Patent Description:
The present disclosure generally relates to safety valves, and more particularly to safety valves having electrical actuators and fully electric safety valves.

Valves typically are used in a well for such purposes as fluid flow control, formation isolation, and safety functions. A common downhole valve is a hydraulically-operated valve, which is known for its reliable performance. However, hydraulically-operated valves have limitations.

For example, the use of a hydraulically-operated valve is depth-limited due to the high hydrostatic pressure acting against the valve at large depths, which may diminish the effective hydraulic pressure that is available to operate the valve. Furthermore, for deep applications, the viscous control fluid in a long hydraulic line may cause unacceptably long operating times for certain applications. In addition, a long hydraulic line and the associated connections provide little or no mechanism to determine, at the surface of the well, what is the true state of the valve. For example, if the valve is a safety valve, there may be no way to determine the on-off position of the valve, the pressure across the valve and the true operating pressure at the valve's operator at the installed depth.

Patent applications <CIT> and <CIT> describe valves in which an electrically operated actuator opens the valve by pushing an internal sleeve linearly to open a flapper (and hence the valve) and also compress a return spring. In <CIT> the flapper can be held in its open position by an electric magnet. <CIT>, <CIT>, <CIT>, <CIT> and <CIT> also disclose electrically operated valves.

The present disclosure provides a downhole valve assembly comprising an actuator, and an electric safety valve which comprises a flapper, a return spring, and an internal tubing sleeve, wherein the actuator is configured to extend to move the internal tubing sleeve from a closed position to an open position, thereby compressing the return spring and causing the internal tubing sleeve to open the flapper; characterized in that the electric safety valve comprises an electric magnet configured to be activated to hold the internal tubing sleeve in the open position, thereby allowing the actuator to be retracted while the internal tubing sleeve remains in the open position with the flapper open.

The actuator can be an electro hydraulic actuator, an electro mechanical actuator, or an electro hydraulic pump. In some configurations, the electric safety valve is fully electric and does not include any hydraulic components. The electric safety valve can further include downhole electronics configured to receive a signal from the surface and control the actuator.

The electric magnet can be configured to magnetically couple to a corresponding magnet disposed in or on a flange of the internal tubing sleeve, the flange configured to compress the return spring when the electric safety valve is in the open position. Alternatively, the electric magnet can be disposed in, on, or adjacent a movable shaft of the actuator and configured to magnetically couple to a corresponding magnet disposed in a wall of the internal tubing sleeve.

In some configurations, the electric magnet can be configured to be activated when the electric safety valve is in an open position, thereby allowing the actuator to be retracted while holding the internal tubing sleeve and flapper in the open position. In some configurations, the electric magnet is configured to be activated prior to extending the actuator and opening the electric safety valve, and during closure, the internal tubing sleeve is retracted prior to retraction of the actuator. Closing of the electric safety valve can be controlled by the electric magnet. The electric safety valve can be moved to a closed position by deactivating the electric magnet.

Another aspect of this disclosure provides a method of operating an electric downhole safety valve, the electric downhole safety valve comprising a flapper, an internal tubing sleeve, a return spring, an actuator, and downhole electronics, wherein the method comprises providing a command from the surface to the downhole electronics; in response to the command from the surface, extending the actuator, thereby shifting the internal tubing sleeve from a closed position to an open position; compressing the return spring; and using the internal tubing sleeve to open the flapper; characterized in that the electric downhole safety valve further comprises an electric magnet and the method further comprises activating the electric magnet to hold the internal tubing sleeve in the open position and retracting the actuator while the internal tubing sleeve is held in the open position by the electric magnet.

The method can include retracting the actuator while the internal tubing sleeve is held in the open position by the electric magnet. The method can include deactivating the electric magnet. Deactivating the electric magnet can allow the return spring to expand, thereby shifting the internal tubing sleeve to the closed position and allowing the flapper to close.

