Abstract:
A self-seeking plug for deployment in a hydraulic line with a leak therein. The plug is configured for circulation through the line and to a resting location adjacently below or past the location of the leak in the line. As a result, the location of the leak may be identified, for example with reference to a tether running between the resting location and the site of deployment. Thus, line repair may more readily ensue. Additionally, and/or alternatively, sealing repair may ensue by way of sealing element(s) outfitted on the plug. Such may or may not be accompanied by an exposable bypass channel through the plug for sake of full hydraulic restoration of the line.

Description:
BACKGROUND 
       [0001]    Exploring, drilling and completing hydrocarbon wells are generally complicated, time consuming and ultimately very expensive endeavors. As a result, over the years increased attention has been paid to monitoring and maintaining the health of such wells. Significant premiums are placed on maximizing the total hydrocarbon recovery, recovery rate, and extending the overall life of the well as much as possible. Thus, logging applications for monitoring of well conditions play a significant role in the life of the well. Similarly, significant importance is placed on well intervention applications, such as clean-out techniques which may be utilized to remove debris from the well so as to ensure unobstructed hydrocarbon recovery. 
         [0002]    In addition to interventional applications, the well is often outfitted with various hydraulic control lines between surface equipment and certain downhole features. In this manner, such features may be manipulated without the requirement of an interventional application. For example, downhole chemical injection or control over valves at downhole locations may be exercised without the time consuming or costly need for a dedicated intervention. Such hydraulic control lines are routinely used for opening and closing of safety, flow control and formation isolation valves, as well as for setting packers to achieve isolation in the well. 
         [0003]    What is more, with advancements in well placement and intelligent completions technologies, it is becoming increasingly more common to multi-drop several downhole tools on one or more hydraulic control lines. For example, technological building blocks are readily available to run three or more flow control valves on shared hydraulic control lines to afford separate control of injected or produced fluids from multiple reservoir intervals. Therein, shared control lines offer the benefit of minimizing the number of control lines necessary for downhole control. This in turn alleviates restrictions that may be present from available feed through passages in packers, liner hangers, or other constrained areas. 
         [0004]    Hydraulic control lines as described above are installed in conjunction with various other completions hardware. Indeed, such lines may be a part of a fairly sophisticated well architecture. For example, the well may have casing terminating at a production region that is governed by a formation isolation valve, with a production screen, shroud and other components therebelow. Further, a host of valves, packers, sleeves and other features for ongoing manipulation may be positioned uphole of the production region. Once more, the formation isolation valve along with the noted features and a host of others may be managed by way of hydraulic control lines running adjacent to, or even embedded within, the casing. 
         [0005]    As with any other downhole components, hydraulic control lines may be subject to unintentional damage. For example, damage resulting in a leak in a line may occur during installation or during later downhole interventions or regular production or injection activities. Regardless, once a leak develops in a hydraulic control line, its functionality, and that of its associated downhole tools, is effectively lost. Also, leakage in the line may provide an unintended pathway for hazardous downhole production fluids to reach the oilfield surface in an uncontrolled manner. 
         [0006]    Further complicating matters for leaking control lines is the fact that the ability to repair hydraulic lines is limited by the nature of downhole architecture as alluded to above. For example, at best, access to a hydraulic control line is likely limited to a narrow annulus between the casing and a production or other access tubing which runs the length of the well. Thus, the ability to reach and repair the line to an effective working condition is unlikely. 
         [0007]    Once more, determining where a leak may be located in the line may not be achieved with any satisfactory degree of certainty. As a result, it may be a significant challenge to determine how the leak may have been caused. Thus, since the cause of the leak remains unknown, the liable party remains unknown. Perhaps even more concerning is the fact that without knowledge of the cause of the leak, operators are severely limited in their ability to properly plan any mitigation measures going forward. 
         [0008]    In light of the various problems associated with a leak in a hydraulic control line, operators are likely to address the matter, at least as a matter of safety. For example, a cement plug may be advanced within the line in a manner sufficient to at least sealably block the emergence of any hazardous downhole fluids through the line as a result of the leak. Thus, personnel and equipment at the oilfield surface may be spared exposure to any significant hazards as a result of the leak. 
