# Patent

## Title
Remote actuation of downhole well tools

## Abstract

A method of selectively actuating well tools includes the steps of: selecting a well tool for actuation by current flow in one direction through a set of conductors; and selecting another well tool for actuation by opposite current flow through the set of conductors. A system includes multiple control devices that control which well tool is selected for actuation in response to current flow in at least one conductor set. A current direction in the conductors selects a certain well tool for actuation. A method of using n conductors to selectively actuate n*(n−1) well tools includes the steps of: arranging the conductors into n*(n−1)/2 sets; connecting the conductor sets to respective groups of the well tools; and controlling direction of current flow through at least one of the sets of conductors, thereby selecting at least one well tool in the respective group of the well tools for actuation.

## Background
CROSS-REFERENCE TO RELATED APPLICATION
The present application claims the benefit under 35 USC §119 of the filing date of International Application No. PCT/US08/75668, filed Sep. 9, 2008. The entire disclosure of this prior application is incorporated herein by this reference.
BACKGROUND
The present disclosure relates generally to operations performed and equipment utilized in conjunction with a subterranean well and, in an embodiment described herein, more particularly provides for remote actuation of downhole well tools.
It is useful to be able to selectively actuate well tools in a subterranean well. For example, production flow from each of multiple zones of a reservoir can be individually regulated by using a remotely controllable choke for each respective zone. The chokes can be interconnected in a production tubing string so that, by varying the setting of each choke, the proportion of production flow entering the tubing string from each zone can be maintained or adjusted as desired.
Unfortunately, this concept is more complex in actual practice. In order to be able to individually actuate multiple downhole well tools, a relatively large number of wires, lines, etc. have to be installed and/or complex wireless telemetry and downhole power systems need to be utilized. Each of these scenarios involves use of relatively unreliable downhole electronics and/or the extending and sealing of many lines through bulkheads, packers, hangers, wellheads, etc.
Therefore, it will be appreciated that advancements in the art of remotely actuating downhole well tools are needed. Such advancements would preferably reduce the number of lines, wires, etc. installed, and would preferably reduce or eliminate the need for downhole electronics.
SUMMARY
In carrying out the principles of the present disclosure, systems and methods are provided which solve at least one problem in the art. One example is described below in which a relatively large number of well tools may be selectively actuated using a relatively small number of lines, wires, etc. Another example is described below in which a direction of current flow through a set of conductors is used to select which of two respective well tools is to be actuated.
In one aspect, a method of selectively actuating multiple downhole well tools from a remote location is provided. The method includes the steps of: selecting one of the well tools for actuation by flowing electrical current in one direction through a set of conductors in the well; and selecting another one of the well tools for actuation by flowing electrical current through the set of conductors in an opposite direction.
In another aspect, a system for selectively actuating multiple downhole well tools from a remote location includes multiple electrical conductors in the well; and multiple control devices that control which of the well tools is selected for actuation in response to current flow in at least one set of the conductors. At least one direction of current flow in the at least one set of conductors is operative to select a respective at least one of the well tools for actuation.
In yet another aspect, a method of using n conductors to selectively actuate n*(n−1) downhole well tools includes the steps of: arranging the n conductors into n*(n−1)/2 sets of conductors; connecting each set of conductors to a respective group of the well tools; and controlling direction of current flow through at least one of the sets of conductors, thereby selecting at least one well tool in the respective group of the well tools for actuation.
One of the conductors may be a tubular string extending into the earth, or in effect “ground.”
These and other features, advantages, benefits and objects will become apparent to one of ordinary skill in the art upon careful consideration of the detailed description of representative embodiments of the disclosure hereinbelow and the accompanying drawings, in which similar elements are indicated in the various figures using the same reference numbers.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view of a prior art well control system;
FIG. 2 is an enlarged scale schematic view of a flow control device and associated control device which embody principles of the present disclosure;
FIG. 3 is a schematic electrical and hydraulic diagram showing a system and method for remotely actuating multiple downhole well tools;
FIG. 4 is a schematic electrical diagram showing another configuration of the system and method for remotely actuating multiple downhole well tools;
FIG. 5 is a schematic electrical diagram showing details of a switching arrangement which may be used in the system of FIG. 4;
FIG. 6 is a schematic electrical diagram showing details of another switching arrangement which may be used in the system of FIG. 4;
FIG. 7 is a schematic electrical and hydraulic diagram showing another configuration of the system and method for remotely actuating multiple downhole well tools;
FIG. 8 is a schematic electrical and hydraulic diagram showing another configuration of the system and method for remotely actuating multiple downhole well tools;
FIG. 9 is a schematic electrical and hydraulic diagram showing another configuration of the system and method for remotely actuating multiple downhole well tools;
FIG. 10 is a schematic electrical diagram showing another configuration of the system and method for remotely actuating multiple downhole well tools; and
FIG. 11 is a schematic electrical diagram showing another configuration of the system and method for remotely actuating multiple downhole well tools.



