The present invention relates to a tool used in connection with systems and arrangements for drilling subsea wells, where the tool is designed to be able to manage and regulate annular well pressures in drilling operations and in well control procedures. More specifically the present invention relates to a circulation tool that will deal with problems encountered with conventional drilling and with other previous art when encountering higher than expected pressure in underground formations.

After an oil and gas well is drilled, a casing is run into the well bore and subsequently cemented therein, in order to complete the oil and gas well for purposes of the production of fluids from various formations of the earth intersected by the well bore.

Typically, the string of casing is made up and run into the well bore using the drilling rig which drilled the well. A well bore is often not drilled along a straight line into the earth and since differing types of formations of earth are intersected by the well bore, it is not uncommon that the casing is intermittently stuck in the well bore at some point. Drilling mud is then typically circulated through the casing and well bore in an attempt to “wash” the casing free to continue running the casing into the well bore. Furthermore, a major hazard in a deep water drilling operation is the uncontrolled release of gas from the fluid system that can occur when gas has been circulated above the blow out preventer undetected. Once the entrained gas reaches the bubble point of the fluid system that is used, the gas is released and expands quickly. The rapid release of gas may unload large volumes of fluid to the rig floor followed by the release of hydrocarbon gas. This may set off a chain reaction which results in a further uncontrolled and dramatic release of gas and drilling fluid at the rig floor, and as the rapid unloading of drilling fluid reduces the applied bottom hole pressure, where this situation may also result in a secondary influx of formation fluids into the wellbore. Even though such uncontrolled release of gas is not a common event, at present this is dealt with by closing a diverter just below the rig floor, to allow the released gas to be vented overboard.

However, even if such diverter diverts the released gas away from personnel, it does not control the release or manage the bottom hole pressure during the event.

Moreover, due to the speed at which the gas is released, the reaction time using the current system technology has been shown to be too slow to fully protect the drill crew. The probability of occurrence increases with the setting depth of the subsea blow out preventer. So-called circulating swedges are used in many applications to circulate fluids down tubing, drill pipe and/or casing, or out of tubing, drill pipe and/or casing. The swedge is then attached to a top of the tubing or the like via a threaded connection. Flowlines at the surface are then attached to the swedge to allow circulation.

US 2019330941 A1 relates to a crossover sub, where the crossover sub includes a tubular housing connected to a drill string in a wellbore, a sealing structure to seal against a wellbore wall, and a sleeve valve disposed within the housing and movable between a closed position and an open position in response to a fluid pressure in a first flow chamber or second, separate flow chamber of the housing. The first flow chamber fluidly connects an upper annulus of the wellbore to a central bore of the drill string downhole of the crossover sub. The second flow chamber fluidly connects a central bore of the drill string up hole of the sealing structure to a lower annulus of the wellbore. The sleeve valve closes the second flow chamber in response to the sleeve valve being in the closed position and opens the second flow chamber in response to the sleeve valve being in the open position.

US 6.220.361 A1 relates to a circulating nipple used to circulate fluid through well casing while running the casing into a well. The circulating nipple has a body portion and an elongated neck portion. The elongated neck portion is adapted for engagement with a pipe wrench for making the nipple up on the casing string. The body defines one or more holes therethrough adapted for receiving a handle or operating bar therein. The operating bar may be used as an alternative to, or in addition to, the use of the pipe wrench for making the nipple up on the casing string. Methods of running casing using the circulating nipple are also disclosed.

There is thus a need for alternatives to today's circulation systems, or at least supplementary solutions for such circulation systems.

An object according to the present invention is to remedy at least one of the above- mentioned disadvantages or problems.

Another object according to the present invention is to provide a “simpler”, cheaper and effectively circulation tool.

These objects are achieved according to the present invention with a circulation device as defined in the independent claim 1. Further embodiments of the invention are defined in the dependent claims.

The present invention relates to a circulation tool, where the circulation tool comprises a setting tool and a pipe element to which a number of gaskets are connected in appropriate ways, where the setting tool comprises a hollow housing in which a cylinder is arranged, a plurality of locking elements further being arranged around a periphery of a lower part of the housing of the setting tool, and wherein each gasket may comprises two or more elements which, when assembled, will form the gasket and which are held together by holding devices.

According to one embodiment of the present invention, the cylinder may be provided with a through-going hole over its entire length L, such that liquid and/or gas may flow through the circulation tool when the circulation tool is assembled to pipes downhole an oil well.

