APPARATUS AND METHOD FOR REMOVING SOIL FROM A CONDUIT

Abstract

An apparatus is provided for removing soil from a well casing for a subsea well that is forced or placed on a seabed. The apparatus comprises a soil disturbance device for displacing the soil within the casing before drilling. A method for removing soil from a well casing for a subsea well that is forced or placed on a seabed is also provided. The method comprises using a soil disturbance device to displace the soil within the casing before drilling.

Description

APPARATUS AND METHOD FOR REMOVING SOIL FROM A CONDUIT n Lzznn / zznz / E / Yi Field of Invention The invention relates to an apparatus for removing soil from a conduit for a submarine well that is forced or placed on the seabed and a method for removing soil from a conduit for a submarine well that is forced or placed on a seabed. Background of the Invention When constructing a subsea well, a hole is generally drilled into the seabed, a conductor is installed in the drilled hole, and cemented in place. Once secured, a drill bit and part of a drill string are passed through the conductor so that drilling of the well can continue below it. For certain well installations (such as when installing a subsea well in a soft seabed), it is possible and / or desirable to install the conductor simply by forcing it into the seabed rather than first drilling a hole. However, this installation method creates soil within the conductor. In such circumstances, the conductor has a first free end that is above the seabed or approximately at the same level as the seabed, and a second buried end that is embedded in the seabed and is Ref. 331849 lower than the free end. In some cases, a conductor casing can be attached to what will be the upper end of the conductor once embedded in the seabed. In such cases, the end of the conductor casing that is not attached to the conductor can be referred to as the conductor's free end. Furthermore, it is possible for the grounding conductor to terminate in a conventionally drilled overhead hole. This can occur, for example, if the overhead hole is drilled and the conductor is installed from a vessel other than a platform. Currently, any soil within the conductor is removed using the drill bit that will be used for the subsequent well drilling. However, this increases drilling time, especially if the drill bit size needs to be changed between cleaning the soil from the conductor and drilling the hole beneath it. Furthermore, because the drill bit is not designed for this purpose, removing soil from the conductor using the drill bit in the drill string can result in incomplete soil removal and / or damage to the conductor. As a result, there is a need for an alternative way to remove earth from a conductor for a subsea well. Summary of the Invention In a first aspect, the present invention provides an apparatus for removing soil from a conductor for a submarine well that is forced or placed on a seabed, wherein the apparatus comprises a closing means for closing the free end of the conductor, and a soil disturbance device for displacing the soil within the conduit prior to drilling. In a second aspect, the present invention provides a method for removing soil from a conductor for a subsea well that is forced or placed on a seabed, wherein the method comprises closing the free end of the conductor and then using a soil disturbance device to displace soil within the conductor prior to drilling. The apparatus of the first aspect can be used to perform the method of the second aspect, and the method of the second aspect can be performed using the apparatus of the first aspect. The following description, which includes optional features, is applicable to both the first and second aspects of the invention. This is because the features of the method can be performed using the apparatus and / or the apparatus can be suitable and / or arranged to perform the features of the method. The features of the apparatus can be features of the apparatus used to perform the method. Therefore, the method may comprise providing and / or using an apparatus of the first aspect, which optionally includes one or more of the optional features described below. One result of removing the soil from a conductor for a subsea well before drilling using the apparatus and method of the present invention is that it is not necessary to remove the soil from the conductor using the drill and drill string. This means that the operating time of the drill string can be reduced (and, therefore, the operating time of the drilling rig and / or drilling equipment, which can be very costly). Furthermore, using the apparatus and method of the present invention means that a tool more suitable for the purpose of removing soil from the subsea well conduit than a drill and drill string can be used. The use of a tool more suitable for the purpose means that the soil can be removed more reliably and / or damage to the conduit can be avoided or at least reduced. The apparatus may not be connected to any part extending to the sea surface. The apparatus may not be part of, or connected to, a drill or drill string. The device can be releasably attached to the driver. The device can be operated using a remotely operated vehicle (ROV). The device can be operated, controlled and / or switched on by an ROV. When the apparatus is installed and the conductor has been forced or placed on the seabed, the conductor can be closed or sealed at the free end using the apparatus and at the buried end by the seabed where the conductor has been forced or placed. The closure means may comprise a cap, plug, or end cap. The closure means is