A VALVE AND A METHOD OF CONTROLLING FLUID FLOW BETWEEN A FLUID SUPPLYING DEVICE AND A FLUID RECEIVING DEVICE

A valve and a method are for controlling fluid flow between a fluid supplying device and a fluid receiving device. The valve has an inlet for connection to the fluid supplying device, and an outlet. The valve has a piston arrangement slidable with respect to a valve body between a closed first position, and an open second position providing fluid communication between the inlet and the outlet upon exposure to a fluid pressure exceeding a predetermined level. The piston arrangement has a first piston area when the valve is in the closed first position, and an additional second piston area when the valve is in the open second position. The valve further has a restrictor arrangement for delaying closing of the valve to allow a fluid supply pressure to bleed off.

FIELD

The present disclosure is related to a valve. More specifically, the disclosure is related to a valve and a method of controlling fluid flow between a fluid supplying device and a fluid receiving device. The valve has an inlet for connection to the fluid supplying device and for receiving a fluid therefrom, and an outlet. The valve, which is controlled by fluid pressure, is configured for being in a closed first position preventing fluid from passing the valve upon exposure to a fluid pressure being below a predetermined level, and for being in an open second position providing fluid communication between the inlet and the outlet upon exposure to a fluid pressure exceeding the predetermined level.

BACKGROUND

The valve disclosed herein is developed primarily in response to a need in the petroleum industry. More particularly, the valve is developed for facilitating fluid transfer between a top drive of a drilling rig and a casing, liner, or drillpipe during a casing-, liner-, or drillpipe running operation. In a casing running operation, a lowermost casing joint of a casing string has been sealed off. A purpose of supplying a fluid during a casing running operation is to fill a casing with a balancing fluid, as will be appreciated by a person skilled in the art.

A conventional method of filling a casing is to run several casing joints, typically six to eight, into the well and then stop the running operation to fill a balancing fluid into the casing string. The filling may be performed by lowering the top drive onto the top portion of the casing string, or by means of a hose from a drilling floor. This conventional method is undesired for numbers of reasons. Firstly, the method requires the running operation to be interrupted. An interruption of the running operation represents a risk of the casing string getting stuck in the bore hole. Secondly, the conventional method is relatively time consuming and thus expensive. Filling a casing string by means of a hose on a deck of an installation requires personnel to enter the so-called red zone of the drilling rig. Personnel working in the red zone of a drilling rig is subject to a substantial risk of serious incidents related to remotely operated equipment and dropped objects.

Publication US2011168410 A1 discloses a drill string flow control valve that comprises a valve housing, a valve sleeve axially movable within a valve housing from a closed position to an open position, a biasing mechanism biasing the valve sleeve into a closed position, and a plurality of pressure vents for allowing a differential pressure to be exerted on the valve sleeve.

Publication CN102839941 A1 discloses an extensible tubing that is extended in two steps. The extensible tubing comprises a first compression spring and a second compression spring. The extensible tubing operates as an on/off valve and requires a fluid supply pressure to be bled of upstream of the valve to allow closing of the valve.

When supplying a fluid to, for example, a casing or drill string extending from a rig in a running operation, the fluid supplying device may typically comprise a Kelly hose being in fluid communication with a source of fluid. In such an application on a rig, the hydrostatic column may be considerable, for example 40 meters.

To control fluid communication between the fluid source on the rig and a fluid receiving device, for example a casing, liner, or drillpipe, the supply of fluid (for filling a casing or drill pipe) may be controlled by means of the fluid supplying device itself, typically by means of an IBOP valve (IBOP—Internal Blowout Preventer) arranged in a top drive of the rig. Such an IBPO would be capable of holding a fluid column. However, an IBOP valve is a safety device that should be used in an emergency situation only, and a rig operator would normally not allow regular use of an IBOP valve for controlling fluid supply in a casing running operation, or in a drilling operation. Thus, a conventional valve may be arranged at an outlet of the fluid supplying device. A valve arranged at an outlet of the fluid supplying device must be capable of holding a hydrostatic column when there is no flow through the fluid supplying device. A valve for the aforementioned purpose may be manually operated. However, a pressure-controlled valve is preferred on a rig to avoid having operators located in a so-called red sone of the rig. A pressure-controlled valve is in its closed position when exposed to a fluid pressure force being less than a predetermined value, and in its open position when exposed to a fluid pressure force being higher than a predetermined value. Thus, to open such a valve, the fluid pressure force must exceed the hydrostatic pressure force at which the valve is designed to open. An increased fluid pressure is typically provided by means of a pump forming part of the fluid supplying device. The increased fluid pressure may result in a considerable differential pressure across the valve, which may result in increased erosion of the valve, and thus reduced operating lifetime of the valve. Further, a considerable differential pressure across the valve may result in turbulent flow and cavitation downstream of the valve.

There is therefore a need for a pressure-controlled valve that in a closed position is capable of holding a predetermined hydrostatic pressure force while the fluid is stationary, i.e., not flowing, and in a fully open position while the fluid is flowing with a pressure being lower than a pressure required for initially opening the valve.

SUMMARY

The object of the invention is to remedy or to reduce at least one of the drawbacks of the prior art, or at least to provide a useful alternative to prior art.