DETAILED DESCRIPTION
It is to be understood that the various embodiments of the present disclosure described herein may be utilized in various orientations, such as inclined, inverted, horizontal, vertical, etc., and in various configurations, without departing from the principles of the present disclosure. The embodiments are described merely as examples of useful applications of the principles of the disclosure, which is not limited to any specific details of these embodiments.
In the following description of the representative embodiments of the disclosure, directional terms, such as “above”, “below”, “upper”, “lower”, etc., are used for convenience in referring to the accompanying drawings. In general, “above”, “upper”, “upward” and similar terms refer to a direction toward the earth's surface along a wellbore, and “below”, “lower”, “downward” and similar terms refer to a direction away from the earth's surface along the wellbore.
Representatively illustrated in FIG. 1 is a well control system 10 which is used to illustrate the types of problems overcome by the systems and methods of the present disclosure. Although the drawing depicts prior art concepts, it is not meant to imply that any particular prior art well control system included the exact configuration illustrated in FIG. 1.
The control system 10 as depicted in FIG. 1 is used to control production flow from multiple zones 12a-e intersected by a wellbore 14. In this example, the wellbore 14 has been cased and cemented, and the zones 12a-e are isolated within a casing string 16 by packers 18a-e carried on a production tubing string 20.
Fluid communication between the zones 12a-e and the interior of the tubing string 20 is controlled by means of flow control devices 22a-e interconnected in the tubing string. The flow control devices 22a-e have respective actuators 24a-e for actuating the flow control devices open, closed or in a flow choking position between open and closed.
In this example, the control system 10 is hydraulically operated, and the actuators 24a-e are relatively simple piston-and-cylinder actuators. Each actuator 24a-e is connected to two hydraulic lines—a balance line 26 and a respective one of multiple control lines 28a-e. A pressure differential between the balance line 26 and the respective control line 28a-e is applied from a remote location (such as the earth's surface, a subsea wellhead, etc.) to displace the piston of the corresponding actuator 24a-e and thereby actuate the associated flow control device 22a-e, with the direction of displacement being dependent on the direction of the pressure differential.
There are many problems associated with the control system 10. One problem is that a relatively large number of lines 26, 28a-e are needed to control actuation of the devices 22a-e. These lines 26, 28a-e must extend through and be sealed off at the packers 18a-e, as well as at various bulkheads, hangers, wellhead, etc.
Another problem is that it is difficult to precisely control pressure differentials between lines extending perhaps a thousand or more meters into the earth. This will lead to improper or unwanted actuation of the devices 22a-e, as well as imprecise regulation of flow from the zones 12a-e. 
Attempts have been made to solve these problems by using downhole electronic control modules for selectively actuating the devices 22a-e. However, these control modules include sensitive electronics which are frequently damaged by the hostile downhole environment (high temperature and pressure, etc.).
Furthermore, electrical power must be supplied to the electronics by specialized high temperature batteries, by downhole power generation or by wires which (like the lines 26, 28a-e) must extend through and be sealed at various places in the system. Signals to operate the control modules must be supplied via the wires or by wireless telemetry, which includes its own set of problems.
Thus, the use of downhole electronic control modules solves some problems of the control system 10, but introduces other problems. Likewise, mechanical and hydraulic solutions have been attempted, but most of these are complex, practically unworkable or failure-prone.
Turning now to FIG. 2, a system 30 and associated method for selectively actuating multiple well tools 32 are representatively illustrated. Only a single well tool 32 is depicted in FIG. 2 for clarity of illustration and description, but the manner in which the system 30 may be used to selectively actuate multiple well tools is described more fully below.
The well tool 32 in this example is depicted as including a flow control device 38 (such as a valve or choke), but other types or combinations of well tools may be selectively actuated using the principles of this disclosure, if desired. A sliding sleeve 34 is displaced upwardly or downwardly by an actuator 36 to open or close ports 40. The sleeve 34 can also be used to partially open the ports 40 and thereby variably restrict flow through the ports.
The actuator 36 includes an annular piston 42 which separates two chambers 44, 46. The chambers 44, 46 are connected to lines 48a,b via a control device 50. D.C. current flow in a set of electrical conductors 52a,b is used to select whether the well tool 32 is to be actuated in response to a pressure differential between the lines 48a,b. 
In one example, the well tool 32 is selected for actuation by flowing current between the conductors 52a,b in a first direction 54a (in which case the chambers 44, 46 are connected to the lines 48a,b), but the well tool 32 is not selected for actuation when current flows between the conductors 52a,b in a second, opposite, direction 54b (in which case the chambers 44, 46 are isolated from the lines 48a,b). Various configurations of the control device 50 are described below for accomplishing this result. These control device 50 configurations are advantageous in that they do not require complex, sensitive or unreliable electronics or mechanisms, but are instead relatively simple, economical and reliable in operation.
The well tool 32 may be used in place of any or all of the flow control devices 22a-e and actuators 24a-e in the system 10 of FIG. 1. Suitably configured, the principles of this disclosure could also be used to control actuation of other well tools, such as selective setting of the packers 18a-e, etc.
Note that the hydraulic lines 48a,b are representative of one type of fluid pressure source 48 which may be used in keeping with the principles of this disclosure. It should be understood that other fluid pressure sources (such as pressure within the tubing string 20, pressure in an annulus 56 between the tubing and casing strings 20, 16, pressure in an atmospheric or otherwise pressurized chamber, etc., may be used as fluid pressure sources in conjunction with the control device 50 for supplying pressure to the actuator 36 in other embodiments.
The conductors 52a,b comprise a set of conductors 52 through which current flows, and this current flow is used by the control device 50 to determine whether the associated well tool 32 is selected for actuation. Two conductors 52a,b are depicted in FIG. 2 as being in the set of conductors 52, but it should be understood that any number of conductors may be used in keeping with the principles of this disclosure. In addition, the conductors 52a,b can be in a variety of forms, such as wires, metal structures (for example, the casing or tubing strings 16, 20, etc.), or other types of conductors.
The conductors 52a,b preferably extend to a remote location (such as the earth's surface, a subsea wellhead, another location in the well, etc.). For example, a surface power supply and multiplexing controller can be connected to the conductors 52a,b for flowing current in either direction 54a,b between the conductors.
