WO2017042152A1

WO2017042152A1 - Valve actuator with a hydraulic locking device

Info

Publication number: WO2017042152A1
Application number: PCT/EP2016/070952
Authority: WO
Inventors: Scott Benjamin Randall
Original assignee: Ge Oil & Gas Uk Limited
Priority date: 2015-09-07
Filing date: 2016-09-06
Publication date: 2017-03-16
Also published as: GB2541943A; GB201515809D0

Abstract

An actuator 10 for a flow or isolation valve which may be used subsea is disclosed. The actuator comprises a piston 11 arranged to be moved between first and second positions, a hydraulic locking mechanism 12 to lock the piston 11 in the first or second position and an electric motor 16 to move the piston 11 from the first to the second position. An electric motor operated subsea actuator 10 may be relatively inexpensively and reliably remotely controlled by an electrical control line 17 such as an electric cable from the surface for example.

Description

VALVE ACTUATOR WITH A HYDRAULIC LOCKING DEVICE

The present invention relates to actuators, such as actuators which may be used subsea to control a flow or isolation valve. In one example, an actuator may be used to control a valve in a subsea control system such as for a blow-out-preventer, a tree system or a manifold for example.

Actuators for valves used in the oil and gas industry are preferably 'failsafe-closed' to reduce the likelihood of an uncontrolled release of hydrocarbons in the event of a loss of power or control or in the event a failure for example. This failsafe-closed state is generally provided by one or more springs which, in the absence of an opening force, urge the valve into the closed state.

Hydraulic fluid is generally used to open a valve by pushing back against the spring force. In subsea oil and gas applications, the hydraulic fluid is normally supplied from a surface location such as from a platform or a vessel for example via an umbilical. The umbilical generally includes several lines for the supply of hydraulic fluid to various subsea actuators. The length of the umbilical will depend upon the circumstances, but for a typical subsea installation it could be several hundred metres or tens of kilometres in length. Because of the need to protect the hydraulic lines over the considerable length in hostile and high pressure subsea environments, the umbilical is very expensive and complicated making it liable to failures from leaks for example.

It would be desirable to reduce the cost and increase the reliability of the operation of actuators for use in controlling valves for example.

In accordance with the present invention there is provided an actuator for a valve, the actuator comprising: a piston arranged to be moved between first and second positions; a hydraulic locking mechanism to lock the piston in the first or second position; and an electric motor to move the piston from the first to the second position.

Using an electric motor to move the piston from the first to the second position, such as to move a flow or isolation valve from a closed to an open position, overcomes the problems of conventional hydraulic systems which require an expensive hydraulic umbilical. In contrast, the electric motor of our invention may be relatively inexpensively and reliably controlled by an electrical control line such as an electric cable which is less expensive and less prone to failure than a hydraulic line which may suffer from leaks and loss of pressure.

The electric motor could be a direct drive motor or have a rotary-linear converter to drive the piston back and forth for example.

The hydraulic locking mechanism could comprise a by-pass conduit connected to each side of the piston with a locking valve in the by-pass conduit to allow fluid to pass therethrough when the piston is to be moved between the first and second positions and to prevent the flow of fluid therethrough when the piston is to be locked in either the first or second position.

The actuator could be used to actuate any appropriate component such as a flow or isolation valve, such as a bore valve, a balanced valve or a non-balanced valve for example. The piston of examples of our actuator may be connected to the appropriate portion of the flow valve, such as a stem, to move the flow valve between the closed and open positions. When used in oil and gas applications, the actuator may include one or more springs as a failsafe closed arrangement.