The housing of the setting tool may in one embodiment be provided, towards each end of the setting tool, with a number of attachment lugs, in order to fasten the circulation tool between two pipes to which the setting tool is to be connected to. The number of attachment lugs may then, for instance, be arranged around an outer periphery of the housing. Each pipe, to which the circulation tool is to be connected, may then be provided with a same number of attachment lugs.

However, it could also be envisaged that the circulation tool could be connected or fastened to the each of the pipe in other ways, for instance through a number of quick connections, a number of male and female connections or the like.

According to one aspect, the hollow housing of the setting tool may be provided with a plurality of locking elements, where the plurality of locking elements may be arranged around a periphery of a lower part of the hollow housing. The plurality of locking elements may be arranged to be operated between a retracted position and an extended position. When the setting tool has been lowered down onto the pipe element comprising the one or more gaskets, and the gasket is to be activated, i.e. brought to a state where the gasket provides a seal between the housing of the setting tool and the pipe element through the use of the cylinder, the plurality of locking elements will be brought to the extended position. In this extended position the plurality of locking elements will form an abutment for the gasket during its activation.

When the locking elements are in a retracted position (i.e. a non-locking position), the setting tool may be lowered down over the pipe element and the gasket connected to the pipe element.

The pipe element may be provided with at least one contact face for the gasket, where the contact face will form an abutment for the gasket when the gasket is activated.

The diameter of the hollow cylinder may be substantially the same as a diameter of the pipe element, thereby allowing as much flow as possible through the circulation tool. The hollow cylinder may in appropriate ways be fixed to an inside of the housing of the setting tool.

In one embodiment the gasket may comprise two separate elements, each separate element forming a half of the gasket, where the two separate elements or halves, when the gasket is to be installed, are arranged around the pipe element, and moved towards each other, whereafter the holding devices will hold the two separate elements or halves of the gasket together.

In an alterative embodiment the gasket may comprise more that two separate elements, where the number of separate elements, when installed and held together through the holding devices, will form a complete gasket.

It could also be envisaged that the gasket could be provided as a hinged connection, where the two separate elements or halves, through one of their ends, could be connected through a hinge, while opposite ends of the two separate elements or halves could be provided with holding devices, in order to allow the two separate elements or halves of the gasket to be connected and held together.

According to one aspect, the holding devices that are used to hold the two separate elements or halves of the gasket together when the two separate elements or halves are assembled, may be magnets. Each end of a separate element or half of the gasket may then be provided with a magnet or the like, where the magnets will ensure that the two separate elements or halves are held together when assembled.

However, it could also be envisaged that the holding devices could be bolts and nuts, where each separate element of the gasket, at each end of the separate element, could be provided with a number of throughgoing holes, and where the separate elements are connected to each other through the use of bolts and nuts.

In one embodiment according to the present invention each element of the gasket may comprise two steel elements connected to each other through a gasket element. When the gasket is to be activated, the two steel elements will be pressed towards each other, this in turn resulting in that the gasket element, the gasket element being arranged between the two steel elements, is squeezed together, thereby expanding in a radial direction. This expansion in the radial direction of the circulation tool will provide a seal between the pipes and the setting tool.

The pipe element may in one embodiment be provided with a shoulder for supporting support members that are used to support the gasket. When the gasket is assembled around the pipe element, the gasket will be held together through the holding device, but the gasket must also be held in a certain position relative the pipe element. Supporting members may then be used to hold the gasket in this position, where the supporting members, for instance, may be a number of “sticks” that in appropriate ways are “hang off’ in the shoulder and the gasket.

The shoulder and/or gasket may then be provided with a number of reception holes for the “sticks”, the “sticks” then being provided with lugs.

Support members could also be a plurality of lips, flanges, lugs or the like arranged around an outer circumference of the pipe element and extending radially out from the pipe element, such that the gasket could be arranged to rest on the support members before the gasket is activated.

According to one aspect, the pipe element may be provided with at least one contact face for the gasket, where the contact face will prevent a movement of the gasket relative the pipe element when the setting tool is used to active the gasket.

Other advantages and features of the invention will become apparent from the following detailed description, the accompanying drawings and the following claims, where

Figure l is a schematic figure of a gasket according to the present invention, showing the gasket in an unassembled state and in an assembled state,

Figure 2 shows in a schematic way how a setting tool is used to active the gasket, and

Figure 3 shows when the circulation tool is installed.