The method can include activating the electric magnet prior to extending the actuator. The method can further include deactivating the electric magnet, allowing the return spring to expand, thereby shifting the internal tubing sleeve to the closed position, and allowing the flapper to close, while the actuator is extended; and retracting the actuator after the flapper is closed.

Certain embodiments, features, aspects, and advantages of the disclosure will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements. It should be understood that the accompanying figures illustrate the various implementations described herein and are not meant to limit the scope of various technologies described herein.

In the following description, numerous details are set forth to provide an understanding of some embodiments of the present disclosure. It is to be understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the disclosure. These are, of course, merely examples and are not intended to be limiting. 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 are possible. This description is not to be taken in a limiting sense, but rather made merely for the purpose of describing general principles of the implementations. The scope of the described implementations should be ascertained with reference to the issued claims.

As used herein, the terms "connect", "connection", "connected", "in connection with", and "connecting" are used to mean "in direct connection with" or "in connection with via one or more elements"; and the term "set" is used to mean "one element" or "more than one element". Further, the terms "couple", "coupling", "coupled", "coupled together", and "coupled with" are used to mean "directly coupled together" or "coupled together via one or more elements". As used herein, the terms "up" and "down"; "upper" and "lower"; "top" and "bottom"; and other like terms indicating relative positions to a given point or element are utilized to more clearly describe some elements. Commonly, these terms relate to a reference point at the surface from which drilling operations are initiated as being the top point and the total depth being the lowest point, wherein the well (e.g., wellbore, borehole) is vertical, horizontal or slanted relative to the surface.

Well completions often include various valves, such as safety valves and flow control valves. Downhole or sub-surface safety valves are often deployed in an upper part of a well completion to provide a barrier against uncontrolled flow below the valve. The valve must be able to operate in a failsafe mode to close and stop well production in case of an emergency. Typically such valves have been hydraulically operated. However, hydraulically operated valves have limitations. For example, the use of a hydraulically-operated valve is depth-limited due to the high hydrostatic pressure acting against the valve at large depths, which may diminish the effective hydraulic pressure that is available to operate the valve. Furthermore, for deep applications, the viscous control fluid in a long hydraulic line may cause unacceptably long operating times for certain applications. In addition, a long hydraulic line and the associated connections provide little or no mechanism to determine, at the surface of the well, what is the true state of the valve. For example, if the valve is a safety valve, there may be no way to determine the on-off position of the valve, the pressure across the valve and the true operating pressure at the valve's operator at the installed depth.

Compared to hydraulic completion systems, electric completion systems can provide reduced capital expenditures, reduced operating expenditures, and reduced health, safety, and environmental problems. Electric completions can advantageously allow for the use of sensors and proactive decision making for well control.

The present disclosure provides electric safety valves, systems (e.g., well completions) including such electric safety valves, and methods of operating electric safety valves. In some configurations, an inductive coupler is used with an electric safety valve or completion including an electric safety valve. The safety valves can have a flapper valve design. The present disclosure also provides an electro-magnet disconnect system. The disconnect system enables a safe and reliable closing mechanism capable of withstanding extreme slam shutting.

Conventional downhole safety valves are typically operated via a hydraulic connection to or from a surface panel. <FIG> illustrate an example hydraulic safety valve having a flapper valve design in open and closed positions, respectively. As shown, the safety valve assembly includes a flapper <NUM>, a return spring <NUM>, a flow tube or sleeve <NUM>, a piston <NUM>, and a control line <NUM>. The position (open or closed) of the flapper <NUM> is controlled via the flow tube or sleeve <NUM> sliding up and down inside the production tubing. The sleeve position is controlled or moved by the return spring <NUM> and/or the piston <NUM>. The flapper <NUM> and return spring <NUM> are biased to the closed position.