In the examples described below, n conductors can be used to selectively control actuation of n*(n−1) well tools. The benefits of this arrangement quickly escalate as the number of well tools increases. For example, three conductors may be used to selectively actuate six well tools, and only one additional conductor is needed to selectively actuate twelve well tools.
Referring additionally now to FIG. 3, a somewhat more detailed illustration of the electrical and hydraulic aspects of one example of the system 30 are provided. In addition, FIG. 3 provides for additional explanation of how multiple well tools 32 may be selectively actuated using the principles of this disclosure.
In this example, multiple control devices 50a-c are associated with respective multiple actuators 36a-c of multiple well tools 32a-c. The actuators 36a-c include pistons 42a-c. It should be understood that any number of control devices, actuators and well tools may be used in keeping with the principles of this disclosure, and that these elements may be combined, if desired (for example, multiple control devices could be combined into a single device, a single well tool can include multiple functional well tools, an actuator and/or control device could be built into a well tool, etc.).
Each of the control devices 50a-c depicted in FIG. 3 includes a solenoid actuated spool valve. A solenoid 58 of the control device 50a has displaced a spool or poppet valve 60 to a position in which the actuator 36a is now connected to the lines 48a,b. A pressure differential between the lines 48a,b can now be used to displace the piston 42a and actuate the well tool 32a. The remaining control devices 50b,c prevent actuation of their associated well tools 32b,c by isolating the lines 48a,b from the actuators 36b,c. 
The control device 50a responds to current flow through a certain set of the conductors 52. In this example, conductors 52a,b are connected to the control device 50a. When current flows in one direction through the conductors 52a,b, the control device 50a causes the actuator 36a to be operatively connected to the lines 48a,b, but when current flows in an opposite direction through the conductors, the control device causes the actuator to be operatively isolated from the lines.
As depicted in FIG. 3, the other control devices 50b,c are connected to different sets of the conductors 52. For example, control device 50b is connected to conductors 52c,d and control device 50c is connected to conductors 52e,f. 
When current flows in one direction through the conductors 52c,d, the control device 50b causes the actuator 36b to be operatively connected to the lines 48a,b, but when current flows in an opposite direction through the conductors, the control device causes the actuator to be operatively isolated from the lines. Similarly, when current flows in one direction through the conductors 52e,f, the control device 50c causes the actuator 36c to be operatively connected to the lines 48a,b, but when current flows in an opposite direction through the conductors, the control device causes the actuator to be operatively isolated from the lines.
However, it should be understood that multiple control devices are preferably, but not necessarily, connected to each set of conductors. By connecting multiple control devices to the same set of conductors, the advantages of a reduced number of conductors can be obtained, as explained more fully below.
The function of selecting a particular well tool 32a-c for actuation in response to current flow in a particular direction between certain conductors is provided by directional elements 62 of the control devices 50a-c. Various different types of directional elements 62 are described more fully below.
Referring additionally now to FIG. 4, an example of the system 30 is representatively illustrated, in which multiple control devices are connected to each of multiple sets of conductors, thereby achieving the desired benefit of a reduced number of conductors in the well. In this example, actuation of six well tools may be selectively controlled using only three conductors, but, as described herein, any number of conductors and well tools may be used in keeping with the principles of this disclosure.
As depicted in FIG. 4, six control devices 50a-f are illustrated apart from their respective well tools. However, it will be appreciated that each of these control devices 50a-f would in practice be connected between the fluid pressure source 48 and a respective actuator 36 of a respective well tool 32 (for example, as described above and depicted in FIGS. 2 & 3).
The control devices 50a-f include respective solenoids 58a-f, spool valves 60a-f and directional elements 62a-f. In this example, the elements 62a-f are diodes. Although the solenoids 58a-f and diodes 62a-f are electrical components, they do not comprise complex or unreliable electronic circuitry, and suitable reliable high temperature solenoids and diodes are readily available.
A power supply 64 is used as a source of direct current. The power supply 64 could also be a source of alternating current and/or command and control signals, if desired. However, the system 30 as depicted in FIG. 4 relies on directional control of current in the conductors 52 in order to selectively actuate the well tools 32, so alternating current, signals, etc. should be present on the conductors only if such would not interfere with this selection function. If the casing string 16 and/or tubing string 20 is used as a conductor in the system 30, then preferably the power supply 64 comprises a floating power supply.
The conductors 52 may also be used for telemetry, for example, to transmit and receive data and commands between the surface and downhole well tools, actuators, sensors, etc. This telemetry can be conveniently transmitted on the same conductors 52 as the electrical power supplied by the power supply 64.
The conductors 52 in this example comprise three conductors 52a-c. The conductors 52 are also arranged as three sets of conductors 52a,b 52b,c and 52a,c. Each set of conductors includes two conductors. Note that a set of conductors can share one or more individual conductors with another set of conductors.
Each conductor set is connected to two control devices. Thus, conductor set 52a,b is connected to each of control devices 50a,b, conductor set 52b,c is connected to each of control devices 50c,d, and conductor set 52a,c is connected to each of control devices 50e,f. 
In this example, the tubing string 20 is part of the conductor 52c. Alternatively, or in addition, the casing string 16 or any other conductor can be used in keeping with the principles of this disclosure.
It will be appreciated from a careful consideration of the system 30 as depicted in FIG. 4 (including an observation of how the diodes 62a-f are arranged between the solenoids 58a-f and the conductors 52a-c) that different current flow directions between different conductors in the different sets of conductors can be used to select which of the solenoids 58a-f are powered to thereby actuate a respective well tool. For example, current flow from conductor 52a to conductor 52b will provide electrical power to solenoid 58a via diode 62a, but oppositely directed current flow from conductor 52b to conductor 52a will provide electrical power to solenoid 58b via diode 62b. Conversely, diode 62a will prevent solenoid 58a from being powered due to current flow from conductor 52b to conductor 52a, and diode 62b will prevent solenoid 58b from being powered due to current flow from conductor 52a to conductor 52b. 
