring projecting from an outer surface of the cutting head for centralising the cutting head within a tubular aperture.

13. A rotating cutting head according to any preceding clause wherein a distal end of the cutting head is tapered to a point.

14. A rotating cutting head according to any preceding clause including at least one sensor.

15. A rotating cutting head according to clause 14 wherein the at least one sensor is a strain sensor that is a cutting sensor to monitor variation of thrust and/or reaction force.

16. A rotating cutting head according to clause 15 wherein the at least one strain sensor is arranged between the nozzle and a reacting surface.

17. A rotating cutting head according to clause 15 or clause 16 wherein the at least one strain gauge is arranged between the block and the housing.

18. A rotating cutting head according to clause 14 wherein the at least one sensor is a liquid sensor to detect level of water on the cutting head.

19. A rotating cutting head according to clause 14 wherein the sensor is a hydrophone and/or a water pressure sensor and/or a vibration sensor. 20. A cutting system including the rotating cutting head according to any of clauses 14 to 19 including a controller for receiving and analysing signals received from the at least one sensor.

21 .A cutting system according to clause 20 wherein the controller issues a command signal to cease cutting upon receipt of a signal, or combination of signals, from the at least one sensor that indicates an undesirable cutting condition.

22. A cutting system according to clause 20 or clause 21 wherein the controller issues a command signal to initiate an action upon receipt of a signal, or combination of signals, from the at least one sensor.

23. A cutting system including the rotating cutting head according to any of clauses 1 to 19; and a telescopic assembly that together form part of a cutting tool; wherein the telescopic assembly is arranged above the cutting head in use and has at least one sliding portion moveable by at least one actuator to enable position of the cutting head to be adjusted.

24. A cutting system according to clause 23 wherein the telescopic assembly comprises at least two sliding portions moveable relative to each other by the at least one linear actuator.

25. A cutting system according to any of clauses 20 to 24 further includes a drive gear for rotating the cutting head, the drive gear comprising at least one electric motor for rotating a drive gear connected to the cutting head.

26. A cutting system according to clause 25 wherein at least two electric motors are provided along the drive gear.

27. A cutting system according to clauses 25 or 26 wherein the drive gear is a central spur gear.

28. A cutting system according to clause 26 wherein each of the at least two electric motors has a means to adjust torque to reflect the number of active motors.

29. A cutting system according to clause 28 wherein the controller, or a second controller controls two of the electric motors to provide redundancy if one electric motor fails. 30. cutting system according to any of clauses 25 to 29 including an automatic shutoff mechanism if a preset level of torque is detected.

31. A cutting system according to any of clauses 25 to 30 wherein the at least one electric motor has a means to monitor and control rotational position.

32. A cutting tool including the cutting head according to any of clauses 1 to 19 and the cutting system according to any of clauses 20 to 31 .

Further clauses:

1. A rotating cutting head comprising: a housing with at least two nozzles arranged in at least one block, the nozzles are connected to at least one line feed by a flow splitting means, the at least two nozzles are each arranged in the at least one block each to direct a cutting fluid from a separate location on the cutting head; wherein each nozzle is located in an angled channel defined in the at least one block and the nozzles are operative to direct cutting fluid at an angle corresponding to that of each angled channel.

2. A rotating cutting head according to clause 1 wherein the nozzles are connected to a single line feed by the flow splitting means.

3. A rotating cutting head according to clause 2 wherein the at least two nozzles are arranged in the at least one block with an inlet for receiving the cutting fluid from the single line feed, the inlet connects to the flow splitting means arranged in the block which has a separate conduit leading to each nozzle.

4. A rotating cutting head according to clause 2 wherein a first nozzle is arranged in a first block having a first inlet for receiving the cutting fluid, and a second nozzle is arranged in a second block having a second inlet and the flow splitting means connects to each inlet to enable flow of cutting fluid from the single line feed by the flow splitting means to each nozzle.

