GB2200154A - Sealing wellheads - Google Patents

Abstract

A seal energising device is provided for use with a seal member in the provision of a seal in well-head apparatus, the device comprising a thruster assembly located in the well-head body 1. The thruster assembly comprises a rotable actuating sleeve 5 to the outer wall of which is threaded reaction ring 4, the actuating sleeve 5 acting on an annular pressure element 7 for the sealing action. The ring 4 carries a series of pivotal levers 11 which on rotation of the sleeve 5 are swung into abutment pins 14 on the body 1 by means of cams on the sleeve 5 whereby the ring 4 is held stationary. By virtue of its threading to the ring 4, the actuator sleeve 5 can now be caused to move downwards for the sealing effect on approtriate rotation of the sleeve 5. <IMAGE>

Description

S~~l~EQe gi~iQg~~~~ice Descrietion The present invention relates to a seal energising device for use with a seal member in the provision of a seal in well-head apparatus.

In the production of oil, a well-head is a heavy piece of apparatus which is installed on top of the surface string of delivery casing or on the conductor pipe giving access to a borehole for the purpose of drilling, controlling pressure in the hole and regulating the flow of fluid via the borehole. The well-head which may require to withstand considerable pressure is usually in the form of a thick-walled casing of forged or cast steel with radial end flange means to enable the well-head to be joined to ancillary equipment.

An annular seal is present in the well-head at the casing string, means being provided to move the seal to an operative sealing position, ie. seal energisation.

Up until now these means have comprised an annular series of screw pusher devices which extended laterally through the well-head wall, the devices including bevelled or conical heads at their inner ends, the arrangement being such that operation of the pusher devices caused the inner ends of the devices to exert a thrust on the annular seal in the axial direction of the well-head for placement of the seal in the operative position. Disadvantages of this arrangement were that the provision of bores in the well-head casing wall for the pusher devices weakened the wall so reducing the ability of the well-head to withstand high operating pressures, thereby giving rise to potential pressure leak paths, and further in some circumstances, actuation of the various thruster devices could be awkward for the operator.

It is an object of the present invention to obviate or mitigate these disadvantages.

According to the present invention there is provided a seal energising device for use with a seal member in the provision of a seal in well-head apparatus including a thruster assembly for axial location relative to the well-head, said thruster assembly comprising a reaction member, an actuating member in threaded engagement with the reaction member, and pressure element acted on by the actuating memberj the energising device additionally including locking means for the reaction member and means for rotating the thruster assembly.

Preferably the pressure element and the actuating member are reLatively rotatable.

Preferably the locking means comprises arrester lever means, abutment means for the lever means, and control means for movement of the lever means into an operative position wherein the lever means engage the abutment means to prohibit rotation of the reaction member.

Preferably the control means comprise a cam device, the lever means comprising pivoted levers.

An embodiment of the present invention will now be described by way of example with reference to the accompanying drawings wherein: Fig. 1 shows a sectional elevation of part of a well-head i nd i cat ing a seal energising device according to the present invention, through section A-A in Fig. 2 Fig. 2 is a partial plan view of the apparatus of Fig. 1 and Fig. 3 is part sectional isometric view of the apparatus of Fig. 1.

Figs. 1 to 3 show a wall 1 of a well-head having therein a seal energising device 2, a tubing (or casing) hanger 3 additionally being indicated. The device 2 serves to energise a seal at the hanger 3 and comprises an axially located thruster assembly including a reaction ring 4, an annular actuating member 5 in screwthreaded engagement with the reaction ring 4 via threads 6 (e.g. acme thread) and a pressure ring 7 carried by the actuating member 5. The member 5 supports the pressure ring 7 via annular ball race 8 permitting relative rotation between the member 5 and the ring 7 while the actuating member 5 can apply an axial thrust on the ring 7 via a plain bearing 9.

A series of annular slots (three) 10 is provided in the reaction ring 4 and each slot 10 houses a reaction arm or lever 11 which is pivotally carried by a vertical pin 12 mounted in the ring 4. Each arm 11 is pivoted into an annular groove 13 in the well-head wall 1, and a series of reaction pins 14 associated with the arms 11 and carried by the wall 1 extend into the groove 13 to serve as abutments for the arms 11. For movement of the arms 11 into the groove 13, a cam lobe system 15 is provided on the actuating member 5 and operate on a wall 11A of the arms 11 when there is relative rotation between the ring 4 and the member 5 to cause appropriate pivoting of the arms 11.

A suitably formed energising ring 16 at the upper end of the member 5 can be coupled to suitable drive means for rotation of the thruster assembly. The drive means may be a purely mechanical drive but could also be a remote fluid drive for example.

The energising device 2 serves to energise elastomer or metal-to-metal seals between the casing or tubing hanger 3 and the well-head body 1.

In operation, the tubing (or casing) hanger 3 is firstly run and thereafter the energising device 2.

Thus the device 2 is located on a suitable running tool and lowered into the well-head until it shoulders on the tubing or casing hanger 3 as shown in Fig. 1. The energising ring 16 is now rotated and the cam system 15 will cause the reaction arms 11 to be pivoted into the groove 13 (see Fig. 2), the device being arranged such that there is initial relative movement between the reaction ring 4 and the energising ring 5, while further rotation of the assembly brings the arms 11 into abutment with the pins 14. Consequently the reaction ring 4 is now locked in position, and further rotation of the ring 16 will cause the actuating member 5 to move downwardly on the thread 6 and thus provide a thrusting action on the pressure ring 7. A strong downward force can therefore be applied on the seal elements and therefore effect a satisfactory seal in the well-head.

As will be seen, the device 2 does not require lateral bores in the well-head wall 1 and in fact well-head penetrations can be kept to a minimum. This encourages the well-head to handle high-pressure conditions and fluid leakages will be minimised.

Further, energisation of this seal can be simply achieved by rotation of the single energising ring 16 in contrast to the prior art systems which required the individual operation of a multiplicity of lateral pusher devices.

The elastomer or metal-to-metal seals can be either independent or in situ or mandrel suspension systems.

Claims (10)

Claims

1. A seal energising device for use with a seal member in the provision of a seal in well-head apparatus comprising a thruster assembly for axial location relative to the well-head, said thruster assembly comprising a reaction member, an actuating member in threaded engagement with the reaction member, and a pressure element acted on by the actuating member; the energising device additionally including locking means for the reaction member and means for rotating the thruster assembly.

2. A seal energising device as claimed in claim 1, wherein the pressure element and the actuating member are relatively -rot-atable.

3. A seal energising device as claimed in claim 1 or claim 2, wherein the locking means comprises arrester lever means, abutment means for the lever means, and control means for movement of te lever means into an operative position wherein the lever means engage the abutment means to prohibit rotation of the reaction member.

4. A seal energis-ing device as claimed in claim 3 wherein the control means comprise a cam device, and the lever means comprise pivotal levers moved by the cam device.

5. A seal energising device as claimed in claim 3 or 4, wherein the reaction member comprises a collar, and the lever means comprises an annular series of levers carried by the collar.

6. A seal energising device as claimed in any one of claims 3 to 5, wherein the abutment means are located in an outer casing surrounding the thruster assembly.

7. A seal energising device as claimed in claim 6, wherein the abutment means are defined by abutment members on an inner wall of said outer casing.

8. A seal energising device as claimed in claim 4, wherein the cam device is located on the actuating member.

9. A seal energising device as claimed in any one of the preceding claims, wherein a ball race is located between the actuating member and the pressure element.

10. A seal energising device substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.