Similarly, current flow from conductor 52b to conductor 52c will provide electrical power to solenoid 58c via diode 62c, but oppositely directed current flow from conductor 52c to conductor 52b will provide electrical power to solenoid 58d via diode 62d. Diode 62c will prevent solenoid 58c from being powered due to current flow from conductor 52c to conductor 52b, and diode 62d will prevent solenoid 58d from being powered due to current flow from conductor 52b to conductor 52c. 
Current flow from conductor 52a to conductor 52c will provide electrical power to solenoid 58e via diode 62e, but oppositely directed current flow from conductor 52c to conductor 52a will provide electrical power to solenoid 58f via diode 62f. Diode 62e will prevent solenoid 58e from being powered due to current flow from conductor 52c to conductor 52a, and diode 62f will prevent solenoid 58f from being powered due to current flow from conductor 52a to conductor 52c. 
The direction of current flow between the conductors 52 is controlled by means of a switching device 66. The switching device 66 is interconnected between the power supply 64 and the conductors 52, but the power supply and switching device could be combined, or could be part of an overall control system, if desired.
Examples of different configurations of the switching device 66 are representatively illustrated in FIGS. 5 & 6. FIG. 5 depicts an embodiment in which six independently controlled switches are used to connect the conductors 52a-c to the two polarities of the power supply 64. FIG. 6 depicts an embodiment in which an appropriate combination of switches are closed to select a corresponding one of the well tools for actuation. This embodiment might be implemented, for example, using a rotary switch. Other implementations (such as using a programmable logic controller, etc.) may be utilized as desired.
Referring additionally now to FIG. 7, another configuration of the control system 30 is representatively illustrated. The configuration of FIG. 7 is similar in many respects to the configuration of FIG. 3. However, only two each of the actuators 36a,b and control devices 50a,b, and one set of conductors 52a,b are depicted in FIG. 7, it being understood that any number of actuators, control devices and sets of conductors may be used in keeping with the principles of this disclosure.
Another difference between the FIGS. 3 & 7 configurations is in the spool valves 60a,b. The spool valves 60 in the FIGS. 3 & 7 configurations accomplish similar results, but in somewhat different manners. In both configurations, the spool valves 60 pressure balance the pistons 42 when the solenoids 58 are not powered, and they connect the actuators 36 to the pressure source 48 when the solenoids 58 are powered. However, in the FIG. 3 configuration, the actuators 36 are completely isolated from the pressure source 48 when the solenoids 58 are not powered, whereas in the FIG. 7 configuration, the actuators remain connected to one of the lines 48b when the solenoids are not powered.
Another difference is that pressure-compensated flow rate regulators 68a,b are connected between the line 48a and respective spool valves 60a,b. The flow regulators 68a,b maintain a substantially constant flow rate therethrough, even though pressure differential across the flow regulators may vary. A suitable flow regulator for use in the system 30 is a FLOSERT(TM) available from Lee Co. of Essex, Conn. USA.
When one of the solenoids 58a,b is powered and the respective piston 42a or b is being displaced in response to a pressure differential between the lines 48a,b, the flow regulator 68a or b will ensure that the piston displaces at a predetermined velocity, since fluid will flow through the flow regulator at a corresponding predetermined flow rate. In this manner, the position of the piston can be precisely controlled (i.e., by permitting the piston to displace at its predetermined velocity for a given amount of time, which can be precisely controlled via the control device due to the presence and direction of current flow in the conductors 52 as described above).
Although the flow regulators 68a,b are depicted in FIG. 7 as being connected between the line 48a and the respective spool valves 60a,b, it will be appreciated that other arrangements are possible. For example, the flow regulators 68a,b could be connected between the line 48b and the spool valves 60a,b, or between the spool valves and the actuators 36a,b, etc.
In addition, the flow regulators may be used in any of the other control system 30 configurations described herein, if desired, in order to allow for precise control of the positions of the pistons in the actuators. Such positional control is very useful in flow choking applications, for example, to precisely regulate production or injection flow between multiple zones and a tubing string.
Note that, in the example of FIG. 7, the conductor 52b includes the tubing string 20. This demonstrates that any of the conductors 52 can comprise a tubular string in the well.
Referring additionally now to FIG. 8, another configuration of the control system 30 is representatively illustrated. The configuration of FIG. 8 is similar in many respects to the configuration of FIG. 7, but differs substantially in the manner in which the control devices 50a,b operate.
Specifically, the spool valves 60a,b are pilot-operated, with the solenoids 58a,b serving to selectively permit or prevent such pilot operation. Thus, powering of a respective one of the solenoids 58a,b still operates to select a particular one of the well tools 32 for actuation, but the amount of power required to do so is expected to be much less in the FIG. 8 embodiment.
For example, if the solenoid 58a is powered by current flow from conductor 52a to conductor 52b, the solenoid will cause a locking member 70a to retract out of locking engagement with a piston 72a of the spool valve 60a. The piston 72a will then be free to displace in response to a pressure differential between the lines 48a,b. If, for example, pressure in the line 48a is greater than pressure in the line 48b, the piston 72a will displace to the right, thereby connecting the actuator 36a to the pressure source 48, and the piston 42a of the actuator 36a will displace to the right. However, when the piston 72a is in its centered and locked position, the actuator 36a is pressure balanced.
Similarly, if the solenoid 58b is powered by current flow from conductor 52b to conductor 52a, the solenoid will cause a locking member 70b to retract out of locking engagement with a piston 72b of the spool valve 60b. The piston 72b will then be free to displace in response to a pressure differential between the lines 48a,b. If, for example, pressure in the line 48b is greater than pressure in the line 48a, the piston 72b will displace to the left, thereby connecting the actuator 36b to the pressure source 48, and the piston 42b of the actuator 36b will displace to the left. However, when the piston 72b is in its centered and locked position, the actuator 36b is pressure balanced.
The locking engagement between the locking members 70a,b and the pistons 72a,b could be designed to release in response to a predetermined pressure differential between the lines 48a,b (preferably, a pressure differential greater than that expected to be used in normal operation of the system 30). In this manner, the actuators 36a,b could be operated by applying the predetermined pressure differential between the lines 48a,b, for example, in the event that one or both of the solenoids 58a,b failed to operate, in an emergency to quickly close the flow control devices 38, etc.
