Technical field

The present invention relates to valves and, in particular, to a choke, control or regulation valve for fluid streams e.g. production streams comprising oil and/or gas from a well.

Background and prior art

Pipelines in various industries include valves such as chokes or regulation valves which are operable to open or close channel for fluid through the valve.

Known choke or regulation valves have a valve body arranged to connect to upstream and downstream sections of a pipeline or flowline such as for conveying a fluid into or away from a well. The valve has a channel for passing fluid through the body. The valve may include a valve member which may be movable to close or open the valve e.g. partially for choking, controlling, or regulating a flow of the fluid through the valve. In some chokes, the valve includes cage where the valve member is arranged inside the cage. By transmitting fluid through perforations in the cage the flow can be conditioned to avoid adverse effects imparted by the fluid upon the valve member. A choke with a cylindrical cage is for example commercially available by Mokveld B.V.

Fluid produced from a well in the oil and gas production industry, can contain abrasive components. Fluid may carry with it solids and debris of various sizes. When starting up a well, the size of solids may be greater than otherwise during normal production, and a clean up operation may be needed. Although the cage can be useful to distribute flow and pressure loss evenly through the valve, over time it is subject to wear and may need to be replaced. Pressure events in the fluid can propagate, e.g. from the well, and may affect the valve and, in some cases can cause damage for example by impacts from debris or fluid forces. Cage and valve member components in some valves are formed of tungsten carbide or similar material, which although may be useful for wear resistance under normal operation may be poorly suited to withstand collapse or destruction in pressure event or impact situations.

At least one aim of the invention is to obviate or at least mitigate one or more drawbacks associated with prior art choke valves. Summary

In light of the above, according to a first aspect of the invention, there is provided a valve comprising: a body; a channel in the body for passing fluid through the valve; a cage arranged to be movable by actuation between different positions, so that in one position one section of the cage extends across the channel and in another position another section of the cage extends across the channel; and a valve member arranged to be movable inside the cage for opening or closing the valve.

By being movable, the cage can advantageously obtain different operational positions in the valve, and may allow the valve to be configured in different ways. The valve may typically be a choke valve, control valve, or regulation valve.

The cage may have at least one section or part comprising perforations therethrough for the fluid to pass through. The perforations may penetrate through a wall structure of the cage. The cage may be arranged to be movable by actuation for moving the cage inside the body for obtaining at least one or another position in which the cage may be arranged so that fluid passing through the valve in use may pass through a wall structure and/or perforations of the cage e.g. through the wall structure. The valve member may be arranged to be movable inside the cage for positioning the valve member either for closing the valve or for opening the valve, fully or partially, for passing fluid through the valve.

The cage may have a first section comprising first perforations. The cage may have a second section comprising second perforations. The cage may be movable for obtaining a first position in which the cage may be arranged so that fluid passing through the valve in use may pass through the first perforations, and a second position in which the cage may be arranged so that fluid passing through the valve in use may pass through the second perforations. When it has the first position, one section of the cage may extend across the channel. When it has the second position, another section of the cage may extend across the channel.

The cage may have a third region comprising walling for providing an impervious barrier to the passage of fluid through the valve or for providing a protective barrier for resisting applied fluid pressure or debris impacts or damage from an upstream passage of the valve. The cage may be movable for obtaining a third position in which the cage may be arranged so that the walling provides the impervious or protective barrier. When it has the third position, yet another section of the cage may extend across the channel.

The perforations of the first section may be different ones to the perforations of the second section. In this way, if the perforations of the first section have deteriorated after a period of use, the cage may be actuated to use the perforations of the second section instead.

The section or perforations of the first section may have the same or different size, material or composition, spacing, pattern, configuration, or distribution to the section or perforations of the second section.

The cage may be movable by linear translation between the different positions. The cage and/or sections thereof may have a cylindrical or annular wall structure having an axis extending from one end to another. The cage may be movable along the axis. Alternatively, the cage may be rotatable between the positions

The valve member may be movable by linear translation from one position to another. The valve member may be movable axially along the cylindrical cage and/or sections thereof. The valve member may comprise a piston head.

Either or both of the first and second sections of the cage may comprise or consist essentially tungsten carbide, or other wear resistant material. Such material may resist frictional wear from the fluid which may include abrasive particles therein when passing the fluid through perforations in the cage. The third section of the cage may comprise or consist essentially of metal, e.g. steel, e.g. duplex or super duplex steel. This may have greater strength for resting impacts or shocks. In general, the different sections of the cage may have different materials.