for closing the free end of the conductor. The closure means may be for sealing the free end of the conductor. The closure means may comprise a seal for sealing the conductor. The closure means may fit and seal the free end of the conductor. The method involves forming a closed and / or sealed volume within the conductor. The free end of the conductor may be closed / sealed before using the ground disturbance device. The free end of the conductor may be closed / sealed for at least part of the time the ground disturbance device is in use. The earth disturbance device is adapted to displace (e.g., dislodge) the earth within the conductor. The earth in the conductor may be entrained or suspended in the liquid inside the conductor because it has a density only slightly higher than the liquid in the conductor, and as a result, little material, once distributed and suspended in the liquid, will remain entrained or suspended in the liquid long enough to allow the liquid and earth to be removed from the conductor. Alternatively or additionally, the earth may be entrained within the liquid inside the conductor as a result of the flow velocity of the liquid through the conductor. The device can be removed and / or separated from the conductor before drilling. The closing means may comprise at least one inlet means. The inlet means may include or comprise an inlet passage for fluid communication between the exterior of the conduit and the interior volume of the conduit (hereinafter referred to simply as the conduit interior). The inlet passage may further comprise one or both of an external inlet port and an internal inlet port. The external inlet port may be adapted to connect to a pressurized liquid source, such as a pump. The pressurized liquid source may be mounted on or as part of an ROV. The pressurized liquid is a liquid that is at a pressure greater than the seawater pressure in the region of the conductor's free end. The pressurized liquid may be seawater drawn from the conductor's free end region and pressurized by the pressurized liquid source. The pressurized liquid source may be a suitable pump mounted on or as part of an ROV. The sealing means may comprise at least one outlet means. Each outlet means may include or comprise an outlet passage for fluid communication between the inside and outside of the conductor. One or more of the outlet passages may comprise an outlet opening onto the outer face of the sealing means (the outer face of the sealing means being the face opposite the inside of the conductor). In this embodiment, the liquid exiting the outlet mouth mixes with the seawater in the region of the outlet mouth. Soil carried or suspended in the water exiting the outlet mouth may settle on the seabed near the conductor or may be carried away from the conductor by local currents. One benefit of the presence of the closing means is that it prevents soil from being redeposited in the conductor. In other embodiments, one or more of the outlet passages may comprise an outlet port on the outer face of the sealing medium. The outlet port may be adapted to couple with a source of negative pressure, such as a pump. This coupling may be a direct connection or through a pipe or tube. This can also be described as drawing the liquid from inside the conduit out of the conductor through one or more outlet passages. A negative pressure in this context is a pressure below the pressure in the conductor. The greater the negative pressure created by the pump or the negative pressure source, the greater the flow rate of the liquid and any entrained or suspended soil out of the conduit through the outlet passage or passages. Another benefit of using the sealing medium is that it allows increasing or decreasing the liquid pressure inside the conductor in relation to the liquid pressure outside and in the conductor mouth region. The earth disturbance device can remove earth from the inner surface of the conductor so that the conductor (at least the length of conductor on which the device operates) is substantially cleansed of earth. While a small amount of earth may remain within and on the inner surface of the conductor after the device has been used / the method performed, this amount may be small enough not to interfere with further drilling beneath the conductor and / or the installation of components such as sheathing, etc., within and / or across the conductor. The device can remove the ground from the conductor around the device. The ground disturbance device can cause the earth within the conductor to become suspended or trapped in a liquid, such as seawater, inside the conductor. The liquid containing the suspended earth can then be removed from the conductor through an outlet to the closing mechanism, thus removing the earth from the conductor. The earth disturbance device may comprise a mechanical earth disturbance device and / or a fluid flow earth disturbance device. Therefore, the method may comprise the use of a mechanical earth disturbance device and / or a fluid flow earth disturbance device to displace the earth within the conductor prior to drilling. The mechanical earth disturbance device and the fluid flow earth disturbance device, if both are present, can be used in combination to displace the earth. The earth disturbance device can be used to remove earth from the conductor and / or clean the inside of the conductor. Once the apparatus has been used and / or the method has been performed, at least part of the conductor may be substantially free of earth. A mechanical ground disturbance device can be a device that displaces the ground by means of a movable physical part of the device that contacts