EP3400370A1

EP3400370A1 - Wear indicator for a joint between a riser and a floating platform

Info

Publication number: EP3400370A1
Application number: EP17711733.0A
Authority: EP
Inventors: Richard Johnston; Craig Robertson; John Gallagher
Original assignee: Oil States Industries UK Ltd
Current assignee: Oil States Industries UK Ltd
Priority date: 2016-02-19
Filing date: 2017-02-20
Publication date: 2018-11-14
Anticipated expiration: 2037-02-20
Also published as: GB2564023A; EP3400370B1; ES2777633T3; SG11201806058SA; GB201611438D0; WO2017141056A1; BR112018016919A2; AU2017219226A1; DK3400370T3; US20190330954A1; GB2564023B; GB2547493A; GB2547493B; PL3400370T3; GB201602949D0; GB201813117D0

Abstract

A packer assembly comprising an inner packer element (8;108) and an outer concentric packer element (9;109), an actuator (26;126) which is slidable over the outer packer element to deflect the outer packer element inwards against the inner packer element and a sensor (34;174) for detecting linear movement of the actuator relative to the outer packer element.

Description

WEAR INDICATOR FOR A JOINT BETWEEN A RISER AND A FLOATING PLATFORM

This invention relates to a packer and more particularly to a packer for providing a seal between two joints and more particularly still to a packer for providing a seal between two concentric tubular members of a telescopic joint and further to a system for monitoring wear or said packer as the tubular members move relative to each other.

When recovering hydrocarbons such as oil and gas from reservoirs which are located subsea, it is necessary to provide a stable pathway for the recovered fluids from the reservoir to the surface. This may involve the use of a fixed platform or rig which extends from the sea bed to the surface with a string of pipes or risers extending between the infrastructure permanently installed subsea and the platform. The infrastructure may be for example a subsea Christmas tree providing an assembly of valves, spools and fittings for intervention into the well below.

However in deeper water it is not always practical to provide fixed moorings between the surface platform and the seabed. In these cases a floating platform such as an FPSO may be used with the top side processing equipment provided on the deck of the FPSO and a casing or riser string provided between the FPSO and the subsea infrastructure.

Movement of the FPSO due to heave, surge or sway caused by localised swells and weather conditions must be accommodated as any such movement at the surface will be transferred into the casing string connected between the FPSO and the subsea infrastructure which can lead to damage to FPSO, the top side equipment, the subsea infrastructure or the casing string itself.

Movement of the FPSO can be accommodated by providing a telescopic joint in the casing string. Such a joint comprises two concentric tubular members or pipes, forming an outer element and an inner element of the joint. The inner element can slide longitudinally or stroke within the outer element and extends out of the end of the outer element. Typically the telescopic joint will be formed with an inner pipe section and an outer pipe section. The outer pipe section is typically connected to the upper most riser joint of the casing string and the inner pipe section is typically connected to the rig floor of the FPSO. The telescopic joint is designed to prevent damage to the riser and control umbilicals by compensating for the vertical movement from heave, surge sway or offset of the drilling vessel. As the position of the vessel moves during these conditions, the length of the telescopic joint changes to compensate for the movement of the vessel thereby maintaining the integrity of the riser.

Tension in the riser is maintained during operation through an SDL tension ring or equivalent such as for example an SDL or KT ring. This maintains tension in the riser whilst the telescopic joint strokes in and out providing compensation for vertical movement of the offshore drilling vessel or FPSO.

When the telescopic joint is being handled it can be locked in the fully retracted position via a latch mechanism which secures the inner pipe section to the outer pipe section and prevents relative movement and thus stroking of the joint.

A seal is provided between the inner and outer pipe sections to maintain a seal between fluids flowing through the telescopic joint and the atmosphere. As the inner and outer pipe sections move relative to one another, friction causes the seal to wear over time. The rate of wear is dependent upon various factors such as operation conditions, local weather patterns and the material characteristics of the seal and can be difficult to predict. Therefore regular monitoring of the integrity of the seal is essential to ensure that remedial action can be taken to replace the seal before the wear becomes so severe that the seal is compromised as this could lead to a leakage of fluids from the joint into the surrounding sea water.

In order to inspect the seal, the telescopic joint has to be recovered to surface and stripped down to gain access to the seal and, if necessary, to replace the seal. As this requires shutting down of production through the telescopic joint and therefore through the riser, this is a very costly process both in terms of time and lost operating revenue.

It is an aim of the present invention to provide a sealing member particularly for use in maintaining a seal between the inner and outer elements of a telescopic joint, in which wear on the seal can be monitored without the need to remove the telescopic joint from the riser.