The valve may further comprise at least one actuator for actuating the cage. The valve may further comprise at least one actuator for actuating the valve member. Either or both actuators may be operated by hydraulic, electric, mechanical, and/or pneumatic operation. In variants of linear translation of the cage, the actuators may be linear actuators.

The valve may comprise biasing means arranged to urge the cage toward a position in which the valve may be closable by the valve member, the actuator may be operable against a force exerted on the cage by the biasing means. The valve may further comprise biasing means arranged to urge the valve member toward a position in which the valve member may close the valve, wherein the actuator may be operable against a force of the biasing means. This may facilitate failsafe-closed operation of the valve.

The body of the valve may be elongate and may have first and second ends and a longitudinal axis. The cage may be movable axially, and/or the valve member may be movable axially, along the axis.

In certain embodiments, the valve may further comprise a housing within the body for housing valve operating means for moving either or both the valve member and the cage. The valve operating means may include either or both of the actuators for actuating the screen and the valve member. The valve may have a flow passage between an outer surface of the housing and an inner surface of a wall of the body around the housing. The housing may have a nose arranged to deflect or guide oncoming flow of the fluid into the flow passage. Thus, fluid may flow through the valve around the housing.

The valve may further comprise a seat for the cage. The cage may be arranged to abut the seat, e.g. in both the first and second positions. The seat may be movable by actuation, e.g. axially, within the valve to reduce or increase an aperture of the channel. In examples where the body has a longitudinal axis, the movement of the seat, the valve member, and/or the cage may be axial.

The valve member may be movable to reduce or increase an aperture of the channel.

The valve member may be operable for choking, controlling, or regulating a flow of fluid through the valve. The fluid may comprise production fluid from a well, e.g. hydrocarbon fluid, e.g. oil, gas, water, gas condensate or mixtures thereof. The fluid may carry solids particles and/or pieces of debris, or rock particles from the well.

According to a second aspect of the invention, there is provided a cage for a valve in accordance with the first aspect of the invention. The cage may comprise at least one section which may have a structure comprising perforations for letting fluid pass through. The cage may have any number, e.g. one or more, such sections. The cage may be being configured to be connected or coupled to an actuator for actuating the cage to move inside the body between positions. The cage may have a first section having a structure comprising first perforations. The cage may have a second section having a structure comprising second perforations. The first section may be configured to span or extend across a channel in the valve, for passing fluid through the first perforations when the cage has a first position. The second section may be configured to span or extend across the channel for passing fluid through the second perforations when the cage has a second position.

The structure may be cylindrical or annular for surrounding and accommodating the valve member inside the cage. The cage may comprise a plurality of sections or parts. Respective sections or parts may comprise cylindrical or annular wall structures. One or more of the sections or parts may have perforations through the wall structure for passing fluid therethrough.

According to a third aspect of the invention, there is provided a pipeline or flowline incorporating the valve in accordance the first aspect of the invention. The pipeline or flowline may be coupled to a well for transmitting fluid into or out of a well.

According to a fourth aspect of the invention, there is provided a method of operating the valve in accordance with the first aspect of the invention, the method comprising the step of actuating the cage to move between the different positions.

The method may further comprise any one or more of the steps of: operating the valve with the cage in a first position, transmitting fluid through perforations of a first section of the cage; moving the cage to a second position; and operating the valve with the cage in the second position, transmitting fluid through perforations of a second section of the screen.

The method may further comprise positioning the valve member to close the valve or open the valve at least partially. The method may further comprise measuring at least one condition or property of the flow downstream from cage, and moving the screen to the second position in dependence upon the measured condition or property.

The method may include comparing the measured condition with a predetermined reference condition, and moving the perforated screen based upon the comparison.

In a further aspect, there is generally provided valve comprising: a body; a cage arranged to be movable by actuation into and/or between different positions with respect to the body; and a valve member arranged to be movable inside the cage for opening or closing the valve. The cage may be arranged to be movable by actuation between different positions, so that in one position one section of the cage extends across a channel in a body of the valve and in another position another section of the cage extends across the channel. The channel may be configured for passing fluid through the valve. More specifically, the channel may be movable by actuation across the body. The different positions may be operational positions.

In a yet further aspect, there is generally provided a cage for the valve of the further aspect.

In another yet further aspect, there is generally provided a pipeline or flowline incorporating the valve in accordance with the further aspect.