The object is achieved through features specified in the description below and in the claims that follow.

The invention is defined by the independent patent claims. The dependent claims define advantageous embodiments of the invention.

In a first aspect of the invention, a valve for controlling fluid flow between a fluid supplying device and a fluid receiving device is provided, the valve having an inlet for connection to the fluid supplying device and for receiving a fluid therefrom, and an outlet, wherein the valve comprises a piston arrangement slidable with respect to a valve body, wherein the piston arrangement is slidable between a closed first position preventing fluid from passing the valve upon exposure to a fluid pressure being below a predetermined level, and an open second position providing fluid communication between the inlet and the outlet upon exposure to a fluid pressure exceeding the predetermined level. The piston arrangement has a first piston area when the valve is in the closed first position, and an additional second piston area when the valve is in the open second position. The valve further comprises a sealed restrictor arrangement for delaying closing of the valve to allow a fluid supply pressure to bleed off.

One effect of providing a piston arrangement having a first piston area when the valve is in the closed first position, and an additional second piston area when the valve is in the open second position, is that a fluid pressure required for keeping the valve in the open second position (while maintaining a fluid flow) is less than the fluid pressure required for opening the valve. Thus, a differential pressure across the valve may be reduced, whereby less power is required for pumping. A reduced differential pressure across the valve may also have a positive effect on any erosion of the valve, and thus on the operating lifetime of the valve. A reduced differential pressure across the valve may further have a positive effect with respect to reduced turbulent flow and reduced cavitation.

Providing the valve with a restrictor arrangement for delaying closing of the valve has the effect that the piston arrangement does not immediately return from its open second position to its closed first position when the pressure of the fluid upstream of the valve is reduced below the predetermined level. Thereby, a fluid supply pressure in the fluid supplying device is allowed to bleed off before the valve arrives at its first, closed position.

In one embodiment is the restrictor arrangement configured for reducing the closing speed of the valve. The valve may return from its open second position to its closed first position at a substantially constant speed.

In an alternative embodiment, the restrictor arrangement may comprise a closing delay nozzle configured for communicating a fluid between two or more fluid reservoirs in response to movement of the piston arrangement. Such fluid reservoirs may, for example, comprise two or more annular chambers surrounding the piston arrangement and containing an incompressible fluid, such as an oil. A closing delay nozzle may further be configured for delaying return of the piston arrangement from its open second position to its closed first position until a predetermined time has lapsed after the pressure of the fluid upstream of the valve has been reduced below the predetermined level.

Such a delay nozzle may for example be based on a principle disclosed in patent publication U.S. Pat. No. 4,378,612 related to a delayed action door closer.

In addition to the area of the first piston and the additional area of the second piston, characteristics of a valve biasing means may define, and thus control, said predetermined level of fluid pressure. As will be appreciated by a person skilled in the art, the characteristics of a biasing means, for example a spring, is the dependence of deflection of the spring versus loading force. In one embodiment, the valve biasing means is arranged in a chamber defined between a portion of the piston arrangement and the valve body.

In one embodiment, the piston arrangement is surrounded by the valve body in the form of a housing. In an alternative embodiment, the valve body is surrounded by a portion of the piston arrangement.

In one embodiment, the piston arrangement of the valve comprises a hollow piston member provided with at least one aperture in a wall of the hollow piston member, and wherein the at least one aperture is provided in a portion of said wall defined between the first piston area and the additional second piston area. When the valve is in its open second position, fluid communication between the inlet and the outlet is thus provided via the at least one aperture, whereby the piston member is utilized as a tubing for flowing fluid through the outlet of the valve.

In one embodiment, the piston member is solid in the meaning that any fluid flowing between the inlet and the outlet flows on an outside of the piston member.

It should be noted that in the embodiments disclosed above, the outlet of the valve is axially displaceable with the respect to the valve body and thus the inlet of the valve, meaning that the valve is extended when moving from its closed first position to its open second position.

The fluid supply pressure is the pressure provided by a pumping device associated with the fluid supplying device and any hydrostatic pressure within the fluid supplying device. By bleeding off the fluid supply pressure, only hydrostatic pressure remains upstream of the present valve. Thereby, the valve may resist any additional pressure that may arise due to mass acceleration of the fluid column acting on the valve. Such an acceleration may typically arise when a top drive, and thus the associated fluid supplying device, is moved vertically.

The valve may be operatively connected to the fluid supplying device, which typically may comprise a Kelly hose.

In one embodiment, the valve forms part of an extensible tubing having a first tubing portion and a second tubing portion, wherein the first tubing portion comprises the valve, and wherein the outlet of the valve is configured for controlling fluid flow into an inlet of the second tubing portion.

In such an embodiment, the second tubing portion may comprise:a housing having a first end portion for receiving fluid from the outlet of the valve, and a second end portion;a core arranged inside the housing and secured thereto;a pipe arranged between the housing and the core, the pipe being axially movable between a retracted position wherein a seal prevents fluid from passing between the core and the pipe, and an extended position wherein the seal does not prevent fluid from passing between the core and the pipe;a piston forming a part of the pipe; anda second tubing portion biasing means configured for urging the pipe towards its retracted position;wherein the pipe is movable towards its extended position upon exposure to a fluid flowing from the first tubing portion into the second tubing portion and providing a fluid pressure force exceeding an opposite force from the second tubing portion biasing means.

