EP2592218A1

EP2592218A1 - Valve assembly for a hydrocarbon wellbore, method of retro-fitting a valve assembly and sub-surface use of such valve assembly

Info

Publication number: EP2592218A1
Application number: EP11188271.8A
Authority: EP
Inventors: Derk Lucas Klompsma; Lubbertus Lugtmeier
Original assignee: Shell Internationale Research Maatschappij BV
Current assignee: Shell Internationale Research Maatschappij BV
Priority date: 2011-11-08
Filing date: 2011-11-08
Publication date: 2013-05-15

Abstract

The invention relates to a valve assembly (40) for a hydrocarbon wellbore (1). The valve assembly comprises an insert assembly (51,52,53) adapted for insertion in the production tubing or the Christmas tree. The insert assembly is provided with at least two passages (54,55); a lower (56,57) and upper (58,59) passage port for each said passage; a valve member (80) in at least one of said passages; and an operating mechanism (74) for operating the valve member. The passages each extend through the insert assembly from the accompanying lower passage port to the accompanying upper passage port. The lower passage port is arranged at the lower end of the insert assembly and the upper passage port is arranged at a distance above the lower end of the insert assembly. The valve member is operable between a flow position, allowing fluid flow between the lower passage port and upper passage port and a blocking position preventing fluid flow between the lower and upper passage port. The invention further relates to a Christmas tree (16) with such valve assembly, a retrofit assembly with such valve assembly, sub-surface use of such valve assembly, a hydrocarbon wellbore with such assembly and a method of retro-fitting a production flow valve with such valve assembly.

Description

The invention is in the field of hydrocarbon production. More specific, the invention relates to a valve assembly, such as a safety valve assembly, for a hydrocarbon wellbore, a tree, a wellbore and retro-fit assembly comprising such a valve assembly and a method of retro-fitting a production flow safety valve.
In hydrocarbon wellbores it is common to use one or more safety valves to provide closure of the production tubing in the event of emergency or for other reasons like maintenance or repair. Such a safety valve can be provided above or below the wellhead.
In case it is provided above the wellhead, the safety valve is in practise often installed inside the so called tree or Christmas Tree (XMT). As in general the tree is arranged above ground level - which level is in case of off-shore the sea bottom and in case of on shore the surface of the land - this safety valve is in the field frequently indicated as surface safety valve (abbreviated as SSV). A surface safety valve is in general a gate valve, having a slide slidable transverse to a bore. Said slide may be manually, hydraulically or pneumatically operated. In this document a surface safety valve is, from time to time, also called an above surface safety valve. The term 'above' is in this respect not intended to have the literal meaning, but is just intended to differentiate over the term 'sub surface safety valve'.
Safety valves arranged below the wellhead are usually arranged at a depth of 100-150 meters below ground level. These safety valves are in the field frequently indicated as sub surface safety valves (SSSV). Known sub surface safety valves are provided as an elongate tubular component which is inserted in the production tubing as tubing retrievable or wire retrievable. In case of tubing retrievable, the component is provided at its upper end and lower end with connection means, like screw thread, for attachment to an upper and lower part, respectively, of the production tubing so that the lower production tubing part, tubular component and upper production tubing part form a continuous string. In order to retrieve a tubing retrievable component, the whole tubing has to be withdrawn from the wellbore bore up to the component surfaces. In case of wire retrievable, the tubular component is inserted as a plug into the production tubing, and fixed to the inner wall of the production tubing, for example by a landing nipple provided inside the production tubing and a lock mandrel having keys provided on the outside of the tubular component. For retrieving a wire retrievable component, a wire provided with a so called jar is to be lowered into the production tubing, the wire/jar is to be coupled to the component, the component is to be disengaged from the production tubing and subsequently retrieved by withdrawing the wire together with the connected component from the production tubing.
The valve mechanism of known sub surface safety valves comprises a control sleeve. This control sleeve is open at both longitudinal ends and pre biased in upward direction by a fail safe spring. The control sleeve can be pushed downwards by hydraulic pressure acting on a rib or flange attached around the control sleeve. When in its upward position the lower end of the sleeve is closed by a flapper. The flapper is in fact a plate which can pivot around a horizontal pivot axis between in a horizontal position, in which the lower end of the control sleeve is closed, and a vertical position, in which the flapper rests against the outside of the wall of the sleeve. By pushing the control sleeve downwards with hydraulic pressure, the flapper is pivoted from its horizontal position to its vertical position allowing production flow to pass through the control sleeve.
In hydrocarbon production, it occurs that it is desired to arrange for an additional tubing extending down into the wellbore, sometimes down to the bottom of the wellbore. Additional tubing might be desired to inject a treatment fluid into the wellbore bore. The treatment fluid can for example be a soap-like substance promoting release of gas or oil from an earth stratum.
In practise this is quite complicated as this additional tubing has to pass the surface safety valve and/or sub surface safety valve. The additional tubing has to be very flexible to allow insertion into the wellbore and to allow passage through the sub surface safety valve. Passage of the surface safety valve is in general achieved by introducing the additional tubing at a level lower than the surface safety valve or by first temporarily removing the surface safety valve, introducing the additional tubing, connecting the additional tubing to a side port below the surface safety valve and replacing the temporarily removed surface safety valve. This is all quite complicated and time consuming.
The object of the present invention is providing a solution for at least some of the above problems associated with introducing an additional tubing extending into the wellbore.
According to a first aspect of the invention, this object is achieved by providing a valve assembly, such as a safety valve assembly, for a hydrocarbon wellbore, said wellbore comprising a production tubing extending from a wellhead in the direction of a lower end of the wellbore;
wherein the valve assembly comprises an insert assembly configured and constructed for insertion in the production tubing; the insert assembly having a lower end which, when inserted in the production tubing, faces downward into a part of the production tubing extending below the insert assembly;
wherein the insert assembly is provided with:

at least two passages, such as two, three, four or five passages;
a lower and upper passage port for each said passage;
a valve member in at least one of said passages; and
an operating mechanism for operating the valve member;
wherein the passages each extend through the insert assembly from the accompanying lower passage port to the accompanying upper passage port; the lower passage port being arranged at the lower end of the insert assembly for allowing fluid flow between the accompanying passage and an accompanying lower flow channel extending downwardly from the insert assembly; and the upper passage port being arranged at a distance above the lower end of the insert assembly for allowing fluid flow between the accompanying passage and an accompanying upper flow channel;
wherein the valve member is operable, by the operating mechanism, between a flow position, allowing fluid flow between the lower passage port and upper passage port and a blocking position preventing fluid flow between the lower and upper passage port.

