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BACKGROUND 
     Various downhole components use control lines for operation. For example, subsurface safety valves, such as tubing retrievable safety valves, deploy on production tubing in a producing well. Actuated by hydraulics via a control line, the safety valve can selectively seal fluid flow through the production tubing if a failure or hazardous condition occurs at the well surface. In this way, the safety valve can minimize the loss of reservoir resources or production equipment resulting from catastrophic subsurface events. 
     One type of safety valve is a deep-set safety valve that uses two control lines for operation. One active control line controls the opening and closing of the safety valve&#39;s closure, while the other control line is used for “balance.” Due to the deep setting of the valve, this balance control line negates the effect of hydrostatic pressure from the active control line. 
     In  FIG. 1 , for example, production tubing  20  has a deep-set safety valve  40  for controlling the flow of fluid in the production tubing  20 . In this example, the wellbore  10  has been lined with casing  12  with perforations  16  for communicating with the surrounding formation  18 . The production tubing  20  with the safety valve  40  deploys in the wellbore  10  to a predetermined depth. Produced fluid flows into the production tubing  20  through a sliding sleeve or other type of device. Traveling up the tubing  20 , the produced fluid flows up through the safety valve  40 , through a surface valve  25 , and into a flow line  22 . 
     As is known, the flow of the produced fluid can be stopped at any time during production by switching the safety valve  40  from an open condition to a closed condition. To that end, a hydraulic system having a pump  30  draws hydraulic fluid from a reservoir  35  and communicates with the safety valve  40  via a first control line  32 A. When actuated, the pump  30  exerts a control pressure P C  through the control line  32 A to the safety valve  40 . 
     Due to vertical height of the control line  32 A, a hydrostatic pressure P H  also exerts on the valve  40  through the control line  32 A. For this reason, a balance line  32 B also extends to the valve  40  and provides fluid communication between the reservoir  35  or pressure from pump  31  and the valve  40 . Because the balance line  32 B has the same column of fluid as the control line  32 A, the outlet of the balance line  32 B connected to the valve  40  has the same hydrostatic pressure P H  as the control line  32 A. 
     As with the deep-set safety valve, there may be other reasons to run multiple control lines downhole to components. Unfortunately, the control lines have to pass uphole to a wellhead. Communicating with multiple control lines through a wellhead can present a number of challenges due to limited space, installation complexity, and sealing issues. The difficulties are exacerbated when subsea wellhead equipment is used. In general, subsea wellhead equipment has restrictions on how many penetrations can be made through it for the use of control lines, fiber optics, etc. 
     Typically, intelligent well completions, deep-set safety valves, and other well system require two or more control lines penetrating the wellhead and running downhole. However, current control line systems have limitations due to the restrictions on the number of wellhead penetrations that can be made as well as issues pertaining to when one of the control lines ruptures. 
     The subject matter of the present disclosure is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above. 
     SUMMARY 
     A multiple control line system uses concentric control lines having an outer control line disposed about at least one inner control line. For example, the concentric control lines can use an inner control line encapsulated within an outer control line. Encapsulated together, the dual control lines only require one penetration through the wellhead to extend downhole. At the wellhead, the dual control lines communicate with an operating system, which can provide hydraulics, fluid, electric power, signals, or the like for downhole components as described herein. Thus, the outer control line can convey a medium, such as fluid, power, electric signals, and optical signals, while the inner control line can convey a same or different medium. 
     At some point downhole, the dual control lines extending along the tubing couple to a manifold having an inlet and at least two outlets. The outer control line terminates at the inlet with a sealed fitting. The inner conduit is allowed to pass through the manifold and out one of the outlets with another sealed fitting. This inner conduit can then convey hydraulics, power, signals, or the like to one or more downhole components, such as a safety valve, a hydraulic sleeve, a sensor, a motor, a solenoid, or the like. 
     A separate control line couples to the other outlet of the manifold with a sealed fitting. Internally, a cross-drilled port for the outlet communicates with the annular space between the inner and outer conduits exposed in the manifold. This allows hydraulics, wiring, power, or the like from the outer control line from the surface to communicate with the separate control line extending from the manifold. From there, the separate control line can couple to the same downhole component as the inner control line or can couple to an entirely different component. 
     More than two control lines can be encapsulated inside one another, and more than one manifold may be used downhole to branch off other control lines. Historically, intelligent well completion tools and deep-set safety valves have required at least two control line penetrations through the wellhead for operation. Using encapsulated control lines and manifolds, the multiple control line system of the present disclosure allows one control line penetration through the wellhead to be used while giving the benefits of multiple separate control lines for operation of downhole components. 