Referring additionally now to FIG. 9, another configuration of the control system 30 is representatively illustrated. The FIG. 9 configuration is similar in many respects to the FIG. 8 configuration, except that the solenoids and diodes are replaced by coils 74a,b and magnets 76a,b in the control devices 50a,b of FIG. 9.
The coils 74a,b and magnets 76a,b also comprise the directional elements 62a,b in the control devices 50a,b since the respective locking members 70a,b will only displace if current flows between the conductors 52a,b in appropriate directions. For example, the coil 74a and magnet 76a are arranged so that, if current flows from conductor 52a to conductor 52b, the coil will generate a magnetic field which opposes the magnetic field of the magnet, and the locking member 70a will thus be displaced upward (as viewed in FIG. 9) out of locking engagement with the piston 72a, and the actuator 36a can be connected to the pressure source 48 as described above. Current flow in the opposite direction will not cause such displacement of the locking member 70a. 
Similarly, the coil 74b and magnet 76b are arranged so that, if current flows from conductor 52b to conductor 52a, the coil will generate a magnetic field which opposes the magnetic field of the magnet, and the locking member 70b will thus be displaced upward (as viewed in FIG. 9) out of locking engagement with the piston 72b, and the actuator 36b can be connected to the pressure source 48 as described above. Current flow in the opposite direction will not cause such displacement of the locking member 70b. 
It will, thus, be appreciated that the FIG. 9 configuration obtains all of the benefits of the previously described configurations, but does not require use of any downhole electrical components, other than the coils 74a,b and conductors 52.
Referring additionally now to FIG. 10, another configuration of the control system 30 is representatively illustrated. The FIG. 10 configuration is similar in many respects to the FIG. 9 configuration, but is depicted with six of the control devices 50a-f and three sets of the conductors 52, similar to the system 30 as illustrated in FIG. 4. The spool valves 60, actuators 36 and well tools 32 are not shown in FIG. 10 for clarity of illustration and description.
In this FIG. 10 configuration, the coils 74a-f and magnets 76a-f are arranged so that selected locking members 70a-f are displaced in response to current flow in particular directions between certain conductors in the sets of the conductors 52. For example, current flow between the conductors 52a,b in one direction may cause the element 62a to displace the locking member 70a while current flow between the conductors 52a,b in an opposite direction may cause the element 62b to displace the locking member 70b, current flow between the conductors 52b,c may cause the element 62c to displace the locking member 70c while current flow between the conductors 52b,c may cause the element 62d to displace the locking member 70d, and current flow between the conductors 52a,c may cause the element 62e to displace the locking member 70e while current flow between the conductors 52a,c in an opposite direction may cause the element 62f to displace the locking member 70f. 
Note that, in each pair of the control devices 50a,b 50c,dand 50e,f connected to the respective sets 52a,b 52b,c and 52a,cof conductors, the magnets 76a,b 76c,d and 76e,fare oppositely oriented (i.e., with their poles facing opposite directions in each pair of control devices). This alternating orientation of the magnets 76a-f, combined with the connection of the coils 74a-f to particular sets of the conductors 52, results in the capability of selecting a particular well tool 32 for actuation by merely flowing current in a particular direction between particular ones of the conductors.
Another manner of achieving this result is representatively illustrated in FIG. 11. Instead of alternating the orientation of the magnets 76a-f as in the FIG. 10 configuration, the coils 74a-f are oppositely arranged in the pairs of control devices 50a,b 50c,d and 50e,f. For example, the coils 74a-f could be wound in opposite directions, so that opposite magnetic field orientations are produced when current flows between the sets of conductors.
Another manner of achieving this result would be to oppositely connect the coils 74a-f to the respective conductors 52. In this configuration, current flow between a set of conductors would produce a magnetic field in one orientation from one of the coils, but a magnetic field in an opposite orientation from the other one of the coils.
It will, thus, be appreciated that a variety of different configurations can be designed in keeping with the principles of this disclosure while still obtaining the many benefits of these principles. The above description has provided several examples of how these principles can be applied to the problems of selectively actuating multiple well tools, but it should be clearly understood that these principles are not limited to the various examples.
In particular, the above description has provided a method of selectively actuating from a remote location multiple downhole well tools 32 in a well. The method includes the steps of: selecting one of the well tools 32a for actuation by flowing electrical current in one direction 54a through a set of conductors 52a,b in the well; and selecting another one of the well tools 32b for actuation by flowing electrical current through the set of conductors 52a,b in an opposite direction 54b. 
The step of selecting the first well tool 32a may include providing fluid communication between a source of fluid pressure 48 and an actuator 36a of the first well tool 32a. The step of selecting the second well tool 32b may include providing fluid communication between the source of fluid pressure 48 and an actuator 36b of the second well tool 32b. 
The method may include the step of flowing fluid between the source of fluid pressure 48 and the actuator 36a of the first well tool 32a for a predetermined period of time through a flow rate regulator 68a, thereby displacing a piston 42a of the actuator 36a of the first well tool 32a a predetermined distance. The flow rate regulator 68a may substantially maintain a predetermined rate of flow of the fluid as a pressure differential across an input and an output of the flow rate regulator varies over time.
The method may also include the steps of preventing the first well tool 32a from actuating while current flows between the conductors 52a,b in the second direction, and preventing the second well tool 32b from actuating while current flows between the conductors 52a,b in the first direction. The step of preventing the first well tool 32a from actuating may include using a first diode 62a to prevent current flow in the second direction 54b, and the step of preventing the second well tool 32b from actuating may include using a second diode 62b to prevent current flow in the first direction 54a. 
The method may also include the steps of selecting a third one of the well tools 32 for actuation by flowing electrical current in a third direction through a second set of conductors 52b,c in the well; and selecting a fourth one of the well tools 32 for actuation by flowing electrical current through the second set of conductors 52b,c in a fourth direction opposite to the third direction.
The above description also provides a system 30 for selectively actuating from a remote location multiple downhole well tools 32 in a well. The system 30 includes multiple electrical conductors 52 in the well and multiple control devices 50 which control which of the well tools 32 is selected for actuation in response to current flow in at least one set of the conductors 52. At least one direction of current flow in the set of conductors 52 is used to select a respective at least one of the well tools 32 for actuation. An opposite direction of current flow in the set of conductors 52 may be used to select a respective other one of the well tools 32 for actuation.
