Abstract:
A device and method of handling a plug in a tubing hanger includes a pressure actuated sequence valve that has multiple outlets. Hydraulic fluid from a remotely operated vehicle (ROV) provides hydraulic fluid that selectively flows through the valve for operating a tool that handles the plug. The valve outlets are ported to separate lines for operating different functions of the tool. Flow to a specific outlet occurs by sequencing the valve to a corresponding position, where the valve is sequenced by changing pressure of the hydraulic fluid. The sequence valve is disposed in a piston that is axially movable within the tool. A stroking rod attaches to the piston, and is actuated by diverting flow to sides of the piston.

Description:
BACKGROUND 
     1. Field of Invention 
     The present disclosure relates in general to a system for controlling operation of a subsea device. More specifically, the present disclosure relates to a pressure actuated sequencing valve assembly that selectively delivers fluid to a plug handling device. 
     2. Description of Prior Art 
     Subsea wells typically include a wellhead housing located on the sea floor; which are lined with one or more casing strings. Casing hangers are mounted in the wellhead housing for supporting the casing strings. In one type of wellhead assembly, a tubing hanger located at the upper end of a string of tubing is installed in the wellhead housing. After the tubing has been installed, the well can be perforated and a production tree landed on the wellhead housing. A plug is usually inserted into the production passage of the tubing hanger to temporarily seal the well when the production tree is being installed on the wellhead housing. Production trees have a number of valves for controlling the well fluid. Trees also have a production flow passage and an isolation sub that stabs into the production passage of the tubing hanger. The plug is generally removed by lowering a tool through the production flow passage of the tree. For a workover operation involving pulling of the tubing hanger, the tree must be disconnected from the wellhead housing. If the tree needed to be retrieved for repair work, this can be done without pulling the tubing. 
     In another type of wellhead assembly, the tree is installed on the wellhead housing before running the tubing. Here the drilling riser connects to the tree, and the tubing hanger is lowered through the drilling riser and lands in the tree. The tubing hanger has a lateral flow outlet that registers with a lateral flow outlet in the tree. In this type of wellhead assembly, the plug is set in the tubing hanger vertical bore above the flow outlet. The tree does not need to be disconnected from the wellhead housing for pulling the tubing for a workover operation. If the tree needed to be retrieved for repair, the tubing would have to be pulled. 
     In the various configurations described above, the tree is a large, heavy and complex assembly conventionally run on a string of drill pipe. The running procedure requires a vessel with a derrick. It may not be economical to utilize the same vessel that drilled the well to complete the well and install the tree. Designs for trees that can be run on a lift line are known. 
     SUMMARY OF THE INVENTION 
     Disclosed herein is a tool for handling a plug in a subsea wellhead assembly. In one example the tool includes an end effector having a latch in selective engagement with the plug and a coupling assembly in selective mechanical cooperation with a latch assembly in the plug. A pressure controlled sequence valve is included in this example that has a valve body, an inlet in the valve body that is in fluid communication with a fluid source, a latch outlet in the valve body that is in fluid communication with the latch, a coupling assembly outlet in the valve body that is in fluid communication with the latch assembly, and a pilot that is selectively sequenced to a position where there is fluid communication between the inlet and the latch outlet and to a position where there is fluid communication between the inlet and coupling assembly outlet. The pilot can be in fluid communication with the fluid source, and wherein the position of the pilot corresponds to a pressure of the fluid in the fluid source. The fluid source can be a remotely operated vehicle and can supply fluid at selective pressures. In an example, the valve body includes a power supply valve body, and the tool further includes, a vent valve body having a latch inlet in the valve body that is in fluid communication with the latch, a coupling assembly inlet in the valve body that is in fluid communication with the coupling assembly, an outlet in fluid communication with a storage tank, and a pilot that is selectively sequenced to a position where there is fluid communication between the outlet and the latch inlet and to a position where there is fluid communication between the outlet and coupling assembly inlet. In this example, when fluid flows from the power supply valve body, fluid is urged from a chamber in the end effector and routed to an inlet of the vent valve body that is in fluid communication with the outlet of the vent valve body. The tool can further have a body, a chamber in the body that defines a cylinder that is in selective fluid communication with the fluid source, a piston movably disposed within the cylinder, and a stem connected