A subsea control system such as a blow-out-preventer, a tree system or a manifold may be provided with the actuator of examples of our invention. The actuator may be provided in combination with a flow valve. Blow-out-preventers, tree systems and manifolds provided with actuators of examples of our invention may be controlled inexpensively and reliably with electrical control lines for the electric motor to move the piston. Electrical control lines are less prone to failure and less expensive to install and maintain than conventional hydraulic umbilicals. Examples of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 shows an example of an actuator according to the present invention;

Figure 2 shows the actuator of Figure 1 with the piston in a second position; Figure 3 shows an example of the actuator arranged to actuate a flow valve;

Figure 4 shows an example of an actuator with a linear electric motor;

Figure 5 shows an example of an actuator with an internal locking valve;

Figure 6 shows an example of an actuator with a balanced flow valve;

Figure 7 shows an example of an actuator with an override; Figure 8 shows an example of an actuator arranged to actuate a ball valve;

Figure 9 shows an example of an actuator with a linear motor arranged to actuate a ball valve;

Figure 10 shows an example of a tree incorporating examples of actuators according to the present invention; Figure 11 shows an example of a manifold system incorporating examples of actuators according to the present invention; and

Figure 12 shows an example of a blow-out-preventer incorporating examples of actuators according to the present invention.

Figure 1 shows an example of an actuator 10 according to the present invention. The actuator 10 includes a piston 11 which is shown in Figure 1 in a first position and which is arranged to be moved to a second position such as shown in Figure 2 for example. A hydraulic locking mechanism 12 is provided to lock the piston 11 in the first or second positions. In this example, the hydraulic locking mechanism 12 comprises a locking valve 13 provided in a by-pass conduit 14 connected at each end to a housing 15 in which the piston 11 is provided. The ends of the by-pass conduit 14 are arranged to be connected to the housing 15 outside the range of movement of the piston 11 within the housing 15. The by-pass conduit 14 enables hydraulic fluid within the housing 15 to be displaced from one side of the piston 11 to the other when the piston is moved in either direction. Closing the locking valve 13 prevents hydraulic fluid passing through the by-pass conduit 14 such that the piston 11 is hydraulically locked in position when the locking valve 13 is closed. An electric motor 16 is provided to move the piston 11 whilst the valve 13 is open. The electric motor 16 may be arranged to move or turn in one direction or another or stop by a control line 17, such as an electrical cable carrying a control signal which may be operated remotely for example. The locking valve 13 may also be opened or closed by a control line, such as an electrical cable. In this example the piston 11 is shown with a stem 18 which may be used to actuate an associated component such as a valve for example. Using an electric motor 16 to move the piston 11 provides an actuator 10 which may be inexpensively and reliably controlled.

Figure 3 shows an example of the actuator 10 connected to a flow valve 20, in this example a gate valve. This gate valve has a moveable gate 21 with an orifice 22 which may be moved back and forth by the stem 18 to be either in line with a perpendicular flow conduit (not shown) allowing the passage of fluid through the flow valve 20 or alternatively to block the flow of fluid. In this example the flow valve 20 has a stem seal 23 to allow movement of the stem 18 but prevent hydraulic fluid leaking from the actuator 10. The stem seal 23 is also provided to prevent fluid passing through the flow valve 20, such as from a well bore for example, from entering the actuator mechanism. The actuator of this example has been provided with a resilient member 24, in this example a spring, to provide a failsafe closed feature.

The hydraulic locking mechanism 12 of the example of Figure 3 includes two locking valves 13, such as solenoid check valves, to provide double redundancy. The one or more locking valves 13 may be provided attached to or on a housing of the actuator 10 or the associated flow valve 20 or any other associated component such as a blowout-preventer, tree system or manifold for example. In this example the by-pass conduit 14 includes a damper 25. The damper 25 may be a restrictor or orifice through which the hydraulic fluid is arranged to flow. Under sufficiently high velocity, such as if the actuator 10 is closed under the force of the spring 24, a significant fluid pressure drop will take place, with a corresponding high level of flow induced shear. This high shear flow will consequently raise the temperature of the actuator fluid. Using the damper 25, much of the spring energy is dissipated into heat, in addition to closing the valve, reducing any impact which might otherwise damage the actuator 10 or any component in the load path of the impact. During normal operation, with the electric motor 16 controlling the movement of the piston 11, the hydraulic fluid will pass through the damper 25 at a reduced velocity, with much less flow induced shear and less energy dissipation providing smooth movement of the stem 18. The by-pass conduit 14 of the example of Figure 3 also includes a compensator 26 to account for rising stem effects produced by volume changes due to the movement of the stem 18. The electric motor 16 of the example of Figure 3 has an associated rotary - linear converter 27 to convert rotary motion produced by the electric motor 16 into linear motion to move the piston 11. The rotary- linear converter 27 may for example be a ball screw or helical spline with back-drive functionality. The electric motor 16 may be provided with a gear set for appropriate movement of a stem 18. An electrical penetration 28 is shown in this example for the control line 17, such as an electrical wire, to control the operation of the electrical motor 16.