the ground. A fluid flow earth disturbance device can be a device that displaces the earth using a fluid flow that comes into contact with the earth and disturbs it. The mechanical earth disturbance device may include, for example, a rod, screw, blades, and / or a scraper used to displace / dislodge earth within the conductor. The rod, screw, blades, and / or scraper may come into contact with the earth within the conductor and displace / dislodge it. The mechanical ground disturbance device may be movable within the conductor. The method may involve moving the ground disturbance device. The mechanical ground disturbance device may be, and / or have at least a part that is, movable along and / or near the inner surface of the conductor to displace the ground. For example, the mechanical disturbance device may have a maximum outer diameter that is approximately the same as the inner diameter of the conductor. For example, the maximum outer diameter of the mechanical ground disturbance device may be at least 90% or at least 95% of the minimum inner diameter of the conductor. The mechanical ground disturbance device may be arranged so that, in use, it can move within the conductor and disturb the ground within the conductor. The mechanical ground disturbance device may also be arranged so that, in use, it can move within the conduit to cause the liquid (e.g., containing soil) to flow out of the conductor through an outlet passage in the sealing medium. The mechanical ground disturbance device may be architecturally integrated and controlled and / or powered by an ROV. The apparatus may include an actuator for moving the mechanical earth disturbance device. The actuator may include an ROV interface. The ROV interface may be integral with the sealing medium and allow the ROV's energy or torque to pass through the sealing medium. In other embodiments, the actuator interface may extend through the sealing medium. In such embodiments, the interface between the actuator and the sealing medium may be sealed so that fluid cannot flow through the sealing medium alongside the actuator. The apparatus may comprise a lance. The lance may extend within the conductor. The mechanical earth disturbance device may be displaced along the lance. The lance may be part of the actuator. The actuator may include a nut. For example, the actuator may include an externally threaded lance and an internally threaded nut. The lance may be a long, relatively thin protrusion that, when the device is installed, extends along at least part of the length of the conduit (this may also be considered and / or referred to as a rod, bolt, screw, post, radius, etc.). The lance may act as a drive screw for the nut. The lance may include a helical screw thread. When the device is mounted on or inside the conductor, the lance may extend along the center of the conductor. The threaded nut may move along, i.e., up and down, the lance as the lance and nut rotate relative to each other. For example, the lance may be rotated, for instance, by an ROV. The lance may be connected to or include an ROV interface.The apparatus may be arranged so that when the ROV interface rotates, the lance also rotates. The rotation of the ROV interface, and therefore of the lance, may cause the nut to move, for example, up and / or down the lance. The apparatus may include a stop at or near the end of the lance furthest from the ROV interface. The stop may be present to retain the nut on the lance and cause it to return up the lance once it has reached the bottom of the lance. If the apparatus includes a centralizer (as described below), the centralizer may act as a stop. When the device is installed on / inside the conductor, the lance and / or nut may be located inside the conductor. The lance and nut may be inside the conductor. The mechanical ground disturbance device may be connected to and / or integral with the nut. The mechanical ground disturbance device may extend radially outward from the nut. The mechanical ground disturbance device may comprise, for example, one or more blades extending radially outward from the nut. The maximum outside diameter of the blades may be approximately equal to (for example, within 95%) the minimum inside diameter of the conductor. Rotating the lance (for example, using the ROV interface) can cause the nut, and therefore the mechanical ground disturbance device, to move along the lance and thus up and down (in an axial direction) within the conductor. The mechanical ground disturbance device can move along the lance between the locking mechanism at the top and the barrier end of the conductor at the bottom of the lance. The movement of the mechanical ground disturbance device can dislodge soil within the conductor. The mechanical ground disturbance device can be moved within the conductor to move the fluid inside it. Therefore, when the mechanical ground disturbance device is moved, the soil within the conductor can be dislodged and subsequently removed from the conductor by the movement of the fluid out of the conductor. The upward movement of the mechanical ground disturbance device (from the buried end toward the free end of the conductor) can push the fluid and / or soil upward and out of the conductor. The device, for example the lance, when installed on the conductor, may extend at least the length (in an axial direction) of the conductor from which the earth is to be removed. This may be the entire length of the conductor. Alternatively, this may be an upper portion of the conductor, such as at least the upper three-quarters or half of the conductor. It may be acceptable for the earth not to be removed from the lowest part of