between the piston and the end effector, so that when fluid is introduced into the cylinder the end effector is axially movable with movement of the piston. The sequence valve can be disposed in the piston. Optionally, the latch outlet is an actuating latch outlet, and the tool can also have a de-actuating latch outlet in the valve body that is in fluid communication with the latch, so that when the sequence valve is positioned with the inlet in fluid communication with the actuating latch outlet, fluid flows to the latch to couple the plug to the end effector, and so that when the sequence valve is positioned with the inlet in fluid communication with the de-actuating latch outlet, fluid flows to the latch to decouple the plug from the end effector. The coupling assembly outlet can be a locking actuator outlet and the tool can further include an unlocking actuator outlet in the valve body that is in fluid communication with the coupling assembly, so that when the sequence valve is positioned with the inlet in fluid communication with the locking actuator outlet, fluid flows to the coupling assembly to anchor the plug to a tubing hanger, and so that when the sequence valve is positioned with the inlet in fluid communication with the unlocking actuator outlet, fluid flows to the coupling assembly to disengage the plug from the tubing hanger. 
     Also provided herein is a method of handling a plug in a subsea wellhead assembly. In an example the method includes providing a plug handling tool having a plug latch, a plug anchor system, and a pressure actuated power supply valve that has an inlet, an outlet in communication with a plug latch actuator, and an outlet in communication with a plug anchor system. The method further includes coupling the plug to the plug handling tool by supplying fluid to the power supply valve at a pressure that sequences the power supply valve to a position so the inlet is in communication with the outlet in communication with the plug latch actuator, inserting the plug into the subsea wellhead assembly, and anchoring the plug in the subsea wellhead assembly. Anchoring the plug is done in this example by supplying fluid to the power supply valve at a pressure that sequences the power supply valve to a position so the inlet is in communication with the outlet in communication with the plug anchor system. The method can further include providing a vent valve having an inlet in communication with the plug latch actuator, an inlet in communication with the plug anchor, and an outlet in communication with a storage tank, and that is sequenced in response to the supply of fluid. The method may further include selectively venting fluid through the vent valve to storage, wherein the fluid is evacuated from the plug latch actuator response to fluid flowing from the power supply valve. Fluid can optionally be supplied by a remotely operated vehicle disposed subsea. The tool included with the method can further have a tool body with a chamber, a piston in the chamber, a stem connecting the piston to an end effector that couples to the plug; in this example the method further includes supplying fluid in the chamber to selectively move the piston, stem, and end effector in an axial direction. 
     Another embodiment of a tool for handling a plug in a subsea wellhead assembly is provided herein that includes a tool body having a cavity that is in fluid communication with a remotely operated vehicle (ROV), an end effector coupled with the tool body having a plug latch system and a plug anchoring system, a piston axially movable within the cavity, and a sequence valve system in the piston. In this example, the sequence valve includes a power supply valve having an inlet, a first outlet and a second outlet respectively in fluid communication with the plug latch system and the plug anchoring system, and a pilot member selectively sequenced in response to a pressure of fluid supplied by the ROV to a first position where the inlet is in communication with the first outlet and to a second position where the inlet is in communication with the second outlet. The sequence valve further includes a vent valve having an outlet, a first inlet and a second inlet respectively in fluid communication with the plug latch system and the plug anchoring system, and a pilot member selectively sequenced in response to a pressure of fluid supplied by the ROV to a first position where the outlet is in communication with the first inlet and to a second position where the outlet is in communication with the second inlet. The tool can further include a stem mounted on an end of the piston that attaches to the end effector, so that when fluid is supplied to aside of the piston, the stem and the end effector are axially moved. The plug latch system can be elongated latching fingers that attach to the plug when fluid flows from the first outlet. Optionally, the plug anchoring system includes members that selectively extend radially outward when fluid flows from the second outlet. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Some of the features and benefits of the present invention having been stated, others will become apparent as the description proceeds when taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a partial side sectional view of an example embodiment of a plug package handling a plug in a wellhead assembly and in accordance with the present invention. 