The control devices 50 may include multiple diodes 62. A first one of the diodes 62a may be used to permit actuation of a first one of the well tools 32a in response to current flow in a first direction between a first set of the conductors 52a,b. A second one of the diodes 62b may be used to permit actuation of a second one of the well tools 32b in response to current flow in a second direction between the first set of the conductors 52a,b with the second direction being opposite to the first direction.
The first diode 62a may prevent actuation of the first well tool 32a when current flows in the second direction between the first set of conductors 52a,b. The second diode 62b may prevent actuation of the second well tool 32b when current flows in the first direction between the first set of conductors 52a,b. 
The control devices 50 may include multiple coil and magnet sets. A first coil 74a and magnet 76a set may be used to permit actuation of a first one of the well tools 32a in response to current flow in a first direction between a first set of the conductors 52a,b and a second coil 74b and magnet 76b set may be used to permit actuation of a second one of the well tools 32b in response to current flow in a second direction between the first set of the conductors 52a,b with the second direction being opposite to the first direction.
The first coil 74a and magnet 76a set may prevent actuation of the first well tool 32a when current flows in the second direction between the first set of conductors 52a,b. The second coil 74b and magnet 76b set may prevent actuation of the second well tool 32b when current flows in the first direction between the first set of conductors 52a,b. 
The system 30 may also include at least one hydraulic line 48a,b in the well and multiple actuators 36. Each of the actuators 36 may be responsive to fluid pressure in the at least one hydraulic line 48a,b to actuate a respective one of the well tools 32. Each of the actuators 36 may be isolated from pressure in the hydraulic line 48a,b until the current flow in the set of conductors 52 flows in a respective predetermined direction.
The well tools 32 may include at least first, second, third and fourth well tools, the control devices 50 may include at least first, second, third and fourth control devices, and the sets of conductors 52 may include at least first and second sets of conductors. The first control device 50a may be configured to select the first well tool 32a for actuation in response to current flow in a first direction between the first set of conductors 52a,b, the second control device 50b may be configured to select the second well tool 32b for actuation in response to current flow between the first set of conductors 52a,b in a second direction opposite to the first direction, the third control device 50c may be configured to select the third well tool 32c for actuation in response to current flow between the second set of conductors 52b,c in a third direction, and the fourth control device 50d may be configured to select the fourth well tool for actuation in response to current flow between the second set of conductors 52b,c in a fourth direction opposite to the third direction.
Telemetry signals may be transmitted via at least one of the conductors 52.
Also provided by the above description is a method of using n conductors 52 to selectively actuate n*(n−1) downhole well tools 32. The method includes the steps of: arranging the n conductors 52 into n*(n−1)/2 sets of conductors; connecting each set of conductors 52 to a respective pair of the well tools 32; and controlling direction of current flow through each set of conductors 52 to thereby selectively actuate the respective pair of the well tools 32.
The controlling step may include selecting a first one of the well tools 32a for actuation by flowing electrical current in a first direction between a first one of the sets of conductors 52a,b; and selecting a second one of the well tools 32b for actuation by flowing electrical current between the first set of conductors 52a,b in a second direction opposite to the first direction.
The step of selecting the first well tool 32a further comprises providing fluid communication between a source of fluid pressure 48 and an actuator 36a of the first well tool 32a. The step of selecting the second well tool 32b may include providing fluid communication between the source of fluid pressure 48 and an actuator 36b of the second well tool 32b. 
The method may include the step of flowing fluid between the source of fluid pressure 48 and the actuator 36a of the first well tool 32a for a predetermined period of time through a flow rate regulator 68a, thereby displacing a piston 42a of the actuator 36a of the first well tool 32a a predetermined distance.
The method may include the steps of preventing the first well tool 32a from actuating while current flows between the conductors 52a,b in the second direction, and preventing the second well tool 32b from actuating while current flows between the conductors 52a,b in the first direction.
The step of preventing the first well tool 32a from actuating may include using a first diode 62a to prevent current flow in the second direction. The step of preventing the second well tool 32b from actuating may include using a second diode 62b to prevent current flow in the first direction.
The method may include the steps of selecting a third one of the well tools 32c for actuation by flowing electrical current in a third direction between a second set of conductors 52b,c in the well; and selecting a fourth one of the well tools for actuation by flowing electrical current between the second set of conductors 52b,c in a fourth direction opposite to the third direction.
Note that multiple well tools 32 may be selected for actuation at the same time. For example, multiple similarly configured control devices 50 could be wired in series or parallel to the same set of the conductors 52, or control devices connected to different sets of conductors could be operated at the same time by flowing current in appropriate directions through the sets of conductors.
In addition, note that fluid pressure to actuate the well tools 32 may be supplied by one of the lines 48, and another one of the lines (or another flow path, such as an interior of the tubing string 20 or the annulus 56) may be used to exhaust fluid from the actuators 36. An appropriately configured and connected spool valve can be used, so that the same one of the lines 48 be used to supply fluid pressure to displace the pistons 42 of the actuators 36 in each direction.
Preferably, in each of the above-described embodiments, the fluid pressure source 48 is pressurized prior to flowing current through the selected set of conductors 52 to actuate a well tool 32. In this manner, actuation of the well tool 32 immediately follows the initiation of current flow in the set of conductors 52.
Of course, a person skilled in the art would, upon a careful consideration of the above description of representative embodiments of the disclosure, readily appreciate that many modifications, additions, substitutions, deletions, and other changes may be made to the specific embodiments, and such changes are contemplated by the principles of the present disclosure. Accordingly, the foregoing detailed description is to be clearly understood as being given by way of illustration and example only, the spirit and scope of the present invention being limited solely by the appended claims and their equivalents.