5. A rotating cutting head according to any preceding clause wherein the flow splitting means has a sacrificial liner. A rotating cutting head according to any preceding wherein the at least two nozzles are equally spaced on an axis of symmetry which is defined in the housing. A rotating cutting head according to any preceding clause wherein the at least two nozzles operate simultaneously to expel cutting fluid at substantially identical cutting angles. A rotating cutting head according to any preceding clause wherein the at least two nozzles operate simultaneously to expel cutting fluid at different cutting angles. A rotating cutting head according to any preceding clause rotating wherein the angled channel is at an obtuse angle with respect to the longitudinal axis of the tool assembly in use. A rotating cutting head according clause 9 wherein the angled channel is at an obtuse angle within a range of between 91 degrees and 180 degrees with respect to the longitudinal axis of the tool assembly in use. A rotating cutting head according to clause 9 or clause 10 wherein the angled channel is at an obtuse angle of 96 degrees with respect to the longitudinal axis of the tool assembly in use. A rotating cutting head according to any preceding clause wherein the at least one block and associated nozzle(s) is/are displaceable from the cutting head. A rotating cutting head according to any preceding clause wherein at least one nozzle is locked in the angled channel by a locking member. A rotating cutting head according to any preceding clause including a centraliser arranged above the nozzles. A rotating cutting head according to clause 14 wherein the centraliser is an annular ring projecting from an outer surface of the cutting head for centralising the cutting head within a tubular aperture. A rotating cutting head according to any preceding clause wherein a distal end of the cutting head is tapered to a point. A rotating cutting head according to any preceding clause including at least one sensor for monitoring cutting related parameters. 18. A rotating cutting head according to clause 17 wherein the at least one sensor is a strain sensor that is a cutting sensor to monitor variation of thrust and/or reaction force.

19. A rotating cutting head according to clause 18 wherein the at least one strain sensor is arranged between the nozzle and a reacting surface.

20. A rotating cutting head according to clause 18 or clause 19 wherein the at least one strain gauge is arranged between the block and the housing.

21. A rotating cutting head according to clause 17 wherein the at least one sensor is a liquid sensor to detect level of water on the cutting head.

22. A rotating cutting head according to clause 17 wherein the sensor is a hydrophone and/or a water pressure sensor and/or a vibration sensor.

23. A rotating cutting head according to any preceding clause wherein the at least one block has a second inlet in communication with the angled channel for receiving pressurised air.

24. A rotating cutting head according to any preceding clause wherein the flow splitting means includes a control mechanism so that flow through the flow splitting means can be altered.

25. A rotating cutting head according to clause 24 wherein the control mechanism for the flow splitting means includes one or more valve.

26. A cutting system including the rotating cutting head according to any of clauses 17 to 25 including a processor for processing received signals from the at least one sensor.

27. A cutting system according to clause 26 wherein the processor issues a command signal to cease cutting upon receipt of a signal, or combination of signals, from the at least one sensor that indicates an undesirable cutting condition.

28. A cutting system according to clause 26 or clause 27 wherein the processor issues a command signal to initiate an action upon receipt of a signal, or combination of signals, from the at least one sensor.

29. A cutting system including the rotating cutting head according to any of clauses 1 to 25; and a telescopic assembly that together form part of a cutting tool; wherein the telescopic assembly is arranged above the cutting head in use and has at least one sliding portion moveable by at least one actuator to enable position of the cutting head to be adjusted.

30. A cutting system according to clause 29 wherein the telescopic assembly comprises at least two sliding portions moveable relative to each other by the at least one linear actuator.

31 . A cutting system according to any of clauses 26 to 30 further includes a drive gear for rotating the cutting head, the drive gear comprising at least one electric motor for rotating a drive gear connected to the cutting head.

32. A cutting system according to clause 31 wherein at least two electric motors are provided along the drive gear.

33. A cutting system according to clauses 31 or 32 wherein the drive gear is a central spur gear.

34. A cutting system according to clause 32 wherein each of the at least two electric motors have a means to adjust torque to reflect the number of active motors.

35. A cutting system according to clause 34 wherein the controller, or a second controller controls two of the electric motors to provide redundancy if one electric motor fails.

36. A cutting system according to any of clauses 31 to 35 including an automatic shutoff mechanism if a pre-set level of torque is detected.

37. A cutting system according to any of clauses 31 to 36 wherein the at least one electric motor has a means to monitor and control rotational position.

38. A cutting tool including the cutting head according to any of clauses 1 to 25 and the cutting system according to any of clauses 24 to 37.

Preferred embodiments of the invention will now be described, by way of example and with reference to the Figures in which:

Brief Description of Figures Figure 1 shows an isometric view of a first embodiment of the cutting head;

Figure 2 shows an isometric view of the first embodiment shown in Figure 1 with a nozzle assembly removed;

Figure 3 shows a cross section of the first embodiment of the cutting head;

Figure 4 shows a cross section of the cutting head shown in Figure 1 and 3 connected to a flow splitting means;

Figure 5 shows a second embodiment of a cutting head with a flow splitting means arranged within the block;

Figure 6 shows a cross section of the cutting head shown in Figure 4 connected to a flow splitting means

Figure 7 shows an exploded view of a block and nozzle assembly;

Figure 8 shows a second embodiment of a block and a prior art nozzle assembly;

Figure 9 shows an isometric view of the connection between the flow splitting means and the cutting head;

Figure 10 shows a cross section of the flow splitting means showing the liner;

Figure 11 shows a telescopic assembly; and

Figure 12 shows an example of a tool.