         FIG. 2  is a partial side sectional view of the plug tooling package of  FIG. 1  in accordance with the present invention. 
         FIG. 3  is a side sectional view of an embodiment of an end effector portion of the plug tooling package of  FIG. 1  and in accordance with the present invention. 
         FIG. 4  is a schematic of an example embodiment of a hydraulic system for use in actuating the plug tooling package of  FIG. 1  and in accordance with the present invention. 
         FIG. 5  is a side sectional view of the end effector portion of  FIG. 3  actuated to latch to the plug and in accordance with the present invention. 
         FIG. 6  is a side sectional view of the end effector portion of  FIG. 5  actuated to deploy a latch from the plug and in accordance with the present invention. 
         FIG. 7  is a side sectional view of the end effector portion of  FIG. 7  actuated to release the plug and in accordance with the present invention. 
     
    
    
     While the invention will be described in connection with the preferred embodiments, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications, and equivalents, as may be included within the spirit and scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION OF INVENTION 
     The method and system of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings in which embodiments are shown. The method and system of the present disclosure may be in many different forms and should not be construed as limited to the illustrated embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey its scope to those skilled in the art. Like numbers refer to like elements throughout. 
     It is to be further understood that the scope of the present disclosure is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. In the drawings and specification, there have been disclosed illustrative embodiments and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation. 
     An example embodiment of a plug handling tool  10  is illustrated in a partial side sectional view in  FIG. 1  being inserted into a main bore  12  of a wellhead assembly  14 . The plug handling tool  10  is being lowered subsea on an end of a wire line  15 . The wellhead assembly  14  includes a production tree  16  having valves and lines for porting fluids produced from a wellbore  17  shown below the wellhead assembly  14 . The production tree  16  is mounted on a wellhead housing  18  which is anchored into the sea floor  19 . A plug  20  is shown attached on a lower end of the plug handling tool  10  and disposed where the main bore  12  passes through a tubing hanger  22  supported within the wellhead assembly  14 . Thus, in one example, handling by the plug handling tool  10  includes lowering the plug  20  subsea into the tubing hanger  22  and coupling the plug  20  to the tubing hanger  22 . Handling by the plug handling tool  10  can include removing the plug  20  from the tubing hanger  22  and raising the plug  20  to the sea surface. 
     When subsea, in an example, control of the plug handling tool  10  can be done through a remote operating vehicle (ROV)  24  shown having an attached control line  25  for sending and receiving commands to the ROV  24  from surface. Other examples include an umbilical, skid based sea bottom mounted power packs, and the like. Further in the example of  FIG. 1 , the ROV  24  communicates with the plug handling tool via a control line  26 . The control line  26  extends from ROV  24  into a receptacle (not shown) provided on an outer surface of a main tool body  28  that houses components of the plug handling tool  10 . As shown, the main tool body  28  anchors to the wellhead assembly  14  so that a portion of the main tool body  28  extends into the production tree  16 . A stem  30  depends from the main tool body  28  deeper into the bore  12  having on its end distal from the main tool body  28  an attached end effector  32 . The plug  20  mounts on an end of the end effector  32  that is distal from stem  30 . Once anchored in the wellhead assembly  14 , the stem  30  can be reciprocated into and outside of the main tool body  28  for discrete positioning of the plug  20  in and out of the tubing hanger  22 . 
