WO2017193163A1

WO2017193163A1 - A valve assembly and a method of installation/operation

Info

Publication number: WO2017193163A1
Application number: PCT/AU2017/050422
Authority: WO
Inventors: Ewan McDonald; Robert T. Brooks
Original assignee: Pro-Test Pty Ltd; Pt Sagatrade Murni
Priority date: 2016-05-10
Filing date: 2017-05-10
Publication date: 2017-11-16
Also published as: AU2017261842A1

Abstract

A valve assembly comprises a housing for allowing passage of fluid therethrough from a first end of the housing to a second end of the housing, the housing comprising an internal bore for receiving a rotatable shaft, a valve member positioned in the housing for preventing flow of fluid in a direction from the second end to the first end in a closed configuration, a movable member positioned relative to the housing, the movable member being adapted for opening and closing a spill port a locking mechanism adapted for allowing releasable engagement of the housing with the movable member, the valve assembly being operable to spill a flow of fluid through the spill port when the valve member is in the closed configuration.

Description

A VALVE ASSEMBLY AND A METHOD OF INSTALLATION/OPERATION

TECHNICAL FIELD

[0001] The present invention relates to a valve assembly and a method of installing a valve particularly in a downhole production string.

BACKGROUND ART

[0002] Pumps and valves are used in the oil and gas industry for pumping fossil fuels from a sub-surface location. These pumps and valves are typically located in a downhole. As a result, maintenance and servicing of the pumps and valves is difficult and presents significant downtime that can result in lost production and increased expenses for workmen and materials. The valves and pumps in particular are subject to abrasion and significant wear and tear during operation. As a result, one or more parts of the valve or pump or the production string may require regular servicing and maintenance. Downtime, the cost of deferred production whilst awaiting hoist attendance, and the time required to pull, clean, and re-run the entire production string adds significantly to the overall running cost. Therefore, it is desirable to provide valves which can be serviced and replaced relatively easily without significant downtime.

[0003] Effective solids management of pumped fluids is another significant technical problem in the art. During a pumping operation, solid particles can become entrained in the pumped fluid. Whilst the entrained solids do not pose any significant technical issues during the pumping cycle, these solid particles can cause significant operational issues if allowed to flow back to the pump when the pump stops pumping fluid during shutdown. Solids entering the pump can also lead to equipment damage, hinder the ability to restart the pump and the resulting costly requirement to replace parts. Therefore, it is also desirable to provide a valve assembly that can prevent the entrained solids such as sand and debris from descending into the pump during the shutdown or other non-pumping periods.

[0004] US patent 4420043 describes a valve for an annulus defined between a tubular work string and a surrounding annular portion of an operative element disposed on a production string, such as a safety valve. The annulus valve comprises an annular valve body (such as an elastomeric mass) which is urged by resilient means into sealing engagement with the exterior of the tubular work string and is shift or out of sealing engagement by use of an annular piston which is responsive to control fluid pressure. [0005] It will be clearly understood that, if a prior art publication is referred to herein, this reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country.

SUMMARY OF INVENTION

[0006] In a first aspect, the invention provides a valve assembly comprising: a housing for allowing passage of fluid therethrough from a first end of the housing to a second end of the housing, the housing comprising an internal bore for receiving a rotatable shaft; a valve member positioned in the housing for preventing flow of fluid in a direction from the second end to the first end in a closed configuration; a movable member positioned relative to the housing, the movable member being adapted for opening and closing a spill port; a locking mechanism adapted for allowing releasable engagement of the housing with the movable member; and the valve assembly being operable to spill a flow of fluid through the spill port when the valve member is in the closed configuration.

[0007] In a second aspect, the invention provides a production apparatus for pumping fluid, the apparatus comprising: a rotatable rod string for driving a downhole pump assembly, a tubing string being provided for receiving the rotatable rod string such that an inner wall of the tubing string provides a flow path for pumped fluid; and the valve assembly, as described above, wherein the internal bore of the housing is adapted for receiving the rod string; and wherein the movable member is provided at or adjacent the inner wall of the tubing string for opening or closing the spill port provided along the tubing string such that the valve assembly prevents the flow of fluid back to a downhole pump assembly in a closed configuration by spilling the flow of fluid through the spill ports and into the annular space outside the tubing string. Any solids in the fluid will also be spilled.

[0008] In a third aspect, the invention provides a method of installing a valve in a downhole production string, the method comprising: providing a tubing string for receiving and enclosing a rotatable shaft such that an inner wall of the tubing string provides a flow path for pumped fluid; positioning a valve downstream relative to a downhole pump assembly, said valve being enclosed in a housing, the positioning step comprising: locking or fastening the housing to a releasable running tool provided along the rotatable shaft; positioning the locked housing and running tool adjacent to a movable member located along the inner wall of the tubing string by inserting the rotatable shaft into the tubing string; and unlocking the housing from the running tool and subsequently attaching or fastening the housing to the movable member.

[0009] In some embodiments, the locking mechanism is adapted to operate in two operating configurations. In a first locked configuration, the locking mechanism allows the housing to be attached or locked to an installation tool or a releasable running tool for assisting in the installation of the housing and the valve member at a desirable location in a downhole. In the first locked configuration, the housing is not attached to the movable member. In a second locked configuration, the valve housing may be uncoupled from the installation tool and fastened or attached to the movable member as a result of which any longitudinal movement or, in some embodiments, any movement, of the housing relative to the movable member is prevented.

[0010] The operation of the locking mechanism in the two operating configurations in combination with the valve member provides two main advantages. In the first locked configuration, the locking mechanism allows the housing to be installed in an easy and convenient manner by becoming coupled to an installation tool. The installation tool may be utilised for positioning the housing at a desirable downhole location in the tubing string. In the second locked configuration, the housing in attachment with the movable member, in at least some operating configurations, not only prevents flow of fluid back to the pump but also allows the fluid flowing back from the second end of the housing towards the first by spilling or draining the residual fluid through the spill ports. The fluid that is spilled or drained will typically be spilled or drained into the annular area outside the production string.

[0011] In an embodiment, the valve assembly comprises a valve seat for contacting the valve member and forming a seal thereby preventing the flow of fluid in the closed configuration. Preferably, the valve seat is provided along an inner wall of the housing.

[0012] In an embodiment, the housing is substantially cylindrical and the housing comprises a first housing portion comprising the valve seat and a second housing portion for enclosing the valve member.

[0013] Preferably, the second housing portion for enclosing the valve member comprises a cylindrical cage including one or more apertures for allowing fluid to flow into and out of the first housing portion. Furthermore, the second housing comprises the second end of the housing wherein one or more circumferentially arranged openings are provided at the second end for allowing flow into and out of the second housing portion.

[0014] In an embodiment, the valve member is biased, preferably by a spring, for substantially preventing flow from the second end to the first end of the housing in the closed position.

[0015] In an embodiment, the housing is adapted for being connected to the releasable running tool in the first locked position, and disconnected from the running tool in the second locked position; the running tool being provided along a length of the rotatable shaft for positioning the housing in a downhole region of a bore or well. Preferably, the releasable running tool is fastened to a portion of the rotatable shaft or the rod string in the first locked configuration.

[0016] In an embodiment, the rotatable shaft comprises a rod string preferably a sucker rod string. Preferably, a polished rod may also be provided for supporting the sucker rod string during use. In a further preferred embodiment, the releasable tool may be mounted at an intermediate location relative to the polished rod and the sucker rod string during use in the first locked configuration.

[0017] In an embodiment, the locking mechanism comprises a locking member, the locking member being adapted for locking the housing with the releasable running tool in the first locking configuration and being adapted for locking the housing with the movable sleeve in the second locked configuration.

[0018] Preferably, the locking mechanism prevents the relative movement between the releasable tool and the housing in the first locking configuration. Similarly, in the second locking configuration, the locking mechanism prevents the relative movement between the housing and the movable member. [0019] In some embodiments, the locking member comprises a first locking portion adapted to be received into a corresponding locking groove provided on the releasable tool in the first locking position; and a second locking portion adapted for being received into a corresponding locking groove provided on the movable sleeve in the second locking position.

[0020] Preferably, the locking member comprises: a first engaging surface for engaging with a corresponding engaging surface on the running tool in the first locked configuration; and a second engaging surface for engaging with a corresponding engaging surface of the movable sleeve in the second locked configuration.