the conductor. This is because it may be acceptable to remove the earth from this section with a drill. This is because incomplete removal of the earth from this part may not impede the installation of coatings, etc., within the conductor, and / or it may be acceptable for this part of the conductor to be damaged by the drilling operation. The mechanical earth disturbance device can be moved along the apparatus. The lance can be centered within the conductor. The device (e.g., the device's lance) can be centered within the conductor by means of a centralizer. The device may comprise a centralizer. The centralizer can be located at or near the bottom of the device (i.e., the end of the device furthest from the closing means). This is because a connection between the device and the conductor at the free end of the conductor can center the device and the lance at the free end of the conductor, and therefore, the centralizer at or toward the buried end of the device's conductor can help ensure that the device (e.g., the lance) is centered toward the buried end of the conduit. The centralizer may be connected to the drawbar. The centralizer may have one or more arms extending radially outward from the drawbar. The centralizer may have an outer surface that, in use, rests against the inner surface of the conductor. The length between the drawbar and the outer surface of the centralizer may be approximately equal to the radius of the conductor. n Lzznn / zznz / E / Yi The centralizer can help to hold and / or guide the appliance through the conductor while the appliance is being installed. Introducing liquid into the conductor can cause the liquid to flow out of the conduit. This liquid flow can be used to remove soil from the conductor, for example, soil that has been displaced and suspended in the liquid inside the conductor. The liquid inlet to the sealing medium may comprise a plurality of openings, such as nozzles or jets, through which the liquid flows into the conductor. These openings may form the liquid flow disturbance device. The openings may also be constrictions through which the liquid flows into the conductor. The openings may produce jets of liquid, such as seawater, which dislodge or disturb the soil and suspend it within the liquid inside the conductor. The liquid, for example, the liquid containing suspended soil, may be removed from the conductor through one or more outlet passages in the sealing medium. This may be due to the liquid flowing into the conduit through the inlet passage and, consequently, the openings. The liquid may be forced into the inlet passage and through the openings under pressure.Therefore, the liquid that comes out of the n Lzznn / zznz / E / Yi openings can form liquid jets that displace the earth inside the conductor and / or cause the liquid to flow out of the conductor. When the apparatus comprises a lance, the openings may be located on the lance. The liquid inlet passage through the sealing means may be in liquid communication with the lance. The lance may have a liquid passage through it. In use, the liquid may flow into and through the lance into the openings. Thus, the lance may provide the fluid flow earth disturbance device. The lance may therefore serve the dual purpose of providing part (the actuator) of the mechanical earth disturbance device and openings for the liquid flow earth disturbance device. When the lance is rotated to move the mechanical earth disturbance device along its length, the openings may rotate, causing the liquid jets expelled from them to rotate.This means that liquid can be projected onto the inner surface of the conductor around its entire inner circumference. The openings can be spaced so that the liquid jets from the openings overlap in an axial direction. As a result, substantially the entire inner surface of the conductor along the length over which the openings are provided can come into contact with the liquid jets. The openings may be located at least at or near the bottom of the lance (the end of the lance furthest from the free end of the conductor). This is so that the fluid flow caused by the fluid flowing into the conductor can occur along the entire length of the apparatus. The openings may be located along the length of the apparatus, for example, along the lance. The apparatus may comprise openings of at least 5 or 10 or more different heights or axial distances along its length. The sealing means may include an outlet passage. Liquid and soil may pass through the outlet. Liquid may flow from the inlet passage (through the openings) to the outlet passage. Therefore, the apparatus is arranged so that liquid may circulate into and out of the conductor. The length of the conductor cleaned by the device can be approximately equal to the length of the device.The liquid can be forced into the conduit through the inlet passage and / or out of the conduit through the outlet passage. For example, liquid can be pumped into and / or out of the conduit through the liquid inlet passage and the outlet passage, respectively. The liquid inlet passage and / or the outlet passage may have a pump interface to which a pump can be connected. The apparatus may comprise one or more pumps for pumping liquid into the inlet passage and / or liquid out of the outlet passage. The liquid, such as seawater, without suspended soil, can be forced into the conduit (for example, through the inlet passage, the lance, and the openings), and the liquid may, once inside the conduit, contain suspended soil before being removed from the conduit through the outlet passage to also remove the soil from the conduit.This process can be repeated until at least