The piston may comprise a transition zone from a larger first pipe portion having a first flow area, and a smaller second pipe portion having a second flow area being smaller than the first flow area.

As such, the piston may be formed by a transition zone from a larger first pipe portion having a first flow area defined between the first pipe portion and the core, and a smaller second pipe portion having a second flow area defined between the second pipe portion and the core, the second flow area being smaller than the first flow area; andwherein the seal is configured for sealing between the smaller second pipe portion and the core when the pipe is closer to its retracted position than to its extended position

Thus, when a force from a fluid pressure acting on the piston is less than a force from the valve biasing means, fluid is prevented from passing through the extensible tubing, and when a force from a fluid pressure acting on the piston is larger than a force from the valve biasing means, the second tubing portion is urged towards its extended position wherein fluid passes through the extensible tubing, whereby fluid is communicated between the fluid supplying device and the fluid receiving device.

A valve according to the invention, which forms part of such an extensible tubing, may facilitate transfer of fluid between a fluid supplying device and a fluid receiving device. The fluid supplying device may, for example, be arranged on a rig and configured for supplying fluid to a casing during a casing running operation (as discussed above), or to a drill string.

As disclosed above, the piston of the second tubing portion may be formed by means of a transition zone between a large bore piping portion having a first flow area, and a small bore piping portion having a second flow area being smaller than the first flow area. The terms large bore and small bore do not define any specific dimensions, but a mutual relationship between the flow areas on either side of the transition zone. Thus, for a piping having a circular cross-sectional flow area defined by an inner wall of the piping, the large bore piping portion is a first piping portion having a first internal diameter, and the small bore piping portion is a second piping portion having a second internal diameter being smaller than the first internal diameter. The flow areas are defined by any space between an external surface of the core and an internal surface of the piping portions. Therefore, the piston may comprise a transition zone from a larger first pipe portion having a first flow area, and a smaller second pipe portion having a second flow area being smaller than the first flow area.

In a preferred embodiment of the valve forming part of an extensible tubing, a cross sectional area defined by an external surface of the core is smaller than a cross sectional area defined by an internal surface of the smaller second pipe portion, thereby providing a radial gap for allowing fluid flow between the core and the smaller second pipe portion. This has the effect of defining a space or gap between the smaller second pipe portion and the core, wherein the gap depends on an axial position of the second tubing portion with respect to the core. Thereby, fluid can flow through the tubing until the seal prevents fluid from passing between the core and the pipe. Thus, at least some of the fluid within the tubing is allowed to drain during retraction of the pipe. A retraction of the pipe occurs when the pressure force against the piston of the pipe is less than the force from the second tubing portion biasing means configured for urging the pipe towards its retracted position.

In a further embodiment, the smaller second pipe portion has a free end, and the seal is arranged within the smaller second pipe portion closer to its free end than to the piston. This advantageously facilitates drainage during retraction of the pipe. In one embodiment, the tubing is arranged so that the closer the seal is to the free end of the smaller second pipe portion, the more fluid is allowed to drain from the tubing before the seal prevents fluid communication out of the tubing.

Preferably, the core has a free end portion pointing away from the first tubing portion, and wherein the piston is positioned axially downstream of the free end portion of the core when the pipe is in its extended position, i.e., the piston is positioned on the pipe so as to extend beyond the free end portion of the core when the pipe is in its extended position. When in the extended position, this has the effect of the smaller second pipe portion being located axially downstream of the free end portion of the core. Thereby, a maximum flow through the tubing is achieved when the pipe is in its extended position.

As an alternative or addition to arranging the seal within the smaller second pipe portion and closer to its free end than to the piston, the seal may be arranged on a portion of the core at an axial position wherein the seal engages the smaller second pipe portion when the extensible tubing is closer to its fully retracted position than to its fully extended position. Thus, at least some of the fluid within the tubing is allowed to drain during retraction of the pipe. In one embodiment, the seal is arranged at an axial position of the core wherein the seal does not engage the smaller second pipe portion until the extensible tubing is fully retracted.

The axially movable pipe may be provided with a restrictor for providing a differential pressure in the fluid flowing into the axially movable pipe. Preferably, any such restrictor is arranged in the larger first pipe portion. One purpose of such a restrictor is to reduce a so-called “spray-effect” of the fluid passing the outlet of the axially moveable pipe. Another purpose of such a restrictor is to facilitate axial displacement of the axially movable pipe towards its extended position. A restrictor facilitating an axial displacement allows use of a heavy duty and more powerful biasing means. A heavy duty and more powerful biasing means may be advantageous with respect to returning the extensible tubing towards its retracted position.

In a preferred embodiment, the first tubing portion (which comprises the valve) is a separate tubing portion connected to the second tubing portion, hence is separable from the second tubing portion. One advantage of providing a first tubing portion being separable from the second tubing portion is that the valve, and thus the extensible tubing, can be adapted to various types of fluid supplying devices simply by selecting a first tubing portion mating with the fluid supplying device. In the event of any damage to, for example, the inlet of the first tubing portion (which comprises the valve), another advantage of providing a first tubing portion being separable from the second tubing portion is that only the first tubing portion needs to be replaced, and not the second tubing portion.

