Downhole tools are employed in a wellbore via a tool string and operated during a specific well application. To facilitate performance of the specific well application, many downhole tools have more than one operational position and may be selectively shifted between operational positions. During milling operations, for example, fluid flow may be controlled by a downhole valve device which is shifted between operational positions to direct fluid flow to a milling tool or to divert the fluid flow to the annulus. The downhole valve device effectively has two modes of operation, namely a milling mode in which the fluid is directed at a high flow rate through the valve device to the milling tool and a circulation mode in which the fluid is diverted into the annulus by the valve device.
In general, the present disclosure provides a system and method related to an actuator having a locking feature enabling selective locking of the actuator in a desired operational position. For example, the actuator may comprise a mandrel which can be used to shift a tool between operational positions. The mandrel is surrounded by a housing which creates a reservoir, e.g. cavity. A magneto rheological fluid is disposed within the cavity and operates in cooperation with the mandrel to enable selective locking of the mandrel at a desired operational position or positions. A selectively activated or applied magnetic field, activated or applied by an electromagnetic coil or a permanent magnet, may be used to selectively increase the viscosity of the magneto rheological fluid to lock the mandrel at the appropriate operational position.
Certain embodiments will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements. It should be understood, however, that the accompanying figures illustrate various implementations described herein and are not meant to limit the scope of various technologies described herein, and:
In the following description, numerous details are set forth to provide an understanding of some illustrative embodiments of the present disclosure. However, it will be understood by those of ordinary skill in the art that the system and/or methodology may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible.
The disclosure herein generally relates to an actuator having a locking feature enabling selective locking of the actuator in a desired operational position. The actuator may be employed as part of or used in combination with a variety of tools. For example, the actuator may be incorporated into or used in combination with downhole tools deployed in a variety of downhole, well related applications. According to an embodiment, the actuator may comprise a mandrel used to shift a tool between operational positions. The mandrel is surrounded by a housing which establishes a reservoir, e.g. cavity. A magneto rheological fluid is disposed within the cavity and operates in cooperation with the mandrel to provide a locking feature which enables selective locking of the mandrel at a desired operational position (or positions).
Selective application of a magnetic field controls the viscosity of the magneto rheological fluid which, in turn, either locks the mandrel, e.g. resists motion of the mandrel, or allows the mandrel to move relative to the housing. In an embodiment, an electromagnetic coil may be used to selectively create a magnetic field which effectively increases the viscosity of the magneto rheological fluid, thus locking the mandrel at the appropriate operational position. In an embodiment, a permanent magnet may be used to create the magnetic field and an electromagnetic coil may be used to selectively deactivate the magnetic field created by the permanent magnet.
In one embodiment of a downhole application, the actuator is used to control a shiftable device positioned along a tool string. By way of example, the shiftable device may comprise a shiftable valve which controls flow of fluid delivered downhole along the tool string. The actuator may be used to control the operational position of a variety of valves in many types of downhole applications.
In a specific application, the actuator is used as part of or in combination with a multi-cycle circulation valve deployed downhole via coiled tubing to provide a high flow rate of circulating fluid during a milling operation. The multi-cycle circulation valve is actuated to provide two modes of operation referred to as a milling mode and a circulation mode. When in a milling mode, the fluid pumped downhole passes through the multi-cycle circulation valve and flows farther downhole to a bottom hole assembly having a milling tool. When the multi-cycle circulation valve is shifted to the circulation mode, the fluid flowing downhole is diverted into a surrounding annulus. The actuator described herein may be employed in such an application to control the shifting of the valve between milling mode and circulation mode. The locking feature of the actuator enables a dependable locking technique for securing the shiftable valve at a desired operational position or positions, e.g a milling mode position or a circulation mode position.
Referring generally to
In a milling application, the shiftable device 26 may comprise a valve, e.g. a multi-cycle circulation valve, which is selectively shifted between a milling mode and a circulation mode. When in the milling mode, the shiftable device/valve 26 receives fluid pumped down through tool string 22 and directs the flow of fluid to the milling tool 34. When the shiftable device/valve 26 is shifted via actuator 28 to the circulation mode, the fluid pumped down through tool string 22 is diverted to a surrounding annulus 36. In this application, the locking feature 30 may be actuated to selectively and temporarily lock the actuator 28, and thus the shiftable device/valve 26, in either the milling mode or the circulation mode. However, the locking feature 30 can be used to lock the actuator 28 at other or additional positions.
Referring generally to
In the embodiment illustrated, the magneto rheological fluid 44 is forced through a restricted passage 48 when the mandrel 38 is shifted with respect to housing 40. The restricted passage 48 is referred to as an orifice (or orifices) and the orifice 48 (or orifices) may be positioned along various types of passageways through which the magneto rheological fluid 44 is forced when mandrel 38 is shifted with respect to housing 40. In the illustrated example, however, the orifice 48 (or orifices) is located through an expanded region 50 of mandrel 38. In some applications, the expanded region 50 may be dynamically sealed with respect to the surrounding surface of housing 40 so as to force the magneto rheological fluid 44 to move through orifice 48 whenever movement of mandrel 38 occurs with respect to housing 40. However, orifice 48 may be positioned at other locations outside of mandrel 38 while remaining in fluid communication with the magneto rheological fluid 44 such that the magneto rheological fluid 44 is forced through the orifice 48 by movement of mandrel 38. The orifice 48 also may have a variety of sizes, shapes, numbers, and/or configurations depending on the parameters of a given application.