a portion of the conductor is substantially free of earth, meaning sufficiently free of earth so that components, such as sheathing, can be mounted inside the conductor without requiring further earth removal operations on the clean portion of the conduit. The fluid flow can then be used to flush the inside of the conductor. In use, the liquid can be forced into the conductor through one or more entry points and, therefore, openings. This results in jets of liquid flowing into the conductor, which can act as a fluid flow ground disturbance device. The liquid jets can dislodge soil within the conductor. The jets can also cause the liquid to leave the conductor and remove soil with it. Before, at the same time as, and / or after the operation of the fluid flow ground disturbance device, the mechanical ground disturbance device can be operated. The device may include a conductor protector. The conductor protector may extend over only a portion of the appliance's length. The conductor protector may extend over only part of the conductor's length when the appliance is installed on the conductor. The conductor protector can be used to protect a portion of the conductor that must not be damaged during the cleaning operation. For example, this could be a portion of the conductor with an internal profile and / or a portion from which other tubular items, such as sheathing, can be suspended. The conductor protector can be used to cover a portion of the conductor's inner surface. The earth disturbance device (e.g., mechanical earth disturbance device and / or liquid flow earth disturbance device) can extend through the conductor shield. The minimum inside diameter of the conductor protector can be substantially the same as the maximum outside diameter of the mechanical earth disturbance device. n Lzznn / zznz / E / Yi When the appliance is not in use, the mechanical earth disturbance device can be housed inside the conductor protector. Therefore, the mechanical earth disturbance device can be protected by the conductor protector, for example, during transport of the appliance. The mechanical earth disturbance device may be housed within the conductor protector when the appliance is being installed on and / or removed from the conductor. This can minimize the risk of damage to the mechanical earth disturbance device and / or the conductor during appliance installation and / or removal. The conductor protector can be used to protect a portion of the conductor that has not been forced or laid on the seabed, i.e., a part that protrudes above the seabed surface. This could be, for example, the upper portion of the conductor. This part of the conductor can be protected (and therefore not cleared by the apparatus's earth disturbance device) since there is no earth to remove from this part of the conductor protector. The conductor protector may be connected to the appliance's closing means. The conductor protector together with the sealing means can, in use, create a seal with the conduit. n Lzznn / zznz / E / Yi The conductor protector can be a tube with a cross-section of shape and / or size corresponding to the portion of conductor that it protects in use. The conductor protector can have an outer diameter that is substantially the same as the minimum inner diameter of the portion of the conductor it protects. Therefore, the conductor protector can fit perfectly onto the part of the conductor it protects. The conductor discussed above may be a conduit for use in a subsea well. The conductor may comprise a conductor casing (i.e., a low-pressure wellhead casing) and / or a conductor pipe. The conductor casing may be attached to the upper end of the conductor pipe. In this case, the conductor protector (if present) may be for protecting (e.g., covering) the conductor casing. Therefore, the conductor protector may be referred to as a conductor casing protector. The conduit can be the first pipe installed in a well from which surface liners can be hung, or are hung. The conduit can be placed on the seabed in a pre-drilled hole. The method may involve drilling a hole in the seabed and then placing the conduit in the hole. Such a scenario may, under certain circumstances, result in some soil becoming trapped inside the conduit, which must be removed. The conduit or pipe can be forcibly driven into the seabed by piloting and / or suction. The conduit can be forced directly into the seabed. The conduit can be forcibly driven into the seabed without first drilling a hole. The conduit can be connected to a suction anchor. The conduit or pipe can be pushed into the seabed by the suction anchor, which is being pulled into the seabed. The conduit could be, for example, the central tube of a suction anchor. The conduit can be forced or laid on the seabed so that a portion of it protrudes above the seabed. This protruding portion can be a support for internal tubulars. For example, the protruding portion could be a conductor casing. In this case, a high-pressure wellhead housing and its associated casing can be landed or suspended from it. The apparatus described above can be installed in the conduit after the conduit has been forced or placed on the seabed. In this case, the earth disturbance device, for example, the fluid flow earth disturbance device, can be used to clear and / or dislodge at least some of the earth during the apparatus's installation in the conduit. For example, fluid can be forced through the apparatus, for example, through the lance, to facilitate its installation. Alternatively, the earth disturbance device cannot be operated until it is fully installed in the conduit. Therefore, the apparatus can be forced through