Hydraulic pressure applied from the surface via the control line <NUM> to the piston <NUM> causes the piston <NUM> to move the sleeve <NUM> downward, thereby compressing the return spring <NUM>, and open the flapper <NUM>. In the illustrated configuration, the sleeve <NUM> includes a radially outwardly projecting flange <NUM> that contacts and compresses the spring <NUM>. Hydraulic pressure in the piston <NUM> maintains the sleeve's position and holds the valve open. As shown, at least a portion of the flapper <NUM> is shielded from flow through the production tubing by a portion of the sleeve <NUM>, so the sleeve <NUM> protects the flapper <NUM> and tubing sealing area from flow erosion. If the hydraulic pressure in the control line <NUM> is released, whether intentionally or unintentionally, the spring <NUM> bias pushes the sleeve <NUM> upward, allowing the flapper <NUM> to close. The spring <NUM> and/or flapper <NUM> bias to the closed position provides a failsafe for the valve, as the spring <NUM> ensures valve closure in case of emergency, such as a catastrophic event on the surface leading to a pressure drop or loss in the hydraulic control line <NUM>.

<FIG> illustrates an example completion string including a safety valve according to the present disclosure positioned in a wellbore <NUM>. The wellbore <NUM> may be part of a vertical well, deviated well, horizontal well, or a multilateral well. The wellbore <NUM> may be lined with casing <NUM> (or other suitable liner) and may include a production tubing <NUM> (or other type of pipe or tubing) that runs from the surface to a hydrocarbon-bearing formation downhole. A production packer <NUM> may be employed to isolate an annulus region <NUM> between the production tubing <NUM> and the casing <NUM>.

A subsurface safety valve assembly <NUM> may be attached to the tubing <NUM>. The subsurface safety valve assembly <NUM> may include a flapper valve <NUM> or some other type of valve (e.g., a ball valve, sleeve valve, disk valve, and so forth). The flapper valve <NUM> is actuated opened or closed by an actuator assembly <NUM>. During normal operation, the valve <NUM> is actuated to an open position to allow fluid flow in the bore of the production tubing <NUM>. The safety valve <NUM> is designed to close should some failure condition be present in the wellbore <NUM> to prevent further damage to the well.

The actuator assembly <NUM> in the safety valve assembly <NUM> may be electrically activated by signals provided by a controller <NUM> at the surface to the actuator assembly <NUM> via an electrical cable <NUM>. The controller <NUM> is therefore operatively connected to the actuator assembly <NUM> via the cable <NUM>. Other types of signals and/or mechanisms for remote actuation of the actuator assembly <NUM> are also possible. Depending on the application, the controller <NUM> may be in the form of a computer-based control system, e.g. a microprocessor-based control system, a programmable logic control system, or another suitable control system for providing desired control signals to and/or from the actuator assembly <NUM>. The control signals may be in the form of electric power and/or data signals delivered downhole to subsurface safety valve assembly <NUM> and/or uphole from subsurface safety valve assembly <NUM>.

<FIG> illustrates an example flapper valve <NUM>. In this embodiment, the flapper <NUM> is pivotably mounted along a flapper housing <NUM> having an internal passage <NUM> therethrough and having a hard sealing surface <NUM>. The flapper <NUM> is pivotably coupled to the flapper housing <NUM>, for example, via a hinge pin <NUM>, for movement between an open position and a closed position. By pivotably coupled, it should be understood the flapper <NUM> may be directly coupled to housing <NUM> or indirectly coupled to the housing <NUM> via an intermediate member.

Additional details regarding safety valves can be found in, for example, <CIT> and <CIT>, the entirety of each of which is hereby incorporated by reference herein. Although the present disclosure describes an actuator used with a subsurface safety valve, it is contemplated that further embodiments may include actuators used with other types of downhole devices. Such other types of downhole devices may include, as examples, flow control valves, packers, sensors, pumps, and so forth. Other embodiments may include actuators used with devices outside the well environment.