         [0009]    Indeed, operators may undertake attempts to position a plug as far downhole as possible but above the likely location of the leak. In this manner, functionality of the line may be restored for all controlled valves and features above the cement plug. Unfortuntately, functionality for controlled valves and features below the cement plug may only be attained upon dedicated interventions directed at such features. For example, where the leak is located between a formation isolation valve and a flow control valve further uphole, the cement plug may be set above the leak in a manner restoring line control over the flow control valve with subsequent control of the formation isolation valve requiring a dedicated intervention. Once more, as noted, restoring complete functionality to the line may not be achieved in this manner. Rather, the line is rendered only partially restored for sake of controlling valves and actuatable features above the leak. 
         [0010]    Of course, setting a plug in a manner described above is a blind exercise, which is why in most historical cases operators were forced to cement the entire length of control line to avoid any potential ambiguity about the location or effectiveness of the plug. 
       SUMMARY 
       [0011]    A plug for a leaking hydraulic line or chemical injection line is disclosed. The plug includes a main body that is configured for fluid driven advancement through an inner channel defined by the line to a location adjacent the leak. The body is outfitted with a substantially sealable biasing outer surface for guided interfacing thereof relative an inner wall of the line during the advancement. Further, the plug may be part of a larger management system for the leak which further includes a tether line coupled to the plug and running to an oilfield surface with the line. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is an enlarged view of an embodiment of a hydraulic line plug advancing toward a leak in a hydraulic line. 
           [0013]      FIG. 2  is an overview depiction of a well at an oilfield accommodating the hydraulic line of  FIG. 1  for control of different actuatable well features. 
           [0014]      FIG. 3A  is a side view of alternate embodiment of the plug of  FIG. 1  advancing toward the leak in the line thereof. 
           [0015]      FIG. 3B  is a side view of the plug of  FIG. 3A  upon reaching a target location adjacent the leak in the line. 
           [0016]      FIG. 3C  is a side view of the plug of  FIG. 3B  upon expansion of a seal element above the leak in the line. 
           [0017]      FIG. 3D  is a side view of the plug of  FIG. 3C  upon opening of a channel through the interior of the plug to allow for hydraulic bypass. 
           [0018]      FIG. 4A  is another embodiment of the plug of  FIG. 1  with an anchor element incorporated thereinto. 
           [0019]      FIG. 4B  is yet another embodiment of the plug of  FIG. 1  configured to drive a curable fluid to the location of the leak. 
           [0020]      FIG. 5  is a flow-chart summarizing an embodiment of employing a hydraulic line plug for management of a leak in a hydraulic line. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    Embodiments are described with reference to certain configurations of completions hardware that make use of hydraulic line control over various downhole actuatable features. In particular, formation isolation valves and isolation packers are depicted. However, other actuatable valves and features may operate via hydraulic control lines as detailed herein. Regardless, once a leak emerges in such a line, embodiments herein include a plug and techniques which may be utilized for identification of the leak location as well as potential avenues for streamlined repair of the leaking line. 
         [0022]    Referring now to  FIG. 1 , an enlarged view of an embodiment of a hydraulic line plug  100  is depicted advancing toward a leak  190  within a hydraulic line  180 . More specifically, the plug  100  may be inserted into the line  180  at a surface location of an oilfield  200  and fluidly pumped through the line  180  as shown (see  FIG. 2 ). By the same token, in the embodiment shown, the main body  130  of the plug  100  is coupled to a tether  140  maintaining a structural connection to the surface. Thus, as the plug  100  advances through the line  180 , its distance may be tracked. Ultimately, as described below, this may allow an operator to establish the location of the leak  190  by way of reference to the tether  140  as examined at surface. 
         [0023]    Continuing with reference to  FIG. 1 , the plug  100  is advanced downhole in the direction depicted in a fluidly circulating manner. More specifically, once inserted into the line  180 , a pumping fluid  125  may be used to drive the plug  100  downhole. At the same time, leaking fluid  150  below the plug  100  may also continue downhole with some exiting the line  180  through the breach or location of the leak  190  as shown. As this fluid circulation is taking place, fins  160  which circumferentially emerge from the body  130  are used to serve as a wiper-type sealing interface between the plug  100  and an inner surface  185  of the line  180 . The fins  160  provide a substantially sealable biasing outer surface in stably guiding the plug  100  downhole. Indeed, as shown, the uppermost fin  160  serves as the direct interface with the pumping fluid  125  such that stable and sealable downhole guiding interface is immediately provided. Additionally, fins may be added to improve seal redundancy or debris wiping functionally. 