     An example of the plug handling tool  10  is shown in a partial side sectional view in  FIG. 2 , where a cavity  33  is included within the main tool body  28 . A piston  34  is depicted axially movable within the cavity  33  and having an end attached to the stem  30 . Seals  36  on an outer periphery of the piston  34  define an upper chamber  38  in the cavity  33  on a side of the piston  34  distal from stem  30 . Seals  36  define a lower chamber  40  in the cavity  33  on a side of the piston  34  that attaches to stein  30 . A bore  42  is shown formed axially through a lower end of main tool body  28  and provides a pathway for stem  30  to extend from within the cavity  33  to its connection with the end effector  32 . Selectively pressurizing one of the upper or lower chambers  38 ,  40  urges piston  34  axially within cavity  33 , thereby moving stem  30 , end effector  32 , and plug  20  into a designated location. Seals  44  are shown mounted in bore  42  for providing a fluid barrier along the interface between stem  30  and bore  42 . Further schematically illustrated in  FIG. 2  is a sequence valve  46  disposed in piston  34 . Described in more detail below, the sequence valve  46  is selectively pressure controlled to deliver hydraulic fluid to components within the end effector  32  for attaching and/or releasing from plug  20 , and also for actuating an anchoring system within plug  20 . 
       FIG. 3  shows an example embodiment of end effector  32  in a side sectional view. In this example, end effector  32  includes an upper body  48 , which is a generally cylindrically-shaped member whose radius projects radially outward in a region proximate a mid-portion of the body  48 . A cylindrically-shaped cavity  50  extends from an end of upper body  48  to proximate the mid-portion of body  48 . A fluid fitting  52  threadingly inserts into cavity  50  and is shown having flow lines  54 ,  56 ,  58 ,  60  that are spaced radially apart from one another and extend axially through fluid fitting  52 . Flow lines  54 ,  56 ,  58 ,  60  respectively register with passages  62 ,  64 ,  66 ,  68  that are formed within upper body  48 . End effector  32  further includes a lower body  70 , which has a cylindrical outer surface and an axial bore  72  formed through the lower body  70 . An end of upper body  48  distal from cavity  50  has a reduced radius to define a passage body  74 , through which passages  62 ,  64 ,  66 ,  68  are formed. Passage body  74  inserts into bore  72 , and has a radius smaller than an inner surface of bore  72 ; an annular space is formed between passage body  74  and bore  72  which defines a cylinder  76 . 
     A piston assembly  78  is shown in the bore  72  and substantially coaxial with passage body  74 . An upper end of piston assembly  78  has a cylindrical outer surface and opening on its end and defines a receptacle  80 , in which passage body  74  is received. An outer surface of receptacle  80  is in contact with an inner surface of bore  72 , seals  82  along on an outer circumference of receptacle provide a fluid barrier between the interface of the receptacle  80  and bore  72 . A cylindrical piston throw  84  mounts on an end of the receptacle  80  and projects in a direction away from passage body  74 . An annular collar  86  attaches to and circumscribes a portion of piston throw  84 . Collar  86  extends from where piston throw  84  joins receptacle  80  to a location between receptacle  80  and a terminal end of piston throw  84  distal from receptacle  80 . The radius of the bore  72  projects radially inward at a transition  88  so that the portion of bore  72  between transition  88  and its end distal from upper end  48  is adjacent an outer surface of collar  86 . In the example of  FIG. 3 , transition  88  is in the lower half of bore  72  so that the axial length of cylinder  76  exceeds the axial length of receptacle  80 ; thereby allowing axial movement of receptacle  80  within cylinder  76 , and thus axial movement of piston assembly  78  within lower body  70 . The outer radius of upper body  48  is profiled radially inward and extends an axial distance in a direction away from cavity  50  to define a shoulder  89  shown inserted into an upper end of bore  72 . Seats  90  on an outer circumference of shoulder  89  form a pressure barrier along the interface between upper body  48  and lower body  70 . 