## Claims

1. A method of selectively actuating from a remote location multiple downhole well tools in a well, the method comprising the steps of:
selecting a first one of the well tools for actuation by flowing electrical current in a first direction through a first set of conductors in the well;
selectively controlling a position of a first piston by permitting the first piston to displace at a first predetermined velocity for a first given amount of time, thereby controlling a duration of actuation of the first one of the well tools, and variably actuating the first one of the well tools;
selecting a second one of the well tools for actuation by flowing electrical current through the first set of conductors in a second direction opposite to the first direction; and
selectively controlling a position of a second piston by permitting the second piston to displace at a second predetermined velocity for a second given amount of time, thereby controlling a duration of actuation of the second one of the well tools, and variably actuating the second one of the well tools.

2. The method of claim 1, further comprising the steps of preventing the first well tool from actuating while current flows through the conductors in the second direction, and preventing the second well tool from actuating while current flows through the conductors in the first direction.

3. The method of claim 2, wherein the step of preventing the first well tool from actuating further comprises using a first diode to prevent current flow in the second direction, and wherein the step of preventing the second well tool from actuating further comprises using a second diode to prevent current flow in the first direction.

4. The method of claim 1, further comprising the steps of selecting a third one of the well tools for actuation by flowing electrical current in a third direction through a second set of conductors in the well; and selecting a fourth one of the well tools for actuation by flowing electrical current through the second set of conductors in a fourth direction opposite to the third direction.

5. A method of selectively actuating from a remote location multiple downhole well tools in a well, the method comprising the steps of:
selecting a first one of the well tools for actuation by flowing electrical current in a first direction through a first set of conductors in the well; and
selecting a second one of the well tools for actuation by flowing electrical current through the first set of conductors in a second direction opposite to the first direction,
wherein the step of selecting the first well tool further comprises providing fluid communication between a source of fluid pressure and an actuator of the first well tool;
and wherein the step of selecting the second well tool further comprises providing fluid communication between the source of fluid pressure and an actuator of the second well tool.