In one embodiment, the first tubing portion (which comprises the valve) is connected to the second tubing portion via a flexible pipe. One effect of connecting a separate, first tubing portion to the second tubing portion via a flexible pipe is that the flexible pipe may absorb any impacts that may arise during operation. A further effect is that the first tubing portion may, during operation, be non-coaxial with respect to the second tubing portion.

An important area of application of the present valve is to use the valve together with an extensible tubing for enabling continuous fluid transfer between a top drive of a drilling rig and a casing, liner, or drillpipe during a casing-, liner- or drillpipe running operation. Thus, the fluid supplying unit may comprise a so-called Saver Sub, while the fluid receiving device may be a top portion of a casing string subject to a running operation. Due to variable configurations of both the fluid supplying device and the fluid receiving device, a required length of extension of the tubing varies accordingly. It is therefore advantageous if the flexible pipe is axially extensible between a retracted position and an extended position. Preferably, such an extensible, flexible pipe comprises a flexible pipe biasing means configured for urging the flexible pipe towards a retracted position upon exposure to an opposite tension force between the first tubing portion (which comprises the valve) and the second tubing portion being less than a biasing force of the flexible pipe biasing means. In one embodiment, the biasing means acting on the flexible pipe is separate from the flexible pipe. In an alternative embodiment, the biasing means acting on the flexible pipe is partly or fully integrated with the flexible pipe.

From the embodiments disclosed above, it should be clear that the extension of the tubing may be provided by means of the axially movable pipe of the second tubing portion, and by means of the extensible, flexible pipe arranged between the first tubing portion and the second tubing portion.

In a second aspect of the invention, a method of controlling fluid flow between a fluid supplying device and a fluid receiving device is provided, wherein the method comprises the steps of:providing a valve according to the first aspect of the invention; andconnecting an inlet of the valve to the fluid supplying device.

The method may further comprise providing an extensible tubing according to the first aspect of the invention, said extensible tubing comprising a first tubing portion which the valve forms part of, and a second tubing portion comprising an axially displaceable pipe.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Positional indications refer to the positions shown in the figures. Similarly, denominations such as upstream and downstream refer to the position shown in the figures.

In the figures, same or corresponding elements are indicated by same reference numerals. For clarity reasons, some elements may be shown without reference numerals in some of the figures.

A person skilled in the art will understand that the figures are just principle drawings. The relative proportions of individual elements may also be distorted.

In the figures, reference numeral20denotes a valve according to the present invention.

The valve20has an inlet11for connection to a fluid supplying device, and an outlet13located axially opposite the inlet11. The inlet11is in the form of a female receptacle provided with internal threads for mating with a male stab of a fluid supplying device, for example a saver sub202, as shown inFIGS.8aand8b.

In the embodiment shown inFIGS.1ato2b, and9ato10d, the valve20has an outlet13that may be exposed to a fluid receiving device, i.e., the valve20may constitute an end portion of a fluid delivery device.

The valve20comprises a piston arrangement21slidable with respect to a valve body12, wherein the piston arrangement21is slidable between a closed first position preventing fluid from passing the valve20upon exposure to a fluid pressure being below a predetermined level, and an open second position providing fluid communication between the inlet11and the outlet13upon exposure to a fluid pressure exceeding the predetermined level.

Characteristics of a valve biasing means, here in the form of a spring30, define said predetermined level of fluid pressure. Thus, the valve20is a pressure-controlled valve. The spring30is housed within a chamber32defined between a portion of the piston arrangement21and the body12of the valve20.

InFIGS.1ato2b, the piston arrangement21is surrounded by the valve body in the form of a housing12. Thus, the chamber32is defined between a portion of the piston arrangement21and the housing12.

InFIGS.9ato10d, a portion of the valve body12is surrounded by a portion of the piston arrangement21. Said portion is hereinafter denoted piston housing251.

The piston arrangement21has a first piston area22facing the inlet11of the valve20when the valve20is in the closed first position, as seen for example inFIGS.1b,9a, and10a. The piston arrangement21has an additional second piston area24.

In the embodiment shown inFIG.2b, for example, the additional second piston area24, like the first piston area, faces the inlet11of the valve20when the valve20is in the open second position.

In the embodiments shown inFIGS.9cand10d, the additional second piston area24is arranged downstream of an annular gasket22′ arranged in a groove in a lower portion of the valve body12. As will be discussed below, in the embodiment shown inFIGS.10to10d, the additional second piston area comprises an additional annular second piston area24, and an additional circular second piston area24′.

Thus, when in a closed first position, as shown inFIGS.1b,9aand10a, only the first piston area22of the valve20will be exposed to any fluid in the inlet11. When the valve20is in the closed first position, the annular gasket22′ protects the additional annular second piston area24, and the additional circular second piston area24′ shown inFIG.10d, from any fluid in the inlet11.

The piston arrangement21of the valve20shown inFIGS.1band2b(and also inFIGS.3ato7b) comprises a piston member25that is hollow and being axially movable with respect to the body12of the valve20. A major portion of the hollow piston member25is arranged inside the body12, which in this embodiment forms a piston housing12. The hollow piston member25is provided with apertures23in a wall thereof. In the embodiment shown, the number of apertures23is four (only three shown) separated at a 90° circumferential spacing. The apertures23are provided in a portion of the wall defined between the first piston area22and the additional second piston area24. The number of apertures may be less or more than four, but at least one aperture.