The outer edge of the piston 11 engages the inside surface of the housing 15 providing a seal. In the example of Figure 3 the seal is enhanced by the provision of an O-ring 29 around the circumference of the piston 11. Of course if a piston 11 with a non- circular cross-section is used an appropriately shaped seal 29 may be provided.

If required, the actuator 10 could periodically have the hydraulic fluid levels topped- up. If used in underwater applications, the hydraulic fluid could be topped-up with a remote-operated-vehicle (ROV) using a hot stab for example which could engage an isolation valve (not shown) connected to the by-pass conduit 14 or housing 15. Figure 4 shows an example of the actuator 10 in combination with a flow valve 20 in a similar arrangement to that shown in Figure 3 except that instead of a rotary electric motor 16 and associated rotary - linear converter 27, the example of Figure 4 has an electric linear motor 30. Figure 5 shows an example of the actuator 10 in which the hydraulic locking mechanism 12 is provided inside the actuator housing 15 instead of externally as in the previous examples. In this example of the hydraulic locking mechanism 12, the locking valve 13 comprises a mechanical poppet valve associated with the piton 11 and stem 17 as shown in greater detail in the enlargement of the hydraulic locking mechanism 12 in the Figure. The volumes on each side of the piston 1 1 are connected by conduits 40 on a first side of the piston 11, the poppet valve 41 and a port 42 on the other side of the piston 11. Any suitable type of valve 13 may be used, but in the example of the poppet valve 41 shown in the enlargement of Figure 5 there is provided a poppet seal interface 43, a left spring 44, a right spring 45, a sliding spring interface 46 and an actuator interface 47. In this example the left spring 44 unseats the poppet and the right spring closes the poppet. The poppet valve 41 allows the piston 11 to move during the valve open stroke.

When the electric motor 16 provides full motor load, the poppet spring load will be such that the poppet valve 41 will open permitting the flow of hydraulic fluid from one side of the piston 11 to the other and enabling the piston 11 to move. Conversely, with no or a light electric motor load, the poppet valve 41 will remain closed preventing the flow of hydraulic fluid from one side of the piston 11 to the other and locking the piston 11 in place.

Figure 6 shows the actuator 10 provided to control a different type of flow valve 20 from Figure 3 to 5. In Figure 6, the actuator 10 is shown connected to a balanced stem valve 20 which includes a fluid pressure balance port 51 to balance the pressure on each side of the gate 52. A cap 54 may be provided on the end of the balanced valve 20.

Figure 7 shows the actuator 10 provided with a mechanical override 60. As can be seen, in this example an override shaft 61 is connected to or provided as an extension of the stem 18. The position of the override shaft 61 at an interface 62 at the end of the housing can provide a visual indication of the status of the actuator 10. When used underwater a seal 63 can provide a barrier to sea water. When the actuator 10 needs to be overridden, for example after a power failure, a ROV may be used to move the override shaft 61, in this example in a linear direction. Alternatively the override shaft 61 could be actuated with rotary motion if a rotary - linear converter such as a thread interface is provided. The override shaft 61 is preferably restrained with a key which may be engaged with the housing for example to prevent rotation.

Figure 8 shows an example of the actuator 10 connected to a ball valve 20 which is actuated by rotation of an actuator rotary stem 71 arranged to rotate a ball 72 within the flow valve 20. Similar to the example in figure 3, a stem seal 73 is provided to contain fluids on each side of the stem. Unlike the previous examples, in this example the piston 11 and hydraulic locking mechanism 12 are provided on the opposite side of the electric motor 16 from the flow valve 20 with the actuator unit sealed at the end 74 furthest from the flow valve 20.

Figure 9 shows an example of the actuator 10 with a ball valve like Figure 8 except with a linear motor 30 rather than the rotary motor 16 of Figure 8.