[0021] The first engaging surface may be provided as a first chamfered edge on the locking member, the first chamfered edge being adapted to be received into a corresponding notch provided on the running tool. The second engaging surface may be provided as a second chamfered edge on the locking member, the second chamfered edge being adapted to be received into a corresponding notch provided on the movable sleeve. Preferably, the angle of inclination of the first engaging surface or the first chamfered edge relative to a longitudinal axis of the rotational shaft is lesser than the angle of inclination of the second engaging surface or second chamfered edge.

[0022] In an embodiment, the valve assembly further comprises retaining means for retaining the locking member in the first locked position and/or for retaining the locking member in the second locked position. Preferably, the retaining means comprises a biased retaining member adapted to be received into one or more detents provided on the locking member. Furthermore, in the first locked position, the biased retaining member is adapted to be retained in a first detent provided on the locking member. In the second locked position, the retaining member is adapted to be retained in a second detent provided on the locking member.

[0023] In another embodiment, the locking member comprises a snap ring. The snap ring may be mounted to an outer surface of the valve housing. The snap ring may be mounted within a groove on the outer surface of the valve housing. The snap ring may enter into a groove on an inner surface of the movable member or sleeve. As the valve housing is being inserted into the tubing string, the snap ring comes into contact with or engages one or more walls of the groove on the inner surface of the movable member or sleeve, which effectively locks the valve housing to the movable member groove. The snap ring may comprise a C-shaped ring. The snap ring may extend from between 60% to 95% around the circumference of the valve housing.

[0024] In this embodiment, the valve housing may be connected to the installation tool or running tool by an anchor mandrel. The anchor mandrel may connect one section of the installation tool or running tool to another section of the installation tool or running tool. The anchor mandrel may comprise an intermediate body having a connector for connecting to a first section of the installation tool or running tool and a connector for connecting to a second section of the installation tool or running tool. The connectors may comprise threaded connectors. An outer surface of the body of the anchor mandrel may comprise one or more projections, such as one or more radial projections. The anchor mandrel may have a collet snap latch connected thereto. The collet snap latch may be slidably connected to the anchor mandrel. The collet snap latch may comprise an outer connection region located on one or more flexible arms, and the anchor mandrel may comprise a recess or tapered region that underlies the one or more flexible arms when the collet snap latch is connected to the anchor mandrel. During run in, the outer connection region of the collet snap latch is connected to the valve housing and the anchor mandrel is connected to the installation tool or running tool. As the valve housing is moved downward through the string, the snap ring engages with the movable member or sleeve such that the snap ring locks the valve housing against relative movement to the movable member or sleeve. Once the snap ring has been landed in the movable member or sleeve, the operator will pick up and take overpull to confirm that the snap ring is properly located in the groove on the movable member. The installation tool or running tool will then be set down slightly and the outer connection region of the collet snap latch disconnected from the valve housing. The running tool may then be further lowered to space out the pump rotor. To retrieve the valve housing, the installation tool or running tool is simply picked up and the collet snap latch engages with the valve housing. Further overpull will ensure that the moveable member or sleeve is in the fully closed or neutral position and will release the snap ring from the movable member, thereby allowing the valve housing to be removed from the tubing string.

[0025] In one embodiment, the outer connection region of the snap latch comprises a threaded region formed on the one or more flexible arms. The one or more flexible arms may comprise a plurality of flexible arms circumferentially equispaced from adjacent arms. In order to disconnect the valve from the collet snap latch when the valve is being run in, once the snap ring has engaged with the movable member or sleeve, the installation tool or running tool may be rotated. This will cause the collet snap latch to rotate relative to the valve (the valve will be typically be prevented from rotating relative to the tubing string once it has been properly installed in the tubing string), which causes the collet snap latch to be unscrewed from the valve housing. Once the collet snap latch has been fully unscrewed, the running tool can be further lowered to space out and properly set the pump rotor into the pump stator. [0026] In another embodiment, one or more shear pins are used to attach the valve or the valve housing to the running tool or the installation tool or to a mandrel in the rod string. A snap ring may be mounted to the valve housing. When the snap ring enters into a groove on an inner surface of the movable member or sleeve, the valve housing is prevented from further downward longitudinal movement. Further lowering of the rod string shears the pins and allows the rod string to continue to move downwardly to thereby properly install the pump rotor in the pump stator. In this embodiment, the running tool or installation tool or rod string may have an engagement region that engages with the valve or valve housing when the running tool or installation tool or rod string is being raised. This will eventually overcome the strength of the snap ring, which causes the snap ring to compress and withdraw from the groove in the movable member. The valve may then be removed from the outer tubing by continued lifting of the running tool or the installation tool or the rod string. When removing the valve from the tubing string, the installation tool or running tool is raised by the operator. This causes the upper ends of the flexible arms of the snap latch to enter into a lower end of the valve housing. The lower end of the valve housing has a complementary thread formed thereon. As the arms of the snap latch are flexible, they can bend inwardly into the recess or the tapered space of the anchor mandrel as the threaded regions of the snap latch move into the threaded region of the valve housing, thereby enabling the snap latch to engage with the valve housing. Further overpull will release the snap ring and enable the valve housing to be removed from the tubing string.

[0027] In one embodiment, rotation of the installation tool or running tool causes the anchor mandrel to rotate. The one or more projections extending from the surface of the anchor mandrel may then engage with the arms of the collet snap latch, thereby causing rotation of the collet snap latch and thus facilitating unscrewing of the collet snap latch from the valve housing. The one or more projections extending from the surface of the anchor mandrel may comprise one or more radial projections that extend along a longitudinal wall of the anchor mandrel, with the one or more projections being located in spaces between adjacent arms of the collet snap latch.

[0028] In one embodiment, the anchor mandrel includes a surface that engages with a complementary surface on the valve housing to thereby enable the valve housing to be pulled out of the tubing string. In one embodiment, the anchor mandrel includes a tapered surface that engages with a complementary tapered surface on the valve housing to thereby enable the valve housing to be pulled out of the tubing string.

[0029] In another embodiment, the collet snap latch is simply connected to the running tool or to the installation tool or the rod string, without requiring an anchor mandrel. [0030] In some embodiments, the running tool or installation tool comprises the rod string or comprises part of the rod string.

[0031] In an embodiment, the movable member is biased, preferably by a spring, for positioning the movable member to close the spill port to a neutral position. Preferably, the movable member comprises a sleeve adapted for being movably mounted along an internal wall of an outer tubing string for opening and closing the spill port located on the outer tube string. Furthermore, the movable member is preferably positioned outside the valve housing for allowing releasable engagement with the housing. As a result, the housing is adapted to be positioned away from the movable member in the first locked configuration.

[0032] In one embodiment, a further sleeve may be installed near or adjacent to the biasing means or spring that is used to position the movable member to close the spill port to a neutral position. The further sleeve may keep the produced solids from accumulating in and around the biasing means or spring which may otherwise hinder the biasing means or spring from properly actuating. The further sleeve may be located adjacent to a lower end of the biasing means or spring.

[0033] In an embodiment, the valve housing comprises a rotation prevention mechanism or device for preventing rotation of the housing relative to the rotatable shaft. Preferably, the rotation prevention mechanism or device is located at or adjacent to the second end of the housing. The rotation prevention mechanism or device may comprise a mechanism that is adapted to lock the housing onto an inner wall locking portion of the outer tubing string and prevents the simultaneous rotation of the valve housing whilst the rod string undergoes rotation during a pumping cycle. In another embodiment, the rotation prevention mechanism or device may comprise a projection or an enlargement that contacts an inner wall of the outer tubing string such that friction between the projection or enlargement and the inner wall of the outer tubing string prevents rotation of the housing relative to the outer tubing string. The rotation prevention mechanism or device may include a portion that can move laterally outwardly into engagement or contact with the inner wall of the outer tubing string. This portion may also be able to move laterally inwardly to move out of contact with the inner wall of the outer tubing string. In another embodiment, the rotation prevention mechanism or device comprises a drag block that is mounted by one or more biasing means (such as one or more springs or one or more elastomeric blocks or bodies) to an outer wall of the housing, the drag block extending into and between flutes/grooves formed on an inner wall of the outer tubing string. In this embodiment, the drag block can move radially inwardly when passing through restrictions to thereby allow passage therethrough whilst moving radially outwardly when the drag block is in the vicinity of the flutes to thereby engage with the flutes or lock into the flutes to thereby prevent rotation of the housing. The rotation prevention mechanism or device prevents rotation of the housing relative to the outer tubing string when the housing is locked to the movable member when the inner rotatable rod string is rotating during pumping operations.