In yet another yet further aspect, there is generally provided a method of operating the valve of the further aspect.

Any of the above first to fourth aspects, or any of the further or yet further aspects, may include any one or more further features as described in relation to any other aspect, wherever described herein.

Embodiments of the invention are advantageous in various ways as will be apparent from throughout herein.

Drawings and specific description

The above aspects will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a cross sectional representation of an “inline” choke valve according to one example;

Figure 2 is a cross section along the A-A of Figure 1 ;

Figure 3 is a cross sectional representation of an “angle” choke valve according to another example;

Figure 4 is a sectional representation of a part of a cage for the valves of any of Figures 1 to 3;

Figure 5 is a sectional representation of a part of a cage for the valves of any of Figures 1 to 3 where one region of the cage exhibits wear; Figure 6 is a sectional representation of part of a cage in another example;

Figure 7 is a sectional representation of part of a cage in another example; and

Figure 8 is a sectional representation of part of an inline choke valve indicating a scan area for detecting wear on a cage.

First referring to Figures 1 and 2, a choke valve 1 is depicted generally. The choke valve 1 has a body 2 and a channel 10 for passing fluid through the body. Thus, fluid can flow downstream between an inlet 12 at a first end 22 of the body and an outlet 14 at a second end 24 of the body 2. The flow of fluid is indicated by arrow F.

Typically, the choke valve 1 can be used in a pipeline or flowline connected to a well, for example, a production flow line where fluid is in the form of produced fluid, e.g. oil, gas, water from the well. The valve 1 may therefore be used to stop or control production from the well.

The valve 1 includes a cage 30 which is movable by actuation, i.e. by means of actuator 44, relative to the body 2. A valve member 40 is arranged inside the cage for opening or closing the valve 1.

By the cage 30 being movable, different configurations of the valve can be obtained. For example, different sections of the cage 30 can be utilised for different functions when moved into an operational position extending across a channel within the body of the valve 1, thereby providing different configurations of the valve 1. For instance:

• one section of the cage 30 may have perforations for letting fluid through;

• one section of the cage 30 may comprise solid or impervious walling; and

• different sections of the cage 30 may comprise different structure and/or materials.

The cage 30 can thus be actuated and moved to an operable position such that the relevant section of the cage providing the desired function or configuration of the valve can be used. Also, if one section of the cage 30 is worn, a fresh section can be put into operable position, by actuating and the cage 30 into position accordingly.

Examples of how the cage 30 may be configured are explained further in the following.

With reference again to Figures 1 and 2, the cage 30 in this example has a first region 30a comprising first perforations, i.e. through a wall structure of the cage 30, and a second region 30b comprising second perforations, i.e. through a wall structure of the cage 30. The cage 30 is movable between first and second positions. Upon obtaining the first position, the cage 30 is arranged so that fluid in order to pass through the valve 1 passes through the first perforations, and upon obtaining the second position, the cage 30 is arranged so that fluid in order to pass through the valve 1 passes through the second perforations.

When open or partially open, the valve 1 allows fluid to pass through the valve. When closed, the valve 1 does not allow fluid to pass through the valve. The valve member 40 can be positioned so that the valve 1 is open partially depending upon the flow required through the valve. The valve member 40 is movable relative to the body 2, in this case by linear translation along the cage 30 and axially along the longitudinal axis 5 of the valve body 2. The cage is also movable by linear translation axially along the axis 5. The valve member 40 can be positioned in different positions in which it partially blocks or plugs the channel 10, with different extent, to control and restrict or choke a flow of fluid through the valve, as required.

Thus, different regions 30a, 30b of the cage 30 can be selectively exposed to the fluid flowing through the aperture 20. Thus, when the one region 30a shows signs of wear, e.g. through abrasion of particles or the like, the cage 30 can be actuated by actuator 44 to move to another position where another region 30b of the cage 30 is exposed to the flowing fluid instead. This can increase the effective lifetime of the cage 30 and longevity of the valve 1.

Furthermore, as will be further explained in the following, the different regions of the cage 20 can be configured for different types of flow regime or different fluids, and thus advantageously can be selected accordingly, noting that the cage 30 by way of the many perforations can impart conditioning and distributing effects upon the fluid that can help to protect the valve member 40 inside the cage 30 from damage or wear.