Figure 1 shows in a schematic way a gasket 3 and a pipe element 3- 2 of a circulation tool T according to the present invention, where the gasket 3 is shown in an unassembled state on the left figure and in an assembled and closed state on the right figure.

The gasket 3 comprises two separate elements 3a, 3b or halves, where each separate element 3a, 3b or half of the gasket 3 comprises a first steel element 3c and a second steel element 3d, where the first and second steel elements 3c, 3d are connected to each other through a gasket element 3e. Each end of either half 3a or half 3b is provided with a holding device 3f. The holding device 3f in this exemplary embodiment is a magnet.

Before the circulation tool T according to the present invention is to be used, the gasket 3 must be installed around the pipe element 2. This is done by guiding the two separate elements 3a, 3b or halves towards the pipe element 2 and each other, so as to connect the two separate elements 3a, 3b or halves to each other through the holding device 3f.

In one alternative embodiment the gasket 3 could be provided as a hinged connection, where the two separate elements 3a, 3b or halves, through one of their ends, could be connected through a hinge (not shown), while opposite ends of the two separate elements 3a, 3b or halves could be provided with holding devices, in order to allow the two separate elements or halves of the gasket to be connected and held together.

When the two separate elements 3a, 3b or halves are connected to each other, as shown in the right figure, the gasket 3 will be hang off in the pipe element 2 by means of by means of support members 9 in form of “sticks”, rods or the like.

The pipe element 2 is then provided with a radially outwardly extending shoulder 10, from which shoulder 10 the support members 9 are hang off from. Similarly, the gasket 3 is provided with a shoulder (not shown) or the like, to which shoulder the support members 9 are connected to.

The pipe element 2 is also provided with a contact face 11 for the gasket 3, where the contact face 11 will prevent the gasket 3 to move in a longitudinal direction of the pipe element 2 during the activation of the gasket 3.

Figure 2 shows a setting tool 1 according to the present invention, where the setting tool 1 is used to activate the gasket 3. The setting tool 1 comprises a hollow housing 4, where a cylinder 5 is arranged inside the hollow housing 4 and in appropriate ways connected to the hollow housing 4. Furthermore, a plurality of locking elements 6 are arranged around a periphery of a lower part of the housing 4, where the locking elements 6 in appropriate ways are arranged to be activated between a retracted position and an extended position.

The setting tool 1 is thereafter lowered down onto the pipe element 2 comprising the gasket 3, where the pipe element 2 is connected to a pipe (not shown) to which the circulation tool T is to be connected to. When the gasket 3 is to be activated in order to provide a tight sealing between the pipe element 2 and the setting tool 1 (i.e. the hollow housing 4 of the setting tool 1) through use of the cylinder, the locking elements 6 are brought to their extended position.

In this extended position the plurality of locking elements will form an abutment for the gasket during its activation.

When the locking elements 6 are activated to their extended position, one end of the cylinder 5 will abut against an upper end of the pipe element 2 and the cylinder 5 can now be activated in order to push the hollow housing 4 of the setting tool 1 away from the pipe element 2. However, the locking elements 6, being in an extended position, will drag along the gasket 3 with them, so that the gasket 3 moves relative to the pipe element 3. The gasket 3 will then move towards the shoulder 10 provided on the pipe element 2. When the gasket 3 abuts or rests against the shoulder 10, a further movement of the setting tool 1 through the extension of the cylinder 5 will cause the gasket 3 to be squeezed, so that the gasket element 3e expands in a radial direction of the pipe element 2. This expansion will result in that a seal is obtained between the pipe element 2 and the housing 4 of the setting tool 1.

Figure 3 shows when the circulation tool T is installed between a first pipe 12 and a second pipe 13 and the gasket 3 is activated, where it can be seen that the cylinder 5 is hollow, in order to allow as much flow as possible through the circulation tool 1.

The circulation tool T is also connected to one or more pipes through inlet(s) (not shown) and/or outlet(s) (not shown) provided in the circulation tool T, such that the circulation tool T may be used to circulate or pump a liquid in or out of the well when needed.

The invention is now explained with several non-limiting exemplary embodiments. A person of skill in the art will appreciate that a variety of variations and modifications can be carried out for the circulation tool as described within the scope of the invention as defined in the appended claims.