[0034] Any of the features described herein can be combined in any combination with any one or more of the other features described herein within the scope of the invention.

[0035] The reference to any prior art in this specification is not, and should not be taken as an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge.

BRIEF DESCRIPTION OF DRAWINGS

[0036] Various embodiments of the invention will be described with reference to the following drawings, in which:

Figure 1 is a sectional view of a downhole production string apparatus in accordance with an embodiment of the present invention.

Figure 2 is a sectional view of an isolated sectional view of a tubing string that forms a part of the downhole production string apparatus valve housing.

Figure 3 is an isolated side view of a valve assembly and rotatable rod string that forms a part of the downhole production string apparatus.

Figures 4 to 6 illustrate sectional views of downhole production string apparatus in an initial installation position.

Figure 7A is a first isolated perspective view of a housing that forms a part of the downhole production string apparatus.

Figure 7B is a transverse end view of the housing in engagement with the running tool, viewed from the lower end.

Figure 7C is an enlarged perspective view of a second end of the housing that forms a part of the downhole production string apparatus.

Figure 8 is a perspective view of a valve member in combination with the running tool and rod string. Figure 9 is an enlarged perspective view of a first end of the housing that forms a part of the downhole production string apparatus.

Figured 10 is an enlarged sectional view of the detent locking mechanism that forms a part of the downhole production string apparatus.

Figures 11A is a sectional view of a downhole production string apparatus in an initial installation position (the first locking position) in accordance with an embodiment of the present invention.

Figure 1 IB is an enlarged view of the locking mechanism illustrated in Figure 11A.

Figure 12A is a sectional view of a downhole production string apparatus in an operational installation position (the second locking position) in accordance with an embodiment of the present invention. In the embodiment shown in figure 12A, the sucker rod string is spaced out for engagement/operation in a downhole pump.

Figure 12B is an enlarged view of the locking mechanism illustrated in Figure 12A.

Figure 13 A is a sectional view of a downhole production string apparatus in which the valve assembly is shown in an open configuration with the spill ports closed.

Figure 13B is an enlarged view of the valve assembly shown in Figure 13A.

Figure 14A is a sectional view of a downhole production string apparatus in which the valve assembly is shown in a closed configuration and with the spill ports open.

Figure 14B is an enlarged view of the valve assembly shown in Figure 14A.

Figure 15 is a perspective view of an anchor mandrel suitable for use in one embodiment of the present invention.

Figure 16 is a perspective view of a collet snap latch for use with the anchor mandrel shown in Figure 15;

Figure 17 is a front sectional view of the anchor mandrel of figure 15 and collet snap latch of figure 16 being connected together and joined to a lower end of the valve housing and being in an orientation adopted during running in.

Figure 18 is a side sectional view of the apparatus shown in figure 17 and being in an orientation adopted during retrieval of the valve. Figure 19 is a perspective view of the collet snap latch of figure 16 being fitted to the outside of the anchor mandrel of figure 15.

Figure 20 is a perspective view of the anchor mandrel and collet snap latch being connected to a lower end of the valve housing.

Figure 21 is a perspective view of the anchor mandrel and collet snap latch being connected to the valve housing, with the rotatable rod string also being shown.

Figure 22 is a perspective view that is similar to that shown in figure 21, but with the anchor mandrel and collet snap latch being disconnected from the valve housing and lowered relative to the valve housing.

Figure 23 is a side sectional view of an embodiment of the present invention showing the valve being locked to the movable sleeve by the snap ring, with the anchor mandrel and the collet snap latch still being connected to the valve housing.

Figure 24 is a front sectional view of another embodiment of the present invention in which the valve housing can be locked to the movable sleeve by use of a snap ring and the valve housing is shear pinned to the rotatable rod string, with figure 24 showing the snap ring at entry to the movable sleeve.

Figure 25 is a top sectional view of the embodiment shown in figure 24.

Figure 26 is a front sectional view of the embodiment shown in figure 24, but with the inner string snap ring engaged in the movable sleeve.

Figure 27 is a top sectional view of the embodiment shown in figure 26.

Figure 28 is a sectional view of another embodiment of the present invention, the valve being installed and being connected to the running tool by shear pins.

DESCRIPTION OF EMBODIMENTS

[0037] Figures 1 to 14 illustrate an exemplary downhole production string apparatus 1000 in accordance with an embodiment of the present invention. The production string 1000 comprises a valve assembly 200 positioned in a tubing string 300 for controlling the flow of fluid being pumped from a sub-surface pump (such as a progressive cavity pump-PCP-not shown) located at a subsurface location in the downhole. The pump is driven by a rotatable shaft provided in the form of a rod string 400 that typically undergoes a rotational motion for driving the sub-surface pump. Whilst, a well-head and surface drive head have not been illustrated in the drawings, embodiments of the downhole production string 1000 may be utilised in conjunction with wellheads and surface driveheads known in the art. Connections between the various tubing components forming the outer tubing 300 may be of any type including but not limited to the known types of couplings for tubing strings. A rod string 400 is positioned within the outer tubing 300 and extends downwardly into the downhole. The rod string 400 may be of any type, such as but not limited to a continuous sucker rod or a standard jointed sucker rod. The rod string 400 comprises an upper end which forms a polished rod 410 that effectively is connected to the rod string 400 and to the surface drivehead. During a pumping operation, the surface drivehead rotates the rod string 400 to transfer rotational power to the polished rod 410. During use, in a pumping operation, the rod string 400 transfers torque to a downhole pump (at a sub-surface location) that is connected via a lower end 420 of the rod string 400 by way of a rotor engagement end 425. In at least some embodiments, a casing surrounds the outer tubing string 300 and an annulus is formed in between the tubing string 300 and the surrounding casing not shown in Figure 1.

[0038] As shown particularly in Figures 1 and 3, the valve assembly 200 is provided downstream/above relative to the sub- surface pump for controlling the flow of fluid pumped through the tubing string 300. The valve assembly 200 comprises a valve housing 210 having a first end portion 212 and a second end portion 214. The valve housing 210 encloses a biased valve body 220 that allows passage of pumped fluid from the first end 212 of the housing 210 to the second end 214 of the housing 210 in an open flow configuration. In a closed configuration, the valve body 220 prevents the flow (backflow) of residual fluid in a direction from the second end portion 214 to the first end portion 212 thereby preventing the flow of fluid back to the pump when the pump is not in operation. The valve body 220 is biased by a coil spring mechanism 225 and forms a seal with a valve seat 240 for preventing flow (backflow) of fluid from the second end 214 to the first end 212 of the valve housing 210 in the closed configuration. The top end of mandrel 605 has lugs 660 that, in the initial running position, hold the valve body offset during run in to the hole (see figure 9).

[0039] In one embodiment, the valve body 220 comprises a poppet having one or more O-rings or a centralizer ring and face seal to assist in forming a seal.

[0040] Referring to Figures 1 and 2, the outer tubing string 300 is provided with spill ports 320 and 340 for draining the residual fluid into the annulus formed between the tubing string 300 and the surrounding casing when the valve body 220 is in the closed position (although only 2 spill ports are shown in figures 1 and 2, it will be appreciated that more than 2 spill ports may be provided. Indeed, the apparatus shown in figures 1 and 2 may have 4 spill ports, or 8 spill ports, or even more spill ports. The valve assembly 200 provides a number of significant technical advantages in comparison with the prior art. These advantages will become apparent in the foregoing sections which focus on the initial installation and subsequent operation of the valve assembly 200 in the downhole production string 1000.

[0041] Turning to Figure 2 in particular, the outer tubing 300 (which may also be referred to as tubing string 300) is illustrated without the valve assembly 200 and the rod string 400 for ease of understanding and illustrative purposes only. The tubing string 300 is provided with a movable member in the form of a biased sleeve 350 that is located along an inner wall of the tubing string 300 and is positioned for opening and closing the spill ports 320 and 340 provided on the tubing string 300. The sleeve 350 is biased by way of a wave spring mechanism 365. The spring mechanism 365 maintains the sleeve 350 in a neutral position such that the spill ports 320 and 340 remain open when the there is no upwardly directed flow of pumped fluid through the tubing string 300 (i.e. when the sub-surface pump is not in operation). It is noted that during pumping, the pressure inside the tubing is higher than outside and when the pump stops, differential pressure forces sleeve 350 to open.