     Still referring to the example of  FIG. 3 , a channel  94  circumscribes an outer surface of piston throw  84  proximate its terminal end and distal from receptacle  80 . A sleeve piston  96  has an annular body  97  which circumscribes a portion of piston throw  84  over channel  94 ; the sleeve piston  96  extends axially past opposite ends of channel  94 . A piston head  98  projects radially inward from the body  97  and into channel  94 , wherein the axial length of the piston head  98  is less than the channel  94 . Piston sleeve  96  can axially reciprocate a designated distance in each direction until piston head  98  interferes with one end of channel  94 . A latch assembly  99  is shown on a terminal end of piston throw  84  that extends axially outward in a direction away from receptacle  80 . Latch assembly  99  includes a series of elongate cantilever members  100  having an end fixed in the piston throw  84 , and a free end disposed axially past an end of piston throw  84 . The cantilever members  100  are provided substantially along the entire circumference of the piston throw  84  and include a cantilever end  102  on their free ends that project radially inward. 
     Similar to the latch assembly  99  is a locking assembly  103  mounted on an outer surface of bore  72 . Locking assembly  103  includes a plurality of elongate lock fingers  104  which have a base secured within outer wall of bore  72  and extend axially outward past the end of lower end  70  and distal from upper end  48 . A finger end  106  is provided on the free end of each lock finger  104 , which is a profiled element that projects radially outward. Also in  FIG. 3 , is an elongate cylindrical stinger  107  that mounts in the terminal end of piston throw  84  and projects axially outward therefrom. In an example, stinger  107  is used for actuating a check valve (not shown) in plug  20  when retrieving plug  20  from tubing hanger  22  ( FIG. 1 ). 
     Referring now to  FIG. 4 , schematically illustrated is an example of a hydraulic circuit  108  that provides fluid communication between ROV  24 , sequence valve  34 , and components in the end effector  32  ( FIG. 3 ). A pump  109  is shown disposed within ROV  24  for pressurizing hydraulic fluid that is delivered to the plug handling tool  10  via supply line  110 . A piston stroke line  112  branches from supply line  110  and is directed to an upper end of piston  34 . Referring back to  FIG. 2 , one optional means for delivering fluid from the piston stroke line  112  to piston  34  includes a port  113  shown formed through a sidewall of main tool body  28 . Similarly, a piston retract line  114  is in communication with a discharge of pump  109  and directed to an opposite end of piston  34  for retracting piston  34 . A port  115  ( FIG. 2 ) is schematically illustrated for delivering fluid to lower chamber  40  for retracting piston  34  that in turn can retract end effector  32 . Valving (not shown) is provided for selectively controlling an amount of flow into one of upper or lower chambers  38 ,  40  for reciprocating piston  34  and end effector  32  in a designated position. 
     Downstream from piston stroke line  112 , a power supply line  116  branches from supply line  110  and is directed to a bore  117  in the piston  34  for housing a power supply valve  118 . The bore  117  and power supply valve  118  make up part of sequence valve  46 . Power supply valve  118  is schematically illustrated as a sequence valve having an inlet connected to power supply line  116 , and four outlets that connect to portions of the end effector  32 . Downstream from power supply line  116  is a pilot line  120  shown connected to a pilot member of power supply valve  118 . Pilot member is pressure operated, and based on an input pressure from pump  109 , pilot member selectively communicates the inlet of power supply valve  118  with one of its outlets. In one example, supplying fluid from the pump  109  at a first designated pressure and through pilot line  120  positions pilot so that fluid through power supply line  116  flows through sequence A and into flow line  54  and passage  62 . In one example, power supply valve  118  is a spool element that moves within bore  117  for providing fluid communication from lines  116 ,  120 , to one or more of lines  54 ,  56 ,  60  and/or passages  62 ,  64 ,  66 ,  68 . Referring now to  FIG. 5 , passage  62  extends through the upper body, passage body  74 , piston throw  84 , and into channel  94 . Providing fluid flow through this path imparts a force on piston head  98  that translates sleeve piston  96  from its position of  FIG. 3  and axially away from upper body  48 . In the position illustrated in  FIG. 5 , the body  97  of piston sleeve  96  circumscribes and moves radially inward the cantilever members  100  of latch assembly  99 , to attach the end effector  32  to plug  20 . Once attached to the end effector  32 , the plug  20  can be deployed downhole into the tubing hanger  22 . Conversely, the plug  20  can be latched onto when in the tubing hanger  22  and subsequently removed therefrom. 