         [0024]    In the depiction of  FIG. 1 , the plug  100  is shown just before reaching the location of the leak  190 . However, once the uppermost fin  160  reaches a location just below the leak  190 , the pumping fluid  125  will now be able to breach the location of the leak  190 . As a result, the plug  100  will come to rest and cease to continue in the downhole direction. Thus, the plug  100  may be thought of as ‘self-seeking’ in relation to finding or reaching the location of the leak  190 . From an operator&#39;s perspective at the surface of an oilfield  200 , this also means that after up to thousands of feet of unspooling, the tether  140  will noticeably cease its spooling out into the hydraulic line  180 . Thus, the operator may be provided with an approximate location of the leak  190 . That is, the depth reflected by the amount of tether  140  that has been drawn from surface to the plug  100  at rest will be indicative of the leak  190  and plug  100  location. 
         [0025]    With the location of the leak  190  now identified, subsequent action may be taken that is targeted at the leak  190  in an intelligent and selective manner. For example, the tether  140  may be broken off from the plug  100  and removed, with the plug  100  left in place as a downhole marker. Alternatively, the plug  100  may be withdrawn from the line  180  by retraction of the tether  140  from surface without decoupling from the plug  100 . In either case, subsequent cement or other plugging of the leak  190  may be undertaken in an intelligent manner as indicated. Further, in an embodiment where the plug  100  is removed via the tether  140 , vent channels may be provided through the main body  130  such that bypass of pumping fluid  125  may occur in conjunction with, and to help promote, the uphole withdrawal of the plug  100 . As described in further detail below, such channels would be smaller in diameter or opening area than the leak  190  and/or exposed only upon the noted withdrawal so as to ensure downhole pumping of the plug  100  to below the location of the leak  190  is not compromised. 
         [0026]    Continuing with reference to  FIG. 1 , a conventional hydraulic control line  180  as depicted, may typically be between ⅛ and ½ of an inch in diameter, perhaps with an inner diameter of about 0.15 inches. Accordingly, to match the inner diameter of such a line  180 , the main body  130  of the plug  100  may be about 0.1 inches in diameter with fins  160  extending over the remaining 0.05 inches or so. Indeed, the fins  160  may be a bit greater in size, but of an elastic, semi-flexible character to ensure the sealable guidance as detailed above. 
         [0027]    Referring now to  FIG. 2 , an overview depiction of a well  280  at an oilfield  200  is shown as alluded to above. The completed well  280  accommodates a host of hardware, including the hydraulic line  180  of  FIG. 1 . More specifically, the line  180  is located in the relatively tight space of an annulus  287  between the casing  285  defining the well  280  and production tubing  250  described below. Regardless, control over different actuatable well features, such as one or multiple packers  240 , flow control valves, or formation isolation valve  260  may be exercised remotely from surface via the control line  180 . For example, an operator may make use of a control unit  210  disposed at the oilfield  200  adjacent the well head  220  to direct a variety of downhole operations including those triggered by the line  180 . 
         [0028]    As indicated in earlier descriptions, the self-seeking plugs and associated variations may also be applied to chemical injection lines. Such lines are routinely used to provide single or multi-point delivery of chemicals to inhibit corrosion, formation of hydrates, scale, etc. If unintended leaks develop in chemical injection lines, the consequences can be just as costly as indicated in the case of hydraulic control lines. 
         [0029]    As indicated, the well  280  is defined by casing  285  as it traverses a formation  290  leading to a production region  275  below the noted formation isolation valve  260 . By way of the hydraulic line  180 , the operator may direct opening of the formation isolation valve  260 . Thus, production through tubing  250  may take place via slotted liner, screen or other appropriate hardware defining the well  280  at the region  275 . Ultimately, such production of hydrocarbons from the formation  290  may reach the surface and be routed through a production line  230  for collection. 
         [0030]    In the embodiment shown, subsequent production from other locations may also take place, perhaps partially aided by use of the control line  180 . For example, later operations may include isolating a zone of the well  280  by actuating the packer  240  and perforating the casing  285  to form a new production region. Indeed, the packer  240  may be employed such that a separate formation layer  295  and production region are isolated relative the well  280  for multi-zonal hydrocarbon recovery. Thus, from the outset, recovery options may be tailored in a zonal fashion. 
         [0031]    Of course, remotely exercising control over such packer  240  or valve  260  features is achieved to the extent that the line  180  is kept in a leak free condition. For example, consider a circumstance where a leak  190  as depicted in  FIG. 1  emerges at a location between the packer  240  and the flow control valve  260 . At the outset, control over both features would be lost. However, surface equipment similar to that employed in threading fiber optics through conventional coiled tubing may be utilized to advance a plug  100  and tether  140  through the line  180  to identify the leak location (see  FIG. 1 ). This may be followed by remedial cement plugging as also detailed regarding  FIG. 1  hereinabove. As such, remote control over the packer  240  may be restored in a reliable manner without the pre-requisite of multiple blind interventional attempts just to locate the leak  190 . Once more, in other embodiments detailed hereinbelow, remote functionality may also be restored to features below the leak  190 , such as the formation isolation valve  260 . That is, in such embodiments the plug application alone may serve to completely restore functionality of the entire hydraulic control line  180 . 