[0042] The sleeve 350 may be provided with two or more O-rings extending around an outer surface thereof, with at least one O-ring being located above the spill ports and at least one O-ring being located below the spill ports when the sleeve is in position to close the spill ports. Alternatively, bonded seals, in which an elastomer is bonded to a steel ring, may be mounted to the sleeve 350, again, to ensure that a seal is formed above the spill ports and below the spill ports when the sleeve is in a position to close the spill ports.

[0043] The sleeve 350 is advantageously adapted for being attached to the valve housing 210 by way of a locking mechanism 500 provided in the valve assembly 200. The locking mechanism 500 also allows the valve housing 210 to be attached to a releasable running tool 600 during initial installation.

[0044] During a typical installation, the valve assembly 200 is connected or mounted on the rod string 400 by using the releasable running tool 600. During installation, the cage shaped valve housing 210 is positioned along the rod string 400 in order to position the housing 210 at the movable member when the pump rotor is at a pre-determined height from landing in the pump stator. The locking mechanism 500 comprises a locking member 520 that is adapted to initially engage with the running tool 600 in an initial installation position in a first locked configuration. The mounted valve housing 210 (with the enclosed valve body 220) is subsequently run into tubing string 300 by using the running tool 600. In order to position and maintain the valve housing 210 at the desired operating location in the downhole, the locking mechanism 500 also allows the valve housing 210 to become uncoupled from the running tool 600 and the rod string 400 and simultaneously get locked onto the biased movable sleeve 350 in the second locked configuration before the rod string 400 is coupled with the sub-surface pump. Figure 4 shows landing of the valve assembly 200 in tubing string 300 for locking.

[0045] Turning to Figures 4 to 6, 10 and 11, the locking mechanism 500 is clearly illustrated in attachment with the running tool 600 in the first locked configuration (also referred to as an initial installation configuration). The locking mechanism 500 comprises a tool latching or tool engaging portion 530 that is provided on the locking member 520. In the initial installation configuration, the tool latching portion 530 engages with a tool notch 610 provided on the running tool 600. A retaining mechanism 650 is also provided for applying a spring loaded bias and retaining the tool latching portion 530 of the locking member 520 in the latching notch 610 provided on the running tool 600. The spring loaded bias for the retaining mechanism 650 is provided by a substantially spherical retaining member 620 that is shaped for being received into a first detent 532 provided on the locking member 520. In the down engagement of locking member 520, the landing face/region 272 of valve seat 240 shoulders out on rod string 400 (see figures 2 and 5). In figure 10, the approximate centre line of releasable running tool 600 is shown by line 800.

[0046] Turning to Figures 1, 9 to 10 and 12, the locking mechanism 500 is illustrated in attachment with the movable sleeve 350 in a second locked configuration. A sleeve engaging portion 540 is provided on the locking member 520. In the second locked configuration, the sleeve engaging portion 540 engages with a sleeve notch 354 and locks the valve housing 210 to the movable sleeve 350. The retaining mechanism 650 applies a spring loaded bias for retaining the sleeve engaging portion 540 in the sleeve notch 354 provided on the movable sleeve 350. The spring loaded bias for the retaining mechanism 650 is provided by the spring-loaded spherical retaining member 620 that is shaped for being received into a second detent 534 that is located adjacent to the first detent 532 provided on the locking member 520.

[0047] Turning to Figures 9 and 10 in particular a plurality of the retaining assemblies or mechanisms 650 are provided in a circumferential arrangement for retaining the locking member

520 in the first detent 534 or the second detent 532 in first locked position or the second locked position. The retaining mechanism 650 comprises a spring assembly 657 for providing a spring loaded bias to the retaining member 620. The spring assembly 657 comprises a coiled spring 658 mounted on a spring mount 659 that provides the spring loaded bias to the retaining member 620. The retaining member 620 is connected to a free end of the coiled spring 658 by way of connecting means 622.

[0048] Turning to Figures 9, 10 and 12B in particular, it is evident that the locking member 520 comprises a first chamfered edge 545 that is provided on the tool engaging portion 530 of the locking member 520. The first chamfered edge 545 abuts a corresponding angled engaging surface in the latching notch 610 when the locking member 520 is in attachment with the running tool 600 in the initial installation position or the first locked configuration. The locking member 520 also comprises a second chamfered edge 535 that is provided on the sleeve engaging portion 540 of the locking member 530. The second chamfered edge 535 abuts a corresponding angled engaging surface in the sleeve notch 354 when the locking member 520 is in attachment with the movable sleeve 350. Advantageously, the angle of inclination (relative to the longitudinal axis of the rod string or tubing string) of the second chamfered edge 535 is lesser than the angle of inclination of the first chamfered edge 545. As a result, the combination of the chamfered edges 535 and 545 provides an angled profile for the locking member 520 which is particularly evident in Figures 9 and 12B. During installation, the angled profile formed by the chamfered edges 535 and 545 (which involves a difference in angular inclination, as discussed above) in combination with the downwardly directed weight of the rod string 400, pushes the tool engaging portion 530 of the locking member 520 out of the latching notch 610 because the sleeve engaging portion 540, particularly the second chamfered edge 535 (with a lesser angle of inclination), is pushed into the sleeve notch 354. As a result, the valve housing 210 becomes locked onto the movable sleeve 350 and relative movement between the valve housing 210 and the movable sleeve 350 is prevented.

[0049] It is important to appreciate that the angled profile, formed as a result of the chamfered edges 535 and 545, assists in releasing the releasable running tool 600 from the valve housing 210. Specifically, in order to release the valve housing 210 from the running tool 600, the angle of the chamfered edge 545 is such that the weight applied upon the rod string 400 for pushing the running tool 600 forces the sleeve engaging portion 540 to move out of the sleeve notch 354. The movement in turn depresses the spring-loaded retaining member 620. As a result, the retaining member 620 disengages from the first detent 534 (provided on the locking member 520) and re-engages with the second detent 532 (provided on the locking member 520).

[0050] In order to re-engage the running tool 600 with the valve housing 210, the running tool

600 is picked up by pulling the rod string 400 in a generally upward direction until the running tool

600 catches on the valve housing 210. It is envisioned during the pulling of the rod string 400, the angled profile of the chamfered edge 535 on the sleeve engaging portion 540 is likely to push against the movable sleeve 350 forcing the locking member 520 to become locked to the running tool 600 once again (the first locked configuration).

[0051] Once the releasable tool 600 is released from the valve housing 210, the tool 600 is positioned downwardly relative to the valve housing 210 (see Figures 4, 11A and 12A) before the rod string 400 becomes attached to the sub-surface pump. As a result, the locking mechanism 500 allows the valve housing 210 and the enclosed valve body 220 to be easily installed and uninstalled by pulling out the rod string 400 and by using the running tool 600 without the need for pulling out the tubing string 300. The applicants have envisioned that the locking mechanism 500 is likely to provide significantly reduced down times during maintenance events that often require replacement of various movable parts in the housing or the valve.

[0052] Figures 7 to 9 provide a detailed illustration of the valve assembly 200. The cylindrical valve housing 210 substantially comprises a two part configuration. An upwardly located valve body housing portion 211 substantially encloses or houses the spring loaded valve body 220. The spring loaded valve body 220 is biased by a coil spring mechanism 225 that extends downwardly relative to the second end 214 of the valve housing 210 during use. The valve body housing portion 211 comprises apertures in the form of cage windows 230 that are provided to surround the biased valve body 220. The cage windows 230 extend in a generally downward direction from the second end 214. The second end 214 also comprises circumferentially arranged slots 217 to allow passage of fluid into and out of the valve housing 210. The slots 217 are particularly useful in allowing flow of fluid across the second end 214 of the valve housing and provide an additional flow path for fluids to compensate for the additional volume taken up by the second end 214 of the valve housing 210 which would otherwise result in a constricted flow path for fluids during use. The outer wall of the valve body housing portion 211 further comprises a rotation prevention mechanism 270. The rotation prevention mechanism 270 prevents the rotation of the valve housing 210 during rotation of the rod string 400 (that drives the sub-surface pump during a pumping operation). The rotation prevention mechanism 270 is adapted to rotationally lock the valve housing 210 onto an inner wall locking portion of the outer tubing string 300 and prevents the simultaneous rotation of the valve housing 210 whilst the rod string 400 undergoes rotation during a pumping cycle. A drag block 270 engages with the flutes 390 on the inner wall of the tubing string 300 (see figure 2) to prevent the valve housing rotating when the valve housing is positioned and locked to the movable sleeve 350. The drag block 270 is held proud of the valve housing second end at 214 by one or more springs, allowing the drag block to move radially inwardly as the spring compresses as the drag block moves through restrictions and also allowing the drag block 270 to move radially outwardly and into place and extend out to engage the fluted grooves 390 in the top sub of the outer string 300, when the valve housing it locked to the movable sleeve. The drag block 270 may have a sloping lower surface and a sloping upper surface to assist in moving radially inwardly as it meets restrictions during longitudinal movement of the housing during insertion or removal.

