Patent Publication Number: US-6902199-B2

Title: ROV activated subsea connector

Description:
FIELD OF THE INVENTION 
   This invention relates in general to connecting subsea flowlines, and in particular to a connector that utilizes a portable jack assembly that is powered by an ROV (remote operated vehicle). 
   BACKGROUND OF THE INVENTION 
   Subsea installations often require the deployment of lines between one subsea piece of equipment and another. These lines, often called jumpers, may extend from a subsea well to a pipeline end termination, a manifold, or to a surface production flowline for production flow. Also, they may provide electrical power, electrical communications, optical communications, hydraulic power and chemicals to subsea trees, manifolds and distribution units. Typical lengths may vary from 20 meters to 4 kilometers. Normally such lines are installed from a reel located on a pipeline barge at the surface. 
   The ends of the flow jumpers must be connected remotely. A variety of different connectors has been developed. While workable, improvements are desired. 
   SUMMARY OF THE INVENTION 
   In this invention, an apparatus is utilized for remotely connecting a subsea flowline to a subsea connector. The apparatus has a connector frame. A tubular mandrel is carried by the frame with one end of the mandrel connected to a flowline and the other end for engagement with the connector hub. The mandrel is movable axially relative to the frame into engagement with the connector hub. 
   The frame has a first engagement point that is stationary relative to it. The mandrel has a second engagement point that moves with the mandrel and is axially spaced from the first engagement point. The frame has a pocket or opening between these engagement points. 
   A telescoping jack assembly is releasably inserted into the pocket. The jack assembly has opposite ends that engage the first and second engagement points. A power interface on the jack assembly causes the jack assembly to move the engagement points axially relative to each other to move the end of the mandrel into engagement with the connector hub. The power interface receives power from an ROV. 
   Preferably, the mandrel has a lock member on its end that is adapted to engage the profile of the connector hub. An actuator is slidably mounted to the mandrel for engaging the lock member. The frame has third and fourth engagement points, one being movable with the mandrel and the other being movable with the actuator. The jack assembly is retrievable from the first pocket and is repositioned into a second pocket between the third and fourth engagement points. An ROV supplies power to the jack assembly again to move the actuator and secure the lock member to the profile at the connector hub. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic view of a flowline jumper having connectors in accordance with this invention, the flowline jumper being lowered into the sea for connecting a subsea wellhead with a manifold. 
       FIG. 2  is a schematic view of the flowline jumper of  FIG. 1 , showing one end connected to the subsea wellhead and the other end in the process of being connected to the manifold. 
       FIG. 3  is a side view of the connector of  FIG. 1  that connects to the subsea wellhead. 
       FIG. 4  is an enlarged sectional view of the connector of  FIG. 3 , taken along the line  4 — 4  of  FIG. 3 , and showing the upper half extended and the lower half retracted. 
       FIG. 5  is an end view of a jack assembly constructed in accordance with this invention for actuating the connector of  FIGS. 3 and 4 . 
       FIG. 6  is a side view of the jack assembly of FIG.  5 . 
       FIG. 7  is a further enlarged partial sectional view of the connector of  FIGS. 3 and 4 , with the jack assembly of  FIGS. 5 and 6  shown connecting the lock member to the profile of the subsea wellhead connector hub. 
       FIG. 8  is a side view of the manifold connector of FIG.  1 . 
       FIG. 9  is a sectional view of the connector of  FIG. 8 , taken along the lines  9 — 9  of  FIG. 8 , and showing the right half extended and the left half retracted. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIG. 1 , a subsea wellhead  11  is shown schematically. Wellhead  11  is typically a subsea tree having a connector hub  13  extending horizontally from one side for the flow of production fluid. In this embodiment, a guide funnel  15  is mounted to and alongside wellhead  11 . Guide funnel  15  faces upward and is located below and in alignment with connector hub  13 . 
   A second piece of subsea equipment, shown to be a manifold  17 , is spaced horizontally from wellhead  11  a distance that typically is in the range from 20 meters to 4 kilometers. Manifold  17  could be other types of subsea equipment, including other subsea wells. In this embodiment, manifold  17  is shown with a connector hub  19  that faces upward for receiving production flow from wellhead  11 . Connector hub  19  could optionally face horizontally. 
