Abstract:
A device and method are provided for storing pipeline pigs and launching the pigs into a subsea production pipeline. The device is installed in line with a pipeline and includes a frame, a magazine containing several rotatable trays for storing and sequentially launching the pigs, and a connector for directing the pigs into a pipeline. Each magazine tray holds several pigs and rotates to align the pigs with a launching tube. The pigs travel through the launch tube and connector and into the pipeline.

Description:
This application claims benefit of Ser. No. 60/162,165 filed Oct. 28, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to pipeline-pig launchers and relates specifically to a launcher used at a subsea location and having a magazine holding a plurality of pigs for launch. 
     2. Description of the Prior Art 
     Oil and gas flowing through a production pipeline can deposit paraffin and other substances on the inner wall of the pipeline. To prevent blockage, producers send pipeline pigs through the pipeline to scrape the walls and remove the deposits. 
     Several pig launchers having storage and launching capabilities are found in the prior art. The device disclosed in U.S. Pat. No. 3,396,789 has a rotatable tool holder that is journaled within a case. The tool holder has a plurality of tubes that can be aligned with the flowline. There is no provision for releasing individual tools from each tube, and if more than one tool is in a given tube, they will all be released when aligned with the flowline. 
     The pig launcher of U.S. Pat. No. 5,884,656 includes a single tube containing multiple pigs and has the ability to launch only one pig at a time. 
     A stabbing configuration and magazine are found in the pig launcher disclosed in U.S. Pat. No. 6,022,421. The pig launcher is landed on a frame having a connector for introducing the pigs into a production pipeline. The launcher has a single tube magazine and can launch single pigs. 
     SUMMARY OF THE INVENTION 
     A pig launcher is provided for use in a subsea location. The launcher has a frame for landing on the sea floor and a magazine for storing and controllably releasing a set of pigs. A drive assembly sequentially releases the pigs, and a set of interconnects releasably connects the pig launcher to a production flowline. An umbilical stab releasably received in a receptacle in the frame is used to control the operation of the drive assembly and receives power from . An umbilical line runs from the stab to a surface platform to supply a source of power for operational control. 
    
    
     Additional objects, features, and advantages will be apparent in the written description that follows. 
     DESCRIPTION OF THE DRAWINGS 
     The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself however, as well as a preferred mode of use, further objects and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is a perspective view of a subsea pig launcher constructed in accordance with this invention. 
     FIG. 2 is a side view of the frame of a subsea pig launcher constructed in accordance with this invention. 
     FIG. 3 is a piping schematic of the frame in FIG.  2 . 
     FIG. 4 is a side sectional view of an umbilical stab for a subsea pig launcher constructed in accordance with this invention. 
     FIG. 5 is a top view of a pig magazine of a subsea pig launcher constructed in accordance with this invention. 
     FIG. 6 is a detail view of a portion, of the pig magazine of FIG.  5 . 
     FIG. 7 is a sectional view of the pig magazine of FIG. 5 taken along section line  7 — 7 . 
     FIG. 8 is a detail view of the locking pin of FIG.  7 . 
     FIG. 9 is a detail view of the engaging pin of FIG.  7 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIGS. 1 through 9 show the preferred embodiment of a subsea pig launcher  10  of the invention. 
     Referring first to FIG. 1, a subsea pig launcher  10  constructed in accordance with this invention generally comprises a tie-in frame  12  and a pig launching magazine  14 . Frame  12  is interconnected between pipeline or flowline  16 , and magazine  14  is landed on frame  12 . 
     Referring now to FIG. 2, tie-in frame  12  generally has a guard structure  18  defining its perimeter. Guard structure  18  has a solid base  20  which prevents structure  18  from sinking through mud on the sea floor, and a plurality of lifting points  22  are positioned on its upper end. An asymmetric wye  24  with an exit  26 , an in-line leg  28 , and a launching tube or branch leg  30  are protected within structure  18 . In-line leg  28  is aligned with exit  26  and runs generally parallel to base  20 . As shown in FIG. 3, branch leg  30  intersects in-line leg  26  at an acute angle and extends generally downward from in-line leg  26 . Exit  26  terminates in a exit flange  32  at one end of structure  18  and in-line leg  28  terminates in an inlet flange  34  at the other end. Exit line  26 , in-line leg  28 , and branch leg  30  are substantially the same diameter as flowline  16 . An electronic pig detector  35  is mounted to detect pigs passing through exit  26 . Launching tube  30  has a remotely actuated, ball-type bypass valve  36 . In-line leg  26  has a remotely actuated, ball-type production valve  38 . A smaller feed line  40  is positioned between valve  38  and inlet flange  34  (FIG. 3) and extends upward from in-line leg  26  terminating in an upwardly facing feed line connector  42 . A remotely actuated, gate-type launching valve  44  is positioned in feed line  40 . A pig line  46  extends from launching tube  30 , curving to run directly upward and terminates in an upwardly facing pig line connector hub  48 . Hub  48  integrally accepts feed line connector  42 . 