[0053] The valve housing 210 also comprises a downwardly located valve seat containing portion 213 that provides the valve seat 240 (best shown in figures 7A, 11A and 11B). As discussed earlier, in a closed configuration, the valve body 220 forms a seal with the valve seat 240 and prevents the flow of fluid in a direction from the second end 214 to the first end 212 of the valve housing 210. The valve seat 240 is provided in the form of a profiled annulus 242 (see Figsl 1A and 13 A) located along an inner wall of the valve seat containing portion 213 for forming the seal with the valve body 220 in the closed configuration. The valve seat containing portion 213 forms a substantially cylindrical section 223. The outer walls of the cylindrical section 223 include the locking mechanism 500 including the profiled locking member 520 that allows the valve housing 210 to be releasably attached to the running tool 600 or the movable sleeve 350 as explained in the earlier sections. The valve seat containing portion 213 also provides circumferentially arranged apertures 655 that each house the retaining assemblies or mechanisms 650.

[0054] Figures 8 and 9 in particular provide a perspective view of the valve body 220 and coil spring mechanism 225 and the releasable tool 600 without the valve housing 210 for ease of understanding and illustrative purposes only. The releasable tool 600 comprises a mandrel 605 with the circumferentially arranged notch 610 that is adapted to engage with the locking mechanism 500 during in the first locked configuration (the initial installation position) as detailed in the earlier sections. The mandrel 605 is provided on the rod string 400 and is used for positioning the valve assembly 200 in the downhole during the initial installation stage. Channels 615 extending substantially along the direction of the longitudinal axis of the mandrel 605 are provided on the outer wall of the mandrel 605. The channels 615 provide a flow path in between housing 210 and the mandrel 605 when the housing is locked to the running tool 600 in the first locked configuration. Therefore, the channels 615 allow the flow of fluid along the tubing string 300 while the valve assembly 200 is being run into position during the initial installation phase. Once the valve housing 210 is disengaged from the mandrel 605 and attached to the movable sleeve 350, the mandrel 605 is positioned downwardly and spaced away from the first end 212 of the valve housing 210 while the pump rotor mechanism is spaced out and engaged in the downhole pump..

[0055] The configuration of the valve assembly 300 not only allows easy installation (and uninstallation) of the production string apparatus 1000 but also provides an efficient and improved mechanism for dumping the residual fluid out of the spill ports 320 and 340 (and the other spill ports that are not shown in the drawings) when the pump is not in operation. Figures 13A and 13B in particular illustrate the flow of pumped fluid whilst the sub-surface pump is in operation and the valve assembly has been installed and is operating in an open position. The flow path of the pumped fluid is illustrated by the generally upwardly directed arrows. In the open operating configuration, the valve housing 210 is attached to the movable sleeve 350 by the locking mechanism 500 in the second locked configuration. Specifically, the sleeve engaging portion 540 of the locking member 520 is received into the sleeved notch 354 provided on the movable sleeve 350. As a result, the valve housing 210 is locked onto the movable sleeve 350. During the pumping operation, the pump is driven by the rotatable rod string 400 in a manner as described in previous sections. The rod string 400 rotates within the internal bore of the valve housing 210. Brass bearings on each end 212 and 214 of the valve housing 210 and a valve body 220 assist with allowing the rod string 400 to rotate freely around the valve body 220. The pressure developed in the pumped fluid pushes the pumped fluid from a sub-surface location along the tubing string 300 in a substantially upwardly direction towards the surface. The pump pressure of the pumped fluid lifts the valve body 220 off the valve seat 240, compressing spring 225. As indicated by the upwardly directed arrows, the pumped fluid passes through the housing 210. Specifically, pumped fluid flows into the first end 212 of the housing through opening 219 located at the first end of the housing 210. The fluid subsequently passes through the gap formed between the valve body 220 and the valve seat 240 and into the valve body enclosing housing portion 211. The pumped fluid subsequently flows in an upwardly direction of the valve body enclosing housing portion 211 through the cage windows 230 and the slots 217 located at an upper end or the second end 214 of the valve housing 210. The inner walls of the tubing string 300 surrounding the second end 214 of the valve housing 210 is also provided by flutes 390 (depicted clearly in Figure 2) to provide an additional flow path for passage of the pumped fluid to compensate for the constriction caused due to the location of the second end 214 of the housing 210.

[0056] Figures 14A and 14B illustrate the operation of the valve assembly in a closed operation configuration. Once again, the valve housing 210 is attached or locked onto to the movable sleeve 350 by the locking mechanism 500 (in the second locked configuration) in a manner as explained in previous sections. The valve assembly 300 typically starts operating in a closed operating configuration when the rod string 400 stops driving the sub-surface pump. As soon as the pump stops pumping fluid in an upward direction, any residual fluid in the tubing string 300 vs. the lower height of fluid in the annular space outside the tubing string starts draining in a downwardly direction towards the pump. The valve assembly 300 in combination with the movable sleeve 350 prevents the residual fluid and any entrapped debris in the residual fluid from draining back to the pump. In the absence of an upwardly directed force (applied by the pumped fluid during pumping) the valve body 220 drops down due to a combination of the coil spring 225 decompressing and the downwardly directed fluid flow and the valve body 220 forms a seal with the valve seat 240 and stops the flow of the residual fluid through the valve seat containing portion 213 of the valve housing 210. The hydrostatic pressure in the tubing string 300 (and the lack of hydrostatic pressure outside the tubing) also results in the downward movement of the spring loaded movable sleeve 350. The downward movement of the sleeve 350 results in the spill ports 320 and 340 becoming open and allowing the residual fluid to be drained out from the valve body housing portion 211 of the housing 210 into the annulus formed in between the tubing string 300 and the casing surrounding the tubing string 300. Specifically, any residual fluids and entrained debris flows out of the valve body housing portion 211 through the cage windows 230 and the spill ports 320 and 340. It is important to appreciate that in the closed position, the valve housing 210 remains locked to the movable sleeve 350 resulting in the downward movement of the valve housing 210 along-with the movable sleeve 350. This arrangement of the valve assembly 200 in conjunction with the moveable sleeve 350 allows the residual fluid to be drained or dumped out of the valve body containing portion 211 of the housing 210 into the annulus. As the hydrostatic fluid pressure in the tubing string 300 drops to equalise with the hydrostatic pressure in the annulus, the movable sleeve 350 eventually moves up and closes the spill ports 320 and 340 due to the bias applied by wave spring mechanism 365. Solids entrained in the residual fluid are also dumped into the annulus and any remaining solids are expected to settle within the valve housing 210 and not reach the sub-surface pump. If the movable sleeve 350 becomes stuck in the dumping position (with the spill ports 320 and 340 open) then the rod string may be pulled in an upwardly direction or the pump restarted, so that pump pressure will force the movable sleeve 350 to the closed position. The applicants expect that such a pulling force will result in the running tool 600 becoming engaged with the housing 210. Further pulling force on the rod string is expected to result in the valve housing 210 becoming disconnected (or unlocked) from the movable sleeve 350 resulting in releasing the movable sleeve 350 and returning the movable sleeve 350 to a neutral position in which the spill ports 320 and 340 are closed. Advantageously, the parts subject to wear from abrasive solids in the pumped fluid are arranged along the rod string 400 in the presently described embodiment. As a result the valve assembly 300 may be refurbished by pulling the rod string 400 and retrieving the sucker rod strings. The damaged or worn out parts of the valve assembly can be easily replaced and positioned on the rod string before positioning the rod string and refurbished valve assembly 300 (mounted on the running tool 600 positioned along the rod string 400).

[0057] If the apparatus of the present invention is used in a highly deviated and horizontal application, spring 225 will advantageously assist in closing the valve body 220.

[0058] Description of the apparatus shown in figures 15 to 23 will now be provided. Much of the assembly shown in figures 1 to 14 will be common with that shown in figures 15 to 23. For convenience, like features in figures 15 to 23 will be denoted by the same reference numerals as used in figures 1 to 14.