It is also an aim of the present invention to provide a sealing member which facilitates real time, remote monitoring of the wear on the sealing member and therefore of the integrity of the seal between the inner and outer elements of the telescopic joint to allow remedial action to be taken when necessary before the integrity of the seal is compromised. According to one aspect of the present invention there is provided a packer assembly comprising an inner packer element and an outer concentric packer element, an actuator which is slidable over the outer packer element to deflect the outer packer element inwards against the inner packer element and a sensor for detecting linear movement of the actuator relative to the outer packer element.

Preferably the outer packer element comprises a profiled outer surface.

Alternatively a setting component is provided between the actuator and the outer packer element. Advantageously the setting component comprises a profiled outer surface.

Preferably the setting component comprises a plurality of bodies mounted between the actuator and the packer assembly. Preferably the plurality of bodies form a segmented ring around between the actuator and the packer assembly. Advantageously the plurality of bodies are radially moveable relative to the packer elements. Preferably each body is substantially C-shaped. More preferably each body of the setting component comprises a spine with a profiled outer surface. Conveniently each body of the setting component further comprises upper and lower arms which extend from the spine inwardly towards the packer assembly. Advantageously a connector strap or bar is provided between adjacent bodies of the setting component. Preferably the connector bar or strap is slidably mounted between adjacent bodies.

Advantageously the actuator comprises a cam surface which cooperates with the profiled outer surface of the outer packer element. Preferably the actuator comprises a substantially tubular sleeve. Advantageously the sleeve is slidably mounted over the outer surface of the outer packer element or the setting component. Preferably also the cam surface of the actuator is provided on an internal surface of the sleeve.

Advantageously the cam surface of the actuator comprises a tapered surface which cooperates with the profiled outer surface of the outer packer element or the setting component to force the outer element radially inwards against the inner packer element.

Preferably the profiled outer surface of the outer packer element comprises a plurality of polyurethane blocks, elements or forms. Preferably the blocks are mounted to a rubber component which forms the inner surface of the outer packer element.

Advantageously the blocks on the outer surface of the outer packer element have a tapered surface which cooperates with the tapered surface on the cam profile on the actuator sleeve.

Advantageously the sleeve is mounted within a chamber containing hydraulic fluid.

Alternatively one or more pistons are mounted to the outer surface of the sleeve.

The or each piston is provided within a piston chamber such that the piston(s) move(s) through the chamber(s) as the sleeve moves vertically.

Preferably the sensor comprises a body which is moveable through a secondary chamber. The body may act as an indicator to provide information to the operator of the status or condition of the packer assembly.

Conveniently one or more apertures are provided between the piston chamber and the secondary chamber to provide a pathway for hydraulic fluid from the chamber within which the piston is provided and the secondary chamber. Preferably the secondary chamber comprises a first portion having a first diameter and a second portion having a second diameter. Preferably also the diameter of the second portion may be smaller than the diameter of the first portion. Advantageously the diameter of the second portion may be around ¼ the diameter of the first portion. As the actuator slides over the outer surface of the outer packer element, hydraulic fluid is forced from the piston chamber into the sensor chamber through the apertures to force the sensor body to move through the sensor chamber.

Advantageously means are provided in the sensor chamber for viewing the position of the sensor within the chamber.

Conveniently a window or slot is provided in the sensor chamber through which the piston can be viewed. Advantageously a scale may be provided adjacent to or on the window slot or alternatively on the sensor. This enables the position of the sensor within or adjacent to the viewing window to provide a simple and accurate indication of the position of the sensor within the chamber and thus the position of the actuator relative to the outer packer element which is affected by wear on the inner packer element. Therefore the operator is able to monitor the position of the sensor in order to provide a real time indication of the extent of travel of the actuator and thus show the extent of wear on the inner packer element.

Conveniently the packer assembly further comprises a linear potentiometer. The linear potentiometer comprises a contact slider and a ground terminal. Preferably the contact slider is connected to the sensor piston and is mechanically moved by the piston. As the contact slider is moved thus the distance between the slider and the ground terminal changes thus changing the resistance of the potentiometer. Conveniently the packer assembly further comprises a wireless transmitter which sends a signal to a wireless receiver indicative of the position of the piston within the packer assembly. Preferably the wireless transmitter reacts to the change in resistance of the potentiometer. This allows the operator not only to monitor the integrity of the seal provided by the inner and outer packer elements, but to do this from a remote location without having to visually inspect the components that the packer assembly is built into. This is especially convenient where the packer assembly is built into a component which is deployed subsea for example or positioned in difficult to view areas of a platform or vessel as it allows the operator to monitor the integrity of the seal from a suitable location on the surface platform or vessel.