In more detail now, within the valve body 2, the choke 1 includes a housing 3. An annular flow region is defined between the outside of the housing 3 and an inner wall of the valve body 2. Fluid flows along the channel 10 through an upstream flow passage 11 around the housing 3. The housing 3 is connected to the inner wall 2i of the valve body 2 by connecting struts 4. The housing 3 is elongate, having a first, upstream, closed end 3a and an open end 3b. The housing of the closed end has a nose 3n facing the flow of fluid for guiding the fluid into the flow passage 11.

The cage 30 and the valve member 40 are operable to move by valve operating means 50 located in the housing 3. The cage 30 and the valve member 40 are independently operable and movable relative to one another. The valve operating means 50 includes the cage actuator 44, in this case a hydraulic actuator, comprising a hydraulic cylinder 44c and a piston 44p. The piston 44p has an extender member 44r which extends from the actuator cylinder 44c and is connected to the cage 30. Operating the actuator 44 produces extension or retraction of the extender member 44r from the cylinder 44c. By extension or retraction of the extender member 44, the cage 30 is moved axially back or forth as indicated by arrows A. The position of the cage 30 (with respect to the body 2 and the channel 10) can thereby be controlled using the actuator 44.

Hydraulic fluid is supplied externally to the chambers 44s, 44t of the actuator 44 for applying force against the piston 44p according to the direction of movement required for the extender 44r and cage 30. A hydraulic line (not shown) is provided e.g. through the struts 4, providing communication of hydraulic fluid between the hydraulic chamber 44s, 44t and an external supply or reservoir.

The valve operating means 50 includes cage spring 37 which is arranged around the hydraulic cylinder 44c in a slot between the hydraulic cylinder 44c and a surrounding, inner wall 3i of the housing 3. The cage spring 37 has an end that abuts an end surface 35 of the slot and another, opposite end that abuts an abutment surface 36 of the extender 44r (which in turn engages the cage 30).

The spring 37 is configured to exert a biasing force for urging the cage 30 toward the second end 24 of the valve 1 , and toward a position with the cage 30 positioned across the channel 10. In order to position the cage 30 therefore, hydraulic pressure is applied in the cylinder 44c against the force of the spring. 37. Thus, if hydraulic power is lost, the spring 37 will push the cage toward the second end 24. This can facilitate the “failsafe closed” functionality of the valve.

The valve operating means 50 also has a closure actuator 54, in this case a hydraulic actuator 54, comprising a cylinder 54c having a piston 54p movable within the cylinder 54c. The piston 54p in turn is connected through a rod 54r to the valve member 40. The actuator 54 includes a closure spring 57 arranged inside the cylinder 54c. The spring 57 is arranged between an end surface 55 of the cylinder 54c and a surface 56 on the rod 54r of the piston 54p. The spring 57 exerts a biasing force on the piston 54p for urging the valve member 50 toward the second end 24 of the valve. Hydraulic fluid in the chamber 54t exerts a force on the piston 54p against the biasing force of the spring 57 to move and position the valve member 54 with respect to the channel, e.g. to open or close the valve. If hydraulic power to the actuator 54 is lost, then the spring 57 will push the valve member 40 by way of the biasing force to the fully closed position where the valve member 40 fully prevents flow through the cage 30 and/or through the valve. In this way, failsafe closed functionality is obtained. The spring 57 can rapidly act to close the channel 10 and/or valve 1 in the event of loss of control of the valve 1 , which can increase safety and prevent production fluid flow from continuing from a well in that situation.

As can be further appreciated, the cage 30 is movable in the axial direction to extend out and away from the open end 3b of the housing 3, so that a wall structure of the cage spans across the channel 10 The position is determined by operating the actuator 44. Similarly, the valve member 40 is movable in the axial direction to extend out and away from the open end 3b of the housing 3. The cage 30 is cylindrical, and the valve member 40 is cylindrical to fit in complementary relationship inside the cage and be slidable within and along the cage 30 in the axial direction. The amount of extension of the valve member 40, e.g. to close or partially close the valve, is determined by its position from operating the actuator 44.