Detailed Description of Figures

Figure 1 to 3 show a preferred embodiment of the cutting head 100. The cutting head 100 has a housing 10 that partially surrounds two nozzles 20.

Each nozzle 20 is arranged in a block 21 which has an inlet 22 for receiving cutting fluid (not shown) that is fed to the nozzle 20 and expelled through a nozzle outlet 23. The nozzle pictured in Figure 7 is an example of a nozzle assembly common to the art. A second inlet 70 is provided as an air feed to the nozzle outlet 23. Air received from the second inlet 70 is first received in a void 71 around the baffle 27. The baffle 27 has apertures 27A (see Figure 7) through which pressurised air from the air feed 72 can pass and is then able to pass through to apertures 29A (as shown in Figure 7) in the aerator plate 29 where pressurised air then mixes with the expelled cutting fluid as jet of cutting fluid with air entrained around the jet that is directed towards the surface to be cut.

The housing 10 defines a circular outer surface that is received into the pipe (not shown). The housing 10 has recessed regions 11 that receive the blocks 21 (see Figure 2).

The recessed regions 11 have an opening that is closed by a keep plate 14. A keep plate 14 is secured in position by threaded pins (not shown) received through two apertures 12. Removal of the keep plate 14 enables the block 21 to be removed for replacement or servicing.

With reference to Figures 2 and 3 the second inlet 70 leads to the channel 24 in which the nozzle 20 is arranged. The second inlet 70 receives an air feed 72 that feeds air to the nozzle 20 and out through the nozzle outlet 23.

A distal end of the cutting head 100 tapers to a point 13. This point 13 helps to guide the cutting head 100 down the pipe that is to be cut.

With reference to Figure 3 the inlet 22 leads to a conduit 25 that feeds cutting fluid to the nozzle 20 and out through the nozzle outlet 23. The nozzles 20 are arranged in channels 24 that are defined within the blocks 21 . The channels 24 are angled with respect to the horizontal axis ‘X’ that is orthogonal to the axis of rotation ‘Y’ of the cutting head 100.

The channels 24 in the pictured embodiment are angled at 6 degrees with reference to the horizontal axis 'X’. It is appreciated that the channels 24 may be provided at different angles. This configuration means that the angle through which the conduit 25 passes is greater than 90 degrees and therefore the conduit 25 is subjected to less abrasion and subsequent wear as cutting fluid is pumped through.

Each nozzle 20 is secured in place by a locking member 26. Removal of the locking member 26 enables access to all other internal component parts, enabling repair and maintenance without requirement to remove a block 21 from the housing 10.

A sensor 80 is provided in between the block 21 and the recessed region 11. The sensor 80 monitors force generated when the nozzle 20 is in use by detecting impact force between the block 21 and the recess 11 in the housing 10.

Figure 5 shows a second embodiment of the cutting head 200 without an air inlet and associated features such as air void 71 and air diffuser 29. Other like parts have the same reference numbers.

Figure 4 shows the cutting head of the first embodiment 100 connected to an external flow splitting means 30.

Figure 6 shows the cutting head of the second embodiment 200 connected to an external flow splitting means 30. The device has two line fees 12, each connected to an inlet 22. There is no air feed, or air inlet. The flow splitting means 30 has a head 33 that receives a single line feed (not shown) that has two separate feeds 32 split from the single line feed 31 .

Figures 4 and 6 show a cross section of a flow splitting means 30 and cutting head 100, 200 at the point at which the single line feed (not shown) splits to the separate fees 32.

Figure 7 includes the air inlet 70 that has a separate feed 72 that receives pressurised air from a source (not shown).

Each separate feed 32 connects to a separate conduit 25 that leads to a separate nozzle 20.

A centraliser 40 is provided on an outer face of the cutting head 100 and flow splitting means 30 assembly. The centraliser 40 is an undulating projection that extends from an outer surface of the assembly to help guide the cutting head through the pipe and to space the cutting head 100 and flow splitting means 30 from the pipe during insertion and use. The centraliser 40 is provided above the point 13 of the cutting head 100, so that the centraliser 40 does not become caught on the walls of the pipe after a cut has been made because the centraliser 40 is above the location at which the cut is made.