In the alternative embodiment of the valve20shown inFIGS.9ato9c, the piston arrangement21comprises the piston housing251, a piston member25, and a piston outlet252. The piston member25is solid so as to allow the fluid flowing between the inlet11and the outlet13to pass on an outside of the piston member25when the valve20is open, as indicated by dotted lines F inFIG.9c. The piston housing251, the piston member25, and the piston outlet252are operatively connected to each other, wherein the piston member25is arranged between the piston housing251and the piston outlet252. A portion of the piston housing251surrounds the body12of the valve20. The piston arrangement21is axially movable with respect to the body12from a closed first position, as shown inFIG.9a, and an open second position, as shown inFIG.9c. The piston member25is secured to a lower portion of piston housing251via fins251′, as best seen inFIG.9b.

The piston arrangement21has a first piston area22defined by the portion of the piston member25facing the inlet11of the valve20, and an additional second piston area24defined between an inner surface of the piston housing251and an outer surface of a side portion of the piston member25. In the embodiment shown, the additional second piston area24is annular and indicated by dotted lines24inFIG.9c.

When the valve20is in the closed first position, as shown inFIG.9a, any fluid pressure from the fluid supply device acts towards the first piston area22only. When the valve20is in the open second position, as shown inFIG.9c, the fluid pressure acts on both the first piston area22and the additional second piston area24.

Turning now toFIGS.10ato10d, which show another embodiment of the valve20. Similar to the embodiment shown inFIGS.9ato9c, the piston arrangement21comprises a piston housing251, a piston member25, and a piston outlet252. However, the piston member25is formed as a sleeve or ring piston25housing a portion of a static member212, which is secured to a portion of the body12via fins212′ protruding from an inner portion of the body12. The fins212′ are best seen inFIG.10c. A seal213prevents fluid from passing between the ring piston25and the static member212. When the valve20is in the open second position, as shown inFIG.10d, the fluid flowing between the inlet11and the outlet13passes on an outside of the ring piston25, as indicated by dotted lines F inFIG.10d. The piston housing251, the piston member (ring piston)25, and the piston outlet252are operatively connected to each other, wherein the piston member25is arranged between the piston housing251and the piston outlet252. A portion of the piston housing251surrounds the body12of the valve20. The piston arrangement21is axially movable with respect to the body12from a closed first position, as shown inFIG.10a, and an open second position, as shown inFIG.10d. The piston member25is secured to a lower portion of piston housing251via fins251′, as best seen inFIG.10b.

The piston arrangement21shown inFIGS.10ato10dhas a first piston area22defined by the portion of the ring piston25facing the inlet11of the valve20, and an additional annular second piston area24defined between an inner surface of the piston housing251and an outer surface of a side portion of the piston member25(ring piston25), and an additional circular second piston area24′ defined by the inner wall of the ring piston25. In the embodiment shown, the additional annular second piston area24and the additional circular second piston area24′ are indicated by dotted lines24,24′ inFIG.10d.

When the valve20is in the closed first position, as shown inFIG.10a, any fluid pressure from the fluid supply device acts towards the first piston area22only. When the valve20is in the open second position, as shown inFIG.10d, the fluid pressure acts on both the first piston area22, and the additional annular and circular second piston areas24,24′.

For all three embodiments of the valve20discussed above, the following applies:

When a fluid pressure acting on the first piston area22provides a force exceeding an oppositely directed force from the spring30, the piston arrangement21will move from a closed first position, as shown inFIGS.1b,9aand10a, to an open second position, as shown in for exampleFIGS.2b,9cand10d. When the valve20opens, referring now to the embodiment shown inFIG.2b, the fluid will flow through the apertures23into the hollow piston member25and through the outlet13of the valve20. In the embodiments shown inFIGS.9c10d, however, the fluid will flow on the outside of the piston member25and through the outlet13of the valve20.

Due to the additional second piston area24, and for the embodiment shown inFIG.10d, the additional circular second piston area24′, which adds (or inFIG.10dadd) to the first piston area22once the valve20opens, the fluid pressure required for keeping the valve20in the open second position becomes less than the fluid pressure required for opening the valve20. This means that the valve20may be configured for holding a desired fluid column, further implying that the fluid pressure required for opening the valve20may be reduced once the valve20starts opening, which allows the valve20to operate at a reduced fluid pressure while feeding fluid through the outlet13of the valve20. A reduced pumping pressure results in reduced differential pressure across the valve20, which may have a positive effect on any erosion of the valve20, and thus on the operating lifetime of the valve20. A reduced differential pressure across the valve20may further have a positive effect with respect to reduced turbulent flow and reduced cavitation. From the embodiments of the valve20discussed above, the embodiment shown inFIGS.10ato10dprovides the largest difference between the first piston area22and the sum of area of the first piston area22and additional annular and circular second piston areas24,24′. A large difference between the first piston area22and the sum of the first piston area22and the additional annular and circular second piston areas24,24′ has the positive effect that the resistance from the spring30can be reduced as compared with embodiments wherein the differences between the areas22,24are less, as shown inFIGS.9ato9c, and particularly inFIGS.1aand2a. A reduced resistance from the spring has the effect that the fluid supply pressure can be reduced. A reduced supply pressure may be positive with respect to the lifetime of the valve, as discussed above. As an alternative to reducing the resistance from the spring30, and thus the fluid supply pressure, the fluid supply pressure for opening the valve20can be increased.