   A flowline jumper  21  is shown being lowered into the sea for connecting connector hub  13  with connector hub  19 . Flowline jumper  21  is preferably a section of steel pipe, which may be either continuous or formed of joints that are secured together. Flowline jumper  21  is shown to have flexibility in this embodiment, although having a flexible flowline is not required of this invention. Flowline jumper  21  has a first connector assembly  23  on one end for connecting to connector hub  13 . Flowline jumper  21  has a second connector assembly  25  on the other end for connecting to manifold connector hub  19 . In this example, flowline jumper  21  has buoyant sections  27  extending around it to add buoyancy. Flowline jumper  21  is shown being lowered into the sea on a lift line  29  deployed from a crane  31  located on a subsea drilling or production vessel  33 . 
   An ROV (remote operated vehicle)  35  is shown assisting in guiding flowline jumper  21 . ROV  35  is a conventional working class self-propelled vehicle capable of performing a variety of subsea tasks. ROV  35  is typically connected by a tether  37  to a tether management system  39 . Tether management system  39  is suspended on an umbilical  41  that is lowered from vessel  33 . 
   In the example shown, a stab  43  on the lower end of connector  23  is aligned with and stabs into guide funnel  15 . Referring to  FIG. 2 , once stabbed into guide funnel  15 , connector  23  hinges over to a horizontal position relative to stab  43  and into alignment with wellhead connector hub  13 .  FIG. 2  shows manifold connector  25  in vertical alignment with manifold connector hub  19  for connection thereto. Buoyant members  27  cause a portion of flowline jumper  21  to elevate upward. The length of flowline jumper  21  is preferably greater than the actual distance from wellhead  11  to manifold  17 . 
   Referring to  FIG. 3 , connector assembly  23  is shown in the folded-over position illustrated in FIG.  2 . Connector assembly  23  has a frame  45  that is now located horizontally 90° relative to stab  43 . Frame  45  has a bottom, two sidewalls  47  and an open top  49 . Frame  45  may be generally rectangular or its sidewalls  47  and bottom may be cylindrical. Hinge  51  mounted to the forward end of frame  45  enables frame  45  to hinge over to the horizontal position relative to stab  43 . 
   Referring to  FIG. 4 , which is an enlarged sectional view of  FIG. 3 , a connector mandrel  53  is mounted within frame  45 . Connector mandrel  53  is a tubular member that has a rearward end that joins to flowline jumper  21  in a conventional manner. Connector mandrel  53  is movable axially relative to frame  45  as can be seen by comparing the upper half of the drawing of  FIG. 4  with the lower half. The upper half of  FIG. 4  shows mandrel  53  in an extended position protruding past the forward end of frame  45 . The lower half of  FIG. 4  shows mandrel  53  in a retracted position with its forward end recessed within the forward end of frame  45 . 
   Connector mandrel  53  is carried within frame  45  by a rearward support  55 . Rearward support  55  comprises laterally extending spokes or members that have rollers  57  on their outer ends. Rollers  57  roll on longitudinal slots  59  formed in sidewalls  47 . The lower half of  FIG. 4  shows roller  57  in a rearward position along slot  59 , and the upper half shows roller  57  at the forward end of slot  59 . 
   A forward support  61  supports mandrel  53  at a point axially forward from rearward support  55 . Forward support  61  also comprises laterally extending spokes or members, each having a roller  63  on the outer end. Rollers  63  roll on slots  65  formed in sidewalls  47 . Slots  65  are parallel to slots  59  and spaced forward from them. In the upper half of  FIG. 4 , roller  63  is shown at the forward end of slot  65 , and the lower half shows roller  63  at the rearward end of slot  65 . Each lateral member of forward support  61  has a rearward facing surface. 
   A pair of rearward shoulders or engagement points  67  are stationarily mounted to the interior of frame  45 . Rearward shoulders  67  are located on opposite sides of mandrel  53  but do not contact mandrel  53 . A retainer  69  is mounted to the forward face of each shoulder  67 . Retainer  69  has a vertical slot  71  therein. A retainer  69  is also mounted to the rearward side of each member of forward support  61 . Similarly, a retainer  69  is mounted to the forward side of each member of forward support  61 . 
   An actuator  73  is carried on mandrel  53  near its forward end. Actuator  73  comprises a ring that surrounds an enlarged portion of mandrel  53 . Actuator  73  includes a sleeve  75  that is secured to the ring portion of actuator  73  and extends forward. Actuator  73  has a pair of retainers  69  on its rearward facing side that are the same in this embodiment as retainers  69  on shoulders  67  and on forward support  61 . 