According to the invention, the insert assembly has at least two passages, the first of which comprises the first valve member, such as a safety valve member. The lower flow channel accompanying this first passage is the part of (the internal of) the production tubing lying below the insert assembly. The upper flow channel accompanying this first passage is the part of (the internal of) the production tubing lying above the insert assembly. Consequently, when the first valve member is open, the first passage comprising the first valve member communicates with the internal of the production tubing so that the production flow, comprising gaseous and/or liquid hydrocarbon, is allowed to pass. The second and optional further passages might comprise a second valve, but can also be without a valve. The lower flow channel accompanying these second and optional further passages are formed by additional tubings, which extend through the internal of the production tubing. The insert assembly thus allows additional tubing to bypass the first valve instead of passing through the first valve. This provides a range of new possibilities, such as: relatively stiff additional tubing can be used; additional tubing having relatively large diameter can be used; easy installing additional tubing at any time it is needed; easy retrieval of additional tubing; easy replacement of additional tubing; introducing a pump or other device deeply down into the wellbore, like in the production zone and/or at the bottom of the wellbore. Taking into account that the additional tubing can be used for a large variety of activities or operations, like injecting a fluid, obtaining samples, obtaining measurements etcetera, and that the diameter, stiffness and other parameters of the tubing are much less bounded by limiting requirements of prior art (like the small diameter and very flexible requirements of prior art), it becomes clear that this additional passage(s) open a wide range of activities or operations which could not be done before.
As follows from the preceding paragraph, the lower flow channel (as wellbore as upper flow channel) accompanying the second and optional further passages do not need to be provided at all times, they might be absent. Just the second and optional further passages and accompanying lower and upper passage port(s) are present and available. Connecting these port(s) with lower and/or upper flow channels is a possibility which might be used in case circumstances require so. It is conceivable that the second and optionally further passages are made available for just in case and will be closed, for example by a valve inside the respective passage, when not in use.
Like the prior art tubular component as discussed above in relation to a sub surface safety valve, the insert assembly according to the invention can be arranged and constructed as either a tubing retrievable or wire retrievable insertion assembly. Further, the insertion assembly according to the invention can be used as a surface safety valve and/or sub-surface safety valve.
Concerning the term 'hydrocarbon wellbore', it is noted that in this application this term comprises not only 'production wellbores through which a hydrocarbon fluid surfaces' but also 'injection wellbores for pressurizing sub-surface formations in order to force hydrocarbon fluid to surface' and 'storage wellbores for sub-surface storage of hydrocarbon fluid'. Further it is noted that a valve arranged in the path of the production flow to be able to interrupt this production flow, is in this application also called a production flow safety valve.
According to a further embodiment of the valve assembly according to the invention, the insert assembly is arranged and/or configured for plugging insertion into the production tubing. The term plugging insertion means that the insert assembly fits like a plug into the production tubing, i.e. when inserted into the production tubing the insert assembly blocks essentially the entire cross section of the production tubing (the passages - when open - of course allowing passage of medium). In case of a sub surface safety valve configuration, the insert assembly will be fully inserted into the production tubing. In case of a surface safety valve configuration, at least the lower part of the insert assembly will be inserted into the upper end of the production tubing. In case of a surface safety valve configuration, it might however also be conceivable that the insert assembly is fully inserted into the production tubing.
According to a further embodiment of the valve assembly according to the invention, the valve member comprises a tube, which extends in the accompanying passage and is axially movable, by the operating mechanism, with respect to the insert assembly between the flow position and the blocking position. Such a valve member allows on the one hand relative large diameters and unimpeded flow and on the other hand simple operating mechanisms for closing and/or opening a port.
According to a further embodiment of the valve assembly according to the invention, wherein movement of the valve member - such as the tube - to the flow position defines an opening direction, and movement of the valve member - such as the tube - to the blocking position defines a closing direction; the operating mechanism comprises:

a spring biasing the valve member - such as the tube - in the closing direction;
a piston member fixed to the valve member - such as the tube -;
a pressure chamber adjacent the side of the piston member facing in the closing direction;
wherein the pressure chamber is provided with an inlet/outlet valve assembly for feeding a hydraulic fluid into the pressure chamber to move the valve member - such as the tube - in the opening direction respectively to discharge said hydraulic fluid from the pressure chamber for moving the valve member - such as the tube - in the closing direction by action of the spring. This type of operating mechanism, which is in the field of hydrocarbon wellbores a proven and reliable mechanism for sub surface safety valves, is also very useful in a valve assembly according to the present invention.