Preferably also the assembly further comprises an outer housing. Conveniently the outer housing surrounds the packer elements and may comprise flanged covers at each end of the housing. Advantageously a latch is provided for securing the flanged covers to the outer housing. Conveniently the latch comprises a profiled locking member and the flanged covers may have angled detents provided therein into which the profiled locking member can be driven. This provides a quick release mechanism to allow the flanged covers to be mounted to or removed from the outer housing which saves time and effort compared to conventional bolted arrangements.

Preferably also one or more spacers may be mounted between the packer elements and the flanged covers of the outer housing. This provides a means of adjusting the wear point on the packer by the setting component which can prolong the life of the packer elements.

Embodiments of the present invention will now be described with reference to the accompanying figures in which:

Figure 1 is a schematic cross sectional view through part of a telescopic joint fitted with a packer according to one aspect of the present invention;

Figure 2 is a perspective view of the packer assembly of the telescopic joint of figure 1 ;

Figure 3 is a top view of the outer packer element of the packer assembly of figure 2;

Figure 4 is a cross sectional view of the outer packer element of figure 3; Figure 5 is a perspective view of an inner packer element of the packer assembly of figure 2;

Figure 6 is a top view of the outer packer element of figure 5; Figure 7A is a schematic cross sectional view of a packer assembly according to a second embodiment of the invention;

Figure 7B is a schematic view of the setting component of the second embodiment of the present invention;

Figure 8 is a cross sectional view through the housing of the second embodiment;

Figure 9 is a schematic view of the second embodiment with the outer housing removed;

Figure 10 is a schematic view of the outer housing of the second embodiment of the invention,

Figures 1 1-13 are schematic views of the latch mechanism between the packer housing and the top and bottom covers, and

Figure 14 is a schematic view of a further embodiment of the present invention. Turning now to the figures, figure 1 shows a schematic view of one embodiment of the present invention incorporated into an outer tubular element 1 of a telescopic joint which is intended to prevent damage to a riser and control umbilicals extending from a subsea location by compensating for vertical movement due to heave, surge or say or offset of a floating drilling platform or vessel. The inner tubular element of the telescopic joint is not shown for clarity.

The outer tubular element 1 of the telescopic joint comprises a generally cylindrical hollow body 2 with a bore 3 extending from one end of the body to the other. In use the inner tubular element of the telescopic joint will be received within the upper end of the bore of the outer tubular element. A substantially tubular housing 4 surrounds the upper end (in use) of the outer tubular element. In the embodiment shown, the housing is integrally formed with the upper end of the outer tubular element. Alternatively it may be mounted on top of the upper end of the outer tubular element. The housing provides support for and seating for sealing elements which act between the inner and outer tubular members and also associated actuating and control components as will be explained in more detail below.

A packer assembly 5 is provided to form a seal between the inner surface of the outer tubular element 1 and the outer surface of the inner tubular member (when inserted) of the telescopic joint. In the embodiment shown a dual set of packer assemblies is provided comprising an upper packer assembly 6 and a lower packer assembly 7 although in practice only a single packer assembly may be used.

Each of the upper and lower packer assemblies 5, 5' comprises an inner and an outer packer element 8, 9. In use the inner packer element 8 is mounted concentrically within the outer packer element 9.

The packer assemblies 6, 7 are each mounted within respective annular recesses 10 in the inner surface of the housing surrounding the upper end (in use) of the outer tubular component 1. A corresponding aperture may be provided in the outer wall of the outer tubular element through which the packer assembly can project into the recess in the housing.

Figure 2 is a perspective view of a packer assembly 5 according to one embodiment of the present invention. Figures 3 and 4 show the outer packer element separated from the inner packer element. As shown in figure 3, the outer packer element 9 is generally torroidal in shape and comprises an inner cylindrical rubber component 11 and an outer cylindrical polyurethane component 12. The outer component is formed by mounting a plurality of polyurethane elements, blocks or forms 13 onto the outer surface of the rubber component 11. Each of the polyurethane elements 13 is substantially rectangular and extends from one side surface 14 of the inner rubber component 11 to the other side surface 15. The thickness of the polyurethane elements 13 gradually increases from each end towards the centre 16 of the polyurethane elements. Thus the polyurethane elements 13 have tapered ends 17 with a raised central region 16 as seen in the cross sectional view of figure 4. The polyurethane elements may be individually mounted to the inner component or may be provided as a unitary element forming a segmented ring.