     The foregoing summary is not intended to summarize each potential embodiment or every aspect of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a wellbore having a string of production tubing, a deep-set safety valve, and a dual control line system in accordance with the prior art. 
         FIG. 2  shows a multiple control line system according to the present disclosure. 
         FIG. 3  shows an arrangement of multiple manifolds and encapsulated control lines for the multiple control line system. 
         FIGS. 4A-4B  illustrate how components of the multiple control line system of  FIG. 2  can be connected to tubing. 
         FIGS. 5 ,  6 , and  7  illustrate configurations of a multiple control line system in accordance with the present disclosure for a deep-set safety valve. 
         FIG. 8  illustrates one configuration of a multiple control line system for a surface controlled sub-surface safety valve according to certain teachings of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 2  shows a multiple control line system  50  according to certain teachings of the present disclosure. The system  50  includes a manifold  100  that disposes at some point downhole from a wellhead  60  of a wellbore. An uphole end of the manifold  100  connects to concentric control lines  120 A-B. A downhole end of the manifold  100  has downhole control lines  130 A-B that branch off therefrom. 
     The concentric control lines  120 A-B pass uphole from the manifold  100  and through the wellhead  60 . At the surface, an operating system  70  communicates with these control line  120 A-B. In general, the operating system  70  can be a hydraulic manifold or well control panel and can have one or more pumps  72   a - b , reservoirs  73 , and other necessary components for a high-pressure hydraulic system used in wells. The operating system  70  can also include electric components for conveying power, electrical, optical, or other signals downhole. These and other possibilities can be used in the disclosed system  50 . For the present disclosure, the operating system  70  is described as being hydraulic for convenience; however, the teachings of the present disclosure are applicable to other types of systems. 
     Extending from the manifold  100 , the downhole control lines  130 A-B pass to one or more downhole components  80 . For example, the control lines  130 A-B can connect to a deep-set safety valve as the component  80  having two actuators  82 A-B. Alternatively, the downhole components  80  may include two separate safety valves with independent actuators  82 A-B. Still further, the downhole components  80  can include a hydraulic device  82 A and an electronic device  82 B or vice a versa. For a hydraulic device, the downhole components  80  can include, but are not limited to, a tubing retrievable safety valve, a downhole deployment valve (DDV) coupled to casing, a hydraulically actuated packer, a hydraulically actuated sliding sleeve, or any other type of hydraulic tool useable downhole. For an electronic device, the downhole components  80  can include, but are not limited to, a sensor, a motor, a telemetry device, a memory unit, a solenoid, or any other electronic component useable downhole. 
     As noted herein, passing control lines through the components of the wellhead  60  can be complicated. Thus, use of the concentric control lines  120 A-B between the operating system  70  and the manifold  100  reduces the complications associated with passing control lines through the wellhead  60 . As shown in  FIG. 2 , the concentric control lines  120 A-B include an inner control line  120 A encapsulated in at least one outer control line  120 B. This encapsulation of the smaller control line  120 A inside the larger control line  120 B means that the lines  120 A-B need to penetrate the wellhead  60  once. Yet, the encapsulated control lines  120 A-B still enable downhole components  80  to use multiple separate control line fluids. 
     The concentric control lines  120 A-B are manufactured as one, and the manifold  100  splits or separates the concentric control lines  120 A-B to the downhole control lines  130 A-B. To assemble the manifold  100 , the outer control line  120 B is cut to a length that exposes enough of the inner control line  120 A to feed through the manifold  100 . A fitting  112  having a jam nut and ferrules crimps and seals the outer control line  120 B in a port  113  of the manifold  100 . 
     The inner control line  120 A exits an opposing port  115  at the bottom of the manifold  100 , and another fitting  114  having a jam nut and ferrules crimps and seals the inner control line  120 A in the port  115 . As shown, the inner control line  120 A can pass directly through the manifold  100  uninterrupted from the uphole end to the downhole end. In this way, the inner control line  120 A does not need to be severed or cut to affix to the manifold  100 , although such an arrangement could be used as needed. The downhole control line  130 A is therefore the same lines as the inner control line  120 A. 