         [0032]    Referring now to  FIGS. 3A-3D , side views of an alternate embodiment of the plug  100  are depicted for application within the hydraulic control line  180 . More specifically, the self-seeking nature of the plug  100  embodiment of  FIG. 1  is now equipped with added capacity in the form of a seal element  300  and bypass channel  301 . Thus, as with the embodiment of  FIG. 1 , the plug  100  may approach and come to a resting location adjacent the leak  190  as depicted in  FIGS. 3A and 3B . However, it may now also provide sealing within the line  180  and above the leak  190  as shown in  FIG. 3C  and even subsequently allow for controlled bypass  301  relative the leak  190  thereafter (see  FIG. 3D ). 
         [0033]    As alluded to above,  FIG. 3A  depicts an alternate embodiment of the plug  100  of  FIG. 1  advancing toward a leak  190  in the self-seeking fashion detailed herein. Specifically, pumped fluid  125  acts upon the fins  160  to drive the plug  100  downhole, so long as the uppermost fin  160  is above the leak  190 . However, once the fins  160  reach a location below the leak  190  as shown in  FIG. 3B , the plug  100  may come to rest. Again, this is due to the fact that such pumped fluids  125  may now have a pathway out of the line  180  through the leak  190 . Thus, such fluid  125  may no longer be directed at the fins  160  with force sufficient to continue driving the plug  100  downhole. 
         [0034]    Continuing with added reference to  FIG. 3C , the plug  100  is equipped with the above noted seal element  300  distanced away from and above the location of the fins  160 . Indeed, this distance is sufficient to ensure that once the plug  100  comes to rest with the fins  160  below the leak  190 , the element  300  is above the leak  190 . Stated another way, the leak  190  is straddled by the fins  160  below and the element  300  above. 
         [0035]    The described seal element  300  may be of a conventional swellable elastomer of a type frequently used in swell packers and other swellable downhole elements often employed in the oilfield industry. Once more, an operator at surface may observe the detection of the leak  190  via the ceasing of the tether  140  to unwind into the line  180 . At this time, as with other conventional swellables, constituents or characteristics of the pumped fluid  125  may be tailored in a fashion so as to help promote the swell. Regardless, depending on a variety of factors, full swell of the element  300  may take between minutes and days. 
         [0036]    Continuing with reference to  FIG. 3C , the line  180  is now of restored functionality above the plug  100 . However, in the embodiment shown, the plug  100  is also outfitted with a secondary swell element  350  below the fins  160 . Notably, since this element  350  is below the fins  160 , it is also below the leak  190  once the plug  100  has come to rest as described hereinabove. Thus, upon swelling, the plug  100  provides sealing both above and below the location of the leak  190 . Therefore, with added reference to  FIG. 3D , a bypass channel  301  may be provided through the plug  100  in a manner that restores hydraulic functionality to the line  180 . That is, the leak  190  is fully isolated from any fluid  125  which traverses the channel  301  for line control. 
         [0037]    With specific reference to  FIG. 3D , the tether  140  is shown removed from the plug  100  once full swelling of the elements  300 ,  350  has been achieved. In one embodiment, removal of the tether  140 , uncorks, sets or otherwise triggers exposure of the bypass channel  301  through conventional means. Of course, rupture disk and other conventional techniques may also be employed to expose the channel  301  once the leak  190  has been isolated. Additionally, in one embodiment setting of an anchoring mechanism may also take place in conjunction with breaking away of the tether  140 . Thus, flow through the bypass channel  301  need not be reduced or mitigated in order to ensure stable retention of the plug  100  in place as depicted. Atmospheric chambers, electrical pulses through the tether  140  and other conventional techniques as detailed below may also be utilized in setting downhole anchors and other tools of the plug  100 . 
         [0038]    Referring now to  FIG. 4A , another embodiment of the plug  100  is shown. In this case, both anchor  450  and swell  400  elements are incorporated into the plug  100 . Once more, the swell element  400  is positioned in an overlapping or no more than a negligible distance uphole of the fins  160 . Thus, once the fins  160  come to rest below the leak  190 , the swelling of the element  400  will occur thereover. That is, rather than straddle the leak  190  with separate elements  300 ,  350 , a single elongated element  400  of sufficient vertical dimensions may be utilized to cover over and isolate the leak  190  (e.g. see  FIG. 3A ). 