Steel rings 18 are mounted on each side 14, 15 of the inner rubber component 11 to hold the hold the inner and outer components together of the outer packer element together. Preferably the elements 13 are bonded or otherwise mounted to the rubber component 11. An O-ring 19, of a resilient material such as rubber, is provided around the outer surface of the steel rings at either side of the outer packer element. The O-ring may sit within a groove in the steel rings. The inner packer element 8 of the packer assembly 5 is shown in figures 5 and 6 and comprises a substantially annular resilient component comprising a polyurethane element 20 with steel end rings 21 mounted on each side 23, 24 of the element 8. In the embodiment shown, the inner packer element is a split packer with one or more rubber strips 22 providing an integral sealing bead which extends across the surface of the inner packer element from one side to the other. In this embodiment, two such beads are provided at diametrically opposite positions on the inner packer element.

Figure 2 illustrates the inner packer element 8 mounted concentrically within the outer packer element 9 to form a packer assembly 5 which is mounted within the recess 10 in the housing 4 surrounding the upper portion of the outer tubular member.

An actuating system 25 is provided within the housing 4 for mechanically applying radial pressure to the outer surface of the outer packer element 9 of the packer assembly 5 and thus applying pressure to the inner packer element 8 against the outer surface of an inner tubular element when inserted into the outer tubular element. The actuating system 25 comprises a piston which reciprocates within a piston chamber in the housing adjacent the recess within which the packer assembly 5 is received. The piston comprises a substantially tubular sleeve component 26 which is mounted in the housing 4 in an annular chamber 27 behind the packer assembly 5. The tubular piston sleeve has an upper portion 28 which has a first thickness, a central portion 29 which has an enlarged thickness with respect to the upper portion and a lower portion 30 which has a reduced thickness with respect to the upper portion of the piston component.

The enlarged central portion 29 of the piston has a tapered cam surface 31 provided on the interior of the central portion which cooperates with the outer tapered surface 17 and raised centre portion 16 of the polyurethane elements 13 mounted on the outer component 12 of the outer packer element as will be described further below.

Where dual packer assemblies 6, 7 are provided such as shown in the embodiment of figure 1 , upper and lower piston sleeve components 26, 26' will be provided to engage with the upper and lower packer assemblies respectively.

The piston sleeve 26 slides within the annular chamber 27 under the influence of hydraulic fluid introduced into the chamber above the sleeve. One or more cross drilled holes 32 are provided in the fluid chamber 27 below the piston sleeve 26 to allow hydraulic fluid to be forced from the chamber 27 into a second chamber 33 within the housing 4 as the piston sleeve advances through the chamber 27. In the embodiment shown, 4 such second chambers are provided although the number of second chambers can be changed dependent upon the requirements of the system.

A sensor which in this embodiment is in the form of a visual indicator 34 is mounted within each of the second chambers. The visual indicators may comprise a piston which is actuated by the introduction of hydraulic fluid into the second chamber 33 from chamber 27. The outer surface of the piston may have a graded or coloured scale or numbered scale applied to it. A window or slot is provided in the side wall of the second chamber 33 adjacent the outer surface of the housing 4 through which the position of the visual indicator 34 can be inspected. Alternatively a graded or numbered scale may be provided on or adjacent to the window against which the position of the visual indicator 34 can be monitored.

A linear potentiometer 35 is mounted within the housing 4 in one of the second chambers 33. The linear potentiometer comprises a contact slider and a ground terminal and produces a change in resistance that is linearly proportional to the distance between the contact slider and the ground terminal.

Springs 36 are provided in the chambers 33 to bias the visual indicators 34 into a first position which indicates no wear on the inner packer element. Preferably the first position is a lower position within the chamber 33. The springs are preferably coil springs which surround an upper portion of the visual indicators. A wireless sender unit 37 is mounted on the housing 4 and receives an electrical signal from the potentiometer 35 and transmits this to a hand held receiver (not shown) which can be used by an operator in a remote location. The operation of the present invention will now be described. A packer assembly 5 is constructed by mounting the inner packer element 8 concentrically within the outer packer element 9. The packer assembly 5 is mounted within the housing 4 and piston sleeve 26 is mounted into the annular chamber 27 of the housing surrounding the packer assembly. As the inner tubular element of the telescopic joint is introduced into the upper end of the bore of the outer tubular member, the packer assembly forms a seal between the inner and outer tubular members such that the inner tubular member can move relative to the outer tubular member without any fluids running through the telescopic joint leaking out between the two tubular members.