     To create the split, the manifold  100  defines a cross-drilled port  117  that intersects with the uphole port  113 . In this way, the cross-drilled port  117  can communicate with the annulus between the outer control line  120 B and the inner control line  120 A. At the cross-drilled port  117 , a fitting  116  having a jam nut and ferrules crimps and seals the other downhole control line  130 B in the manifold  100 . 
     Both control lines  120 A/ 130 A and  120 B/ 130 B can convey hydraulic fluid between the operation system  70  and downhole components  80 . Alternatively, one set of control lines (i.e.,  120 A/ 130 A) can convey electric wiring, fiber optics, or the like, while the surrounding control lines  120 B/ 130 B can convey hydraulics. The reverse is also possible as is the arrangement of both lines  120 A/ 130 B and  120 B/ 130 B conveying electric wiring, fiber optics, or the like rather than hydraulic fluid. 
     The operating system  70  can have multiple lines  74 A-B extending from actuators  72 A-B, which can be pumps, reservoirs, power supplies, control units, sensor units, etc. An uphole manifold  76 , which can be a reverse of the disclosed manifold  100 , can be used uphole of the wellhead  60  to combine the system&#39;s multiple lines  74 A-B to the concentric lines  120 A-B. This uphole manifold  76  can be separate from the wellhead  60  or can be incorporated into a control line hanger (not shown) disposed in the wellhead  60 . 
     Although two concentric control lines  120 A-B are shown in  FIG. 2  used with a manifold  100 , it will be appreciated that multiple manifolds  100  can be used along the length of concentric control lines to branch off any number of outer control lines. Thus, the teachings of the present disclosure are not restricted to only two concentrically arranged control lines. 
     As shown in  FIG. 3 , for example, the multiple control line system  50  can include two or more manifolds  100 A-B and multiple concentric control lines  120 A-C. In this example, the concentric control lines  120 A-C include an inner control line  120 A, an intermediate control line  120 B, and an outer control line  120 C, although more can be used. A first manifold  100 A has a distal end of the outer control line  120 C crimped and sealed therein so it communicates with a branching control line  121 C. Meanwhile, the intermediate control line  120 B along with the encapsulated inner control line  120 A pass through this first manifold  100 A to another manifold  100 B. 
     At this second manifold  100 B, a distal end of the intermediate control line  120 B is crimped and sealed therein so it communicates with a branching control line  121 B. Meanwhile, the inner control line  120 A pass through this second manifold  100 B to components further downhole. As will be appreciated, the branching off the various control lines  120 A-C can be used to operate separate downhole components independently or to achieve any variety of useful purposes downhole. 
     In general, the disclosed manifold  100  can dispose at any desirable point downhole from a wellhead. For example, the manifold  100  as shown in  FIG. 2  can dispose far downhole near the downhole components  80  to which the downhole control lines  130 A-B connect. This enables the concentric control lines  120 A-B to be run as one armored control line along the majority of tubing. This conserves space in the annulus and reduces the complication of protecting and securing the control lines on the tubing. As an alternative, the manifold  100  can be set uphole near the wellhead  60  or at any point along the tubing string. For example, the manifold  100  can be set at a point along the tubing where one line needs to branch off to one downhole component while the other line may extend further downhole to connect to another downhole component. 
     Preferably, the manifold  100  plumbs to a safety valve or other downhole component and deploys through the wellhead  60  when run downhole. In one arrangement shown in  FIG. 4A , for example, the manifold  100  can be attached to tubing  20  above a downhole component  80 , such as a safety valve. In this embodiment, the components are attached by straps or bandings  24  known in the art that are typically used to strap control lines to tubing  20 . 
     In another arrangement shown in  FIG. 4B , an independent sub-assembly  86  houses the manifold  100 . The sub-assembly  86  is connected between the tubing  20  and the downhole component  80 , such as a safety valve. The sub-assembly  86  defines wells  88  in its outside surface to accommodate the components. Again, bandings  24  or other devices can be used to hold the components in the wells  88  of the sub-assembly  86 . In addition to the arrangements shown in  FIGS. 4A-4B , one skilled in the art will appreciate that other arrangements can be used to attach the manifold  100  to the tubing  20  and/or the downhole component  80 . 
     With an understanding of the multiple control line system  50  of the present disclosure provided above, discussion now turns to example implementations of the disclosed system used with various downhole components. For example, multiple control line systems  90 A-C in  FIGS. 5 through 7  operate with a deep-set safety valve  150 , while the multiple control line system  90 D in  FIG. 8  operates with a surface controlled sub-surface safety valve  170 . In each of these examples, the multiple control line systems  90 A-D includes a well control panel or manifold of a hydraulic system  70 , which can have one or more pumps  72   a - b , reservoirs  73 , and other necessary components for a high-pressure hydraulic system used in wells. 