   A lock member  77  is also carried at the forward end of mandrel  53 . As shown also in  FIG. 7 , in this embodiment, lock member  77  is an expansible collet that has a rearward enlarged end in engagement with a groove or profile  79  encircling mandrel  53 . Collet  77  also has a forward end that is enlarged for engaging a connector hub profile  81 . Connector hub profile  81  comprises an annular groove surrounding connector hub  13  near its rearward end. Lock member  77  has a natural position that is shown in  FIG. 4  in which the forward end is at a greater diameter than the rearward end. Actuator sleeve  75  has an inner band that engages lock member  77  and pushes it inward when actuator  73  moves forward. The inward position, shown in  FIG. 7 , shows the forward end of lock member  77  locked into connector hub profile  81  and the rearward end of lock member  77  remaining in engagement with mandrel profile  79 .  FIG. 4  shows actuator sleeve  75  in a retracted position, with the hook bias of lock member  77  causing it to be pulled outward. 
   The space between rearward shoulder  67  and forward support  61  is open and accessible from open top  49 , defining a first pocket  83 . Similarly, the space between forward support  61  and the rearward side of actuator  73  is also open and accessible to open top  49  (FIG.  3 ), defining a second pocket  85 . 
   A jack assembly  87  is schematically illustrated in first pocket  83 . In the upper half of  FIG. 4 , jack assembly  87  is extended, while in the lower half, jack assembly  87  is retracted. Jack assembly  87  provides the necessary force to push mandrel  53  from the retracted position shown in the lower half of  FIG. 4  to the extended position shown in the upper half of FIG.  4 . Furthermore, the same jack assembly  87  locates within second pocket  85  for pushing actuator  73  from the retracted position shown in  FIG. 4  to the extended position shown in FIG.  7 . 
   Referring to  FIG. 5 , jack assembly  87  is a portable unit having a frame member  89  on at least one end. Frame member  89  comprises a rigid plate that is in the shape of a horseshoe, defining a slot  90  between its legs for sliding over connector mandrel  53  (FIG.  4 ). In this embodiment, frame member  89  connects to four hydraulic cylinders  91 , although this number can vary. Preferably, two hydraulic cylinders  91  are located on one side of slot  90  and two hydraulic cylinders  91  are located on the other side of slot  90 , so that hydraulic cylinders  91  will be on opposite sides of connector mandrel  53  when installed as shown in FIG.  4 . 
   Hydraulic cylinders  91  are parallel to each other, each having a piston rod  93  that extends parallel to the axis of mandrel  53  ( FIG. 4 ) once installed. Piston rod  93  in this embodiment extends from only one end of each hydraulic cylinder  91 . One retainer plate  95  connects two of the piston rods  93  together on one side of slot  90 . Another retainer plate  95  connects the other two piston rods  93  on the other side of slot  90 . Retainer plates  95  are elongated rectangular members positioned vertically and configured for sliding into the slots  71  of retainers  69  (FIG.  4 ). Preferably a stationary shaft  97  extends coaxially a short distance from the opposite end of each hydraulic cylinder  91 . Each shaft  97  is fixed to one of the hydraulic cylinders  91  in this embodiment. Retainer plates  99 , which are identical to retainer plates  95 , connect two of the shafts  97  on each side of slot  90 . 
   An ROV interface  101  is mounted to an upper portion of frame member  89 . Interface  101  comprises a conventional connector for connecting to ROV  35  for supplying hydraulic fluid pressure to hydraulic cylinders  91 . ROV interface  101  connects to each end of each hydraulic cylinder  91  for extending and retracting piston rods  93 . Preferably hydraulic cylinders  91  are connected in parallel so that each piston rod  93  moves in unison with the others. Buoyant material  103  is bonded to frame member  89  and to hydraulic cylinders  91  for reducing the weight of jack assembly  87  in water. A handle  105  is secured to the upper portion of frame member  89  for engagement by ROV  35  to convey jack assembly  87 . 