the earth within the conduit. Once the apparatus is fully installed, and the closing means have sealed the upper end of the conduit (the free end), the apparatus and therefore the earth disturbance device can be used to remove substantially all the earth from the conduit (at least from the length of the conduit over which the apparatus extends). The device can be installed in the conduit before it is forced out or placed on the seabed. Therefore, the conduit can be forced out or placed on the seabed with the device already mounted on it. The apparatus (e.g., the earth disturbance device, such as the mechanical earth disturbance device and / or the liquid flow earth disturbance device) can operate while the conduit is being forced or placed on the seabed. Therefore, the earth can be dislodged and / or removed from inside the conduit while it is being forced or placed on the seabed. Thus, the apparatus can make it easier to force or place the conduit on the seabed. When the apparatus is mounted on the conduit before forcing or placing it on the seabed, fluid can escape from the conduit through an outlet passage while the conduit is being forced or placed on the seabed. Fluid can be pumped out of the conduit, for example through the outlet passage, to create suction within the conduit. This can assist and / or facilitate the forcing or placement of the conduit on the seabed. The suction may be in addition to the suction provided by a surrounding suction anchor (if present). Regardless of whether the apparatus is installed in the conduit before or after it has been forced into or placed on the seabed, the apparatus will be driven into the earth within the conduit. The mechanical earth disturbance device and / or the fluid flow earth disturbance device may be operated while the apparatus is being forced into or through the earth within the conduit. Once the soil has been removed from the conduit, the apparatus can be removed. After this, a drill and / or drill string can be passed through the conduit so that a hole can be drilled beneath it. The apparatus cannot be operated until the conduit is forced into the seabed in the desired position. Thus, the apparatus can be forced through the earth into the conduit while the conduit is being forced into the seabed. However, the apparatus can be arranged to allow fluid to drain from the conduit (for example, by opening the outlet passage) while the conduit is being forced into the seabed. This is so that the apparatus does not impede the forced insertion of the conduit into the seabed. The method may comprise providing the apparatus, installing the apparatus in the conduit, closing the end of the conduit with the sealing means, operating the earth disturbance device, forcing liquid into and out of the conduit through the inlet and outlet conduits, removing the earth from the apparatus, and / or removing the apparatus from the conduit. Although the terms submarine and seabed, etc., are used here, it should be appreciated that this means the bed below any large body of water such as an ocean, lake, etc., and in any corresponding waterbed. n Lzznn / zznz / E / Yi The term "soil" as used herein refers to any seabed material (i.e., waterbed) into which the conduit has been forced or placed. This may include, for example, sand, rocks, pebbles, stones, clay, mud, organic matter, etc. The apparatus and method may be used with soft soil. For example, soil that is soft enough for a suction anchor to be drawn into it. The device may be called a ground withdrawal device. The invention described above has been described largely with reference to a conductor. It should be understood that the reference to the conductor includes reference to conduits used in underwater or subsea applications. A system comprising the apparatus and the conductor or conduit may be provided. The apparatus and / or conduit may comprise one or more of the features described above, including optional features. The system may include at least one ROV that controls, operates, and / or powers the apparatus. A system comprising the apparatus of the present invention and one or more ROVs is particularly advantageous because, although ROVs have significantly less power than drilling rigs or other drilling vessels, they have sufficient power to operate the apparatus. The ROV and apparatus are significantly less expensive to operate and are less likely to damage the pipeline than a platform or other drilling vessels. Although the device and method described in this document are for removing soil from a conduit for a subsea well, they could also be used to remove soil or other debris from other conduits for other purposes and / or in other locations. Brief Description of the Figures Certain preferred embodiments of the present invention will now be described by way of example only with reference to the accompanying figures, in which: Figure 1 shows an apparatus for removing soil from a conduit or pipe for a subsea well that is forced or laid on a seabed; and Figure 2 shows the apparatus mounted in a conduit for a subsea well. Figure 1 shows a soil removal apparatus 1 for removing soil from a conduit for a subsea well that is pushed under pressure into a seabed. Detailed Description of the Invention Apparatus 1 comprises an earth disturbance device 2 comprising a mechanical earth disturbance device 4 and a liquid flow earth disturbance device 6. n Lzznn / zznz / E / Yi The mechanical ground disturbance device 4 comprises a plurality of blades. The blades are connected to an internally threaded nut 8 which is mounted on an externally threaded lance 10. The lance 10 is connected at its upper end to an ROV interface 