     As described previously, the deep-set safety valve  150  of  FIGS. 5 through 7  installs on production tubing (not shown) disposed in a wellbore, and the safety valve  150  controls the uphole flow of production fluid through the production tubing. In use, the safety valve  150  closes flow through the tubing in the event of a sudden and unexpected pressure loss or drop in the produced fluid, which coincides with a corresponding increase in flow rate within the production tubing. Such a condition could be due to the loss of flow control (i.e., a blowout) of the production fluid. During such a condition, the safety valve  150  is closed by relieving the hydraulic control pressure which actuates the safety valve to the closed position and shuts off the uphole flow of production fluid through the tubing. When control is regained, the safety valve  150  can be remotely reopened to reestablish the flow of production fluid. 
     In the dual control line system  90 A of  FIG. 5 , for example, two control lines  120 A-B extend from the wellhead  60  and down the well to the manifold  100  and the deep-set safety valve  150 . One of the control lines  120 A communicates with the pump  72  of the hydraulic system  70 , while the other control line  120 B communicates with the reservoir  73  of the hydraulic system  70  in a manner similar to that described in U.S. Pat. No. 7,392,849, which has been incorporated herein by reference in it its entirety. 
     In the control line system  90 B of  FIG. 6 , two control lines  120 A-B extend from the wellhead  60  and down the well to the manifold  100  and the deep-set safety valve  150 . In this configuration, however, both control lines  120 A-B communicate with the one or more pumps  72   a - b  of the hydraulic system  70  and are separately operable. Using this configuration, operators can open and close the deep-set safety valve  150  in both directions with hydraulic fluid from the control lines  120 A-B being separately operated with the hydraulic system  70 . Either way, one of the control lines (e.g.,  120 B) in  FIGS. 5-6  acts as a balance line. This balance line  120 B can offset the hydrostatic pressure in the primary control line  120 A, allowing the safety valve  150  to be set at greater depths. 
     As another alternative, the configuration of the control line system  90 C in  FIG. 7  has the balance control line  120 B terminated or capped off below the wellhead  60 . Thus, only the primary control line  120 A runs to the surface and the hydraulic system  70 , while the balance control line  120 B for offsetting the hydrostatic pressure terminates below the wellhead  60  with a cap  125 . 
     In each of these implementations, one or more connection lines  74 A-B couple from the hydraulic system  70 . In  FIGS. 5-6 , the dual lines  74 A-B can connect to a reverse manifold  76  that combines the lines  74 A-B into the concentric control lines  120 A-B. In  FIG. 7 , one line  74 A may only be needed. Passing through the wellhead  60  as one penetration, the concentric control lines  120 A-B extend down the tubing to the manifold  100 , which may be situated close to the deep-set safety valve  150 . Here, the outer control line  120 A/ 130 A branches off from the inner control line  120 B/ 130 B. 
     For its part, the safety valve  150  in  FIGS. 5-7  can include any of the deep-set valves known and used in the art. In one implementation, the deep-set safety valve  50  can have features such as disclosed in incorporated U.S. Pat. No. 7,392,849. In general, the deep-set safety valve  150  uses hydraulic pressures from the two downhole control lines  130 A-B to actuate a closure  165  of the valve  150  so the valve  150  can be set at greater depths downhole. 
     As best shown in  FIG. 5 , for example, the primary or active control line  130 A can operate a primary actuator  160 A in the valve  150 , while the second or balance control line  130 B can operate a second actuator  160 B. As shown, the closure  165  can include a flapper  152 , a flow tube  154 , and a spring  156 . The primary actuator  160 A can include a rod piston assembly known in the art for moving the flow tube  154 . The balance actuator  160 B can also include a rod piston assembly known in the art for moving the flow tube  154 . These and other actuators  160 A-B and closures  165  can be used in the safety valve  150  for the disclosed control systems  90 A-C. 