   In operation, after stab  43  lands in guide funnel  15 , connector assembly  23  is folded over to the horizontal position shown in FIG.  2 . Then ROV  35  will convey jack assembly  87  ( FIG. 6 ) to connector  23 . As shown in the lower half of  FIG. 4 , ROV  35  ( FIG. 2 ) will slide jack assembly  87  into first pocket  83 . Retainer plates  95  will slide into the retainers  69  attached to rearward shoulders  67 , and retainer plates  99  slide into the retainers  69  on the rearward sides of forward support  61 . Jack assembly  87  is retracted while this occurs. The position of jack assembly  87  could be reversed, if desired, so that retainer plates  95  engaged forward support  61  and retainer plates  99  engaged rearward shoulders  67 . 
   ROV  35  ( FIG. 2 ) engages interface  101  ( FIG. 6 ) and supplies hydraulic fluid pressure to cause piston rods  93  to extend as illustrated in the upper half of FIG.  4 . Piston rods  93  push mandrel  53  from the retracted position to the extended position with its end engaging or abutting the end of connector hub  13 . 
   The operator on vessel  33  ( FIG. 2 ) then signals ROV  35  to grasp handle  105  and pull jack assembly  87  from first pocket  83 . Once removed, ROV  35  then causes hydraulic fluid pressure to flow to the opposite ends of hydraulic cylinders  91 , causing piston rods  93  to retract. Once retracted, the operator slides jack assembly  87  into second pocket  85  as illustrated in FIG.  7 . Retainer plates  95  are shown engaging retainers  69  of actuator  73  while retainer plates  99  are shown engaging retainers  69  on the forward side of forward support  61 . The operator causes ROV  35  to supply hydraulic fluid pressure to extend piston rods  93 , causing actuator sleeve  75  to push lock member  77  into engagement with profile  81  of hub connector  13 . The amount of extension in pocket  85  is not as much as in pocket  83  in this example, although that could differ. 
   The operator then withdraws jack assembly  87  from second pocket  85  and brings jack assembly  87  over for actuating second connector assembly  25  (FIG.  2 ).  FIGS. 8 and 9  illustrate one embodiment of a second connector  25 , which differs in that second connector  25  connects vertically, rather than horizontally. Consequently there is no need for a hinge similar to hinge  51  (FIG.  4 ). Otherwise, the components are generally the same and operate the same way. The second connector assembly  25  has a frame  107  that differs from the frame of the first embodiment in that it preferably has a funnel  109  stationarily mounted on its lower end. Funnel  109  engages a shroud  111  that surrounds manifold connector hub  19  in this embodiment. Shroud  111  has upward extending fingers that snap into releasable engagement with funnel  109 . 
   Mandrel  113  is secured by supports  115 ,  117  to frame  107 . Each support  115 ,  117  has a guide roller  119  that engages an axially extending slot  121 . Frame  107  has an open side  123  in the same manner as open top  49  of frame  45  (FIG.  3 ). A first pocket  125  is located between a rearward or upper shoulder  127  in the interior of frame  107  and forward or lower support  117 . A second pocket  129  is located between forward support  117  and an actuator sleeve  133 . Actuator sleeve  133  engages a lock member  135 . 
   The operation of the second connector assembly  25  is the same as the first connector assembly  23  except it does not hinge over. The same jack assembly  87  is first installed in first pocket  125  by ROV  35  ( FIG. 1 ) to advance mandrel  113  forward or downward into engagement with connector hub  19 . The right side of  FIG. 9  shows mandrel  113  in the extended position, while the left side shows it in the retracted position. Then, ROV  35  removes jack assembly  87  from open side  123 , retracts it and installs it in pocket  129 . ROV  35  actuates jack assembly  87  to push actuator sleeve  133  downward, causing lock member  135  to lock to connector assembly  25 . The operator then removes jack assembly  87  and retrieves it to vessel  33  ( FIG. 1 ) if the subsea work has been completed. The same jack assembly  87  can be used for other making up other connections. 
   The invention has significant advantages. The connectors are remotely actuated with the assistance of an ROV. The connectors do not have hydraulic components, rather are mechanically actuated by a portable jack assembly. The same hydraulic jack assembly can be utilized for a vertical connector and a horizontal connector. 
   While the invention has been shown in only one of its forms, it should be apparent to those skilled in the art that it is not so limited but is susceptible to various changes without departing from the scope of the invention. For example, rather than hydraulic, the jack assembly could utilize a mechanical device such as threaded rods that are rotated by an ROV.