         [0039]    Continuing with reference to  FIG. 4A , setting of the anchor element  450  may be achieved by way of a pull upward on the tether  140  from surface. Thus, teeth  477  of an expansive member  475  may be forced into biting engagement with an inner surface of the control line  180  as the member  475  is wedged outward over an inner deflector  425 . In an embodiment where a bypass channel is provided in conjunction with setting of the anchor element  450 , restoration of full functionality of the control line  180  may be achieved with the plug  100  of  FIG. 4A . 
         [0040]    Referring now to  FIG. 4B , yet another embodiment of a leak management technique is depicted which utilizes a plug  100  as detailed herein. More specifically, the plug  100  may be of a more refined configuration similar to that depicted in  FIG. 1 . However, in this embodiment, the plug  100  is utilized after locating and identifying the leak  190 . Indeed, with any of the other embodiments of  FIG. 3A-3D  or  4 A which may involve remedial repair to the line  180 , such repair may optionally take place after identification of the location of the leak  190 . However, in the specific embodiment of  FIG. 4B , such identification takes place, followed by re-insertion of a plug  100  configured to drive an epoxy, cement, or other curable seal fluid  410  to the location of the leak  190 . For example, note the tether  140  being maintained in a taut fashion as the pumping fluid  125  forces the plug  100  downhole. The plug  100  of  FIG. 4B  is not being utilized in a self-seeking manner relative the leak  190 . Rather, the tether  140  of  FIG. 4B  is specifically being used as a measurement guide in more precise positioning of the plug  100  above the leak  190  after the location thereof is already known. 
         [0041]    Referring now to  FIG. 5 , a flow-chart is shown summarizing an embodiment of employing a hydraulic line plug for management of a leak in a hydraulic line. The plug is self-seeking relative locating a leak in the line as detailed hereinabove and indicated at  520 . Accordingly, a tether coupled to the plug may be monitored from surface as noted at  530 . Thus, as indicated at  540 , the location of the leak in the line may be established. With such information now available, the line may be sealed above the leak as indicated at  550 , for example through a follow-on application as noted hereinabove with reference to  FIG. 4B  or even  FIGS. 3A-3D  and/or  4 A. Of course, due to the self-seeking nature of the plug, it may be configured to achieve the seal directly without requirement of subsequent plug re-insertion (see  FIGS. 3A-3D  and  4 A). 
         [0042]    Continuing with reference to  FIG. 5 , with the line sealed above the leak, it may be used to operate hydraulic features in the well that are also above the leak and coupled to the line (see  580 ). Additionally, depending on the particular plug configuration, sealing below the leak may also be provided and a bypass channel exposed through the plug as noted at  560  and  580 . Where such capacity is provided, the entire leak may be isolated in a manner that hydraulic features below the leak are also operable as indicated at  590 . In one embodiment, this type of sealing and bypass are achieved through a single elongated seal over the entire leak, as opposed to separate seals at either side thereof (see  FIG. 4A ). Regardless, complete functionality may be restored to the line in this manner. 
         [0043]    Embodiments described hereinabove include hydraulic line plugs and techniques for managing leaks in hydraulic lines. This may include providing the capacity to locate and/or control leaks. Thus, the amount of time and expense lost to multiple attempts at directing a plug to a most appropriate leak site may be minimized Once more, as opposed to partial functionality, a line may be restored to full functionality without the requirement of a dedicated intervention, in a manner heretofore unseen. 
         [0044]    The preceding description has been presented with reference to presently preferred embodiments. Persons skilled in the art and technology to which these embodiments pertain will appreciate that alterations and changes in the described structures and methods of operation may be practiced without meaningfully departing from the principle, and scope of these embodiments. For example, self-seeking plugs as detailed herein may be utilized for delivery of add-on tools apart from seal or anchoring elements. Such may include pressure, temperature and other measurement or diagnostic type devices delivered in the manner detailed. Additionally, the term “leak” as used herein may refer to an unintentional fluid path as noted hereinabove or even an intentional fluid path such as a designed breach of a hydraulic line. Regardless, the foregoing description should not be read as pertaining only to the precise structures described and shown in the accompanying drawings, but rather should be read as consistent with and as support for the following claims, which are to have their fullest and fairest scope.