The actuator assembly <NUM> can be or include various types of actuators, such as electrical actuators. For example, in some configurations, the actuator assembly <NUM> is or includes an electro hydraulic actuator (EHA), an electro mechanical actuator (EMA), or an electro hydraulic pump (EHP). An EHA can allow for quick backdrive or actuation and therefore quick close functionality, which advantageously allows for rapid closure of the valve <NUM> when desired or required.

In some configurations, the actuator assembly <NUM> is fully electric and the safety valve assembly <NUM> is fully electric. In other words, the safety valve assembly <NUM> includes no hydraulic components. In some such configurations, the actuator assembly <NUM> is or includes an EMA.

In some configurations, the present disclosure advantageously provides a downhole electro-mechanical actuator in combination with an electrical magnet to control a valve, such as a downhole safety valve <NUM>, for example as shown in <FIG> and <FIG>. The safety valve can include various features of the configurations shown in <FIG>. However, compared to the example valve of <FIG>, the safety valves of <FIG> and <FIG> include, and their position is controlled by, an electric actuator <NUM> rather than hydraulic pressure applied via a control line from the surface. The actuator <NUM> is controlled and powered by a downhole electronics cartridge <NUM>. The downhole electronics <NUM> can be connected to the surface via an electrical cable, for example, cable <NUM> (shown in <FIG>). In a closed mode or position of the safety valve, the actuator <NUM> is fully retracted such that the return spring <NUM> is fully expanded, and the flapper <NUM> is closed.

<FIG> schematically illustrates the principle of a linear electro-mechanical actuator, for example as may be included in valve assemblies according to the present disclosure, such as the valve assemblies of <FIG> and <FIG>. As shown, an electrical motor <NUM> is powered and controlled by embedded downhole electronics <NUM>. Motor rotation is converted into linear motion via a gear box <NUM> and screw mechanical assembly <NUM>. In use, the motor <NUM> is activated by a surface command received and interpreted by the downhole electronics <NUM>. The required linear force is obtained by the torque applied by the motor <NUM> at gear box entry.

<FIG> schematically illustrates the principle of an electrical magnet <NUM>, for example as may be included in valve assemblies according to the present disclosure, such as the valve assemblies of <FIG> and <FIG>. As shown, the electrical magnet, or e-magnet <NUM>, includes a magnetic core <NUM>. The core <NUM> includes a coil of wires <NUM> having an appropriate number of turns to induce a required magnetic field when the coil <NUM> is powered on with a DC current. The magnetic field B (indicated by arrows <NUM> in <FIG>) creates a force F inside each section area A of the core assembly according to the equation: <MAT>.

A force up to 40N can be induced by a magnetic field of <NUM> Tesla per cm<NUM>. As core materials commonly used are known to saturate above <NUM> Tesla, a force up to <NUM> N can be achieved with a core section in the order of <NUM><NUM>.

<FIG> schematically illustrate operation of safety valves according to the present disclosure, such as the valve <NUM> of <FIG>. <FIG> shows the valve <NUM> in a closed position, with the electro-mechanical actuator (EMA) <NUM> in a fully retracted position and the E-magnet <NUM> not activated. <FIG> shows the valve opening in response to a command from the surface to the downhole electronics <NUM>. As shown, the EMA <NUM> is extending, and the E-magnet <NUM> is still not activated. Extension of the EMA <NUM> (e.g., a piston <NUM> of or coupled to the EMA <NUM>) compresses the return spring <NUM>. Extension of the EMA <NUM> (e.g., a piston <NUM> of or coupled to the EMA) moves the internal tubing sleeve <NUM> toward, into contact with, and/or past the flapper <NUM> to open the flapper <NUM>. In <FIG>, the valve is fully opened, the EMA <NUM> is in the fully expanded position (and the return spring <NUM> can be fully compressed and/or the internal tubing sleeve <NUM> can be shifted to hold open and protect the flapper <NUM>), and the E-magnet <NUM> is not yet activated.