     Referring again to FIG. 2, an upwardly facing magazine receptacle  50  is mounted on frame  12 . Magazine receptacle  50  is a tube aligned vertically and having a conical guide funnel  52  at its upper end. A similarly shaped umbilical receptacle  54  is mounted on frame  12 , the receptacle being aligned vertically and having a guide funnel  56  at its upper end. FIG. 4 shows an umbilical stab  58  adapted to land in umbilical receptacle  54  and that has electric and hydraulic circuits (not shown) which are remotely actuated through an umbilical line  60  to the surface. Umbilical stab  58  has a body portion  62  with a stab portion  64  extending therefrom. Stab portion  64  is cylindrical and sized to be closely accepted in receptacle  54 . Umbilical  60  is supported relative to body portion  62  by a hinged harness  63  mounted to hinge about a horizontal axis. A support portion  66  sealingly extends into a cavity  68  of stab portion  64  and has a lifting ring  67  on its upper end. Lifting ring  67  is mounted to support portion  66  to rotate about a horizontal axis. Hydraulic fluid from line  60  or from a stab panel  61  as known in the art can be pumped into a cavity  68  to raise or lower body portion  62  relative to stab portion  64 . This activates a lock  70  which is adapted to engage a corresponding notch (not shown) in receptacle  54  and lock stab  58  to receptacle  54  when support portion  66  is in a lower position. Above stab portion  64 , body portion  62  carries a plurality of downward facing electric and hydraulic connectors  72 . Connectors  72  are positioned to mate with upward facing electric and hydraulic interconnects  73  (FIG. 2) on receptacle  54 . Interconnects  73  connect the electric and hydraulic circuits of umbilical stab  58  to a circuit on frame  12  discussed in further detail below. 
     Referring again to FIG. 1, pig launching magazine  14  generally comprises a frame  80  having four corner struts  82 , an upper end plate  84 , and a lower end plate  86 . As seen in FIG. 7, a central shaft  88  spans end plates  84 ,  86  and carries a plurality of launching trays  90 . The embodiment depicted in FIG. 7 has eight trays  90 ( a )- 90 ( h ) The first tray  90 ( a ) is rigidly fixed to shaft  88  and the remaining trays  90 ( b )- 90 ( h ) can freely rotate about shaft  88 . Each tray  90  has end plates  92  which sandwich a plurality of staging chambers  94  but leave the ends of chambers  94  open. Staging chambers  94  are sized to accept a suitable pipeline pig  95  for pipeline  16  and are arrayed on launching trays  90 . Referring to FIG. 5, each tray  90  has eleven staging chambers  94 ( a )- 94 ( k ); ten to be loaded pigs  95  (FIG. 7) and one for launching. The number of trays  90  and chambers  94  per tray depends on how many pigs  95  are desired to be carried in magazine  14  and related space constraints. Other numerical combinations of trays  90  and chambers  94  per are within the scope of this invention. 
     Referring again to FIG. 7, tray separators  96  are spaced between launching trays  90 ( b )-( h ) and stationarily secured to corner struts  82  (FIG.  6 ). Each has a circular inner hole which allows a portion of vertically adjacent trays  90  to abut. Tray  90 ( a ) abuts upper end plate  84 , and tray  90 ( h ) abuts lower end plate  86 . Each tray separator  96  and lower end plate  86  have a single circular pass-through  98  adapted to seal the perimeter of a pig tube  94  and allow passage of a pipeline pig from a higher positioned pig tube  94  to a lower positioned pig tube  94 , and in the case of the lower end plate  76 , into a pig tube stub  100 . Also, tray separators  96  have circular outer guard edges  97 , positioned along the circumference of launching trays  90  to tangentially abut vertically adjacent staging chambers  94  and guard against entrance of contaminants into magazine  14  and staging chambers  94 . Circular inner guard edges  99  are positioned concentrically inward of outer guards  97  to tangentially abut an inner edge of staging chambers  94  and further guard against entrance of contaminants into staging chambers  94 . 