Figure 7 shows an exploded view of the nozzle assembly 90 and block 21A, 21 B that is part of the cutting head 100, 200. The nozzle assembly 90 is formed from a number of component parts.

The nozzle 20 is arranged in a baffle 27 that receives a nozzle retainer 28. An air diffuser 29 is seated in a recess on a front face of the baffle 27 and has a pin 29B that is located in a notch 27B provided on a front face of the baffle 27.

A locking member 26 is arranged over a distal end of the nozzle 20, locking the nozzle assembly 90 within the block 21 . The locking member 26 has a threaded outer wall (not shown) and has a hex head so that the locking member 26 can be screw fitted to an inner wall 24A of the block. The locking member 26 thereby locks the nozzle 20, baffle 27, air diffuser 29 and nozzle retainer 28 to the block 21 .

A proximal end of the baffle 27 is positioned by a locating pin 27C for orientation (see Figure 5).

A rear part of the block 21 A in use contains the elbow conduit 25 that leads to the nozzle 20. A front part of the block 21 B houses the nozzle 20.

Figure 8 shows a second embodiment of a block 21 A, 21 B which contains a flow splitting means (not shown) within the block to divide flow of cutting fluid from the single line feed 31 along two separate conduits within the block 21A, 21 B to the two nozzles (not shown).

The block is formed from two parts, an inner part 21A that receives the single line feed 31 , and outer (rear) parts 21 B that house the nozzles, and each have an air inlet 70.

One nozzle is arranged within each outer block part 21 B and expels cutting fluid through the nozzle exit 23. The nozzles are held in place by a locking member 26. Each outer block part 21 B also has an air inlet 70 that is also in fluid communication with the nozzle.

In use the block 21 A, 21 B shown in Figure 5 is arranged in a housing so as to be part of the rotating cutting head.

Figure 10 show a diagrammatic representation of a flow splitting means 30at which flow of cutting fluid is split from the single line feed 31 to the separate flow channels 32. An inner surface of the joint has a sacrificial liner 50 that provides a protective layer that is worn down to prevent damage to the inner surfaces of the flow splitter. Figure 8 shows a telescopic assembly 60 comprising two sliding portions, a base member 61 and an upper extending member 62 moveable relative to each other by three actuators 63. The telescopic assembly 60 is arranged in use between the gripper (not shown) and the cutting head 100. The gripper is fixed in an upper region of the pipe to be cut and forms a datum point for the tool. Below the gripper in use is the telescopic member 60 and the cutting head 100 (see Figure 9).

In use the base member 61 and upper extending member 62 can be connected to any part of the tool below the gripper and between the cutting head, which may typically include the flow splitting means 30, the cutting head 100 or the swivel mechanism 64 (see Figure 9).

The pictured actuators 63 are linear actuators which enable adjustment of the position of the rotating cutting head 100 within the pipe (not shown), permitting fine adjustment of the position of the cutting head (not shown in Figure 8) without requirement to adjust position of the whole tool within the pipe. The telescopic assembly allows a castellated or non-linear cut to be performed.

The linear actuators 63 are seated on the base member 61.

Figure 9 shows an example assembly of a tool 500 including a cutting head 100 and a telescopic assembly 60.

At the distal end of the tool 500 there is provided the cutting head 100. The cutting head 100 is connected to the flow splitting means 30. The flow splitting means 30 connects to a swivel mechanism 64 that enables the flow splitting means 30 and cutting head 100 to rotate during cutting whilst proximal parts of the tool 500 remain static.

The swivel mechanism 64 is connected to the telescopic means 60 that enable fine adjustment of the depth of the cutting head 100 within the pipe (not shown). The telescopic assembly 60 connects to grippers 300. The pictured tool 500 has two grippers 300 that are each fixed to the wall of the pipe to locate the tool 500 in place.

Above the grippers 300 is a packer 400. The packer 400 is inflated within the pipe (not shown) to form a sealed annulus between the packer 400 and the pipe (not shown). A head of the packer 400 has a lifting means 410 which enables initial positioning of the tool 500 in the pipe.

The tool 500 can be assembled and dissembled. Each part of the tool 500 connecting by a connection means.

The invention has been described by way of examples only and it will be appreciated that variation may be made to the above-mentioned embodiments without departing from the scope of protection as defined by the claims.