According to a further embodiment of the valve assembly according to the invention, at least two said passages are each provided with an accompanying valve member, and the operating mechanism is arranged and configured as a common mechanism for operating these valve members together with one mechanism. In case the valve members comprise, in accordance with an earlier embodiment, each a valve and/or in case the operating mechanism comprises, in accordance with an earlier embodiment, a spring, piston member and pressure chamber, this is, for example, be achieved when these at least two passages and accompanying tubes comprise a common said spring, a common said piston member and a common said pressure chamber. This allows simultaneously closing two or more passages with one mechanism. One mechanism for operating a multiple of valves saves constructional space and consequently allows relatively large passage diameters. Further, taking into account that in case of emergency not only the production flow passage but also additional passages will require reliable closing off, the reliability of the valve assembly as a whole is increased. In this respect, it will be clear that for safety reasons it might be preferred to provide all passages with a valve member and to arrange and configure the operating mechanism as one mechanism operating all valves together.
Notwithstanding that for safety reasons it might be preferred that all passages have a valve member which is operable with one common operating mechanism, it might be preferred for other reasons that at least two said passages are each provided with a valve and that these passages and accompanying valves each have a separate operating mechanism (in other words: their own operating mechanism) to allow operation of these valves independently from each other. As will be clear, this can be in combination with two passages having a common mechanism for operating their valves. In case the valve members comprise, in accordance with an earlier embodiment, each a valve and/or in case the operating mechanism comprises, in accordance with an earlier embodiment, a spring, piston member and pressure chamber, this is, for example, be achieved when at least two said passages are each provided with an accompanying said tube, and wherein these at least two passages and accompanying tubes each comprise a separate said spring, a separate said piston member and a separate said pressure chamber.
According to a further embodiment of the valve assembly according to the invention, a flapper valve is provided in a section of a said passage, which flapper valve is spring biased into a closed position blocking the passage; and wherein this passage, accompanying tube and flapper valve are arranged for opening the flapper valve upon passing the tube through the section of this passage and closing the flapper valve upon withdrawing the tube from the section of this passage. According to the present invention, this flapper valve might serve as a said valve member of a valve assembly according to the invention, in which case the tube serves as actuating member for operating the flapper valve. However, it is also possible to use the tube as valve member which is moveable between the flow position and blocking position whilst the flapper valve is permanently kept open by the tube; or to use neither the tube or the flapper as valve member but another valve member. In this latter two cases, the flapper valve might serve as closing mechanism (one could also say as second valve member in the same passage) in case the passage is out of use or not yet in use. For example, during installation of the valve assembly according to the invention, it might be necessary to ensure that no flow, like production flow or other flow, can pass the valve assembly. In said latter two cases, the passage provided with the flapper valve can be taken into use by pushing a tube through the section provided with the flapper valve. As will be clear, all passages through the insert assembly might be provided with a flapper valve, but this is not a requirement. It is also very wellbore conceivable that some or almost all of the passages are provided with a flapper valve, whilst the others are not.
To prevent leakage through a passage of a valve assembly according to the invention, a said passage having an accompanying said tube can be provided with at least one inner seal, which is attached to the inside of the passage, extends circumferentially around the tube and seals circumferentially against the tube to prevent fluid from bypassing the tube between the outside of the tube and the inside of the passage. As will be clear, all passages through the insert assembly might be provided with an inner seal, but this is not a requirement. It is also very wellbore conceivable that some or almost all of the passages are provided with an inner seal, whilst the others are not. An inner seal might for example not be necessary, when the passage is just a channel which is at its lower and upper port leak tight connected to additional tubing.
According to a further embodiment of the valve assembly according to the invention, a said tube comprises a radial aperture through the tube wall, which radial aperture is part of the accompanying lower or upper passage port; wherein, when the tube is in its blocking position, the radial aperture is, at the outside of the tube, closed by the inner wall of the accompanying passage for closing the accompanying lower or upper passage port, respectively; and wherein, when the tube is in its flow position, the radial aperture is, at the outside of the tube, in flow communication with the accompanying lower or upper flow channel, respectively. On the one hand, this enables a very simple opening/closing operation - just by shifting the tube -, whilst on the other hand it allows passage ports with a passage surface as large or larger than the cross sectional surface of the tube so that a medium can flow essentially unimpeded through the lower or upper port. In case the tube might be open at both ends, the operation of the tube will not be hindered in its movement by pressure prevailing in the lower or upper flow channel. As will be clear, all tubes might be provided with a radial aperture, but this is not a requirement. It is also very wellbore conceivable that some or almost all of the tubes are provided with a radial aperture, whilst the others are not.
According to a further embodiment of the valve assembly according to the invention, the tube has a closed lower end, and the radial aperture forms the lower passage port, which lower passage port projects downwardly from the insert assembly when the tube is in its flow position. This configuration allows the tube to serve as valve member in a situation when the medium flow to be controlled by the valve arrives at the lower port in axial direction of the tube and has to leave at the upper port in axial direction as wellbore. Note that although the medium arrives at the lower port in axial direction, the radial aperture will force the flow temporarily in a radial direction to enter the tube.
According to a further embodiment - having a tube with closed lower end - of the valve assembly according to the invention, a first said inner seal lies, viewed in the blocking position of the tube, above - and preferably also close to or adjacent - the radial aperture whilst a second said inner seal lies, viewed in the blocking position of the tube, below - and preferably also close to or adjacent - the radial aperture. These seals prevent at the location of the radial aperture, in blocking position of the tube, bypass of medium around the tube in both the upward direction (from lower port to upper port) and the downward direction (from upper port to lower port).
According to a further embodiment - having a tube with closed lower end - of the valve assembly according to the invention, the insert assembly is provided with a pressure equalizing line debouching on the one hand into the lower flow channel of the accompanying passage and on the other hand into the passage at a location, which lies, when the tube is in its blocking position, below the radial aperture. In case the lower flow channel is under overpressure relative to the inside of the tube, this considerably reduces the forces required to move the tube from blocking position to flow position. With this embodiment, optionally a sealing - which seals against the tube - can be provided on the inside of the passage above as wellbore as below the location or around the location where the equalizing line debouches into the passage.
According to a further embodiment of the valve assembly according to the invention, the insert assembly comprises a radial bore which forms, together with the radial aperture, the upper passage port, wherein the radial bore has one end debouching into the passage and the other end facing away from the passage for connection to the upper flow channel; and wherein a said radial aperture and the radial bore are aligned radially when the tube is in its flow position. Such a bore provides connection to an upper flow channel which extends radially with respect to the axial direction of the insert assembly. Concerning the term bore, it is to be noted that the cross sectional shape - i.e. the shape transverse to the flow through the bore - might be round, but does not need to be round. The cross sectional shape might be oval, square, rectangular or any other shape.
According to a further embodiment of the valve assembly according to the invention, a third said inner seal is provided above - and preferably also close to or adjacent - the radial bore and a fourth said inner seal is provided below - and preferably also close to or adjacent - the radial bore. These seals prevent at the location of the radial bore, in blocking position as wellbore as flow position of the tube, bypass of medium around the tube in both the upward direction (from lower port to upper port) and the downward direction (from upper port to lower port).
According to a further embodiment - having a radial bore - of the valve assembly according to the invention, the tube or passage is closed in an area above the radial aperture and the radial bore.
According to a further embodiment of the valve assembly according to the invention, wherein the insert assembly is provided with an outer seal, which is attached to the outside of the insert assembly, extends circumferentially around the insert assembly and seals, when the insert assembly is inserted into the production tubing, circumferentially against the inner side of the production tubing to prevent fluid from bypassing the insert assembly between the outside of the insert assembly and the inside of the production tubing.
According to a further embodiment of the valve assembly according to the invention, wherein the insert assembly is provided with a circumferential hanger rib for support onto a hanger seat, such as a landing nipple, extending around the insert assembly. A hanger ribs resting on a hanger seat, like a landing nipple, is in the field of hydrocarbon wellbore a wellbore known technique for mounting components inside a tubing, like a production tubing. These known techniques as wellbore as yet unknown variants thereof are very wellbore suited for use in combination with the invented valve assembly. In relation to this embodiment, the hanger rib might comprise:a continuous rib extending continuously all around the insert assembly; and/or
a multiplicity of rib segments, like keys or locking dogs, arranged at intervals circumferentially around the insert assembly.
As is wellbore known in the field of hydrocarbon wellbores, a landing nipple is arranged on the inside of a tubular wall and comprises in general one, two or more circumferential grooves formed in the inner wall surface of a tubular element. Below these one, two or more circumferential grooves, the inner wall surface provides a sealing area. Such a landing nipple is often used in combination with a component having so called lock mandrel. A lock mandrel comprises in general a fishing neck to allow retrieval of the component and a number of keys arranged externally around the circumference of the component. Usually these keys are spring loaded and can assume three positions:

a retracted position in which the keys are radially retracted within the component; a projecting;
spring loaded position in which the keys project radially outward from the component and are radially movable against the action of a spring; and
a locked position in which the keys project radially outward from the component and are kept unmovable with respect to the component by a locking mechanism.