6. The method of claim 5, further comprising the step of flowing fluid between the source of fluid pressure and the actuator of the first well tool for a predetermined period of time through a flow rate regulator, thereby displacing a piston of the actuator of the first well tool a predetermined distance.

7. The method of claim 6, wherein the flow rate regulator substantially maintains a predetermined rate of flow of the fluid as a pressure differential across an input and an output of the flow rate regulator varies over time.

8. A system for selectively actuating from a remote location multiple downhole well tools in a well, the system comprising:
multiple electrical conductors in the well;
multiple control devices that control which of the well tools is selected for actuation in response to current flow in at least one set of the conductors, at least one direction of current flow in the at least one set of conductors being operative to select a respective at least one of the well tools for actuation, the control devices selectively controlling a duration of actuation of the at least one of the well tools selected for actuation, thereby variably actuating the at least one of the well tools;
at least one hydraulic line in the well; and
multiple actuators, each of the actuators being responsive to fluid pressure in the at least one hydraulic line to actuate a respective one of the well tools.

9. The system of claim 8, wherein the control devices comprise multiple diodes, a first one of the diodes being operative to permit actuation of a first one of the well tools in response to current flow in a first direction through a first set of the conductors, and a second one of the diodes being operative to permit actuation of a second one of the well tools in response to current flow in a second direction through the first set of the conductors, the second direction being opposite to the first direction.

10. The system of claim 9, wherein the first diode prevents actuation of the first well tool when current flows in the second direction through the first set of conductors, and wherein the second diode prevents actuation of the second well tool when current flows in the first direction through the first set of conductors.

11. The system of claim 8, wherein each of the actuators is isolated from pressure in the hydraulic line until the current flow in the set of conductors flows in a respective predetermined direction.

12. The system of claim 8, wherein each of the actuators includes an actuator piston which is pressure balanced until the current flow in the set of conductors flows in a respective predetermined direction.

13. The system of claim 8, wherein the well tools comprise at least first, second, third and fourth well tools, wherein the control devices comprise at least first, second, third and fourth control devices, wherein the sets of conductors comprise at least first and second sets of conductors, and
wherein the first control device is configured to select the first well tool for actuation in response to current flow in a first direction through the first set of conductors, the second control device is configured to select the second well tool for actuation in response to current flow through the first set of conductors in a second direction opposite to the first direction, the third control device is configured to select the third well tool for actuation in response to current flow through the second set of conductors in a third direction, and the fourth control device is configured to select the fourth well tool for actuation in response to current flow through the second set of conductors in a fourth direction opposite to the third direction.

14. The system of claim 8, wherein telemetry signals are transmitted via at least one of the conductors.

15. A system for selectively actuating from a remote location multiple downhole well tools in a well, the system comprising:
multiple electrical conductors in the well; and
multiple control devices that control which of the well tools is selected for actuation in response to current flow in at least one set of the conductors, at least one direction of current flow in the at least one set of conductors being operative to select a respective at least one of the well tools for actuation,
wherein the control devices comprise multiple coil and magnet sets, a first coil and magnet set being operative to permit actuation of a first one of the well tools in response to current flow in a first direction through a first set of the conductors, and a second coil and magnet set being operative to permit actuation of a second one of the well tools in response to current flow in a second direction through the first set of the conductors, the second direction being opposite to the first direction.

16. The system of claim 15, wherein the first coil and magnet set prevents actuation of the first well tool when current flows in the second direction through the first set of conductors, and wherein the second coil and magnet set prevents actuation of the second well tool when current flows in the first direction through the first set of conductors.

17. A method of using n conductors to selectively actuate n*(n−1) downhole well tools, the method comprising the steps of:
arranging the n conductors into n*(n−1)/2 sets of conductors;
connecting each set of conductors to a respective group of the well tools;
controlling direction of current flow through at least one of the sets of conductors, thereby selecting at least one well tool in the respective group of the well tools for actuation,
wherein the controlling step further comprises selecting a first one of the well tools for actuation by flowing electrical current in a first direction through a first one of the sets of conductors, and selecting a second one of the well tools for actuation by flowing electrical current through the first set of conductors in a second direction opposite to the first direction,
wherein the step of selecting the first well tool further comprises providing fluid communication between a source of fluid pressure and an actuator of the first well tool, and
wherein the step of selecting the second well tool further comprises providing fluid communication between the source of fluid pressure and an actuator of the second well tool.

18. The method of claim 17, further comprising the step of flowing fluid between the source of fluid pressure and the actuator of the first well tool for a predetermined period of time through a flow rate regulator, thereby displacing a piston of the actuator of the first well tool a predetermined distance.

19. The method of claim 17, further comprising the steps of preventing the first well tool from actuating while current flows through the conductors in the second direction, and preventing the second well tool from actuating while current flows through the conductors in the first direction.

20. The method of claim 19, wherein the step of preventing the first well tool from actuating further comprises using a first diode to prevent current flow in the second direction, and wherein the step of preventing the second well tool from actuating further comprises using a second diode to prevent current flow in the first direction.

21. The method of claim 17, further comprising the steps of selecting a third one of the well tools for actuation by flowing electrical current in a third direction through a second set of conductors in the well; and selecting a fourth one of the well tools for actuation by flowing electrical current through the second set of conductors in a fourth direction opposite to the third direction.