12. Along the length of the lance 10 there are a plurality of openings 14 (for clarity, only one of the twelve sets of openings 14 is labelled with a reference number in the figure). The openings 14 provide the liquid flow earth disturbance device 6. The apparatus 1 comprises a liquid inlet 16. The liquid inlet passage 16 is in liquid communication with the openings 14. The apparatus 1 comprises an outlet passage 18 through which liquid and soil can exit the conduit. The inlet passage 16 and the outlet passage 18 extend through a cap 20. The cap 20 can be used to seal the conduit when the apparatus 1 is installed. Appliance 1 comprises a duct protector 22. The duct protector 22 is connected to the cover 20. When appliance 1 is installed in a duct, the duct protector 22 covers, and optionally contacts, an upper portion of the duct. Towards the bottom of the lance 10 there is a centralizer 24. The centralizer 24 serves to guide and hold the lance 10 within the duct. The centralizer 24 also acts as a stop to prevent the nut 8 from coming off the bottom of the lance 10 when the lance rotates. Figure 2 shows the apparatus 1 of Figure 1 mounted in a conduit 26. In this case, the conduit 26 is the center tube of a suction anchor 28. Although the apparatus 1 is shown in a center tube 26 of a suction anchor, the conduit for a subsea well cleared by the apparatus 1 need not be part of a suction anchor. The apparatus can equally be used to displace earth from a conduit that is not part of a suction anchor. Such a conduit may have been forced into the seabed by a means other than suction, such as by means of piles or placed in a drilled hole. At the top of conduit 26 is a conductor casing 30. Once conduit 26 has been forcibly inserted into the seabed, at least the conductor casing 30 may protrude from the top of the seabed. Therefore, there may be no soil inside the conductor casing 30 after conduit 26 has been forcibly inserted into the seabed. Appliance 1 is installed in duct 26 as shown in Figure 2. The lower end of the lance 10 and the centralizer 24 are first inserted into the upper end of duct 26. Appliance 1 is held and guided downwards into duct 26 by the centralizer 24. Appliance 1 is further inserted into the duct until the duct protector 22 is inside the conductor housing 30 and the cap 20 is in contact with the top of duct 26 (i.e., the top of the conductor housing 30). Then, appliance 1 can seal with the upper end of conduit 26 through cap 20 and / or the conduit protector 22. At this point, a closed volume can be formed inside conduit 26. The closed volume is formed inside conduit 26 by the upper end being sealed by at least cap 20 and the lower end being sealed with earth. Apparatus 1 can be installed inside conduit 26 before the conduit is forcibly inserted into the seabed. Alternatively, apparatus 1 can be installed inside conduit 26 after the conduit 26 has been forcibly inserted into the seabed. In either case, apparatus 1 will be forced through the earth into conduit 26. The earth disturbance device 2 (e.g., mechanical earth disturbance device 4 and / or fluid flow earth disturbance device 6) can be operated when the apparatus is forced through the earth into conduit 26. This can facilitate the installation of apparatus 1. The mechanical ground disturbance device 4 can be operated by rotating the lance 10. The lance 10 can be rotated using the ROV interface tool 12. The rotation of the lance 10 causes the nut 8 to move along the lance 10. This causes the blades of the mechanical earth disturbance device 4 connected to the nut 8 to also move along the lance 10 so that they can act to displace the earth. As the lance 10 continues to rotate, the nut 8 moves down the lance 10 until it reaches the stop at the end of the lance 10 (in this case, the centralizer 24). At that point, as the rotation continues, the nut 8, along with the blades 4, moves back down the lance 10 until it reaches the top. The up-and-down movement of the blades 4 along the lance 10 inside the conduit displaces the soil within the conduit and moves the fluid so that the soil can be removed from the conduit 26. The fluid flow earth disturbance device 6 can be operated by forcing fluid in through inlet 16, through lance 10, through openings 14 into the conduit and then out of the conduit 26 through outlet 18. The fluid can be forced through this fluid path by means of one or more pumps (not shown) connected to fluid inlet 16 and / or outlet 18. The flow of fluid from openings 14 to outlet 18 can displace the soil within conduit 26 and remove it from it because the soil is suspended within the fluid. The openings 14 can be constrictions such that the fluid flowing through them forms jets that act to dislodge the surrounding soil. The mechanical earth disturbance device 4 and / or the fluid flow earth disturbance device 6 can displace the earth and cause it to become suspended in the fluid within the conduit and / or can cause the fluid (e.g., with suspended earth) to flow out of the conduit 26, e.g., through outlet 18. Therefore, the mechanical earth disturbance device 4 and / or the fluid flow earth disturbance device 6 can act to remove the earth from the conduit 26. Once the soil has been removed from conduit 26, apparatus 1 can be removed from conduit 26. Once apparatus 1 has been removed, a drill and drill string can be passed through the clean conduit so that drilling can be carried out to create a well below conduit 26. It is hereby stated that, as of this date, the best method known to the applicant for putting the aforementioned invention into practice is the one that is clear from the present description of the invention.