The technique using a landing nipple and a lock mandrel is also suitable for mounting a valve assembly according to the invention into a hydrocarbon wellbore.
According to a further embodiment of the valve assembly according to the invention, the insert assembly comprises a lower insert part and an upper insert part; wherein the lower insert part comprises the passage and is adapted for said plugging insertion into the production tubing; and wherein the operating mechanism is provided in the upper insert part and the tube is suspended from the upper insert part to project into the passage of the lower insert part. This multiple part configuration - the insert assembly might be build up from more than the named two part - allows installation of the insert assembly in steps. This is especially of interest for sub surface use, but might also be applied in case of (above) surface use. If necessary, the upper insert part with the operating mechanism and tubes can be replaced or temporarily removed without removing the lower insert part. In this embodiment, earlier mentioned flapper valves or other type of valve might be arranged inside each passage of the lower part in order to be close the passages of the lower insert part when the upper insert part is (temporarily) removed.
According to a second aspect, the object of the invention is achieved by providing a tree for a hydrocarbon wellbore, said wellbore comprising a production tubing extending from a wellhead in the direction of a lower end of the wellbore and a tree arranged onto the wellhead; wherein the tree is provided with a valve assembly according to the first aspect of the invention.
According to a further embodiment of the second aspect of the invention, the upper passage port of a first said passage is flow connected to, and preferably horizontally aligned with, a flow wing port of the tree; wherein the first passage and accompanying valve member define a production flow safety valve.
According to a third aspect, the object of the invention is achieved by providing a retrofit assembly for a tree of a hydrocarbon wellbore, wherein the retrofit assembly comprises:

a spool to be mounted on top of a - already present - tree of a hydrocarbon wellbore with the longitudinal axis of the spool axially aligned with the vertical axis of the tree; and
a valve assembly according to the first aspect of the invention, wherein the upper passage port of a first said passage is flow connected to, and preferably horizontally aligned with, a flow wing port of the tree; and wherein the first passage and accompanying valve member define a (above) surface safety valve for the production flow, such as an upper master valve or lower master valve;
wherein the spool is internally provided with a circumferential seat surface facing upwardly and wherein the insert assembly is externally provided with a mating circumferential support surface facing downwardly.

According to a fourth aspect, the object of the invention is achieved by the sub-surface use of a valve assembly according to the first aspect of the invention in a hydrocarbon wellbore, said wellbore comprising a production tubing, which extends from a wellhead in the direction of a lower end of the wellbore and which is internally provided with at least one nipple, such as a landing nipple; wherein the insert assembly is adapted to be completely inserted into the production tubing and externally provided with locking means, such as locking dogs, adapted for engagement into a said nipple; and wherein a first said passage and accompanying valve member define a sub-surface safety valve for the production flow.
According to a fifth aspect, the object of the invention is achieved by providing a method of retro-fitting a valve, such as production flow safety valve, of a hydrocarbon wellbore comprising a production tubing, the method comprising the following steps:

removing a valve, such as a production flow safety valve, to be retrofitted from a hydrocarbon wellbore;
placing a valve assembly according to the first aspect of the invention into the wellbore by inserting the insert assembly in plugging manner into the production tubing;
arranging a said passage provided with an accompanying valve member such that the lower port of the passage allows, when the accompanying valve member is in the flow position, flow communication between the passage and the internal of the production tube.

According op a further embodiment of the fifth aspect of the invention, the method comprises the further step of:

attaching an additional tubing to the lower end of the insert assembly such that the additional tubing is connected in sealing manner to a further passage, which additional tubing is arranged inside the production tubing and extends from the insert assembly in the direction of the lower end of the wellbore.

According to a fifth aspect, the object of the invention is achieved by providing a hydrocarbon wellbore, comprising one or more selected from the group comprising:

a valve assembly according to the first aspect of the invention;
a tree according to the second aspect of the invention;
a retrofit assembly according to the third aspect of the invention;
a valve used according to the fourth aspect of the invention.

The invention will now be explained by way of example with reference to the accompanying drawings, wherein:

Figure 1 shows a cross-sectional view of an exemplary hydrocarbon wellbore, in this example a hydrocarbon production wellbore, provided with a system for injecting a treatment fluid into the production zone of the hydrocarbon wellbore in accordance with the present invention;
Figure 2 shows a view of a Christmas tree of a hydrocarbon wellbore according to the invention;
Figures 3a and 3b show a view of a sub surface safety valve assembly according to the invention, wherein Figure 3a shows the assembly in blocked position and figure 3b shows the assembly in flow position.