Independently of reducing the resistance from the spring30or increasing the pressure from the fluid supply device, typically by increasing the pumping pressure, the following positive effect is achieved: Due to the relatively large differences between the first piston area22and the sum of the first piston area22and the additional annular and circular second piston areas24,24′ shown inFIGS.10ato10d, a correspondingly large difference in pressure from the fluid supply device may be applied for opening the valve20and keeping the valve20open. Thus, a fluid supply pressure from for example a pumping device may be considerably reduced once the valve20opens.

In the embodiments shown, the chamber32housing the valve spring30is configured to contain a substantially incompressible fluid, for example an oil. The chamber32is in fluid communication with a restrictor arrangement40for delaying closing of the valve20to allow a fluid supply pressure to bleed off. Seals for preventing leakages are shown in the figures, but the seals are not discussed in any further details given that such seals will be apparent for a person skilled in the art.

In the embodiments shown, the restrictor arrangement40comprises a closing delay nozzle42extending from a lower portion of the chamber32, further through an annular lip portion or piston44extending radially with respect to valve body12, and onto a variable volume reservoir46, as best seen inFIGS.1band2b. Alternatively, however, the restrictor arrangement may comprise for example a flow choke valve or other means commercially available in the marked for reducing, for example, a flow velocity through the restrictor arrangement40and thus reduce the closing speed of the valve20. Alternatively, or additionally, the restrictor arrangement40may be configured for delaying return of the piston arrangement from its open second position to its closed first position until a predetermined time has lapsed after the pressure of the fluid upstream of the valve has been reduced below the predetermined level.

The variable volume reservoir46is in the embodiment shown inFIG.2bdefined by a piston member lip48protruding radially outward from the piston member25, and the internal wall of the valve housing12. The piston member lip48has an active face for receiving any fluid from the chamber32, and a passive face opposite the active face. The passive face of the piston member lip48is in fluid communication with ambient air.

In the embodiments shown inFIGS.9cand10d, the variable volume reservoir46is defined by the annular lip portion44protruding radially inward from the piston housing251, an internal wall of the piston housing251, a shoulder portion of the body12, and the external wall of the valve body12

When the valve20is in the first closed position, as shown inFIGS.1b,9aand10a, a volume of the variable volume reservoir46is close to zero.

When the valve20opens in response to a fluid pressure, a volume of the chamber32is reduced and any fluid within the chamber32is urged from the chamber32and into the variable volume reservoir46via the closing delay nozzle42. In the embodiment shown inFIG.2bthe piston arrangement21has moved axially downward to a position wherein the piston member lip48abuts against a shoulder at a lower end portion of the valve housing12and wherein a volume of the variable volume reservoir46is at its maximum.

InFIGS.9cand10d, the piston arrangement21has moved axially downward to a position wherein a shoulder of the valve housing251abuts against a shoulder at a lower end portion of the valve body251.

In one embodiment, the closing delay nozzle42is provided with a check-valve (not shown) configured for providing one-way delay, and only so that substantially no delay is provided when the valve20opens and moves from the position shown in, for example,FIG.2bto the position shown inFIG.3a.

Turning now toFIG.3aet seq, which show the valve20forming part of an extensible tubing1. In the extensible tubing1, hereinafter also denoted tubing1, the valve20forms part of a first tubing portion10, which comprises the valve20shown inFIGS.1ato2b, however with a flange11′ added to a lower portion of the piston member25, i.e., added to the outlet13of the valve20. The flange11′ has been connected to a mating flange104′ arranged at a first end portion104of a second tubing portion100, for example by mean of bolts (not shown). In the embodiments shown, the first tubing portion10and the second tubing portion100are thus separable. An advantage of providing separable tubing portions10,100is that the tubing1can be easily adapted to special needs without having to replace the complete tubing1. For example, if another length of the second tubing portion100is desired, only the second tubing portion100may be replaced. If another type of valve20is desired (configured, for example, for a different opening/closing pressure), or if the threads in the inlet are damaged, or if another dimension or type of inlet11is required, only the first tubing portion10may be replaced.

Although the valve20shown inFIGS.3ato7bis the valve according to the embodiment shown inFIGS.1ato2b, it should be clear that the alternative valves20shown inFIGS.9ato9c, or inFIGS.10ato10d, may form part of the extensible tubing1.

When the valve20in the embodiment shown inFIGS.1ato2bopens, the fluid will flow through the apertures23into the hollow piston member25, further through the outlet13of the valve20, and then into the second tubing portion100. InFIG.5a, such a fluid flow is illustrated by dotted lines F. The fluid flows past core securing fins121connecting the core120to a surrounding housing102, as best seen inFIG.5b.

When the valves20in the embodiments shown inFIGS.9ato10dopens, the fluid will flow on the outside of the piston member25.

