GB2389128A

GB2389128A - Operating downhole devices

Info

Publication number: GB2389128A
Application number: GB0211022A
Authority: GB
Inventors: Steven Martin Hudson
Original assignee: Flight Refuelling Ltd
Current assignee: Cobham Mission Systems Wimborne Ltd
Priority date: 2002-05-14
Filing date: 2002-05-14
Publication date: 2003-12-03
Also published as: GB0211022D0

Abstract

A subsurface safety valve operating device comprising a member (6) arranged to be moveable under the action of ambient downhole pressure and control means (10) for controlling movement of the moveable member under the action of the ambient downhole pressure.

Description

2389 1 28

Operating downhole devices This invention relates to the operation of downhole devices.

s Various devices must be operated m downhole situations by which it is meant below the surface in wells, typically within the oil and gas industry. Wherever a device has to be operated a source of power is needed in order to bring about that operation. In downhole situations there are a number of options available for providing power, such as using batteries or supplying power from a remote 10 location via an electrical connection. However, each of these methods has associated disadvantages.

It is an object of this invention to provide a different way of operating downhole devices.

According to one aspect of the present invention there is provided a downhole device comprising a member arranged to be moveable under the action of ambient downhole pressure and control means for controlling movement of the moveable member under the action of the ambient downhole pressure.

According to another aspect of the present invention there is provided a method

of operating a downholc device using the ambient downhole pressure to drive the device.

According to yet another aspect of the present invention there is provided a 5 method of operating a downhole device using the ambient downhole pressure comprising the steps of arranging a member of the device to be moveabJe under the action of ambient downhole pressure and using control means to control movement of the moveable member under the action of the ambient downholc pressure.

It will be understood that ambient downhole pressure means that pressure that surrounds the device when downhole and acts on any external surface of the device. 15 In such a device and method, the control means is used for controlling the ability of the ambient pressure to move the moveable member. There are two main ways in which this can be achieved - In one case the control means determines whether the ambient pressure can cause a force to act on the moveable member tending to make it move and in the other case the control 20 means determines whether the moveable member is free to move. In said other case the moveab]e member may be permanently subject to the action of the

ambient pressure, this may be by direct exposure to the pressure.

The device may comprise a main body relative to which the moveable member is arranged for movement. The control means may comprise holding means for holding the moveable member against movement relative to the main body.

5 Typically the holding means will be releasable holding means. The holding means may comprise a latch.

The moveable member may comprise a piston. The main body may comprise a cylinder within which the piston is arranged for movement. It will be lo understood that the expression cylinder is used in this specification In the sense

of vessel within which a piston can move and there is no suggestion that the cylinder need be of cylindrical shape.

The main body may comprise a chamber which is sealable against ambient 15 pressure. At least one surface of the chamber may be defined by the moveable member. The pressure in and/or the volume of the chamber may be alterable by movement of the moveable member. The chamber may be defined by walls of the cylinder and a face of the piston.

20 The downhole device may have a prepared state in which the tnoveable member is in a prepared position from which the moveable member is ll !

( moveable under action of ambient pressure and an operated state in which the moveable member is in another position.

The device may be prepared for operation by arranging the interior of the s chamber to be at a first pressure which is lower than the ambient pressure where the device is to be operated. The device may be prepared by sealing the chamber during assembly so that the pressure in the chamber is substantially the same as the environmental or atmospheric pressure where assembly occurs.

10 In a method of using the device, the device may be prepared at a first location having a first pressure and moved to a second location for operation, the ambient pressure at the second location being higher than the first pressure.

The first location may be at the surface. The second location will be downhole.

15 According to a particular aspect of the invention there is provided a downhole device comprising a main body having a cylinder, and a piston arranged for movement m the cylinder, walls of the cylinder and a face of the piston at least partially defining a chamber sealable against ambient pressure, the piston being subject to the action of ambient pressure but bemg held in a first position by 20 releasable holding means, and the arrangement being such that when the holding means Is released, if the ambient pressure exceeds the pressure in the

chamber, the piston will move in the cylinder under action of the ambient pressure. The movement of the moveable member under action of the ambient pressure 5 may be used as a source of dove. The moveable member may be connected to other members.

The downhole device may comprise return means for returning the device towards the prepared state from the operated state. Where the device comprises 10 a chamber sealed against ambient pressure, the return means may comprise means for opening the chamber to ambient pressure. This can facilitate the movement of the moveable member in a direction opposite to that which occurs under action of the ambient pressure. The return means may comprise spring means, which may be disposed in the chamber for acting on the s moveable member.

The control means may comprise triggering means arranged to allow the moveable member to be moved under the action of ambient pressure when predetermined conditions are met. The control means may comprise receiver 20 means for receiving signals from a remote location. The control means may comprise sensor means for sensing at least one parameter such as temperature

or pressure. The control means may comprise timer means. The predetermined conditions may comprise any one of or any combination of: reception of predetermined signals sensed parameters reaching predetermined values elapsing of predetermined time periods.

The downhole device may be an actuator device which is arranged for operating and/or controlling the operation of another device. Such an actuator device might be retrofitted to existing components. Alternatively the downhole device may be a fully functional device in its own right.

In one development of the Invention the downhole device comprises a subsurface safety valve. Subsurface safety valves per se are well known. The function of such valves is to shut off a well if reasons of safety make this necessary. Means must be provided to operate ie shut, the valve. Because of 15 the possible dangers that might be faced a very reliable shutoff mechanism is needed. In a subsurface safety valve embodying the present invention valve means are provided and arranged to be closed by movement of the moveable member.

In some instances a downhole actuator device of the present invention may be

provided for use in operating a distinct subsurface safety valve. I An embodiment of the present mvcnton will now be described by way of example only with reference to the accompanying drawings in which: figure I shows a subsurface safety valve embodying the invention which is located in tubing of a well; Figure 2 shows the subsurface safety valve of Figure I in a configuration O reached after operation.