Figure 1 shows schematically a hydrocarbon wellbore, in this case a hydrocarbon production wellbore 1, according to the invention. The hydrocarbon wellbore 1 comprises a wellbore or borehole 4 which has been drilled from the surface 3 through a number of earth formations 5, 6, 7, 8 up to a production formation 9. The production formation 9 comprises hydrocarbons, for example oil and/or gas. The wellbore 4 is lined with casings 12 and a liner 15 which is suspended from the lowermost casing 12 by means of a liner hanger 13. The liner 15 extends from the lowermost casing 12 to the production formation 9 and comprises perforations 11 for allowing fluid communication from the production formation 9 to a production zone 10 of the hydrocarbon wellbore 1.
A production tubing 14 is disposed within the casings 12 and the liner 15 of the wellbore 4. The production tubing 14 may be constructed in various ways. For example, the production tubing 14 comprises sections of standard production tubing which are connected together by threads. The production tubing 14 extends from a wellhead 2 of the hydrocarbon wellbore 1 to the production zone 10. Production fluids, such as oil and/or gas, may be conveyed to the wellhead 2 at the surface 3 through the interior of the production tubing 14. A Christmas tree 16 is installed on the wellhead 2 so as to control fluid flow in and out of the wellbore 4.
A sub surface safety valve assembly 17 (also called down hole safety valve 17) according to the invention is installed within the production tubing 14. In this exemplary embodiment, the sub surface safety valve 17 is constructed as a surface-controlled subsurface safety valve. The safety valve 17 is situated at a depth which is greater than 50 m, for example at approximately 100 m. The safety valve 17 provides emergency closure of the production tubing 14 in the event of an emergency. The safety valve 17 is designed to be fail-safe, i.e. the wellbore 4 is isolated in the event of failure or damage to the surface production control equipment. An annular space 25 is defined between the outer radial surface of the production tubing 14 and the casings 12. A hydraulic control line 18 extends from the surface 3 within the annular space 25 to the safety valve 17 so as to control the safety valve.
A packer member 24 is arranged between the production tubing 14 and the liner 15 so as to secure in place a lower portion of the production tubing 14 and to substantially isolate the annular space 25 from the interior of the production tubing 14. For example, the packer member 24 comprises a means for securing the packer member 24 against the wall of the liner 15, such as a slip arrangement, and a means for establishing a reliable hydraulic seal to isolate the annular space 25, typically by means of an expandable elastomeric element. The portion of the production tubing 14 below the packer member 24 is generally referred to as the tail.
The hydrocarbon wellbore 1 according to the invention comprises an additional tubing 19. This additional tubing might for example be a system for injecting a treatment fluid into the production zone 10. The system for injecting a treatment fluid into the production zone 10 comprises a treatment fluid injection tubing 19 having an upper supply end 20 and a lower discharge end 21. The upper supply end 20 is installed in the Christmas tree 16.
The treatment fluid injection tubing 19 is arranged in the interior of the upper part of the production tubing 14, which upper part extends from the Christmas tree 16 to the safety valve 17. The treatment fluid injection tubing 19 passes the safety valve 17 and runs further downward through the interior of the lower part of the production tubing 14 up to the lower discharge end 21 in the production zone 10. Thus, the treatment fluid injection tubing 19 extends below the safety valve 17 and below the packer member 24. The treatment fluid injection tubing 19 may be several kilometres long.
The treatment fluid injection tubing 19 comprises an upper pipe which runs from the wellbore 2 to the safety valve 17, a passage duct which passes the safety valve 17, and a lower pipe which extends from the safety valve 17 to the production zone 10. The inner diameter of the pipes may be less than 1 cm, preferably less than 0.5 cm. However, according to the invention the inner diameter of the tubing 19 may be much larger than 1 cm as well, for example 2.5 cm or larger. Further according to the invention, the additional tubing 19 can be stiff or rigid. The lower end of the treatment fluid injection tubing 19 might comprise a treatment fluid injection valve 22.
Although the additional tubing 19 is above described as a system for injecting a treatment fluid into the production zone 10, it is noted that, with respect to the present invention, this is just an example of an additional tubing which can be useful in a hydrocarbon wellbore. Additional tubing 19 for other purposes are within the scope of this invention very wellbore conceivable. Within the scope of the invention, an additional tubing 19 might also serve as a guide bringing a measurement device, a tool, an inspection means (like a camera), or any other object to any level between the wellhead and the production zone. Further, an additional tubing might serve the purpose of taking a sample from any level between the wellhead and the production zone.
Figure 2 shows schematic view of a (Christmas) tree 16 according to the invention for a hydrocarbon wellbore according to the invention. The tree 16 comprises an original tree 16a and an additional spool 16b on top of the original tree 16a. The additional spool 16b is part of a retro fit assembly comprising this spool 16b and a valve assembly 40 according to the invention. The spool 16b serves the purpose of mounting the valve assembly 40 in the tree 16 by means of a hanging technique which is as such conventional in the field of hydrocarbon wellbores.
With the term 'original tree' is indicated that it is a tree of an already existing hydrocarbon wellbore, such as a tree of an already existing hydrocarbon production wellbore. Before retrofitting, this original tree 16a contained a so called swab valve, a so called upper master valve and a so called lower master valve. Reference no. 31 indicates the location where the swab valve was located, no. 32 the location where the upper master valve was located and no. 33 the location where the lower master valve was located. Further, no. 34 indicates the so called killer wing valve mounted on a killer wing port 38 and no. 35 indicates the so called flow wing valve mounted on the flow wing port 39 for discharging production flow. The lower end of the original tree 16a is mounted on the wellhead 2 and the production tubing 14 hangs with its upper end in the lower end of the original tree or (not shown) in the wellhead 2.
The spool 16b is mounted on the upper end of the original tree 16a. This mounting can be done in conventional manner as is wellbore known to the skilled person, like a manner as is also used for mounting the tree 16a onto the wellhead 2. The upper end of the spool 16b is closed by a cap 36 provided with a pressure gauge 37. This cap 36 with pressure gauge 37 was previously mounted on top of the original tree 16a.
The spool 16b is provided with so called hanger nipples, an upper hanger nipple 41 and a lower hanger nipple 42. These hanger nipples are essentially circumferential recesses formed in the inner wall of the spool 16b. At its lower side, the spool 16b is internally provided with a seat surface 43 facing upwardly and extending in circumferential direction al around.
Further, the spool 16b is provided with a side port 45 and valve 44 to allow a fluid flow to exit or enter the spool 16b. A hydraulic port 46 is provided for hydraulic fluid to enter and/or leave the spool 16b in order to allow control of a hydraulic operated device inside the spool. No. 47 indicates an optional additional hydraulic port.
The valve assembly 40 as shown in figure 2 comprises an insert assembly made of three parts: a lower insert part 51, an upper insert part 52 and a so called bull plug 53. For clarity of the drawing, these parts 51, 52 and 53 are shown, in disassembled state, on the same vertical level with respect to the spool 16b and tree 16a as they will have in mounted condition. With respect to 'the same vertical level' it is noted that the locking dogs 79 are - due to a small error in the drawing - shown at a slightly lower vertical level than the landing nipple 42 in which theses dogs will engage. The locking dogs 79 and landing nipple 42 should lie on the same horizontal line.