Hydraulic fluid is forced into the upper end of the chamber 27 in which the piston sleeve 26 is mounted. As the fluid enters the chamber, the piston sleeve 26 is pushed downwards into the chamber. As the piston sleeve extends into the chamber, the cam surface 31 on the interior of the central portion 29 of the piston sleeve contacts the tapered outer surface 17 of the outer packer element and pushes the outer packer radially inwards which in turn deflects the inner packer element 8 and forces the inner packer element into closer contact with the outer surface of the inner tubular member of the telescopic joint to maintain the seal around the inner tubular member of the joint.

As the inner tubular member of the telescopic joint strokes within the outer tubular member, friction between the inner surface of the inner packer element 8 and the outer surface of the inner tubular member causes wearing of the inner PU surface 20 of the inner packer element which affects the integrity of the seal between the inner and outer tubular members.

As the inner packer element wears, the thickness of the packer assembly 5 reduces and the piston sleeve can move further into the chamber 27 under influence of the hydraulic fluid. This causes the cam surface 31 on the piston sleeve 26 to moves further down the outer tapered surface 17 of the outer packer element 9 to maintain the seal around the inner tubular component.

As the piston sleeve 26 moves downwards over the outer surface of the outer packer element 9, this energizes the hydraulic fluid in the chamber below the piston sleeve 26. The hydraulic fluid is forced by the piston sleeve through the cross drilled holes 32 and into the lower portion of the fluid chamber 33 in which the visual indicators 34 are mounted. The further the piston sleeve 26 rides up the tapered surface 17 and moves over the outer surface of the outer packer element 9 to maintain a seal by the inner packer element 8, the more hydraulic fluid is forced from the lower portion of the piston chamber 27 into the fluid chambers 33 and the visual indicators 34 are pushed against the spring bias and move upwards relative to the viewing windows to provide a real time, on-going indication of the position of the piston sleeve 26, and therefore of the relative wear of the inner packer element 8 of the packer assembly 5.

This allows the operator to monitor the wear on the inner packer element 8, and thus the effective seal around the inner tubular component of the telescopic joint without having to disturb the joint or reduce or stop flow of fluids through the joint and to take remedial action before the wear on the inner packer element reaches a critical point where the seal is compromised.

Additionally, as the visual indicators 34 move through the fluid chambers 33 under the influence of the hydraulic fluid entering the chambers, the slider on the linear potentiometer similarly moves and the movement is detected by the wireless transmitter which sends a signal to a remote receiver. This allows an operator working remotely from the joint to monitor the condition of the seal between the telescopic elements of the joint without having to disturb the joint or even be in close proximity to it.

In the above embodiment shown the actuation assembly for the upper and lower packer assemblies is similar, with the piston sleeve of the lower packer assembly mounted in the opposite orientation to the piston sleeve surrounding the upper packer assembly. A further and more preferred embodiment of the invention is illustrated in figures 7- 10 with like numerals used to identify similar components but increased by 100. In this embodiment the dual packer assembly 105 comprises an inner sealing packer element 108 and an outer energising packer element 109 as before, however the outer packer has a similar form as the inner packer in that both inner and outer packer elements are substantially annular with the inner packer element mounted concentrically within the outer packer element. Rings 1 18 may be provided at the upper and lower edges of the outer packer element to encase the two packers together.

A plurality of blocks or dogs 150 are mounted between the outer packer element and the tubular sleeve component 126 and form a setting component which assist in forcing the packer assembly against the inner member of a telescopic joint to prevent leakage of fluids between the inner and outer members as they move relative to one another.

The dogs are radially moveable towards the outer packer element 109. The outer upper surface 151 of the dogs are tapered to match the tapered cam surface 131 on the actuating sleeve such that as the actuating sleeve pushes down on the dogs in this embodiment, the dogs are pushed radially inwardly against the outer packer element. As the inner packer element 108 wears against the barrel, the dogs 150 are pushed inwards by the sleeve which therefore maintains the pressure holding the inner packer onto the inner barrel. This causes the sleeve member 126 to move downwardly within the housing.

The dogs have a substantially C-shape with a spine element 161 and upper and lower arms 162 which extend from the spine element. The spine and arms define a recess or slot 163 across the inner face of the dogs. In use elongate inserts are provided between the slots of adjacent dogs. In the embodiment shown the inserts are substantially rectangular but could be arcuate in some embodiments. As the sleeve member 126 moves downwardly and pushes the dogs radially inwardly, the inserts 164 minimize the risk of the edges of the dogs pinching the outer surface of the outer packer 109. The inserts ensure that the dogs move inwardly by the same amount and maintain smooth operation of the dogs. In this embodiment, a plurality of actuating pistons 165 are fastened to the lower portion 166 of the outer surface sleeve. The pistons have a cylindrical body. In this embodiment there are three pistons but there could be one or more pistons in some embodiments. Each piston moves vertically with the sleeve. Each piston in the preferred embodiment is fastened to the sleeve by a screw 168 or other fixing member which passes through a horizontal bore 169 in the piston into a receiving aperture in the outer surface of the sleeve.