Claims

1. An apparatus for removing soil from a conduit for a subsea well that is forced or placed in the seabed, characterized in that the conduit has a first free end that is above or approximately at the level of the seabed and a second buried end that is embedded in the seabed, and the apparatus comprises a closing means for closing the free end of the conduit and a soil disturbance device for displacing soil within the conduit prior to drilling.

2. The apparatus according to claim 1, characterized in that the closing means comprises a cap, lid or plug suitable for closing the free end of the conduit.

3. An apparatus according to claim 1 or 2, characterized in that the earth disturbance device comprises a mechanical earth disturbance device.

4. An apparatus according to claim 3, characterized in that it comprises a lance along which the mechanical earth disturbance device is arranged to move. n Lzznn / zznz / E / Yi 5. An apparatus according to claim 4, characterized in that it is arranged so that the mechanical earth disturbance device moves along the lance when the lance rotates.

6. An apparatus according to any of the preceding claims, characterized in that the earth disturbance device comprises a liquid flow earth disturbance device.

7. An apparatus according to claim 6, characterized in that it comprises a plurality of openings through which the liquid can flow into the conduit, thus forming the liquid flow earth disturbance device.

8. An apparatus according to claim 7 when dependent on claim 4, characterized in that the openings are located in the lance.

9. An apparatus according to any of the preceding claims, characterized in that it comprises a duct protector for covering a portion of the inner surface of the duct.

10. An apparatus in accordance with any of the preceding claims, characterized in that it comprises a centralizer located at or near the end of the apparatus n Lzznn / zznz / E / Yi away from the closing means.

11. An apparatus in accordance with any of the preceding claims, characterized in that the conduit is a conductor.

12. An apparatus in accordance with any of the preceding claims, characterized in that the conduit is a central tube of a suction anchor.

13. An apparatus according to any of the preceding claims, characterized in that the closing means comprises at least one outlet passage, and at least one outlet passage is for the flow of liquid and soil carried or suspended out of the conduit.

14. An apparatus according to claim 13, characterized in that one or more outlet passages of the closing means are provided with an outlet port, and at least one outlet port is suitable for connection to a low-pressure source.

15. An apparatus according to any of the preceding claims, characterized in that the closing means comprises at least one inlet passage, and at least one inlet passage is for the flow of liquid into the conduit.

16. An apparatus according to claim 15, characterized in that one or more of the inlet passages of the closing means are provided with an inlet port, and at least one of the inlet ports is suitable for connection to a pressurized liquid source.

17. A system for removing soil from a conduit, characterized in that it comprises an apparatus according to claim 14 and a low-pressure source, wherein the low-pressure source is an outlet pump, and the outlet pump is configured to cause a low pressure in the outlet passage or passages with which it is in liquid communication.

18. A system according to claim 17, characterized in that the outlet pump is part of or mounted on a remotely operated vehicle.

19. A system for removing soil from a conduit, characterized in that it comprises an apparatus according to claim 16 and a pressurized liquid source, wherein the pressurized liquid source is an inlet pump, the inlet pump being configured to pump liquid to or each inlet passage with which it is in liquid communication.

20. A system according to claim 19, characterized in that the inlet pump is part of or mounted on a remotely operated vehicle.

21. A method for removing soil from a conduit for a subsea well that is forced or placed in the seabed, characterized in that the conduit has a first free end that is above or approximately at the level of the seabed and a second buried end that is embedded in the seabed, comprising closing the free end of the conduit with a closing means and using a soil disturbance device to displace the soil within the conduit prior to drilling.

22. A method according to claim 21, characterized in that it comprises forcing liquid into the conduit and / or forcing liquid with soil suspended therein from the conduit through one or more outlet passages in the closing means to also remove the soil from the conduit.

23. A method according to claim 21 or 22, characterized in that it comprises providing and / or using the apparatus according to any of claims 1 to 16 or a system according to any of claims 17 to 20.

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