In this example, the valve 1 notably also includes a seat 70 for the cage 30. That is, the cage 30 when in an operable position across the channel 10, is arranges so that a surface of the cage 30 abuts the seat 70. The seat 70 extends ring-wise around the open end of the cage 30. The seat 70 in this example is also adjustable within the valve body 2, in that it can be actuated to different positions axially. Fluid may flow through the valve through the wall structure of the cage 30 and through an aperture 20 of the channel 10 between the seat 70 and the valve member 40, the aperture 20 of the channel 10 being dependent upon the mutual positions of the seat 70 and the valve member 40. An actuator 74 is provided for actuating the seat to move the seat 70. The actuator 74 comprises a spring 77 and a hydraulic chamber 74c which can be supplied with fluid against the force of the spring 77 to position the seat 70 as desired. The spring 77 and actuation surface 74p is fitted in a pocket defined between an inner collar of the body 2 and an annular wall portion 79 around the collar 78. The spring 77 is arranged to about the end wall 75 of the slot and exert a biasing force against the actuation surface 74p, and by connection of the surface 74p to the rod 74r, urge or position the seat 70 axially.

The ability to position the seat 70 can facilitate configurability of the channel 10 through the valve. In early phases of production, well pressures may remain relatively stable and it may be desirable to set the seat 70 and/or valve member 40 to provide some flow resistance. As pressures reduce in the well, lower resistance from the valve may be required to obtain desired Cv values through the valve, and then the seat 70 and/or valve member 40 may be set accordingly by moving them axially to open the channel 10. This configurability may sustain production for longer than compared with prior art valves. Further, the seat 70, or at least surfaces exposed to flow from the upstream flow passage 11 may usefully comprise or consist of steel, e.g. duplex steel material which can withstand unforeseen impacts from debris or particles and pressure events in the passage 11 , which may facilitate collapse or failure of the valve. The seat 70 may also be movable in such an event to close the passage 11 against larger particles and debris, e.g. by operating the seat actuator 74 in dependence upon measured conditions.

With reference now to Figure 3, another choke valve 101 is depicted. Features corresponding to those of the choke 1 are described using the same reference numerals but incremented by one hundred.

The choke valve 101 has a valve body 102 and a channel 110 through the body 102. The valve 101 has an inlet 112 and an outlet 114. Fluid flowing along the channel 110 from the inlet 112 to the outlet 114 passes through an aperture 120 which is controlled by the valve member 140. A first tubular section 102a of the body at the inlet is arranged to extend at an angle, here perpendicular, to a second section 102b of the body at the outlet 114. Thus, the fluid is diverted around a bend or corner from the inlet to the outlet.

A third section 102c of the body provides a housing inside of which valve operating means 150 are housed including the actuators 144 and 154 for the cage 130 and the valve member 140 respectively.

The second and third sections 102b, 102c of the body together define an elongate cylindrical structure having a longitudinal axis 105 extending end-to-end.

A section of the cage 130 spans the channel 110. Fluid passes through perforations of a first region 130a of the wall structure of the cage 120. Upon actuation, the cage 130 is movable by translation along axis 105 to a second position where the fluid can pass through perforations of a second region 130b of the wall structure cage 130.

The cage 130 is cylindrical and the valve member 140 is movable axially within the cage to close the channel 110 if required. The actuators 144, 154 are hydraulic and operated by hydraulic fluid against pistons 144p, 154p against the bias of respective springs 137, 157. The spring 137 acts against an end surface 135 of the body 102 and a surface of the cage 130, urging it toward the end 124, for failsafe operability similar to the choke valve 1 described above. The spring 157 acts against an end surface 155 in cylinder 154c and a surface of the piston rod 154r to which the valve member 140 is connected.

A section of the cage 130 extends from the third section 102c of the body across the channel 110 and abuts against an inner wall of the body in the second section 102b of the body 102. No separate seat is provided in this example.

The valve member 140 is configured to block or plug the channel 110 entirely, or partially for controlling or choking a flow of fluid through the choke valve 101. The valve member 140 is cylindrical and is arranged in complementary sliding fit within the cage 130.

Linear translation of the cage 130 and or valve member 140 can be effective for transmission and utilisation of power. It can also facilitate rapid reaction to close the valve using springs, acting linearly, in the event of loss of hydraulic power.

The surface or surfaces of the cage 30, 130 that contact or are exposed to fluid flowing through the valve comprise or consist essentially preferably tungsten carbide, or other wear resistant material.

Referring now additionally to Figures 4 to 8, different cage variants are considered. In Figures 4 and 5, the cage 230 has perforations 238 which penetrate through a cylindrical wall structure 237 of the cage 230. The perforations 238 are spaced apart axially by equal spacings. When used, e.g. in the valve 1, 101 in place of cage 30, 130, the section of the cage 230 in operable position across the channel 10 lets fluid through the perforations 238. In Figure 4, the perforations 238 in the region 232 have been subjected to wear by the fluid passing through that region of the cage. Moving the cage to a different position so that a different part of the cage 230 is in operational position so as to span across the channel 10, perforations in that other section of the cage 230 can be utilised and the performance of the cage maintained.