<FIG> shows the valve fully opened, the EMA <NUM> fully extended, and the E-magnet <NUM> activated. In some configurations, the E-magnet <NUM> is configured to interact with, e.g., magnetically interact or couple with, a corresponding magnet or magnetic component <NUM> when activated. In the illustrated configuration, the magnet or magnetic component <NUM> is disposed in or on the flange <NUM> of the internal sleeve <NUM>. As the EMA <NUM>, or piston or shaft <NUM> thereof, extends, the EMA <NUM> (or piston or shaft <NUM>) axially displaces the flange <NUM>, thereby compressing the spring <NUM>. When the spring is fully compressed <NUM> and the valve is fully open, the magnet or magnetic component <NUM> is aligned with (e.g., radially aligned with and/or at generally or about the same axial depth as) the E-magnet <NUM>, as shown in <FIG>.

Activation of the E-magnet <NUM> can hold the internal tubing sleeve <NUM> in its shifted position (e.g., the position holding open and protecting the flapper <NUM>, for example as shown in <FIG>) via magnetic coupling between the E-magnet <NUM> and magnet or magnetic component <NUM>. <FIG> shows the EMA <NUM> (e.g., the piston or shaft <NUM>) retracted, with the E-magnet <NUM> still activated, thereby maintaining the internal tubing <NUM> in its shifted position and the valve in a fully open position. <FIG> shows the EMA <NUM> retracted and the E-magnet <NUM> de-activated. With the EMA retracted, de-activation of the E-magnet <NUM> allows the return spring <NUM> to expand and bias the internal sleeve <NUM> back to its original, closed position, allowing the flapper <NUM> to close such that the valve <NUM> is in a fully closed position or state.

<FIG> illustrates another example electric safety valve <NUM> including an EMA <NUM> and an E-magnet <NUM>. In the configuration of <FIG>, the E-magnet <NUM> is included in, on, or adj acent the piston or shaft <NUM> of the actuator <NUM>. The E-magnet <NUM> is therefore in-line (e.g., axially aligned with or aligned along a common axis parallel to a longitudinal axis extending through the bore of the internal tubing sleeve <NUM>) with the actuator <NUM>, or piston or shaft <NUM> of the actuator <NUM>. In the illustrated configuration, the corresponding magnet or magnetic component <NUM> is disposed within the body or wall of the internal tubing sleeve <NUM>.

<FIG> schematically illustrate operation of safety valves according to the present disclosure, such as the valve of <FIG>. <FIG> shows the valve in a closed position, with the electro-mechanical actuator (EMA) <NUM> in a fully retracted position. The E-magnet <NUM> is activated in order to initiate the coupling between the sleeve <NUM> and the actuator <NUM> and prepare the EMA <NUM> for actuation. <FIG> shows the valve opening in response to a command from the surface to the downhole electronics <NUM>. As shown, the E-magnet <NUM> is activated and the EMA <NUM> (e.g., the piston or shaft <NUM>) is extending. Extension of the EMA <NUM> (e.g., the piston or shaft <NUM>) compresses the return spring <NUM>. Extension of the EMA <NUM> (e.g., piston or shaft <NUM>) moves the internal tubing sleeve <NUM> toward, into contact with, and/or past the flapper <NUM> to open the flapper <NUM>. In <FIG>, the valve <NUM> is fully opened, the EMA <NUM> is in the fully expanded position (and the return spring <NUM> can be fully compressed and/or the internal tubing sleeve <NUM> can be shifted to hold open and protect the flapper <NUM>), and the E-magnet <NUM> is kept activated. Continued activation of the E-magnet <NUM> can hold the internal tubing sleeve <NUM> in its shifted position (e.g., the position holding open and protecting the flapper <NUM>, for example as shown in <FIG>). If the EMA <NUM> has enough holding force, the motor can be shut-in. The valve is monitored for EMA back-drive, and if back-drive is detected, the EMA <NUM> can be powered on and actuated to the proper shaft position.