The second tubing portion100comprises said housing102having said first end portion104and also a second end portion106located axially opposite the first end portion104.

A core120is arranged inside the housing102. In the embodiments shown, the tubing1has a circular cross-section and the core120is made from a circular, solid rod arranged coaxially within the housing102. A top or upstream portion of the core120is secured to a portion of the housing102, whereby the core120may be considered as “hanging” within a housing102having a substantially vertical longitudinal axis, as shown, or the core120may be considered as “cantilevered” within a housing102having a substantially horizontal longitudinal axis.

The second tubing portion100further comprises a pipe110arranged between the housing102and the core120. The pipe110is axially movable between a retracted position wherein an annular seal112prevents fluid from passing between the core120and the pipe110, and an extended position wherein the seal112does not prevent fluid from passing between the core120and the pipe110.FIGS.3a-5aand8ashow the pipe110being in the retracted position, whileFIGS.6-7band8bshow the pipe110being in the extended position.

The second tubing portion100further comprises an internal piston114forming part of the pipe110, and a second tubing portion biasing means116, here in the form of a spring, configured for urging the pipe110towards its retracted position.

The pipe110is movable from its retracted position towards its active position when the valve20(in the first tubing portion10) is in the second open position, and when a fluid pressure acting on the piston114provides a force exceeding an opposite force from the second tubing portion biasing means or spring116configured for urging the pipe110towards its retracted position.

In the embodiment shown, the piston114is constituted by a transition zone114from a larger first pipe portion111having a first flow area, and a smaller second pipe portion111′ having a second flow area being smaller than the first flow area. Hereinafter, the larger first pipe portion will also be denoted first piping portion111, and the smaller second piping portion111′ will also be denoted second piping portion111′. The first piping portion111has an internal diameter being larger than an internal diameter of the second piping portion111′ located downstream of the first piping portion111.

A cross-sectional area defined by an external surface of the core120is smaller than a cross sectional area defined by an internal surface of the second piping portion111′, thereby providing a radial gap for allowing fluid flow between the core120and the second piping portion111′. In the embodiment shown, an annular space is thus defined between the core120and the second piping portion111′. The annular space is larger than the space required for fitting the core120within the second piping portion111′. In a preferred embodiment, a flow area of the annular space is equal to or larger than the flow area of the second piping portion111′.

When fully retracted, as shown inter alia inFIGS.3a-5a, the annular seal112protruding from an inner surface of the second piping portion111′ abuts against a side portion of the core120. The annular space between the core120and the second piping portion111′ is thus sealed and fluid is prevented from passing through the annular space. InFIGS.5aand6, a further annular seal112′ is arranged in a recess on the core120. The further annular seal112′ is arranged on the core120to provide a “double seal” once the piston114of the second tubing portion100has passed the annular seal112′ during retraction of the pipe110of second tubing portion100. Such an arrangement of a further seal112′ may be applicable also for the embodiments shown inFIGS.3b,4b, and7b.

In an alternative embodiment (not shown), the second tubing portion100may be provided with the seal112′ arranged in the recess of the core120only. In such an alternative embodiment with the seal112′ arranged in the recess on the core120only, the seal112′ may be arranged closer to the free end portion123of the core120than to the position shown inFIGS.3aand4. However, the axial position of the seal112′ shown inFIGS.5aand6has been optimized with respect to drainage of fluid from within the tubing1when the pipe110retracts from its extended position. The drainage takes place substantially until the pipe110is fully retracted.

The annular space defined between the core120and the second piping portion111′, as well as the arrangement of one or both of the seal(s)112,112′, are advantageous with respect to drainage of fluid from within the extensible tubing1when the pipe110retracts from its extended position, as will be discussed below.

In the embodiments shown inFIG.3aet seq, the second tubing portion biasing means116for urging the pipe110towards its retracted position (see for exampleFIG.3b) is in the form of a helical spring116adapted to provide a desired resistance against an opening force defined by a fluid pressure and the area of the piston114. As an alternative to a spring, the biasing means may be in the form of a compressible fluid, such as a gas.

In some applications, however, the extensible tubing1may be subject to a considerable hydrostatic pressure. An example of one such application is a casing running operation in which a fluid column acting on the valve20in the extensible tubing1may be as much as 40 meters, or even more. The fluid may have a specific gravity of up to 2.2 times that of water. It is possible, for example, to design the tubing1(seeFIG.1b) with a second tubing portion biasing means, for example a spring116, capable of resisting a force from a static fluid column of 40 meters having a specific gravity of 2.2. The height of the fluid column and its specific gravity will vary considerably, for example from one rig to another.

Thus, a great number (or varieties of configurations) of second tubing portions100would be required for servicing the marked. Using a valve that forms part of the fluid supplying device to control supply of fluid to the inlet11of the tubing1, could therefore be one way of avoiding or mitigating the force effect of a fluid column acting on the inlet11of the tubing1. In a casing running operation, an IBOP valve (IBOP—Internal Blowout Preventer) arranged in a top drive (see item206inFIGS.8aand8b) would be capable of holding such a fluid column. However, an IBOP valve is a safety device that should be used in an emergency situation only, and a rig operator would normally not allow regular use of an IBOP valve for controlling fluid supply in a casing running operation, or in a drilling operation. Advantageously, instead, the present valve20shown in the embodiment could serve the purpose of controlling the fluid from the fluid supplying device.