A tube 170 is formed within the body of the housing and the piston 165 is located within the tube. As the sleeve moves vertically, the piston 165 moves vertically through the tube. Each piston is housed within its own dedicated tube in the housing. Each tube is of a diameter slightly larger than the diameter of the piston body to ensure a close fit between the tube 170 and the cylindrical body. The lower end of the piston tube 171 has one or more cross drilled apertures 172 which allow hydraulic fluid in the tube below the piston body to communicate with a secondary tube 173 within which a position indicator 174 is located. The indicator is a substantially cylindrical body 175 which in the preferred embodiment has three differently coloured sections 176. The indicator body may have a diameter substantially similar to the diameter of the piston body. The upper portion of the secondary tube 173 has a diameter slightly larger than the diameter of the indicator body to ensure a close fit between the outer surface of the indicator body and inner surface of the tube but the lower section of the secondary tube has a smaller diameter than the upper section. In the preferred embodiment, the lower section of the secondary tube is around ¼ of the diameter of the piston tube such that a vertical movement of the piston of 1 cm through the piston tube will result in a vertical movement of 4 cm of the indicator body in the secondary tube.

Each piston tube 170 in the housing has an associated secondary tube 173 with a sensor in the form of a position indicator 174 mounted in the secondary tube with a fluid passageway between the lower end of the piston tube and the lower end of the secondary tube. Each of the pistons are mounted at the same position around the sleeve and so move vertically by the same amount as the sleeve, and therefore each position indicator is similarly moved by an equivalent amount. A window 180 is provided in the outer surface of the housing which is aligned with the secondary tube(s) 173. A grading or scale may be provided on or adjacent to the window. Hydraulic fluid in the piston chamber is forced through the cross drilled holes 172 into the chamber in which the visual indicators are mounted.

In the preferred embodiment, three actuating pistons are fastened to the sleeve, each moving through a piston tube and three secondary tubes are provided each with a position indicator providing a visual indication of the wear on the.

The visual indicators preferably have graduated colours to give an indication of wear as the rod passes the viewing window in the chamber. In some embodiments, a spring may be connected between the top of the indicator rod and the top of the fluid chamber returns the indicator rod to the rest position when the sleeve moves upwards within the housing.

In the illustrated embodiment, upper and lower packer assemblies 105, 105' are mounted within the housing, each assembly having inner and outer packer elements 108, 109. In some embodiments the sleeve 126 of the upper packer assembly may be moved vertically downward within the housing to push the locking dogs 150 radially inwardly whilst the sleeve 126' of the lower packer assembly is moved upwards to produce the same movement in the locking dogs 150' of the lower packer assembly. Alternatively, both sleeves 126 126' may be moved vertically in the same direction to produce radial movement of the dogs 150, 150' against the outer packer 109.

Each of the upper and lower packer assemblies have three position indicators 174 which can be viewed through the windows 180 in the outer surface of the housing to provide a quick and simple way for the operator to identify wear on the packers.

The operation of this embodiment is similar to the first embodiment in that as the packer assemblies wear, the thickness of the packer assemblies reduce and the sleeves 126, 126' can move further vertically under the influence of hydraulic actuating fluid. This causes the cam surface 131 on the piston sleeves to move further down the outer tapered surface 117 of the outer packer element 109 to maintain the seal around the inner tubular component.

As the piston sleeve 126 moves downwardly over the outer surface of the outer packer element, this causes the pistons 165 to move vertically with the sleeve. As the pistons 165 move through the tubes 170, the hydraulic fluid in the tube is energised and forced through the cross drilled holes 172 into the secondary tubes where the fluid forces the position indicators to rise within the tube. As noted above, the ration of the volumes of the piston tube and the secondary tubes can be controlled to ensure that a minimum movement of the piston body with the tube 170 causes a maximum movement of the position indicator within the secondary tube to allow for close maintenance and early intervention as the packer wears. By monitoring the section of the position indicator that is visible through the viewing window, an operator can quickly and easily check the condition of the packer elements without having to interrupt the operation of the telescopic joint. Any change in the condition of the packer elements will be readily noted via ongoing checking and monitoring of the position indicators. This allows for early intervention to be made before the condition of the packer elements becomes critical. In an embodiment in which the upper and lower sleeves 126, 126' move in opposite directions, references to upwardly and downwardly above will be understood by the skilled person to cover the appropriate movements in that that embodiment.