<FIG> show the valve closure mode via de-activation of the e-magnet <NUM>. Closure mode can be triggered intentionally or automatically in the case of electrical shut-down (failsafe mode). De-activation of the E-magnet <NUM> releases the magnetic coupling with the internal sleeve <NUM>, allowing the return spring <NUM> to expand and bias the internal sleeve <NUM> back to its original, closed position, and allowing the flapper <NUM> to close such that the valve is in a fully closed position or state (<FIG>). As the e-magnet <NUM> is magnetically decoupled from the actuator <NUM>, the slam force is not transmitted to EMA shaft <NUM>. In other words, the internal sleeve <NUM> can be retracted to its original, closed position without movement of or force on the actuator shaft <NUM>. <FIG> shows the valve fully closed with the EMA <NUM> (e.g., shaft or piston <NUM>) retracted and the e-magnet <NUM> de-activated. The valve <NUM> can be re-opened by repeating the process shown in <FIG>.

In some valves according to the present disclosure, there is a magnetic coupling, for example, instead of a fixed mechanical link, between the actuator <NUM> and the internal tubing sleeve <NUM>, which advantageously prevents or reduces the likelihood of damage to the actuator <NUM> during a slam closure. In some configurations, the downhole electronics <NUM> drive the actuator <NUM> in valve open mode only. In use, the actuator <NUM> can be set in extension mode to compress the spring <NUM>, then retracted as soon as the e-magnet <NUM> is activated, thereby ensuring a failsafe operating mode. In use, the e-magnet <NUM> can be activated as soon as full open mode is reached. In other configurations, the e-magnet <NUM> is activated prior to extension of the actuator <NUM> to compress the spring <NUM>. The e-magnet <NUM> can be released or powered off for valve shut-in to ensure failsafe operating mode. The e-magnet <NUM> can be strong enough to keep the spring <NUM> compressed. In some configurations, several magnets can be combined to achieve the desired or required strength. The e-magnet <NUM> retaining force (e.g., on the internal tubing sleeve <NUM> and/or spring <NUM>) can be combined with additional mechanical friction if needed to compress the return spring <NUM>. In some configurations, the e-magnet <NUM> is disposed in a housing mandrel (a non-moving part), which can facilitate connection to the downhole electronics <NUM>. In other configurations, the e-magnet <NUM> is disposed on the shaft or piston <NUM> of the actuator <NUM> (a moving part). In some configurations, valve shut-in is not under control of the EMA <NUM>, but instead advantageously under control of e-magnet <NUM> power release only. In other configurations, valve shut-in can be under control of both the EMA <NUM> and the e-magnet <NUM>.

For example, the terms "approximately," "about," "generally," and "substantially" may refer to an amount that is within less than <NUM>% of, within less than <NUM>% of, within less than <NUM>% of, within less than <NUM>% of, and/or within less than <NUM>% of the stated amount. As another example, in certain embodiments, the terms "generally parallel" and "substantially parallel" or "generally perpendicular" and "substantially perpendicular" refer to a value, amount, or characteristic that departs from exactly parallel or perpendicular, respectively, by less than or equal to <NUM> degrees, <NUM> degrees, <NUM> degrees, <NUM> degrees, <NUM> degree, or <NUM> degree.

Claim 1:
A downhole valve assembly (<NUM>) comprising:
an actuator (<NUM>), and
an electric safety valve (<NUM>) comprising a flapper (<NUM>), a return spring (<NUM>), and an internal tubing sleeve (<NUM>),
wherein the actuator (<NUM>) is configured to extend to move the internal tubing sleeve from a closed position to an open position, thereby compressing the return spring (<NUM>) and causing the internal tubing sleeve (<NUM>) to open the flapper (<NUM>);
characterized in that the electric safety valve (<NUM>) comprises an electric magnet (<NUM>) configured to be activated to hold the internal tubing sleeve in the open position, thereby allowing the actuator (<NUM>) to be retracted while the internal tubing sleeve (<NUM>) remains in the open position with the flapper (<NUM>) open.