In the embodiments shown inFIG.4aet seq, the valve20forming the first tubing portion10is operatively connected to the second tubing portion100via a flexible pipe50. The flexible pipe50may absorb any impacts that may arise during operation of the tubing1. Further, the flexible pipe50may allow the first tubing portion10to move and become non-coaxial with respect to the second tubing portion100, which is a situation that may arise during operation.

If the fluid pressure acting on the piston114of the pipe110provides a force exceeding an oppositely directed force from the spring116, the pipe110will move from the retracted position shown inFIG.5ato the extended position shown in, for example,FIG.6. InFIG.6, the pipe110is in its fully extended position, wherein the piston114is positioned axially downstream of a free end portion123of the core120, thereby providing a fully open flow passage through the tubing1.

InFIGS.7aand7b, a force from the fluid flow through the tubing1has exceeded counteracting forces from the spring30of the valve20, the spring116of the second tubing portion100, and a force from a spring52arranged in connection with the flexible pipe50. InFIGS.7aand7b, the tubing1is at its maximum extension, which is provided by means of the extension of the flexible pipe50in addition to the extension of the second tubing portion100, as shown inFIG.6.

FIGS.8aand8bshow, in a smaller scale and partially in cross-section, an embodiment of an extensible tubing1in which the present valve20forms part of the extensible tubing1.

InFIGS.8aand8b, the extensible tubing1is in a retracted position and extended position, respectively, above a top portion of a casing string230during a casing running operation.

In the example shown inFIGS.8aand8b, the extensible tubing1is operatively connected to a top drive200of a rig. The extensible tubing1is of the type shown inFIGS.4a-7b.

A top portion of the first tubing portion10, which comprises the present valve20, is connected to a saver sub202housed within a skirt204. For illustrative purposes, the skirt204is shown partially in section, and the top portion of the extensible tubing1(which comprises the valve20) is housed within a lower portion of the skirt204. The top drive200further comprises an IBOP valve206(IBOP-Internal Blowout Preventer) configured for closing a fluid flow in the event of an emergency situation, and particularly in a drilling operation wherein fluid may flow from a subsea reservoir and up to the rig.

An elevator220, which is operatively connected to the top drive200via a pair of bails222, carries the casing string230. The casing string230is made up by connecting casing sections232(two sections shown) on top of the casing string230during a casing running operation, as will be appreciated by a person skilled in the art.

During the casing running operation, a balancing fluid must be supplied to the casing string230. By means of the extensible tubing1, the casing string230can be continuously filled, both during make-up of the connection of two casing sections232and thereafter during running into the well.

InFIG.8a, the valve20is in the closed first position, whereby the extensible tubing1is in a fully retracted position in which both the pipe110of the second tubing portion100and the flexible pipe50are in retracted positions. Thus, inFIG.8a, there is no fluid flow through the tubing1.

InFIG.8b, a fluid pressure of the fluid located upstream of the first tubing portion10has been increased, for example by means of a pump operatively connected to the fluid supplying device. The fluid pressure has been increased to a level wherein the valve20of the first tubing portion10has been urged from a closed first position (see details inFIG.4b) to an open second position (see details inFIG.5a).

When the valve20opens, fluid flows into the pipe110of the second tubing portion100. If the fluid flow pressure exceeds the force from the spring116within the second tubing portion100, and also the force from the spring52of the flexible pipe50, both the pipe110and the flexible pipe50are displaced axially to their extended positions. In said extended positions, as shown inFIG.8b, the free end113of the (smaller) second pipe portion111′ has entered into a top portion of the uppermost casing section232. Thus, inFIG.8b, the extensible tubing1is shown in its extended position, as also shown in further details inFIG.7b. InFIG.8b, there is a sideway clearance between the second pipe portion111′ and the casing section232so that the casing section232does not represent any obstruction when the extensible tubing1is moved from its fully retracted position (seeFIG.8a) to its extended position, and from its extended position to its fully retracted position. The sideway clearance has a further effect that any sideway movement of the extensible tubing1does not influence any axial alignment between the uppermost casing section232and the casing secured to the drill floor240via slips242, during make-up of the connection of the casing sections232. It should be noted that the sideway clearance is preferred also in an embodiment wherein the extensible tubing1is not provided with the flexible pipe50.

From the disclosure herein, it should be appreciated that the valve20according to the invention may be utilized to automatically control an extensible tubing1used, for example, in a casing running operation, as shown inFIGS.8aand8b.

By means of the valve20, the extensible tubing1may be controlled by the fluid pressure within the fluid supplying device only. In one embodiment, at least some of the fluid within the extensible tubing1is allowed to drain during movement from its extended position to its fully retracted position, whereby any spill of fluid is substantially eliminated. The valve20according to the invention is configured to allow the fluid pressure of the fluid flowing into the inlet of the extensible tubing1to be reduced once the valve20has started opening.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, thereby allowing those skilled in the art to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed to limit the claim. Use of the verb “comprise” and its conjugations do not exclude the presence of elements or steps additional to those stated in a claim. The article “a” or “an” preceding an element does not exclude the presence of a plurality of such elements.