The lower insert part 51 is, in this example, formed by a massive body of steel having two longitudinal passages, a first passage 54 having a large diameter and a second passage 55 having a smaller diameter. Both passages 54 and 55 have an open lower end 56, 57 and open upper end 58, 59. A spring biased flapper valve 60, 61 is provided in both passages. These flapper valves 60, 61 are shown in (vertical) open position. In closed position these flapper valves 60, 61 will extend horizontally to shut off the passages 54 and 55 completely in order to prevent flow from passing through the passages 54 and 55. A radial bore 62 provides a side port in the first passage 54.
The lower insert part 51 is optionally provided with a hydraulic line 92. When mounted into the spool 16a, 16b, this hydraulic line 92 will be connected with hydraulic port 47. Hydraulic line 92 can be used for operation of a wide range of devices. It can for example be used for operation of the flapper valve 60 and or flapper valve 61. It can however also be used for operation of a device arranged below the first insert part 51 inside the tubing 14. It is for example conceivable that a device operated by means of hydraulic line 92 is arranged at the bottom of the wellbore.
In order to provide sealing, the lower insert part 51 is provided with: one or more outer seals 65 extending all around the circumference of the lower end of the insert part; one or more outer seals 91 extending around the circumference of the upper end of the lower insert part; one or more inner seals 66 provided in the second passage; one or more inner seals 67 provided in the first passage above the bore 62; one or more inner seals 68 provided in the first passage below the bore; and one or more inner seals 93 provided in the first passage at the lower end of the first passage.
To mount the lower insert part 51 in the tree 16, the cap 36 is - when present - removed and the lower insert is simply lowered into the spool 16b until the downwardly facing support surface 63 comes to rest on the mating seat surface 43. Tie down bolts 69 may be used to fix the lower insert part 51 in the spool 16b. When the support surface 63 rests on the mating seat surface 43, the lower end of the lower insert part 51 projects into the upper end of the production tubing. The lower end of the lower insert part 51 fits like a plug in the upper end of the production tubing 14. The outer seal 65 seals circumferentially against the inner side of the production tubing 14 to prevent fluid from bypassing between the outside of the insert assembly and the inside of the production tubing. A further tubing 84 might be mounted - in sealing manner - to the lower port 57 of the second passage 55.
The upper insert part 52 comprises a body part 71 supporting a first tube 72 and a second tube 73. In order to accommodate the first and second tube in slidable manner in the upper insert part, the upper insert part is provided with passages corresponding to the passages in the lower insert part. The diameter of the first tube 72 is less than, preferably about, the diameter of the first passage 54 so that the first tube can shift vertically with respect to the first passage. Correspondingly, the diameter of the second tube 73 is less than, preferably about, the diameter of the second passage 55 so that the second tube can shift vertically with respect to the second passage 55. Both tubes 72 and 73 are carried by and fixed to a common piston member 74. The first tube 72 has an upper end 77 and the second tube 73 has an upper end 78. The lower ends of both tubes 72, 73 are open. The piston member 74 is immovable with respect to the tubes 72 and 73. A spring 76 pre-biases the piston member 74 in upward direction, the blocking direction. In order to be able to push the tubes 72 and 73 downward against the action of the spring 76, a hydraulic pressure chamber 75 is provided at the upper side of the piston member 74. This hydraulic pressure chamber can be filled with and relieved from hydraulic medium via hydraulic port 46.
To mount the upper insert part 52 in the tree 16, the cap 36 is - when present - removed and the upper insert is simply lowered into the spool 16b until the locking dogs 79 are radially aligned with the lower hanger nipple 42. The locking dogs 79 may be spring biased so that they automatically engage in the lower hanger nipple. In order to prevent disengaging of the locking dogs 79 from the lower hanger nipple, the locking dogs may be fixated to prevent them from withdrawing in radial inward direction. This principle of locking by means of locking dogs and an hanger nipple is a technique wellbore known to a person skilled in the field of hydrocarbon wellbores. When the locking dogs engage in the lower hanger nipple, the first tube 72 projects into the first passage 54 and the second tube 73 projects into the second passage 55. The inner seal 66 seals circumferentially against the outer side of the second tube 73 and the inner seals 67 and 68 seal circumferentially against the first tube 72 to prevent fluid from bypassing between the inner side of the respective passage and the outer side of the respective tube. During mounting of the upper insert part 52 into the tree 16, the second tube 73 will push the flapper valve 61 - which is initially in closed horizontal position - into its vertical open position. The flapper valve 60 will however not be opened by the first tube as the flapper valve 60 is arranged lower. In case the flapper valve 60 would be arranged higher and/or in case the first tube would be longer, also the flapper valve 60 would be opened when mounting the upper insert part 52 in the tree. Similarly, opening of the flapper valve 61 would not occur during mounting of the upper insert part in the tree, in case the flapper valve 61 would have been arranged lower and/or in case the second tube would be longer. In mounted condition, an outer seal 85 prevents bypass between the spool wall and the outside of the upper insert part 52.
Figure 2 shows the tubes 72 and 73 in a condition in which they are fully pushed downwards in the so called flow position. In this position, the first tube 72 has pushed the flapper valve 60 open as wellbore. In case the flapper valve 61 would have been arranged lower and/or the second tube would have been longer, also the flapper valve 61 would have been opened now by the second tube 73. When the tubes are in the so called flow position, the radial aperture 80 in the first tube 72 is radially aligned with the bore 62 and the side port 39.
When the tubes are in the so called flow position, production fluid can, as indicated with arrows 81 and 82, flow from the production tubing into the lower end of the first passage, into the lower end of the first tube, through the first tube 72, through the radial aperture 80, through the bore 62 into the side port 39 of the original tree 16a. The first passage 54 in the upper insert part 52 has a closed upper end, whilst the first tube 72 is preferably open at its upper end. Alternatively, the upper end 77 of the first tube might be closed, in which case the upper end 83 of the first passage 54 in the upper insert part 52 has preferably a venting opening.
Upon relieving the pressure in the pressure chamber 75, the piston member 74 and tubes 72, 73 will be pushed upwards by the spring 76 to the blocking position. In this blocking position, the flapper valve 60 will be closed and the radial aperture 80 will be lie opposite a closed inner wall of the first passage 54 so that no flow is possible.
A secondary fluid flow through the second passage 55 and second tube is possible both in the blocking position and in the flow position of the tubes 72, 73. This is due to the fact that in this configuration the flapper valve 61 is always open, that the second tube is open at both ends, and that the second passage is open at both ends 57 and 84. This secondary flow can leave or enter the tree via the side port 45 and may be controlled by a control valve 44. Taking into account that the second tube 73 and second passage 55 always allow flow, it is also possible to use these for introducing - for example by means of a wire - an instrument, tool, sensor or other device into the wellbore.
In order to provide additional protection against leakage of any fluid through the upper end of the spool 16b, a bull plug 53 may be provided. This bull plug 53 has locking dogs 86 for locking engagement in upper landing nipple 41 and an outer seal 87.