     Either way, with the primary control line  130 A charged with hydraulic pressure, the primary actuator  160 A opens the closure  165 . For example, the piston of the actuator  160 A moves the flow tube  154  down, which opens the flapper  152  of the safety valve  150 . For its part, the hydraulic pressure from the balance control line  130 B offsets the hydrostatic pressure in the primary control line  130 A by acting against the balance actuator  160 B. For example, the balance actuator  160 B having the balance piston assembly acts upward on the flow tube  154  and offsets the hydrostatic pressure from the primary control line  130 A. Therefore, this offsetting negates effects of the hydrostatic pressure in the primary control line  130 A and enables the valve  50  to operate at greater setting depths. 
     If the balance control line  130 B loses integrity and insufficient annular pressure is present to offset the primary control line&#39;s hydrostatic pressure, then the valve  150  can fail in the open position, which is unacceptable. To overcome unacceptable failure, the control system  90 A-C can include a fail-safe device or regulator  140  disposed at some point down the well. The regulator  140  interconnects the two control lines  130 A-B to one another and acts as a one-way valve between the two lines  130 A-B in a manner disclosed in co-pending application Ser. No. 12/890,056, filed 24 Sep. 2010, which is incorporated herein by reference in its entirety. 
       FIG. 8  illustrates another control line system  90 D for a typical surface controlled sub-surface safety valve  170 . Much of the system  90 D is similar to that described previously. Again, the system  90 D has the operating system  70  coupled by connection lines  74 A-B to a reverse manifold  76 , and concentric control lines  120 A-B run from the wellhead  60  to a downhole manifold  100 . 
     Branching from the manifold, the system  90 D includes first and second control lines  180 A-B interconnected to one another by a one-way connecting valve  188  and connected to a single control port  172  on the safety valve  170 . With the two control lines  180 A-B run from the surface to the safety valve  170 , one of the control lines  180 B can power the safety valve  170  open while the second control line  180 A can be used to close the valve  170 . 
     For example, the control line  180 B can be the main line, while the hydraulic system  70  maintains the other control line  180 A closed at the wellhead to prevent exhausting of control fluid through it. The hydraulic system  70  at the surface applies hydraulic pressure to the control port  172  via control fluid in the control line  180 B. The hydraulic pressure moves the internal sleeve  174  against the spring force  176 . When sufficiently moved, the internal sleeve  174  opens the flapper  178  that normally blocks the internal bore  171  of the safety valve  170 . 
     To close the safety valve  170 , the hydraulic system  70  can exhaust the second control line  180 A to a fluid reservoir (not shown), allowing the release of hydraulic pressure of the control fluid. The connecting valve  188  prevents control fluid from migrating back up through the main control line  180 B. The release allows the spring force  176  to move the internal sleeve  174  and permits the flapper  178  to close the bore  171 . 
     Likewise, the operation system  70  can communicate control fluid to the safety valve  170  via the second control line  180 A to open the safety valve  170  in the event the first control line  180 B is blocked or damaged. The one-way connecting valve  188  prevents the control fluid in the control line  180 A from entering into the other control line  180 B. 
     Moreover, the control line system  90 D can aid in keeping the control fluid substantially clean of debris and can reduce the potential for blockage. For example, the control lines  180 A-B can have sumps  182 A-B to collect debris and can have in-line filters  186 A-B to filter debris from the control fluid. During use, control fluid and associated debris is allowed to migrate through the system  90 D so that the potential for blockage can be reduced. In addition, operators can cycle the safety valve  170  open and closed by applying control fluid with the main control line  180 B and exhausting the control fluid with the other control line  180 A. These and other techniques can be used, include those disclosed in U.S. Pat. Publication No. 2009/0050333, which is incorporated herein by reference in its entirety. 
     The foregoing description of preferred and other embodiments is not intended to limit or restrict the scope or applicability of the inventive concepts conceived of by the Applicants. In exchange for disclosing the inventive concepts contained herein, the Applicants desire all patent rights afforded by the appended claims. Therefore, it is intended that the appended claims include all modifications and alterations to the full extent that they come within the scope of the following claims or the equivalents thereof.

Summary:
Concentric control lines have an outer line disposed about one or more inner lines. Encapsulated together, the lines only require one penetration through the wellhead to extend downhole. At the wellhead, the lines communicate with an operating system, which can provide hydraulics, electric power, signals, or the like for downhole components. Beyond the wellhead, the concentric lines extend along the tubing to a manifold. The outer line sealably terminates at the manifold&#39;s inlet, while the inner conduit passes out an outlet with a sealed fitting to connect to a downhole component. A downhole line couples to an outlet of the manifold and communicates internally with the outer conduit terminated at the manifold&#39;s inlet. This downhole line can then extend to the same downhole component or some different component.