[0059] Figures 15 to 23 show various views of an alternative arrangement for introducing the valve housing into a rotatable rod string. Turning initially to figures 20, 21 and 22, the valve housing 210 is connected to a collet snap latch 732. The collet snap latch 732 is slidably connected to the anchor mandrel 700 which is, in turn, connected at its upper end to polished rod 410 of drill string 400 and connected at its lower end to rod 420 of the drill string. The valve housing 210 carries a snap ring 702, which is mounted in a groove formed in an outer surface of the valve housing 210. A seal 704, which may be in the form of an O-ring or other elastomeric seal type, is mounted just upstream of snap ring 702.

[0060] Figure 21 shows the collet snap latch 732 being connected to the valve housing 210. In this arrangement, the valve housing 210 moves with the drill string 400, which is connected to the anchor mandrel 700. Figure 22 shows the collet snap latch 732 being disconnected from the valve housing 210, with the drill string 400 being lowered such that the collet snap latch 732 has moved downwardly with respect to the valve housing 210.

[0061] Figures 15 to 20 show various views of the components of the anchor latch mechanism 700. The anchor latch mechanism 700 includes an anchor mandrel body 706. The anchor mandrel body 706 includes longitudinal channels 708 which provide a flow path for liquid when the anchor mandrel body is connected to the valve housing 210 via the collet snap latch 732. The anchor mandrel body 706 includes a lower end 710 having a bore 712. As best shown in figures 17 and 18, bore 712 has an internal thread 714. As also shown in figures 17 and 18, the upper end of the anchor mandrel body 706 has a bore 716 that also has an internal thread 718. The polished rod 410 can be threadably connected to the bore 716 and the drill rod 420 can be threadably connected to the bore 712 to thereby incorporate the anchor mandrel 700 into the rotatable rod string 400. A retaining ring 421, which can overlie a grub screw 423, assists in maintaining the connection between the drill rod 420 and the bore 712. A similar grub screw 425 assists in maintaining the connection between the polished rod 410 and the bore 716.

[0062] Returning now to figure 15, the anchor mandrel body 706 also includes a plurality of longitudinally extending radial projections, some of which are numbered as 720. The longitudinally extending radial projections are equally spaced around the diameter of the anchor mandrel body 706, with each projection being circumferentially equispaced from an adjacent projection. The longitudinal channels 708 may pass through the spaces between adjacent projections.

[0063] The anchor mandrel body 706 also includes a raised land 724. Raised land 724 has an oblique lower shoulder 726 and a sloping upper shoulder 728. The function of these shoulders will be explained in further detail hereunder. The anchor mandrel body 706 also includes a recessed region or a tapered region 730. This is best shown in figure 18.

[0064] The anchor mandrel also includes a collet snap latch 732. The collet snap latch 732 is in the form of a generally hollow cylindrical member having a plurality of arms, some of which are numbered as 734, 736, extending from a cylindrical lower section 738. The arms 734, 736 can flex inwardly and outwardly about their lower ends. Arm 734 includes a threaded upper region 740. All of the other arms include a similar threaded upper region. The arms collectively form a threaded upper region on the collet snap latch 732 that enables the valve housing 210 to be connected thereto by a complementary internal threaded region. As shown in figure 16, each of the arms 734, 736 are separated from adjacent arms by spaces 742.

[0065] The collet snap latch 732 is slidably fitted to the anchor mandrel body 706, as shown in figures 17 and 18. The threaded regions 740 of the arms 734, 736 overlie the recessed region 730 of the anchor mandrel body 706. In this way, space is provided for the arm 734, 736 to flex downwardly or inwardly into the recessed region 730. Figure 19 shows a perspective view of the assembled anchor latch mechanism 700 in which the collet snap latch 732 has been fitted to the anchor mandrel body 706.

[0066] Figures 17 and 18 show sectional views of the anchor latch mechanism 700 being connected to the valve housing 210. As can be seen from figure 17 and 18, the lower end of the valve housing 210 is open and has an internal thread 744 formed thereon. As shown in figures 17 and 18, the lower end of the valve housing 210 is connected to the anchor latch mechanism 700 by the complementary threads 740, 744 engaging with each other. The upper shoulder 728 of the raised land 724 on the anchor mandrel body 706 engages with a complementary sloped shoulder 746 on the inner surface of valve housing 210. Projection 720 and 722 on the anchor mandrel body 706 can also be seen in figure 17. As best shown in figure 19, projection 720 extends through the space 742 between adjacent arms of the collet snap latch 732.

[0067] The body 706 also includes a downwardly facing shoulder 810. When the collet snap latch 732 is attached to the valve housing 210 and the apparatus is being run in, the downwardly facing shoulder 810 comes into contact with the upwardly facing shoulder 812 that is formed on the ends of the arms of the collet snap latch 732. The lower end 820 of the collet snap latch 732 forms a shoulder. In the running in position shown in figure 17, shoulder 820 is spaced a short distance above a shoulder 822 that is formed by retaining ring 421. As shown in figure 17, as the apparatus is being run in, the shoulder 728 on the mandrel body 706 is spaced from the shoulder 746 on the inside of the valve housing 210.

[0068] Figure 23 shows a valve housing being connected to or locked to the movable sleeve by use of a snap ring 702. In figure 23, the valve housing is connected to the anchor mandrel body 706 and collet snap latch 732 as described with reference to figures 16 to 22. In figure 23, the snap ring 702 has moved into a complementary groove 748 in the movable sleeve 350. The groove 703 is of complementary shape to the outer surface of the snap ring 702. As the valve housing 210 is moved downwardly, the snap ring 702 enters into the movable sleeve 350, which causes the snap ring 702 to be compressed into its own mounting groove 703. When the snap ring 702 comes into alignment with groove 748 in the movable sleeve 350, the snap ring 702 snaps outwardly and engages with the groove 748. This acts to lock the valve housing 702 to the movable sleeve 350. The cooperating faces 810, on anchor mandrel 706, and 812, on collet snap latch 732, are in contact and hold the threads 740 in a locked position with threads 744 on valve housing 210 during running the rod string 400 into the hole.

[0069] The snap ring arrangement for connecting or locking the valve housing to the movable sleeve as shown in figure 23 may be used with the drill string arrangement as shown in figures 1 to

14 or used with the drill string and anchor mandrel arrangement as shown in figures 15 to 22. If the arrangement shown in figures 15 to 22 is used (as is shown in figure 23), installation of the valve housing into the connected or locked position with the movable sleeve can involve inserting the valve housing into the movable sleeve by lowering the rod string that has the valve housing attached to it, as shown in figures 17 to 21. When the snap ring 702 snaps into the inner groove on the movable sleeve 350, the valve housing 210 is effectively locked to the movable sleeve. The operator confirms this by picking up the rod string and taking overpull to confirm that the snap ring is located. The rod string is then set down to a neutral position, and rotated. Rotation of the rod string causes the anchor mandrel body 706 to rotate. This, of course, also causes the projections 720, 722 to rotate which, in turn, rotates the collet snap latch 732. Accordingly, rotation of the rod string can result in the snap latch 732 unscrewing itself from the threads 744 of the valve housing 210. Once the collet snap latch 732 has been fully unscrewed from the valve housing, the rod string can be further lowered to space out the pump rotor.

[0070] To retrieve the valve housing from the outer string, in the event that maintenance or repair is required, the rod string is picked up (see figure 18) the lower end of the collet snap latch 732, face 820 is contacted by the upper face 822 of the retainer ring 421. The upper ends of the arms 734, 736 of the collet snap latch 732 will move into the lower opening of the valve housing 210. As the threads of the threaded region 740 of the collet snap latch 732 come into contact with the threads of the internal thread 744 of the valve housing 210, the arms 732, 734 will flex downwardly into the recessed region 730 of the anchor mandrel body 706. As the rod string continues to move upwardly, the threads of threaded region 740 of the collet snap latch 732 will snap past each of the threads of the internal thread 744 of the valve housing 210 until the lower face/shoulder 746 of the valve housing 210 comes into contact with the shoulder/face 728 of the anchor mandrel body 706. Continued pickup of the rod string will eventually result in sufficient force being applied by the drill string to overcome the snap latch 702. At this time, the snap latch 702 will compress into its groove 703. This will effectively remove the snap latch 702 from the groove 748 in the movable sleeve 350, thereby allowing the valve housing 210 and the rod string 400 to be lifted up and out of the well. As shown in figure 18, not only does shoulder 728 of the mandrel body 706 come into contact with shoulder 746 of the valve housing, but lower shoulder 820 of the collet snap latch 732 comes into contact with the upper shoulder/face hundred and 22 of retainer ring 421. This also assists in retrieving the valve housing.