Figure 3 shows schematically the safety valve assembly 17 of figure 1 in more detail. Figure 3a shows the assembly in blocking position (the valves being closed) and figure 3b shows the assembly in flow position (the valves being opened) .
The safety valve assembly 17 of figure 3 is used as a sub surface safety valve assembly. The safety valve assembly 17 is configured as one unit so that - contrary to the example of figure 2 - it can be installed as one unit into the production tubing 14. This installing might be done with a wire line technique which is known to a person skilled in the field of hydrocarbon wellbores. Fixation of the safety valve assembly inside the production tubing might be done also with know techniques (not shown), like - as is described as an example in relation to figure 2 - a landing nipple formed in the internal of the production tubing and locking dogs provided on the outside of the safety valve assembly.
Referring to figure 3, the safety valve assembly 17 comprises an insert assembly arranged in a cylindrical housing 100 which is except for passages to be described closed at its upper side 121 and lower side 122. The cylindrical housing 100 is provided with two passages, a first passage 101 and a second passage 103. Both passages extend from the lower end face of the housing 100 up to the upper end face of the housing 100. A tube is arranged in each passage. First tube 102 is arranged in the first passage 101 and second tube 103 is arranged in second passage 104.
A control compartment 123 is provided inside the housing 100. This control compartment comprises a spring 106, a piston member 105 and a hydraulic pressure chamber 107. The first and second tube 102 and 104 are both fixed to and immovable with respect to the piston member 105. The spring 106 pre-biases the piston member 105 in upward direction. The hydraulic pressure chamber 107 exerts a downward force onto the piston member 105 when it is filled with a hydraulic fluid - indicated by arrow 124 - under a pressure sufficient to overcome the force of the pre-biased spring 106. In order to prevent leakage of hydraulic medium from the pressure chamber to the spring 106, a seal 114 is mounted to the piston member 105 for sealing engagement with the inner wall of the control compartment 123.
The tubes 102 and 104 are each provided with one or more radial apertures 108 and 109, respectively. The lower ends 110 and 111 of both tubes are closed. The upper ends 125 and 126 of both tubes (see figure 3b) are both open.
A pressure equalizing line 119 is provided in the lower part of the housing. This pressure equalizing line 119 debouches with its lower end into the internal 127 of the production tubing. In order to prevent a build up of pressure in the compartment containing the spring upon compression of the spring 106, this pressure equalizing line might debouch in the compartment containing the spring 106. Due to the lower end 110 of the first tube being closed, the first tube might experience large upward forces in case the pressure in the internal 127 of the production tubing is high. Consequently large hydraulic pressure in the pressure chamber 107 might be required to push the tubes downward. The hydraulic power required to push the piston member 105 and tubes 102, 104 downward might be reduced by providing the pressure equalizing line 119 with an equalizing port 121 debouching into the passage 101 at a location which lies below the radial passage 108 when the first tube is in its blocking position. Above and below the equalizing port 121, a circumferential seal 117 and circumferential seal 118 are provided to define a pressure equalizing space around the first tube 102. When the first tube 102 is pushed downwards, the equalizing line 119 provides fluid communication between the internal 127 of the production tubing and the internal of the first tube 102 as soon as the radial aperture 108 passes the upper seal 117. As a result, the upward pressure acting on the closed lower end 110 of the first tube is compensated for.
Outer seals 112 and 113 are provided on the outside of the housing 100. These seals extend all around the housing 100 and seal against the inner wall of the production tubing 14 in order to prevent bypass of hydrocarbon fluid (gas and/or liquid) around the insert assembly 17. In order to prevent similar bypass around the tubes 102 and 104 through the passages 101 and 103, respectively, several inner seals 115, 116, 117 and 118 are provided.
The first passage 101 communicates at both ends with the inner space 127, 129 of the production tubing 14. The second passage 103 is at both ends sealingly connected to a further tubing 84, which extends through the production tubing. The diameter of the second tube 104 will consequently be smaller than the diameter of the additional tubing 84. It is noted that depending on circumstances, the second tube 104 can also be absent or might have an open bottom end. Absence of the second tube 104 or an open bottom end of tube 104, allows the additional tubing to be used easier as guide channel for an instrument, sensor, tool or other device to be brought deep into the wellbore. Note however, that, although less easy due to the radial passage 109, this guide function can also be provided in presence of the second tube 104 having closed lower end 111.
The safety valve assembly 17 functions as follows. Figure 3a shows the blocked position, in which there is nu flow communication between the upper end and the lower end of the insert assembly. In this blocked condition, the spring exerts a pre-tension force directed in upward direction in order to keep the piston member and tubes in blocked position. Starting from this blocked position, hydraulic fluid is supplied (arrow 124) to the hydraulic pressure chamber 107. This causes the piston member 105 and tubes 102 and 104 to move downward to the flow position as shown in figure 3b. In this flow position, hydrocarbon fluid (gas and/or liquid) is allowed to flow through radial apertures 108 into the first tube 102, flows upward through the first tube 102 and leaves the first tube 102 to enter the production tubing 14 again at a location above the insert assembly 100. Similarly, a treatment fluid or other fluid can be passed through the insert assembly when the piston member 105 and tubes 102 and 104 are in flow position. Treatment fluid supplied from - for example - the surface arrives through additional tubing 84 at the upper end of the insert assembly 100. This fluid enters the second tube 104 through its open upper end 126, passes through the second tube 104 downwards and leaves the second tube 104 through the radial aperture(s) 109 to continue downwards through the part of the additional tubing 84 extending below the insert assembly 100. In order to keep the insert assembly 100 in its flow position, the high pressure in the pressure chamber 107 is to be maintained. In case the safety valve assembly 17 is to be closed, for emergency reasons or other reasons, the hydraulic pressure in the pressure chamber is released (lowered) and the spring 106 will push the piston member 105 and tubes 102, 104 to the blocked position of figure 3a. This functions as a fail safe mechanism.
As will be clear, a production wellbore can according to the invention be equipped with a surface configuration of the safety valve assembly according to the invention - for example the one as illustrated in figure 2 - as well as a sub-surface configuration of the valve assembly according to the invention - for example the one as illustrated in figure 3. Furthermore, the configuration of the (above surface) valve assembly as shown and elucidated with reference to figure 2 can also be applied as sub surface valve assembly instead of the safety valve assembly 17 as shown in figure 3. Similarly, it will be clear that the configuration of the (sub surface) valve assembly as shown and elucidated with reference to figure 3 can also be applied as (above) surface valve assembly instead of the valve assembly as shown in figure 2.
The description above describes exemplary embodiments of the present invention for the purpose of illustration and explanation. It will be apparent, however, to the skilled person that many modifications and changes to the exemplary embodiments set forth above are possible without departing from the scope of the invention. It is noted that the features described above may be combined, each individually or in any combination of features, with one or more of the features of the claims.