     Referring back to  FIG. 4 , adjusting pressure of fluid being discharged from pump  109  into pilot line  120  to a second designated pressure sequences power supply valve  118  to a position B. In position B fluid in power supply line  116  is diverted to an outlet connected to line  56  which flows into passage  64 . As shown, passage  64  communicates with cylinder  76 . Referring now to  FIG. 6 , passage  64  extends through upper body  48  an axial distance and is redirected to terminate at an end of cylinder  76  proximate cavity  50 . Introducing fluid into cylinder  76  from passage  64  urges piston assembly  78  away from upper body  48 , so that collar  86  is adjacent the lock fingers  104  of locking assembly  103 . When plug  20  is attached to end effector  32 , and collar  86  is set in the position of  FIG. 6 , collar  86  pushes the finger ends  106  radially outward to actuate a plug latch assembly  121  on plug  20  for anchoring plug  20  within tubing hanger  22  ( FIG. 1 ). Included with the plug latch assembly  121  are plug latches  122  that project radially outward from plug  20  and into recesses (not shown) in tubing hanger  22 . A lock sleeve  123  is schematically illustrated within plug  20  that is contacted by the finger ends  106  to deploy the plug latches  122  radially outward. It is believed it is within the capabilities of those skilled in the art to develop details for the plug latch  122  and lock sleeve  123  for proper anchoring of plug  20 . 
     Referring back to  FIG. 4 , when pump  109  delivers fluid at a third designated pressure pressure in pilot line  120  urges pilot to a position C. While in position C, power supply line  116  communicates with flow line  60  and passage  68  to deliver fluid to channel  94 . As shown in  FIG. 7 , passage  68  extends from upper body  48  through piston assembly  78  into a side of channel  94  distal from line  62 . Flowing fluid through flow line  60  and passage urges sleeve piston  96  axially away from plug  20 , so that piston sleeve  96  no longer circumscribes latch assembly  99 . As such, plug  20  can be released from end effector  32 . This action may take place after landing an anchoring plug  20  within tubing hanger  22  ( FIG. 1 ) or after having retrieved plug  20  from within the wellbore and disengaging plug  20  from end effector  32  above surface. 
     Referring now to  FIG. 6 , to accommodate fluid flow through the passages  62 ,  64 , and  66  when the piston assembly  78  reciprocates away from upper body  48 ; tubes  124 ,  126 ,  128  are included that within passages  62 ,  64 ,  66  that each have an end fixed into a base of the receptacle that faces a terminal end of passage body  74 . The tubes  124 ,  126 ,  128  have axial bores through their length that allow fluid flow. Free ends of the tubes  124 ,  126 ,  128  reciprocatingly insert into bores  130 ,  132 ,  134  that are formed axially into an end of the passage body  74  that faces the bottom of receptacle  80 . Seals are shown on the outer circumference of tubes  124 ,  126 ,  128 , to provide a pressure barrier against that prevents fluid in passages  62 ,  64 ,  66  from flowing into bores  130 ,  132 ,  134 . In an example of operation, as piston assembly  78  moves axially away from upper body  48 , the tubes slide within passages  130 ,  132 ,  134  away from cavity  50 . The travel of the piston assembly  78  is less than the length of the tubes  124 ,  126 ,  128 , so the free ends of the tubes  124 ,  126 ,  128  will remain in the bores  130 ,  132 ,  134  during the entire stroke of the piston assembly  78 ; and thereby maintain fluid communication across the separation of the passage body  74  and piston assembly  78 . 
