Methods and apparatus for monitoring components of downhole tools
Disclosed herein is a surface controlled subsurface safety valve (SCSSV) that includes a moveable component of the SCSSV and a stationary component of the SCSSV. A sensor element is also included which is configured to sense position of the moveable component relative to the stationary component. Further disclosed herein is a method for sensing position of an object which includes placing a component comprising magnetostrictive material in a location calculated to be contacted by a separate component and causing a stress on the material with the separate component. The method further includes measuring a change in magnetic permeability of the material.
This application claims the benefit of an earlier filing date from U.S. Provisional Application Ser. No. 60/618,826 filed Oct. 14, 2004, the entire disclosure of which is incorporated herein by reference.
BACKGROUNDDownhole tools having movable components, such as but not limited to surface controlled subsurface safety valves (SCSSV) are ubiquitously utilized and sometimes mandated in the hydrocarbon exploration and recovery art. Both safety systems and simply exploration or production devices could be improved by enhancements in means to monitor the positions thereof.
Using SCSSV's as a particular example, it is important for an operator to have knowledge of the position and/or condition of SCSSV's for various reasons. Traditionally, such knowledge has been gained by monitoring flow volume from the well and control line pressure at the surface. These methods work well in instances where the well is operating correctly and where the SCSSV is not an excessive distance from the source of the control signal. Where operating parameters of the well are not ideal however, and/or the SCSSV is a substantial distance from the source, such as in sub-sea applications, traditional methods for adjudging the position of the valve are suspect and cannot be relied upon. Doubt in this regard for any downhole tool is generally the initiator of lost time and potentially unnecessary expense. Uncertainty is never beneficial to the hydrocarbon industry; better means of determining things such as SCSSV position/condition will be welcomed by the art.
SUMMARYDisclosed herein is a downhole tool that includes a moveable component and a stationary component. A sensor element is also included to sense position of the moveable component relative to the stationary component.
Further disclosed herein is a method for sensing position of an object which includes placing a component comprising magnetostrictive material in a location calculated to be contacted by a separate component and causing a stress on the material with the separate component. The method further includes measuring a change in magnetic permeability of the material.
BRIEF DESCRIPTION OF THE DRAWINGSReferring now to the drawings wherein like elements are numbered alike in the several figures:
Obtaining more knowledge about downhole tools can be occasioned, even in real time, by careful and creative positioning of sensory devices. In some embodiments hereof, the sensing device(s) comprise a magnetostrictive material such as Terfenol-D commercially available from Etrema Products, Inc. The magnetostrictive material exhibits different magnetic permeability when placed under stress, and particularly compression, than it does when not under stress. Magnetic permeability is measured by supplying a current to a coil around the magnetostrictive material. This property is reliable and repeatable and the material itself is highly robust making Terfenol-D a useful sensing material for downhole tools. It is to be appreciated that Terfenol-D is but a single example of a magnetostrictive material and that others with similar properties could be substituted. In the exemplary embodiment of Terfenol-D, reference is made to U.S. Pat. No. 6,273,966 which is fully incorporated herein by reference, wherein Terfenol-D is described in more detail. In the event a check is desired, a second magnetostrictive device is deployed in proximity to the first but which is not exposed to the stress creator intended to be measured. Any permeability change due to conditions not related to the stress creator being measured will register on both devices, making resolution of the target stress creator clear and reliable. In other embodiments hereof permanent magnets, hall effect sensors and mechanical, electrical or optical limit switches or optical readers may be employed. In each embodiment the goal is to obtain more direct and rapid indication of a particular condition or position of a device downhole, such as for example one or more of the components of a SCSSV. It is also to be understood that one or more of the types of sensors may be employed in the same device and one or more of the same type of sensor may be employed in the same devices.
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Sensors 30 and 32 are informationally connected to sensor electronics 34 which are programmed to interpret what has been sensed and emit a signal to be propagated to a remote location along schematic cable 36, which may be hydraulic, electric, optic or wireless in configuration.
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It is important to understand that all of the above embodiments are exemplary in nature and that the concept of positioning a sensor element relative to a moveable and stationary component to sense relative position of the two components is applicable to all tools that include a moveable and stationary (or even another moveable) component. These include such as sliding sleeves, cross-over tools moveable service tools, any type of safety valve, open/close sleeves, etc.
While preferred embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation.
Claims
1. A downhole tool comprising:
- a moveable component of the downhole tool;
- a stationary component of the downhole tool; and
- a sensor element configured to sense position of the moveable component relative to the stationary component.
2. A downhole tool as claimed in claim 1 wherein the sensor element is a magnetostrictive material having predictable change in magnetic permeability when stressed.
3. A downhole tool as claimed in claim 1 wherein the sensor is a hall effect type sensor.
4. A downhole tool as claimed in claim 1 wherein the sensor is a mechanical switch type sensor.
5. A downhole tool as claimed in claim 1 wherein the sensor is a optical sensor.
6. A downhole tool as claimed in claim 1 wherein the moveable component is a closure member.
7. A downhole tool as claimed in claim 1 wherein the moveable component is a flow tube.
8. A downhole tool as claimed in claim 1 wherein the moveable component is a piston.
9. A downhole tool as claimed in claim 6 wherein the closure member includes a cam surface configured to bear against the sensor element in one of an open condition and a closed condition of the closure member.
10. A downhole tool as claimed in claim 8 wherein the piston includes a magnet and the stationary component supports the sensor element which is configured to sense the magnet.
11. A downhole tool as claimed in claim 6 wherein the closure member supports the sensor element such that the sensor element is in communication with a torsion spring locating against the closure member.
12. A downhole tool as claimed in claim 11 wherein the sensor element is in communication with a power spring.
13. A downhole tool as claimed in claim 1 wherein the sensor element is two sensor elements, one positioned at one end of the travel of the moveable component and the other positioned at another end of travel of the moveable component.
14. A downhole tool as claimed in claim 13 wherein the sensors are carried by the moveable component.
15. A downhole tool as claimed in claim 14 wherein the sensors are carried by the stationary component.
16. A method for sensing position of an object comprising:
- placing a component comprising magnetostrictive material in a location calculated to be contacted by a separate component;
- causing a stress on the material with the separate component; and
- measuring a change in magnetic permeability of the material.
17. A method for sensing position for an object comprising:
- placing a magnetostrictive material in a location, the location including a coil;
- applying a current to the coil;
- measuring magnetic permeability of the material; and
- comparing measured magnetic permeability to known permeability of the magnetostrictive material in an unstressed condition.
18. A method for sensing position for an object as claimed in claim 17 where the method further comprises:
- determining whether the material is stressed to conclude a position of the object in one of in contact with the material and spaced from the material.
Type: Application
Filed: Oct 13, 2005
Publication Date: Jul 20, 2006
Inventors: Brian Shaw (Broken Arrow, OK), Charles Tompkins (Tulsa, OK)
Application Number: 11/249,809
International Classification: E21B 47/00 (20060101); E21B 34/10 (20060101);