Claims

Valve assembly for a hydrocarbon wellbore, said wellbore comprising a production tubing extending from a wellhead which is provided with a Christmas tree to a downhole end of the wellbore, the valve assembly comprising:
an insert assembly adapted for insertion into the production tubing or the Christmas tree, the insert assembly having a lower end for facing towards the downhole end of the wellbore, wherein the insert assembly is provided with:
at least two passages, such as two, three, four or five passages;

a lower and upper passage port for each said passage;

a valve member in at least one of said passages; and

an operating mechanism for operating the valve member;

wherein the passages each extend through the insert assembly from the accompanying lower passage port to the accompanying upper passage port;

the lower passage port being arranged at the lower end of the insert assembly for allowing fluid flow between the accompanying passage and an accompanying lower flow channel extending downwardly from the insert assembly; and

the upper passage port being arranged at a distance above the lower end of the insert assembly for allowing fluid flow between the accompanying passage and an accompanying upper flow channel;

wherein the valve member is operable, by the operating mechanism, between a flow position, allowing fluid flow between the lower passage port and upper passage port and a blocking position preventing fluid flow between the lower and upper passage port.
Valve assembly according to claim 1, wherein the valve member comprises a tube, which extends in the accompanying passage and is axially movable, by the operating mechanism, with respect to the insert assembly between the flow position and the blocking position.
Valve assembly according to one of the preceding claims, wherein movement of the valve member to the flow position defines an opening direction, and movement of the valve member to the blocking position defines a closing direction, wherein the operating mechanism comprises:
a spring biasing the valve member in the closing direction;

a piston member fixed to the valve member;

a pressure chamber adjacent the side of the piston member facing in the closing direction;

wherein the pressure chamber is provided with an inlet/outlet valve assembly for feeding a hydraulic fluid into the pressure chamber to move the valve member in the opening direction respectively to discharge said hydraulic fluid from the pressure chamber for moving the valve member in the closing direction by action of the spring.
Valve assembly according to one of the preceding claims,
wherein at least two said passages are each provided with an accompanying said valve member and the operating mechanism is arranged and configured as a common mechanism for operating these valve members together with one common mechanism; and/or
wherein at least two said passages are each provided with an accompanying said valve member and these passages and accompanying valve members each have a separate operating mechanism allowing operation of these valves independently from each other, each separate operating mechanism optionally comprising a separate said spring, a separate said piston member and a separate said pressure chamber; and/or
wherein the valve assembly comprises at least three said passages and accompanying said valve members, wherein at least two of these passages and accompanying valve members each comprise a separate operating mechanism, each separate operating mechanism optionally comprising a separate said spring, a separate said piston member and a separate said pressure chamber.
Valve assembly according to one of the preceding 2-4, wherein a flapper valve is provided in a section of a said passage, which flapper valve is spring biased into a closed position blocking the passage; and wherein this passage, accompanying tube and flapper valve are arranged for opening the flapper valve upon passing the tube through the section of this passage and closing the flapper valve upon withdrawing the tube from the section of this passage.
Valve assembly according to one of the preceding claims 2-5, wherein a said passage having an accompanying said tube is provided with at least one inner seal, which is attached to the inside of the passage, extends circumferentially around the tube and seals circumferentially against the tube to prevent fluid from bypassing the tube between the outside of the tube and the inside of the passage.
Valve assembly according to one of the preceding claims 2-6, wherein a said tube comprises a radial aperture through the tube wall, which radial aperture is part of the accompanying lower or upper passage port;
wherein, when the tube is in its blocking position, the radial aperture is, at the outside of the tube, closed by the inner wall of the accompanying passage for closing the accompanying lower or upper passage port, respectively; and
wherein, when the tube is in its flow position, the radial aperture is, at the outside of the tube, in flow communication with the accompanying lower or upper flow channel, respectively.
Valve assembly according to claim 7,
wherein the tube has a closed lower end, and the radial aperture forms the lower passage port, which lower passage port projects downwardly from the insert assembly when the tube is in its flow position, and optionally:
wherein, viewed in the blocking position of the tube, a first said inner seal lies above the radial aperture whilst a second said inner seal lies below the radial aperture; and/or

wherein the insert assembly is provided with a pressure equalizing line debouching on the one hand into the lower flow channel of the accompanying passage and on the other hand into the passage at a location, which lies, when the tube is in its blocking position, below the radial aperture; and/or

wherein the insert assembly comprises a radial bore which forms, together with the radial aperture, the upper passage port, wherein the radial bore has one end debouching into the passage and the other end facing away from the passage for connection to the upper flow channel; and
wherein a said radial aperture and the radial bore are aligned radially when the tube is in its flow position.
Valve assembly of any of claims 6-8, wherein a third said inner seal is provided above the radial bore and a fourth said inner seal is provided below the radial bore; and/or
wherein the tube or passage is closed in an area above the radial aperture and the radial bore.
Valve assembly according to one of the preceding claims, wherein the insert assembly is provided with an outer seal, which is attached to the outside of the insert assembly, extends circumferentially around the insert assembly and seals, when the insert assembly is inserted into the production tubing, circumferentially against the production tubing to prevent fluid from bypassing the insert assembly between the outside of the insert assembly and the inside of the production tubing.
Valve assembly according to one of the preceding claims,
wherein the insert assembly is provided with a circumferential hanger rib for support onto a hanger seat, such as a landing nipple, extending around the insert assembly; and
wherein the hanger rib optionally comprises:
a continuous rib extending continuously all around the insert assembly; and/or

a multiplicity of rib segments, like locking dogs, arranged at intervals circumferentially around the insert assembly.
Valve assembly according to one of the preceding claims, wherein the insert assembly comprises a lower insert part and an upper insert part;
wherein the lower insert part comprises the passage and is adapted for said plugging insertion into the production tubing; and
wherein the operating mechanism is provided in the upper insert part and the tube is suspended from the upper insert part to project into the passage of the lower insert part.
Retrofit assembly for a Christmas tree of a hydrocarbon wellbore, wherein the retrofit assembly comprises:
a spool to be mounted on top of the Christmas tree of the hydrocarbon wellbore with the longitudinal axis of the spool axially aligned with the vertical axis of the Christmas tree; and

a valve assembly according to one of claims 1-11, wherein the upper passage port of a first said passage is flow connected to, and preferably horizontally aligned with, a flow wing port of the tree; and wherein the first passage and accompanying valve member define a surface safety valve for the production flow;

wherein the spool is internally provided with a circumferential seat surface facing upwardly and wherein the insert assembly is externally provided with a mating circumferential support surface facing downwardly.
Sub-surface use of a valve assembly according to one of claims 1-11 in a hydrocarbon wellbore, said wellbore comprising a production tubing which extends from a wellhead in the direction of a downhole end of the wellbore and which is internally provided with at least one landing nipple;
wherein the insert assembly is adapted to be inserted into the production tubing and is provided with external locking means adapted for engagement into one of said at least one landing nipple; and
wherein a first said passage and accompanying valve member define a production flow safety valve.
Method of retro-fitting a valve of a hydrocarbon wellbore comprising a production tubing or a Christmas tree, the method comprising the steps of:
removing a valve to be retrofitted from the hydrocarbon wellbore;

placing a valve assembly according to one of the claims 1-11 into the wellbore by inserting the insert assembly in plugging manner into the production tubing or the Christmas tree;

arranging a said passage provided with an accompanying valve member such that the lower port of the passage allows, when the accompanying valve member is in the flow position, flow communication between the passage and the internal of the production tube.
Method of claim 15, including the step of attaching an additional tubing to the lower end of the insert assembly such that the additional tubing is connected in sealing manner to a further passage, which additional tubing is arranged inside the production tubing and extends from the insert assembly in the direction of the downhole end of the wellbore.