Referring again to the embodiment of actuator 28 illustrated in
When electromagnetic coil 52 is energized via electrical power supplied by conductors 54, the magnetic field is established and the viscosity of magneto rheological fluid 44 is increased substantially. Similarly, de-energizing the electromagnetic coil 52 by removing electrical power reduces or removes the magnetic field and decreases the viscosity of magneto rheological fluid 44. While the electromagnetic coil 52 is energized and the viscosity of magneto rheological fluid 44 is increased, flow of the magneto rheological fluid 44 through orifice 48 is restricted (due to the high viscosity) thus effectively locking mandrel 38 at that position with respect to housing 40. In an embodiment shown in
Depending on the parameters of a given application, the mandrel 38 may be shifted by a variety of mechanisms while the magneto rheological fluid 44 is in a low viscosity state. In the illustrated embodiment, the mandrel 38 has an interior passage 58 which effectively provides a mandrel orifice 60 through which fluid may be flowed to bottom hole assembly 32 or to other components farther downhole relative to actuator 28. In drilling applications, for example, fluid pumped down through an interior of tool string 22 may be flowed through mandrel orifice 60 and interior passage 58 to the milling tool 34.
By establishing a sufficient flow of fluid through mandrel orifice 60 and interior passage 58, pressure builds against mandrel 38 until a sufficient force is established to shift the mandrel 38 in the direction of fluid flow. In the illustrated example, this motion of mandrel 38 is resisted by a spring member 62, e.g. a coil spring or other suitable spring. The spring member 62 may be positioned to act against, for example, a shoulder 64 of mandrel 38. In this example, a sufficient force is created by fluid flowing through orifice 60 and acting against mandrel 38 to overcome the friction force of seals 46 and the counteracting spring force established by spring member 62. However, when the flow through orifice 60 is sufficiently reduced, the force applied by spring member 62 is able to shift the mandrel 38 back in an opposite direction relative to housing 40.
As described above, however, applying power to electromagnetic coil 52 increases the viscosity of magneto rheological fluid 44 and effectively locks the mandrel 38 at that position because the viscous magneto rheological fluid 44 does not readily pass through orifice 48. The forces exerted either by fluid flowing against orifice 60 or by spring member 62 are not sufficient to overcome the resistance to movement of mandrel 38 provided by the combination of the viscous magneto rheological fluid 44 and orifice 48. It is understood that the amount of power applied to the electromagnetic coil 52 may be varied and/or variable, which thereby varies the viscosity of the magneto rheological fluid 44 and allows the magneto rheological fluid 44 to provide a force to resist movement of the mandrel 38, acting in a manner similar to, for example, a shock absorber or the like.
Referring generally to
To facilitate explanation of the use of actuator 28 and locking feature 30, a milling operation example is described but such example should not be limiting with respect to the various uses of actuator 28 and locking feature 30. With respect to the milling operation example,
When it is desired to shift from milling mode to circulation mode, electrical power sent to the electromagnetic coil 52 is disconnected. As a result, the viscosity of the magneto rheological fluid 44 and the drag coefficient of the magneto rheological fluid 44 passing through orifice 48 are reduced, as illustrated in
After shifting to circulation mode, electrical power is again sent to the electromagnetic coil 52 to generate a magnetic field which again increases the viscosity of the magneto rheological fluid 44, as illustrated in
When it is desired to shift from circulation mode to milling mode, the pump rate with respect to fluid flowing through mandrel orifice 60 is reduced to decrease the differential pressure acting against mandrel orifice 60. Additionally, electrical power supplied to the electromagnetic coil 52 is disconnected to interrupt the magnetic field and to reduce the viscosity of the magneto rheological fluid 44. At this stage, the force generated by spring member 62 is sufficient to overcome the drag of the magneto rheological fluid passing through orifice(s) 48 and the friction resistance provided by seals 46 so as to shift mandrel 38, as illustrated in
The actuator 28 with its locking feature 30 may be used in a variety of well and non-well related applications to provide a simple technique for locking the actuator, and thus locking a shiftable tool, in a desired operational position. In well applications, the actuator 28 and locking feature 30 may be used to control fluid flow control devices, e.g. valves, or other devices depending on the specifics of a given application. In flow control applications, the locking feature 30 (in the form of, for example, magneto rheological fluid 44 and orifice 48) may be used to secure valve 66 in open flow or closed flow configurations. In milling applications, for example, the valve 66 may comprise or be part of a multi-cycle circulation valve system to facilitate locking of the system in selected modes, such as a milling mode or a circulation mode.
Depending on the application, the tool string 22 may comprise many types of components and systems selected for carrying out a given operation or operations. Similarly, the actuator 28 may be formed in various configurations with various styles of mandrel, housing, seals, electromagnetic coil, and/or other features. Similarly, the composition of the magneto rheological fluid may be adjusted according to the structure of the actuator 28 and/or the environment in which the actuator 28 is to be utilized. Additionally, electrical power may be supplied by a variety of power sources 56 at appropriate levels selected according to the type, number and configuration of the electromagnetic coil or coils which form electromagnetic coil 52. In an embodiment(s), the actuator 28 may be configured to lock the mandrel in more than two desired operational positions, as will be appreciated by those skilled in the art. In an embodiment, the magneto rheological fluid 44 may act as a shock absorber or the like wherein it exhibits resistance to flow but does not flow freely, etc.
Although a few embodiments of the system and methodology have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of this disclosure. Accordingly, such modifications are intended to be included within the scope of this disclosure as defined in the claims.