Figure 1 shows a subsurface safety valve 1 disposed within tubing 2 of a well and in a prepared (open) state whereas Figure 2 shows the valve in an operated (closed) state.

As mentioned above, the function of subsurface safety valves per se is well known, their purpose being to shutoff a well if the situation dictates.

Different forms of valve can be envisaged for acting as a subsurface safety 20 valve. In the present case the exact type of valve is of less interest than the mechanism used in order to drive the valve into a closed position.

In the present embodiment the valve comprises a gate 3 having a fluid transmission bore 4 and being rotatably mounted about a central axis. The gate 3 is moveable around the axis between an open position as shown in Figure 1 in which fluid in the tubing 2 can pass through the bore 4 and closed position s as shown In Figure 2 in which no fluid can pass through the gate 3 such that the well is shutoff.

A first end of a drive rod 5 is pivotally connected to the gate 3 and a second end of this drive rod 5 is connected to a piston 6. The piston 6 is arranged to lo move within a cyhnder 7 provided within a main body 8 of the valve.

A chamber 9 is defined within the main body 8 by walls of the cylinder 7 and a face of the piston 6. This chamber 9 is, in normal circumstances, sealed from the ambient pressure surrounding the valve 1. Furthermore, the valve I is IS arranged so that in normal operating conditions when the piston 6 is in the prepared position, as shown in Figure I, pressure in the chamber 9 is much lower than the ambient downhole pressure surrounding the valve l. In practice this may be achieved by simply manufacturing or assembling the valve I at the surface such that the chamber 9 is filled with air at atmospheric pressure.

20 Once the valve I is moved to a downhole location where the ambient pressure is much higher, the desired pressure differential between the chamber 9 and the

surroundings will naturally occur.

It will be appreciated that such a pressure differential will tend to force the piston 6 to move within the mum body 8 to decrease the volume of the s chamber 9 and correspondingly increase the pressure therein.

However, a releasable latch mechanism 10 is provided to hold the piston 6 against such movement. The presence of the latch 10 allows the valve 1 to be disposed downhole with the piston 6 unable to move and the gate 3 remaining 10 in the open position.

On the other hand, once the releasable latch 10 is released, the piston 6 is able to move within the cylinder 7 reducing the volume of the chamber 9 and pulling the drive rod 5 towards the main body 8. As the drive rod 5 is pulled 15 towards the main body 8, the point on the gate 3 to which the drive rod 5 is connected moves towards the main body causing the gate 3 to rotate to the closed position shown in Figure 2.

Thus, the valve I is operated by action of the ambient pressure and no 20 dedicated power source is required to provide the necessary force to close the valve.

An electronics control module 12 is provided for controlling the operation of the releasable latch 10. In particular, the electronics module]2 is used to control when the releasable latch 10 is released to allow closing of the valve 1.

The electronics module 12 can control this operation on the basis of various S predetermined conditions. In particular, it Is envisaged that the electronics module comprises timing means, receiving means for receiving signals from a remote location, and sensor means for sensing local parameters such as pressure and/or temperature. Any one of, or any combination of, delays timed by the timing means, signals received by the receiving means and parameters 10 sensed by the sensor means may be used to trigger closing of the valve 1.

Whilst the specific description above has been directed to the example of

operating a subsurface safety valve, it will be appreciated that the present invention is of wider applicability in that ambient pressure may be used to

1 S drive a large number of different downhole devices.

Claims

( CLAIMS:

1. A downhole device comprising a member arranged to be moveable under the action of ambient downhole pressure and control means for controlling movement of the moveable member under the action of the ambient downhole 5 pressure.

2. A downhole device according to claim l in which the control means is arranged to determine whether the ambient pressure can cause a force to act on the moveable member tending tO make it move.

3. A downhole device according to claim I in which the control means is arranged to determine whether the moveable member is free to move.

4. A downhole device according to any preceding claim in which the device 15 comprises a main body relative to which the moveable member is arranged for movement.

5. A downhole device according to claim 4 in which the control means comprises holding means for holding the moveable member against movement 20 relative to the main body.

/

6 A downhole device according to claim 5 in which the holding means comprises a latch.

7. A downhole device according to any one of claims 4 to 6 in which the 5 movable member comprises a piston, and the main body comprises a cylinder within which the piston is arranged for movement.

8. A downhole device according to any one of claims 4 to 7 in which the main body comprises a chamber which is sealable against ambient pressure, at 10 least one surface of the chamber being defined by the moveable member and the pressure in and/or the volume of the chamber being alterable by movement of the moveable member.

9. A downhole device according to any preceding claim which has a prepared 15 state in which the moveable member is in a prepared position from which the moveable member is moveable under action of ambient pressure and an operated state in which the moveable member is in another position.

10. A downhole device according to claim 9 when dependent on claim 8 20 wherein during operation and in the prepared state, the interior of the chamber is at a first pressure which is lower than the ambient pressure where the device

is to be operated.

l

11. A downhole device according to claim 1, comprising a main body having a cylinder, and a piston arranged for movement in the cylinder, walls of the S cylinder and a face of the piston at least partially defining a chamber sealable against ambient pressure, the piston being subject to the action of ambient pressure but being held in a first position by releasable holding means, and the arrangement being such that when the holding means is released, if the ambient pressure exceeds the pressure in the chamber, the piston will move in 10 the cylinder under action of the ambient pressure.

12. A downhole device according to any one of claims 1 to 11 which comprises a subsurface safety valve operable by the action of ambient downhole pressure.

13. A downhole device according to claim 12 in which the safety valve comprises valve means arranged to be closed by virtue of movement of the movable member.