[0071] Figures 24 to 27 show another embodiment in which a valve housing being connected to or locked to the movable sleeve by use of a snap ring. Again, the embodiment shown in figures 24 to 27 has a number of features in common with the features shown in figures 1 to 23. For convenience, like parts will be denoted by like reference numerals.

[0072] Figures 24 and 25 show sectional views of the valve housing 210 being introduced into the outer string 300. The movable sleeve 350 can also be clearly seen in figures 24 and 25. In figures 24 and 25, the valve housing is being introduced into the outer string and has not yet been connected to or locked to the movable sleeve 350. As can be seen from figures 24 and 25, the snap ring 702 on the valve housing 210 has not yet entered into the movable sleeve 350.

[0073] In the embodiment shown in figures 24 to 27, the valve housing 210 is connected to mandrel 770 by way of shear pins 772. In particular, aligned bores 774, 776 are formed in the mandrel and valve housing, respectively, and shear pins 772 are inserted into the aligned bores to thereby connect the valve housing 210 to the mandrel 770. Although figures 24 and 26 only show a single shear pin, it will be appreciated that a plurality of shear pins may be used. Advantageously, 4 shear pins are used.

[0074] Figures 26 and 27 show the valve housing 210 that has been moved downwardly by the rod string so that the snap ring 702 has moved into the groove 748 in the movable sleeve 350. As shown in figures 24 and 25, the movable sleeve 350 includes an inner groove 748 which is of complementary shape to the outer surface of the snap ring 702. As the valve housing 210 is moved downwardly, the snap ring 702 enters into the movable sleeve 350, which causes the snap ring 702 to be compressed into its own mounting groove 703. When the snap ring 702 comes into alignment with groove 748 in the movable sleeve 350, the snap ring 702 snaps outwardly and engages with the groove 748. This acts to lock the valve housing 702 to the movable sleeve 350. This is best shown in figures 26 and 27.

[0075] Once the snap ring 702 is properly housed in the groove 748 in the movable sleeve 350, the valve housing 210 is effectively locked to the movable sleeve 350 and relative longitudinal movement between the valve housing 210 and the movable sleeve 350 is no longer possible. Once the valve housing 210 comes into contact with a stop member 780, further relative downward movement of the movable sleeve and the valve housing is no longer possible. Any movement would be of both parts together, and would be resisted by the spring means 355. As a result, the downwardly applied force passing through the rod string causes the shear pins to break, thereby disconnecting or unlocking the valve housing from the rod string. Downward movement of the rod string may then continue so that the pump rotor can be properly placed in the pump stator.

[0076] In order to remove the valve 200 from the outer casing in the embodiment shown in figure 27, the rod string 770 is provided with a shoulder 782 that comes into contact with a complementary shoulder 784 formed at the lower end of the valve housing 210. As a result, as the rod string is raised, the shoulder 782 comes into contact with the shoulder 784 and thus the upward force applied to the rod string is also applied to the valve housing. This force will be sufficiently strong to overcome the strength of the snap ring 702, which results in the snap ring compressing and coming out of groove 703. This unlocks or disconnects the valve housing 210 from the slidable sleeve 350. The valve housing and valve may then be lifted out of the outer tubing by extracting the rod string from the outer tubing. [0077] As shown in figures 24 to 27, the movable sleeve 350 has three seals 790, 792, 794. At least one seal is located above the spill port 340 and at least one seal is located below the spill port 340 (as shown in figures 24 to 27, there are 2 seals above the spill port and 1 seal below the spill port when the movable sleeve closes the spill port). This ensures that the movable sleeve 350 forms a good seal around the seal ports 340 when the movable sleeve 350 is in position to close off the seal ports 340. The seals 790, 792, 794 may be in the form of O-rings, or similar elastomeric seal type, that are seated in the grooves formed in the movable sleeve 350.

[0078] In the embodiment shown in figure 28, which is essentially identical to that shown in figures 24 to 27, a slightly different sealing arrangement is used on the movable sleeve 350. In particular, moulded seals 800, 802 are formed on the outer surface of the movable sleeve 350. These moulded seals form a bonded seal where elastomeric seals are bonded to a steel ring or elastomeric seals are bonded to the sleeve 350.

[0079] In embodiments of the present invention, locking washers or torque lock pins may be used to lock all threads that could otherwise be at risk of backing out while in use due to the large vibrational and backspin forces applied during rotation of the rod string and downhole pump, and as shown in Figure 28.

[0080] In the present specification and claims (if any), the word 'comprising' and its derivatives including 'comprises' and 'comprise' include each of the stated integers but does not exclude the inclusion of one or more further integers.

[0081] Reference throughout this specification to 'one embodiment' or 'an embodiment' means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases 'in one embodiment' or 'in an embodiment' in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more combinations.

[0082] In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims (if any) appropriately interpreted by those skilled in the art. [0083] The skilled person will appreciate that although the invention has been described in terms of specific embodiments with reference to the drawings which are set forth in detail, it should be understood that the drawings have been provided for the purposes of illustration only and that the invention should not be considered to be limited solely to the features as shown in the drawings. Alternative embodiments and operating techniques will become apparent to those skilled in the art. The present invention encompasses modifications which can be made without departing from the spirit of the described invention.

Claims

1. A valve assembly comprising: a housing for allowing passage of fluid therethrough from a first end of the housing to a second end of the housing, the housing comprising an internal bore for receiving a rotatable shaft; a valve member positioned in the housing for preventing flow of fluid in a direction from the second end to the first end in a closed configuration; a movable member positioned relative to the housing, the movable member being adapted for opening and closing a spill port; a locking mechanism adapted for allowing releasable engagement of the housing with the movable member; and the valve assembly being operable to spill a flow of fluid through the spill port when the valve member is in the closed configuration.

2. A valve assembly comprising: a housing for allowing passage of fluid therethrough from a first end of the housing to a second end of the housing, the housing comprising an internal bore for receiving a rotatable shaft; a valve member positioned in the housing for preventing flow of fluid in a direction from the second end to the first end in a closed configuration; a movable member positioned relative to the housing, the movable member being adapted for opening and closing a spill port; a locking mechanism adapted for allowing releasable engagement of the housing with the movable member; the valve assembly being operable to spill a flow of fluid through the spill port when the valve member is in the closed configuration, and a rotation prevention mechanism or device for preventing rotation of the housing during rotation of the rod string whilst the valve housing is engaged with the movable member.

3. A valve assembly as claimed in claim 1 or claim 2 wherein the locking mechanism is adapted to operate in two operating configurations wherein in a first locked configuration, the locking mechanism allows the housing to be attached or locked to an installation tool or a releasable running tool for assisting in the installation of the housing and the valve member at a desirable location in a downhole and wherein in the first locked configuration, the housing is not attached to the movable member and in a second locked configuration, the valve housing is uncoupled from the installation tool and fastened or attached to the movable member as a result of which any longitudinal movement of the housing relative to the movable member is prevented.

4. A valve assembly as claimed in claim 3 wherein in the second locked configuration the valve housing is uncoupled from the installation tool and fastened or attached to the movable member as a result of which any movement of the housing relative to the movable member is prevented.

5. A valve assembly as claimed in any one of the preceding claims further comprising a valve seat for contacting the valve member and forming a seal thereby preventing the flow of fluid in the closed configuration.

6. A valve assembly as claimed in claim 5 wherein the valve seat is provided along an inner wall of the housing.

7. A valve assembly as claimed in any one of the preceding claims wherein the housing is substantially cylindrical and the housing comprises a first housing portion comprising the valve seat and a second housing portion for enclosing the valve member.

8. A valve assembly as claimed in claim 7 wherein the second housing portion for enclosing the valve member comprises a cylindrical cage including one or more apertures for allowing fluid to flow into and out of the first housing portion.

9. A valve assembly as claimed in claim 7 or claim 8 wherein the second housing comprises the second end of the housing wherein one or more circumferentially arranged openings are provided at the second end for allowing flow into and out of the second housing portion.

10. A valve assembly as claimed in any one of the preceding claims wherein the valve member is biased to a position for substantially preventing flow from the second end to the first end of the housing in the closed position.

11. A valve assembly as claimed in any one of the preceding claims wherein the housing is adapted for being connected to the releasable running tool in the first locked position, and disconnected from the running tool in the second locked position; the running tool being provided along a length of the rotatable shaft for positioning the housing in a downhole region.