In Figure 6, a cage 330 has first section 332 with first perforations 338 and another, second section 333 with second perforations 339 that penetrate through the wall structure 337. The perforations 339 have greater diameters than the perforations 338, d2 > d1. The first section 332 has perforations 338 configured optimised for well production streams. The second section 333 can be better suited for clean-up operations, e.g. prior to commencing production from a well, where larger particles of debris may be carried in the fluid from the well, and the large diameter d2 allows the larger particles to pass through the perforations 338. In order to start production from a well, this “clean up” cage 330 can be useful due to the larger holes in the cage. With a prior art choke, the cage may need changing after a while. With an actuated cage as described herein, the one part 332 of the cage 330 can be for “clean up” and after the clean-up is complete, the part 333 with regular production can be moved into service. As will be appreciated, this can be done by moving the cage 330 to be positioned so that the section 333 is arranged in operational position across the channel 10, 110 so that fluid passing through the valve has to travel the perforations 338 of the section 333.

In Figure 7, the cage 430 has three sections 431 , 432, and 433, wherein the latter two sections 432, 433 comprise first perforations 438 and second perforations 439 through the wall structure 437 of the cage 430. The perforations 438 are like the perforations 238 of Figure 5 and the perforations 338 of Figure 6. The perforations 439 however are different, each having a stepped internal pathway 439s between the opening 439x and exit 439z of the perforation. This configuration of the perforations 439 provides a greater pressure reducing effect upon the fluid passing through the perforations 439, i.e. more flow resistance. Thus, the section 439 of the cage 430 can be suited particularly for high pressure applications and for protecting the valve member.

The wall structure of section 431 of the cage 430 comprises cylindrical walling which is impervious to fluid. The section 431 does not have perforations. The section 431 is used to prevent collapse and protect the valve member 40, 140 inside the walling in an adverse situation such as in a high pressure and/or debris impact event in the fluid upstream, e.g. propagating into the valve, e.g. in the upstream flow passage 11. The section 431 comprises material comprising or consisting essentially of metal, preferably duplex steel. The steel material can provide high strength and good properties to withstand impact and collapse.

The material of the section 431 differs from that of either or both of sections 432 or 433. The sections 432 and 433 comprise or consist essentially of tungsten carbide, or another suitable frictional wear resistant material. Alternatively, only an outer layer of wall material of the sections 432, 433 in areas which are subject to contact from fluid passing through the perforations 432, 433 comprises or consists essentially of tungsten carbide or other suitable material. This may delay the onset of wear in the sections of the cage and facilitate long term use. As can be appreciated, the cage 430 upon suitable actuation can be positioned so that any of the sections 431, 432, 433 are arranged to extend across the channel 10. The cage 430 may be positioned to move the “anti-collapse” section 431 into position where the section extends across the channel 10. This could take place in a failsafe closed configuration for example if loss of control of the valve takes place, or in response to conditions which may be monitored, e.g. pressure conditions, in the flow upstream and/or downstream of the valve being anomalous or exceeding normal limits, requiring for example the valve and production flow to be shut down, e.g. for safety purposes.

The cage 430 is also positionable so that the section 432 or the section 433 is arranged across the channel 10 for flow through the perforations 438 or the perforations 439depending upon requirements.

Clearly a wide range of other variants are possible using different regions with mixed sizes, different materials, other configuration, and/or patterns of perforations, e.g. for different purposes. The pattern may be consistent for the whole of the cage or screen, e.g. for particular purpose. The sizes, configuration, and/or pattern may be different in different sections of the cage for different purposes.

With regard to materials, any of the cages or sections thereof described above may comprise or be formed of material comprising or consisting essentially of metal, plastics, tungsten carbide or any combinations thereof. More specifically, those cages or sections thereof comprising perforations preferably comprise or consist essential of tungsten carbide, but other materials, e.g. metals may be used as an alternative.