     A pig tube stub  100  is joined to lower end plate  86  and extends downward. Stub  100  has a pig line connector  102  at its end adapted to connect and seal with connector hub  48 . Pig line connector  102  is preferably a collet connector known to those skilled in the art which can be actuated remotely by hydraulics. In addition to the pig tube stub  100  for passage of a pipeline pig, connector  102  has separate passages for the flow from feed line  40  to an upper feed line  104  and for connecting a circuit on frame  12  to a control module  103  on magazine  14  (FIG.  5 ). Upper feed line  104  runs out of connector  102  and into upper end plate  84  (FIG. 6) axially aligned above stub  100 , allowing fluid from feed line  40  to flow into a column of staging chambers  94  and back out stub  100 . A cylindrical magazine stab  105  extends downward from-magazine  14  and is adapted to be closely accepted in receptacle  50 . 
     A drive assembly is shown in FIG. 5. A toothed drive disk  106  is joined to the top of shaft  88  above upper plate  84 . At least one hydraulic actuator  108  is mounted on upper plate  84  to engage drive disk  106  and rotate shaft  86  and the upper most launching tray  90 ( a ). Drive disk  106  is configured such that one outward stroke of actuator  108  rotates upper plate  84  approximately the same angular distance as between staging chambers  94 , thus moving one pig tube  94  generally into the same position as its adjacent pig tube  94 . A protective cage  109  is positioned on plate  84  to protect drive disk  106  and actuator  108 . 
     An indexing mechanism is seen in FIGS. 7 through 9. Referring to FIG. 8, a hydraulically actuated lock pin  110  is joined to upper plate  84  and can be hydraulically extended into or retracted out one of a plurality of pin receptacles  112  in end plate  92  of upper most launching tray  90 ( a ). Each pin receptacle  112  corresponds to a pig tube  94  and is positioned such that when pin  110  is extended into a pin receptacle  112 , it locks the corresponding pig tube  94  in alignment with stub  100  to prevent rotation of launching tray  90 ( a ). Receptacle  112  is shaped as a female cone and pin  110  is shaped as a male cone to compensate for small misalignment of pin  110  and receptacle  112 . 
     Referring to FIG. 9, launching trays  90  have a hydraulically actuated engaging pin  114  that functions like locking pin  110  and is hydraulically extendable into and retractable out of a tray pin receptacle  116  in the adjacent launching tray  90 . For simplicity of discussion, trays  90 ( a ) and  90 ( b ) are described, but all trays except lower tray  90 ( h ) have an engaging pin  114 , and all except upper tray  90 ( a ) have a tray pin receptacle  116 . Pin receptacle  116  has a release piston  118  reciprocatingly retained therein and biased in an upward position. Release piston  118  has an engagement stub  120  which extends outward through a notch  122  in tray  90 ( b ), and when piston  118  is in an upper position, into a notch  124  in the corresponding separator plate  96  adjacent to pass-through  98 . With engagement stub  120  in, notch  124 , pass-through  98  is aligned with the upper end of pig tube  94  on tray  90  ( b ). Also, tray  90 ( b ) is locked to separator plate  96  and cannot rotate. As engaging pin  114  is extended into receptacle  116 , it displaces piston  118  and moves stub  120  out of notch  124  in separator  96 . With stub  120  out of notch  124  and pin  114  in receptacle  116 , tray  90 ( b ) is locked to tray  90 ( a ), and they will rotate in unison. 
     Referring generally to FIG. 1, an electric and hydraulic feed from line  60  is connected to a hydraulic circuit on frame  12  through connectors  72  on umbilical stab  58 . This supplies electricity and hydraulic pressure to operate a control module  103  on magazine  14 . Control module  103  is configured to detect pig passage with pig detector  35 , open and close valves  36 ,  38 , and  44 , and actuate hydraulic actuator  108  and pins  110  and  114 . A stab panel  126  positioned on frame  12  (FIG. 2) allows electric and hydraulic input from an ROV as an alternative to stab  58 . 