     Referring back to  FIG. 4 , operating pump  109  at a fourth designated pressure, the pilot is urged into a position D by pressure in pilot line  120 , which communicates power supply line  116  with flow line  58  and passage  66 . Thus while the power supply valve  118  of  FIG. 4  is in position D, fluid from power supply line  116  is delivered to chamber  76  via passage  66 . As shown in  FIG. 3 , passage  66  communicates with cylinder  76  in a side opposite from passage  64 , and as such, retracts piston assembly  78  to its position of  FIG. 3 , thereby drawing plug  20  adjacent the lower terminal end of lower body  70 . This is in contrast to the setoff distance between the lower end of lower body  70  and upper end of plug  20  as shown in  FIG. 7 . As such, selectively providing fluid to opposing ends of the receptacle and into cylinder  76  can reciprocate plug  20  proximate and distal from lower body  70 . 
     Referring back to  FIG. 4 , also included with the sequence valve  46  is a vent circuit sequence valve  136  shown in a bore  137  in the piston  34 , where the vent circuit sequence valve  136  can sequence in the same manner as power supply valve  118 . In this example, sequencing of the vent circuit sequence valve  136  is controlled through pressure delivered in pilot line  138  which branches from supply line  110  downstream of pilot line  120 . As shown, vent circuit sequence valve  136  has inlets that are respectively in communication with lines  60 ,  54 ,  58 , and  56 . Vent circuit sequence valve  136  has a single outlet that communicates with one of its inlets depending on the designated pressures delivered. The vent circuit sequence valve  136  of  FIG. 4  is set to communicate with one of cylinder  76  or channel or  94 , but on an opposite side of either receptacle  80  or piston head  98  from power supply valve  118 . Thus when fluid flows through power supply valve  118  to urge receptacle  80  or sleeve piston  96  within cylinder  76  or channel  94 , fluid present in cylinder  76  or channel  94  can be vented therefrom through vent circuit sequence valve  136  and allow movement of receptacle  80  and/or sleeve piston  96 . In an example, pressure in the fluid from pump  109  is at a first designated pressure, power supply valve  116  and vent circuit sequence valve  136  are in position A, and in communication with channel  94 , but on opposite sides of piston head  98 . Thus as fluid into channel  94  from passage  62 , fluid in channel  94  on an opposite side of piston head  98  can be emptied from channel  94  and into passage  68 . 
     Springs  139 ,  140  are shown respectively coupled with power supply valve  116  and vent circuit sequence valve  136 . In an example, springs  139 ,  140  retract the pilot into a blocked or no flow position when less than a operational designated pressure is present in pilot lines  120 ,  138 . Further illustrated in  FIG. 4 , is a vent line  142  that connects to an outlet of vent circuit sequence valve  136  for transporting fluid exiting vent circuit sequence valve  136  back to a tank  143  shown disposed in ROV  24 , wherein an inlet to pump  109  is fed by flow line from tank  143 . Vent circuit sequence valve  136  can be a spool element, that when selectively moved within bore  137  can provide communication from lines  58 ,  60  and/or passages  66 ,  68  to line  142 . An optional isolation valve  144  is shown in vent line  142  for isolating vent line  142  from tank  143 . In an example, the second designated pressure is greater than the first designated pressure, the third designated pressure is greater than the second designated pressure, and the fourth designated pressure is greater than the third designated pressure. In another example, the first designated pressure is around 500 psig, the second designated pressure is around 1000 psig, the third designated pressure is around 1500 psig, and the fourth designated pressure is around 2000 psig. 
     Referring back to  FIG. 2 , optionally, the latch assembly  99 A can be a series of dogs that project radially outward and connect on an inner circumference of plug  20 . Similarly, locking assembly  103 A can project in direct communication with plug latch assembly  121  for deploying plug latches  122  radially outward into contact with tubing hanger  22  ( FIG. 1 ). 
     The present invention described herein, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While a presently preferred embodiment of the invention has been given for purposes of disclosure, numerous changes exist in the details of procedures for accomplishing the desired results. These and other similar modifications will readily suggest themselves to those skilled in the art, and are intended to be encompassed within the spirit of the present invention disclosed herein and the scope of the appended claims.