In Figure 8, an example of the cage 230 is shown in combination with the seat 70 and valve member 40 in choke valve 1. The valve member 40 and the seat 70 are positioned in a predetermined position, so that the cage and perforations in the region 230a can be investigated or “scanned”. In order to find region with wear this valve allows a scan the of the whole cage to be performed for comparing the valve Cv with the Cv using the new cage. This is done by moving the valve member 40 towards the seat 70 until only a small gap is left between the seat and the piston. With the valve member 40 and seat 70 in position, the cage 230 is slowly moved and the valve flow coefficient, Cv, is measured. The area along the cage 30 with wear will then have change in Cv. Alternatively, the flow can be measured, and if measured parameters of the flow are different when compared with when fluid is transmitted through another section of the cage, by moving position of the cage across the channel 10, it may be inferred whether the condition of the cage and/or perforations in certain regions of the cage has deteriorated.

In use, the inlet 22, 122 of the choke valve 1, 101 is connected to a first section of pipeline, e.g. connecting to a well, and the outlet 24, 124 of the valve is connected to a second section of pipeline, e.g. connecting to downstream production processing equipment. Fluid is supplied through the first pipeline section into the inlet. The fluid passes through the valve and out of the outlet into the second pipeline section. In one mode of operation, the cage 10, 110 is positioned across the channel 10, 110 in the valve. The valve member is open. The fluid passes through perforations in the first region 30a, 130a of the valve 1 , 101. The cage 10 by operation of the actuator 44 is moved into the second position, and another, second region 30b, 130b of the cage 30, 130 spans the aperture 20, 120. The fluid passes through the perforations in the second region 30b, 130b of the cage 30, 130. The cage 30, 130 is for example moved from the first to the second position depending upon expected wear or after a certain time in use in the first position. In order to choke or restrict the flow of fluid, the valve member 40, 140 is operated by the actuator 54 to position the valve member 40 within the valve body 2, 102 to close or partially close the channel 10, 110. To determine the wear condition of the cage 30, 130, one or more properties of fluid, such as flow rate, valve flow coefficient Cv, or pressure, passing through the valve 1 , 101 is monitored before and after use. For example, before use, the cage 30, 130 and valve member 40, 140 are positioned in defined positions. Fluid is transmitted though the valve 1, 101 and measurements of the property of the flow are made. Later, after a period of normal use of the valve with the cage 30, 130 in that position, the same measurement is repeated. If the measured property has changed, then it is inferred that the cage 30, 130 has been subject to wear. If the measured property is associated with wear which does not meet a predetermined desired condition, then the cage 30, 130 is moved to another position to arrange a different section of the cage in position across the channel 10, 110 where performance is improved.

Advantageously, the solutions herein can increase the time before a choke valve 1, 101 needs maintenance and at the same time increase production. By actuation of the cage 30, 130, the cage can be moved in order to make the wear equal over the whole cage. This can increase the lifetime of the cage. In order to have a collapse free choke, a part of the cage close to the valve member 40, 140, can be made of metal like duplex, super duplex, 6Mo. This may provide for a strong cylindrical cage structure. In the event of an impact which may otherwise break the valve member and tungsten carbide part of the cage, the actuator 44 can push the metal part of the cage against the seat and close the valve.

An advantage of the actuated seat is to be able to increase the Cv when the pressure from the well after some time of production, is reduced. This can then increase the production compared with a regular choke. This can be done by moving the seat away from the actuator side making the flow area of the cage larger and increasing the Cv and production.

Although examples above have been described with reference to hydraulic actuators, either or both of the actuators for operating the cage and the valve member can in other variants be any one or more of electric, hydraulic, mechanical, and pneumatic actuators.

Although the cage is linearly translated using linear actuators in the examples above, in other variants, the cage can be rotated to position the cage so that in a first position flow of fluid through perforations of one region of the cage and in a second position flow goes through perforations of another region of the cage.

Although the examples depicted describe a cylindrical cage, perforated screens of other forms are in other variants used. For example, a planar screen which transects a tubular section of the valve could be employed, with the walling of the screen having different regions with perforations through which the fluid may pass.

The valve 10, 110 above is termed a choke valve.

In other examples, a regulation valve or a control valve has the same features.

In addition to well streams or production streams, the valve can be used in other applications. It may be applied in other processes or applications, and may be used as a process-critical valve. Accordingly, the valve can be a critical control valve in any process, for example on land, offshore, or subsea. The control valve does not need to be used directly for controlling a well stream. Indeed, the process also does not need to be related to oil and gas industry, but can be a critical process in any industry, including for instance food production, mining industry, nuclear power stations, aerospace, etc.