12. A valve assembly as claimed in any one of the preceding claims wherein the locking mechanism comprises a locking member, the locking member being adapted for locking the housing with the releasable running tool in the first locking configuration and being adapted for locking the housing with the movable sleeve in the second locked configuration.

13. A valve assembly as claimed in any one of the preceding claims wherein the locking member comprises a first locking portion adapted to be received into a corresponding locking groove provided on the releasable tool in the first locking position; and a second locking portion adapted for being received into a corresponding locking groove provided on the movable sleeve in the second locking position.

14. A valve assembly as claimed in any one of the preceding claims wherein the locking member comprises a first engaging surface for engaging with a corresponding engaging surface on the running tool in the first locked configuration; and a second engaging surface for engaging with a corresponding engaging surface of the movable sleeve in the second locked configuration.

15. A valve assembly as claimed in claim 14 wherein the first engaging surface comprises a first chamfered edge on the locking member, the first chamfered edge being adapted to be received into a corresponding notch provided on the running tool and the second engaging surface comprises a second chamfered edge on the locking member, the second chamfered edge being adapted to be received into a corresponding notch provided on the movable sleeve.

16. A valve assembly as claimed claim 15 wherein an angle of inclination of the first engaging surface or the first chamfered edge relative to a longitudinal axis of the rotational shaft is lesser than an angle of inclination of the second engaging surface or second chamfered edge.

17. A valve assembly as claimed in any one of the preceding claims wherein the valve assembly further comprises retaining means for retaining the locking member in the first locked position and/or for retaining the locking member in the second locked position.

18. A valve assembly as claimed in claim 17 wherein the retaining means comprises a biased retaining member adapted to be received into one or more detents provided on the locking member.

19. A valve assembly as claimed in claim 18 wherein in the first locked position, the biased retaining member is adapted to be retained in a first detent provided on the locking member and in the second locked position, the retaining member is adapted to be retained in a second detent provided on the locking member.

20. A valve assembly as claimed in any one of claims 1 to 11 wherein the locking member comprises a snap ring.

21. A valve assembly as claimed in claim 20 wherein the snap ring is mounted to an outer surface of the valve housing.

22. A valve assembly as claimed in claim 20 or claim 21 wherein the snap ring is mounted within a groove on the outer surface of the valve housing.

23. A valve assembly as claimed in any one of claims 20 to 22 wherein the snap ring enters into a groove on an inner surface of the movable member or sleeve to lock the valve housing to the groove on the movable member.

24. A valve assembly as claimed in any one of the preceding claims wherein the valve housing is connected to the installation tool or running tool or a drill string by an anchor mandrel.

25. A valve assembly as claimed in claim 24 wherein the anchor mandrel connects one section of the installation tool or running tool or drill string to another section of the installation tool or running tool or drill string.

25. A valve assembly as claimed in claim 24 or claim 25 wherein the anchor mandrel comprises an anchor mandrel body having a connector for connecting to a first section of the installation tool or running tool or drill string and a connector for connecting to a second section of the installation tool or running tool or drill string.

26. A valve assembly as claimed in any one of claims 24 to 25 wherein the anchor mandrel has a collet snap latch connected thereto.

27. A valve assembly as claimed in claim 26 wherein the collet snap latch comprises an outer connection region located on one or more flexible arms, and the anchor mandrel comprises a recess or tapered region that underlies the one or more flexible arms when the snap latch is connected to the anchor mandrel.

28. A valve assembly as claimed in any one of claims 24 to 27 wherein an outer surface of the body of the anchor mandrel comprises one or more radial projections

29. A valve assembly as claimed in claim 27 wherein the outer connection region of the collet snap latch comprises a threaded region formed on the one or more flexible arms and the one or more flexible arms comprise a plurality of flexible arms spaced from adjacent arms and in order to disconnect the valve from the snap latch when the valve is being run in, once the snap ring has engaged with the movable member or sleeve, the installation tool or running tool is rotated to cause the collet snap latch to rotate relative to the valve housing which causes the collet snap latch to unscrew itself from the valve housing.

30. A valve assembly as claimed in any one of claims 24 to 29 wherein the anchor mandrel includes a surface that engages with a complementary surface on the valve housing to thereby enable the valve housing to be pulled out of the tubing string.

31. A valve assembly as claimed in claim 30 wherein the anchor mandrel includes a tapered surface that engages with a complementary tapered surface on the valve housing to thereby enable the valve housing to be pulled out of the tubing string.

32. A valve assembly as claimed in any one of the preceding claims wherein the movable member is biased for positioning the movable member to close the spill port to a neutral position.

33. A valve assembly as claimed in any one of the preceding claims wherein the movable member comprises a sleeve adapted for being movably mounted along an internal wall of an outer tube string for opening and closing the spill port located on the outer tube string.

34. A valve assembly as claimed in any one of the preceding claims wherein the movable member is positioned inside the housing for allowing releasable engagement with the housing.

35. A valve assembly as claimed in any one of the preceding claims wherein a further sleeve is installed near or adjacent to the biasing means or spring that is used to position the movable member to close the spill port to a neutral position wherein the further sleeve keeps produced solids from accumulating in and around the biasing means or spring which may otherwise hinder the biasing means or spring from properly actuating.

36. A valve assembly as claimed in any one of the preceding claims wherein the valve housing comprises a rotation prevention mechanism or device for preventing rotation of the housing relative to the rotatable shaft.

37. A valve assembly as claimed in claim 36 wherein the rotation prevention mechanism or device is located at or adjacent to the second end of the housing.

38. A valve assembly as claimed in claim 36 or claim 37 wherein the rotation prevention mechanism or device comprises a mechanism that is adapted to lock the housing onto an inner wall locking portion of the outer tubing string and prevents the simultaneous rotation of the valve housing whilst the rod string undergoes rotation during a pumping cycle.

39. A valve assembly as claimed in claim 36 or claim 37 the rotation prevention mechanism or device comprises a projection or an enlargement that contacts an inner wall of the outer tubing string such that friction between the projection or enlargement and the inner wall of the outer tubing string prevents rotation of the housing relative to the outer tubing string.

40. A valve assembly as claimed in any one of claims 36 to 38 wherein the rotation prevention mechanism or device includes a portion that can move laterally outwardly into engagement or contact with the inner wall of the outer tubing string and laterally inwardly to move out of contact with the inner wall of the outer tubing string.

41. A valve assembly as claimed in any one of claims 36 to 38 wherein the rotation prevention mechanism or device comprises a drag block that is mounted by one or more biasing means to an outer wall of the housing, the drag block extending into and between flutes formed on an inner wall of the outer tubing string.

42. A valve assembly as claimed in any one of claims 1 to 10 wherein one or more shear pins are used to attach the valve or the valve housing to the running tool or the installation tool or to a mandrel in the rod string.

43. A valve assembly as claimed in any one of the preceding claims wherein the valve member is biased to move to a close position when pumping of fluid upwardly through the tubing is stopped.

44. A valve assembly as claimed in claim 43 wherein the valve member is biased by a spring.

45. A valve assembly as claimed in claim 44 wherein the spring is located upwardly from the valve member.

46. A production apparatus for pumping fluid, the apparatus comprising: a rotatable rod string for driving a downhole pump assembly, a tubing string being provided for receiving the rotatable rod string such that an inner wall of the tubing string provides a flow path for pumped fluid; and the valve assembly as claimed in any one of the preceding claims, wherein the internal bore of the housing is adapted for receiving the rod string; and wherein the movable member is provided at or adjacent the inner wall of the tubing string for opening or closing the spill port provided along the tubing string such that the valve assembly prevents the flow of fluid back to a downhole pump assembly in a closed configuration by spilling the flow of fluid through the spill port.

47. A method of installing a valve as claimed in any one of claims 1 to 45 in a downhole production string, the method comprising: providing a tubing string for receiving and enclosing a rotatable shaft such that an inner wall of the tubing string provides a flow path for pumped fluid; positioning the valve downstream/upwardly relative to a downhole pump assembly, said valve being enclosed in a housing, the positioning step comprising: locking or fastening the housing to a releasable running tool provided along the rotatable shaft; positioning the locked housing and running tool adjacent to a movable member located along the inner wall of the tubing string by inserting the rotatable shaft into the tubing string; and unlocking the housing from the running tool and subsequently attaching or fastening the housing to the movable member.

48. A method as claimed in claim 47 wherein the running tool comprises a drill string or comprises part of a drill string.