The actuator 10 described above may be provided in many applications or subsea control systems such as in a tree, a manifold and a blow-out-preventer. Figure 10 shows an example of a tree 100 provided with actuators 10. The actuators 10 may each be associated with a corresponding flow valve. In this example of a tree, a wellhead 101 is provided with a tubing hanger 102 and a tree connector 103 on which is provided a master valve block 104 and a tree cap 105. The actuators 10 have been found to provide reliable control of flow valves within the tree 100 with reliable and inexpensive control from electrical control wires which may be controlled from the surface for example.

Figure 11 is an example of a manifold system 200 including a number of actuators 10 each provided with an associated flow valve. In this example flow line 201 is an oil production line, flow line 202 is a water injection line, flow line 203 is a well test line, flow line 204 connects to the water injection line 202, flow lines 205 and 206 connect to an oil production tree via the oil production line 201 and valve 207 is an actuator 10 controlled pigging valve.

Figure 12 shows an example of blow-out-preventer 300. In this example ring gaskets 301 are provided above an annular BOP 302 with a clamp 303 below it. Ram BOPs 304 are provided with a drilling spool 305 and a valve 306 which is controlled by the actuator 10 of an example of our invention as explained above. The blow-out- preventer 300 is shown in this example provided on a wellhead 307 with casing 308.

The use of the actuator 10 with flow or isolation valves 20, tree systems 100, manifold systems 200 and BOPs 300 described above may be combined in any desired arrangement of subsea systems. For example, the actuators 10 may be provided in a cluster tree and manifold arrangement, a template tree and manifold arrangement, a tree with a production flow base featuring a production isolation valve, a daisy chained plurality of tree systems, a single tree tied-back to a surface platform or multiple combinations of all of the above.

Examples of the actuator 10 described above with an electric motor 16, 30 may be relatively inexpensively and reliably remotely controlled, such as from a surface location, by an electrical cable which is less expensive and less prone to failure than a hydraulic line which may suffer from leaks and loss of pressure. The hydraulic locking mechanism 12 may be self-contained and also not require any controlling supply of hydraulic fluid, reducing costs and increasing reliability. The actuator 10 may be used to actuate any appropriate component such as a flow or isolation valve 20 and used in a subsea control system such as a blow-out-preventer, a tree system or a manifold or with a combination of components or in a combination of systems.

Claims

CLAIMS:

1. An actuator for a valve, the actuator comprising: a piston arranged to be moved between first and second positions; a hydraulic locking mechanism to lock the piston in the first or second position; and an electric motor to move the piston from the first to the second position.

2. The actuator according to claim 1, wherein the electric motor is arranged to be controlled by an electrical control line.

3. The actuator according to claim 1 or claim 2, wherein the electric motor produces a rotary movement and is coupled to a rotary-linear converter to move the piston.

4. The actuator according to claim 1 or claim 2, wherein the electric motor is a direct drive motor.

5. The actuator according to any preceding claim, wherein the hydraulic locking mechanism comprises a by-pass conduit having open ends in fluid communication with each side of the piston with a locking valve in the by-pass conduit to allow hydraulic fluid to pass therethrough when the piston is to be moved between the first and second positions and to prevent the flow of hydraulic fluid therethrough when the piston is to be locked in either the first or second position.

6. The actuator according to claim 5, wherein the by-pass conduit is provided externally to a housing in which the piston is mounted.

7. The actuator according to claim 5, wherein the by-pass conduit is provided internally within a housing in which the piston is mounted.

8. The actuator according to any of claims 5 to 7, wherein the by-pass conduit includes a damper.

9. A flow valve coupled to an actuator according to any preceding claim, wherein the actuator is arranged to open and close the flow valve.

10. The flow valve according to claim 8, wherein the actuator provides a linear motion to open and close the flow valve.

11. The flow valve according to claim 9, wherein the actuator provides a rotary motion to open and close the flow valve.

12. A control system including an actuator or flow valve according to any one of the preceding claims.

13. A subsea tree including an actuator or flow valve according to any one of claims 1 to 11.

14. A manifold system including an actuator or flow valve according to any one of claims 1 to 11.

15. A blow-out-preventer including an actuator or flow valve according to any one of claims 1 to 11.