In Figures 10-13 the housing of the packer is provided with a latch which allows the top and bottom flanged covers of the packer housing to be connected to and quickly released from housing of the packer.

In this embodiment the latch comprises a dog assembly which has a housing 200 mounted externally at the top and bottom of the packer housing. The housing 200 of the dog assembly has an axial bore 201 within which a latch screw 202 is mounted. The latch screw has a thread 203 on at least a part of the external body of the screw and a head 204 which may be integrally formed with the body of the screw. The head is provided internally of the housing when the screw is inserted into the housing. A corresponding thread is provided internally within the housing of the dog assembly. The head of the screw has a profile which is enlarged with respect to the body of the screw and the head of the screw is inserted into a cooperating profile in the rear face of a latch dog such that movement of the screw through the dog assembly housing moves the latch dog inwardly and outwardly with respect to the external surface of the top or bottom cover of the packer housing.

The outer surface of the latch dog has a profile that in this embodiment provides two angled teeth or pins which extend into cooperating angled detents in the outer surface of the top or bottom cover when the latch dog is driven into a locking position which pulls the cover down onto the packer housing and preloads the connection.

This holds the covers in place on the packer housing but provides a quick release mechanism to allow the packer housing to be quickly connected to the top and bottom covers which can replace a more traditional bolted connection between the top and bottom covers and the packer housing. This provides for a reduction in the time and effort required in building the telescopic joint and also provides for a reduction in time and therefore operating cost required for any maintenance and repair that requires the top or bottom cover of the joint to be removed from the packer housing to allow access to the packer. Figure 14 illustrates a further embodiment in which a spacer 220 is mounted above or below the body of the packer 108 to alter the relative position of the packer and the dogs 150 within the packer housing. This has the effect of adjusting the wear point on the packer by the dogs 150. In the embodiment illustrated the spacers are shown as being above and/or below the packer 108 but they could alternatively be provided above and/or below the locking dog 150 in order to vertically alter the position of the locking dog rather than the packer. During use and over time, the action of the dogs 150 acting on the outer surface of the packer element may cause the packer element to wear along the external surface. By providing a means for altering the effective wear point on the packer external surface, the life of the packer element may be increased which provides a further substantial advantage in managing the life of the packer element and thereby improving the operation and maintenance of the telescopic joint. Spacers may be mounted above or below the packer or the dogs. In some embodiments spacers may be mounted both above and below the packer and/or the dogs to provide a number of different relative operating positions between the packer element and the dogs.

The present invention therefore converts linear mechanical operation of an actuation sleeve into a visual signal or an electronic signal which is indicative of the position of the condition of the packer assembly and therefore the integrity of the seal between the inner and outer sections of the telescopic joint. This provides a simple and effective way of monitoring the integrity of the seal without having to inspect the seal or disassemble the components into which the seal is mounted. Thus production time is not lost due to shut down of the flow of hydrocarbons through the telescopic joint.

Whilst the specific description relates to the use of such a packer assembly in a telescopic joint, the invention may be utilised in other non-telescopic joint applications.

Claims

1. A packer assembly comprising an inner packer element and an outer concentric packer element, an actuator which is slidable over the outer packer element to deflect the outer packer element inwards against the inner packer element and a sensor for detecting linear movement of the actuator relative to the outer packer element.

2. A packer assembly according to claims 1 , wherein the outer packer element comprises a profiled outer surface.

3. A packer assembly according to claim 1 or 2, wherein a setting component is provided between the actuator and the outer packer element.

4. A packer assembly according to claim 3, wherein the setting component comprises a profiled outer surface.

5. A packer assembly according to claim 3 or 4, wherein the setting component comprises a plurality of bodies mounted between the actuator and the packer assembly.

6. A packer assembly according to any of claims 3-5, wherein the plurality of bodies form a segmented ring between the actuator and the packer assembly.

7. A packer assembly according to claim 6 wherein the plurality of bodies are radially moveable relative to the packer elements.

8. A packer assembly according to any of claims 5-7, wherein each body is substantially C-shaped.

9. A packer assembly according to any of claims 5-8, wherein each body of the setting component comprises a spine with a profiled outer surface.

10. A packer assembly according to claim 9, wherein each body of the setting component further comprises upper and lower arms which extend from the spine inwardly towards the packer assembly.