     In operation, frame  12  is lowered to the sea floor and connected into pipeline  16  such that fluid flowing in pipeline  16  can flow directly through in-line leg  28  and out exit  26  (FIG.  1 ). Pig launching magazine  14  is loaded with pipeline pigs  95  (FIG. 7) leaving one pig tube, preferably  94 ( k ), of each tray  90  empty. Magazine  14  is then lowered onto frame  12  with stab  105  being received in receptacle  50 . Stab  105  supports magazine  14  to stand vertically, and pig line connector  102  is aligned with connector hub  48  and actuated to join and seal with connector hub  48 . Cavity  68  of umbilical stab  58  (FIG. 4) is pressurized with hydraulic fluid from line  60  to maintain support portion  66  in a raised upper position. Umbilical stab  58  is then lowered from the surface onto frame  12  with stab portion  64  in receptacle  54  supporting body portion  62  above receptacle  54 . Pressure is released from cavity  68 , body portion  62  slowly moves to a lower position and support portion  66  activates lock  70 , thus locking umbilical stab  58  to frame  12 . 
     Hydraulic pressure and electric signals are sent through line  60  and umbilical stab  58  and through hub  48  and connector  102  into control module  103  to operate module  103 . Alternately, signals can be sent-from the ROV panel  126 . Module  103  extends hydraulic actuators  108 . Actuators  108  engage the teeth of drive disk  106  and rotate shaft  88  such that the pig tube  94  adjacent to the empty tube  94 , here pig tube  94 ( a ), of launching tray  90 ( a ) is generally aligned with tube stub  100  and over empty staging chambers  94 ( k ) of trays  90 ( b )- 90 ( h ) (FIG.  7 ). Module  103  also actuates locking pin  110 . When the pin receptacle  112  corresponding to tube  94 ( a ) passes under pin  110 , pin  110  is forced into receptacle  112  locking tube  94 ( a ) of tray  90 ( a ) over empty chambers  94 ( k ) of trays  90 ( b )-( h ). Also, pin  110  in receptacle  112  ensures fine alignment of tube  94 ( a ) of tray  90 ( a ) with tube stub  100  and empty staging chambers  94 ( k ) of trays  90 ( b )- 90 ( h ). Pig  95  in tube  94 ( a ) is now in position to launch. 
     With pig  95  in position, module  103  opens feed line valve  44  allowing fluid from flowline  16  to flow up through feed line  40 , through upper feed line  104 , and into staging chambers  94  pressurizing behind pig  95 . Bypass valve  36  is then opened by module  103  and the fluid pressure pushes pig  95  into flowline  16 . As pig  95  passes pig detector  35 , module  103  is signaled to first close valve  36 , then valve  44 . The next pig tube  94 ( b ) is rotated into position as described above and its pig  95  is released. The above procedure is repeated until all pigs  95  in tray  90 ( a ) have been released. 
     Next, module  103  actuates engagement pin  114  in tray  90 ( a ) to force it into the pin receptacle of tray  90 ( b ). This displaces release piston  118  of tray  90 ( b ) and locks tray  90 ( a ) and tray  90 ( b ) to rotate together. As piston  118  is displaced, engagement stub  120  is moved out of notch  124  in the separator plate  96 , unlocking tray  90 ( b ) from its corresponding separator plate  96 . Module  103  extends hydraulic actuators  108 , thus rotating shaft  88 , tray  90 ( a ), and tray  90 ( b ) to generally align pig tube  94 ( a ) of tray  90 ( b ) containing a pig  95  into alignment with empty chambers  94 ( k ) of trays  90 ( c )-( h ) and pig stub  100 . Pin  110  is actuated to extend into the corresponding receptacle  112  to align and lock tube  94 ( a ) of tray  90 ( b ) and a tube  94  of tray  90 ( a ) in position. As above, module  103  opens feed line valve  44 , pressurizing behind pig  95 , then opens bypass valve  36  to pass pig  95  into flowline  16 . As pig  95  passes detector  35 , module  103  closes valve  36  and valve  44 . 
     These steps are repeated with each level of trays  90 ( c )- 90 ( h ) until all of pigs  95  have been released. Magazine  14  can then be retrieved to the surface after releasing connector  102 . On the surface magazine  14  can be re-loaded with pig  95  for future pigging. 
     While the invention is 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.