1 1. A packer assembly according to any of claims 5-10, wherein a connector strap or bar is provided between adjacent bodies of the setting component.

12. A packer assembly according to claim 1 1 , wherein the connector bar or strap is slidably mounted between adjacent bodies.

13. A packer assembly according to any of claims 2 or claims 3-12 when dependent upon claim 2, wherein the actuator comprises a cam surface which cooperates with the profiled outer surface of the outer packer element.

14. A packer assembly according to any of claims 2-13, wherein the actuator comprises a substantially tubular sleeve.

15. A packer assembly according to claim 14, wherein the sleeve is slidably mounted over the outer surface of the outer packer element or the setting component.

16. A packer assembly according to any of claims 13 or claims 14 or 15 when dependent upon claim 13, wherein the cam surface of the actuator is provided on an internal surface of the sleeve.

17. A packer assembly according to any of claims 13-16 when dependent upon claim 2, wherein the cam surface of the actuator comprises a tapered surface which cooperates with the profiled outer surface of the outer packer element or the setting component to force the outer element radially inwards against the inner packer element.

18. A packer assembly according to any of claims 2-17, wherein the profiled outer surface of the outer packer element comprises a plurality of polyurethane blocks, elements or forms.

19. A packer assembly according to claim 18, wherein the blocks are mounted to a rubber component which forms the inner surface of the outer packer element.

20. A packer assembly according to claim 19, wherein the blocks on the outer surface of the outer packer element have a tapered surface which cooperates with the tapered surface on the cam profile on the actuator sleeve.

21. A packer assembly according to any of claims 14-20, wherein the sleeve is mounted within a chamber containing hydraulic fluid.

22. A packer assembly according to claim 21 , wherein one or more pistons are mounted to the outer surface of the sleeve.

23. A packer assembly according to claim 22, wherein the or each piston is provided within a piston chamber such that the piston(s) move(s) through the chamber(s) as the sleeve moves vertically.

24. A packer assembly according to any of the previous claims wherein the sensor comprises a body which is moveable through a secondary chamber.

25. A packer assembly according to claim 28, wherein one or more apertures are provided between the piston chamber and the secondary chamber to provide a pathway for hydraulic fluid from the chamber within which the piston is provided and the secondary chamber.

26. A packer assembly according to claim 24 or 25 wherein the secondary chamber comprises a first portion having a first diameter and a second portion having a second diameter.

27. A packer assembly according to claim 26 wherein the diameter of the second portion is smaller that then diameter of the first portion.

28. A packer assembly according to claim 27 wherein the diameter of the second portion is around ¼ the diameter of the first portion.

29. A packer assembly according to any of the preceding claims, the arrangement being such that as the actuator slides over the outer surface of the outer packer element, hydraulic fluid is forced from the piston chamber into the sensor chamber through the apertures to force the sensor body to move through the sensor chamber.

30. A packer assembly according to any of the preceding claims, wherein means are provided in the sensor chamber for viewing the position of the sensor within the chamber.

31. A packer assembly according to claim 30, wherein a window or slot is provided in the sensor chamber through which the piston can be viewed.

32. A packer assembly according to claim 31 , wherein a scale may be provided adjacent to or on the window slot or alternatively on the sensor.

33. A packer assembly according to any of the preceding claims, wherein the packer assembly further comprises a linear potentiometer.

34. A packer assembly according to any of the preceding claims, wherein the packer assembly further comprises a wireless transmitter which sends a signal to a wireless receiver indicative of the position of the piston within the packer assembly.

35. A packer assembly according to any of the preceding claims wherein the assembly further comprises an outer housing.

36. A packer assembly according to claim 35 wherein the outer housing surrounds the packer elements and comprises flanged covers at each end.

37. A packer assembly according to claim 36 further comprising a latch for securing the flanged covers to the outer housing.

38. A packer assembly according to claim 37 wherein the latch comprises a profiled locking member.

39. A packer assembly according to claim 38 wherein the flanged covers have angled detents provided therein into which the profiled locking member can be driven.

40. A packer assembly according to any of claims 36-40 further comprising one or more spacers mounted between the packer elements and the flanged covers of the housing.

41. A packer assembly substantially as hereinbefore described with reference to and a shown in the accompany figures.

42. A telescopic joint comprising and outer tubular member and a concentric inner tubular member, the inner member being slidably received within the outer member and a packer assembly according to any of the preceding claims provided between the inner wall of the outer tubular member and the outer wall of the inner tubular member.

43. A telescopic joint substantially as herein before described with reference to and as shown in the accompanying figures.