Abstract:
A multi-channel swivel with the wear capability of rigid hard seal means by providing a single mandrel and multiple outer bodies to allow each body to have one or more seals inserted into one or both ends of each body, thereby allowing for three or more seal paths in the swivel.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
         [0001]    Patent application titled “FLUID SWIVEL WITH COOLING PORTING” filed on the same date.  
         STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
         [0002]    N/A  
         INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISK  
         [0003]    N/A  
         BACKGROUND OF THE INVENTION  
         [0004]    The field of this invention is that of multi-port hydraulic swivels for the purpose of communicating high pressure liquids or gasses from a non-rotating location to a rotating location. The most common application is on the central shaft of a hose reel in which the central shaft of the reel rotates with the drum. The drum will be rotating as the hose is rolled out to its intended service. The pressure fluid supply to the reel will characteristically not be rotating, and therefore a rotating union will be required between the non-rotating fluid supply and the rotating main shaft of a reel drum.  
           [0005]    The importance of this type swivel has greatly increased as the drilling of oil and gas wells has moved to deep offshore waters. Drilling contemporarily occurs in 8,000 to 10,000 feet of seawater. In lowering the drilling system to these depths and in lowering certain completion and testing equipment, continuous pressure contact is desired to be maintained between the surface and the subsea equipment being lowered and/or operated. In some cases operational pressure is required as the equipment is lowered. In other cases, maintaining pressure on the system is a safety consideration. If the operator releases the pressure, the hose will become disconnected from the heavy package being lowered and allow the hose to be recovered. This is especially important if the heavy package becomes stuck on lodged in deep water.  
           [0006]    As greater depths are encountered and higher pressures are desired to be maintained as the reel and swivel are rotated. This higher pressure and the inherently higher number of rotations associated with deeper water depth cause specific problems with the swivels.  
           [0007]    A first problem is that a high degree of wear tends to occur in soft seals which can be inserted into machined grooves in the inner or outer surface of the mating parts. If a harder seal can be utilized at the higher pressures, a better or more extended wear life can be provided. An opposing pair of seals can be installed in the end of the outer body to a stopping shoulder and followed by a threaded gland to act as the opposing shoulder. On the other end of the outer body a second set of seals can be inserted to the opposite side of the central shoulder and again followed by a gland. This configuration can be utilized for a single or dual channel swivel, but there are needs for triple and quadruple channel swivels which cannot be serviced in this manner as there are only two ends to the outer body.  
           [0008]    A second problem is that the higher pressure and higher number of rotations generates heat. Heat generated on the outside of the seals disperses into the outer body which has progressively greater area as the distance moves away from the seals, and has a relatively large outer surface to dissipate the heat to the environment. The heat generated at the I.D. of the seal moves toward the centerline of the mandrel portion of the swivel, and literally runs into the heat generated on the opposite of the mandrel. The heat has no place to go, so it builds up to higher temperatures. The higher temperatures characteristically increase the friction, generating more heat at an even faster rate. In some cases we have seen, the heat gets so high in contemporary applications that the seals are actually cooked and fail.  
         BRIEF SUMMARY OF THE INVENTION  
         [0009]    The object of this invention is to provide a multi-channel swivel which will allow for three or more channels with seals of a material which must be inserted into the end of the bore rather than being bent to allow insertion into a groove in the bore of the Outer Body or into a groove on the Mandrel. 
       
    
    
     BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS  
       [0010]    [0010]FIG. 1 is a partial section thru a subsea blowout preventer stack and a view of a reel in which a swivel of this invention would be used.  
         [0011]    [0011]FIG. 2 is a schematic showing how a swivel of this invention is used.  
         [0012]    [0012]FIG. 3 is a half section of a swivel of this invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0013]    Referring now to FIG. 1, a blowout preventer (BOP) stack  10  is landed on a subsea wellhead system  11 , which is supported above mudline  12 . The BOP stack  10  is comprised of a wellhead connector  14  which is typically hydraulically locked to the subsea wellhead system  11 , multiple ram type blowout preventers  15  and  16 , an annular blowout preventer  17  and an upper mandrel  18 . A riser connector  19 , and a riser  20  to the surface are attached for communicating drilling fluids to and from the surface.  
         [0014]    Reel  30  has a frame  31 , spool  32 , and a swivel  33  mounted on the central shaft of the spool (not shown). Hose and/or cable reel  34  is shown going from the spool  32  of the reel  30  to a control box  35  on the subsea blowout preventer stack  10 . From the control box  35 , appropriate hoses  37  go to control various functions, such as ram blowout preventer  16 .  
         [0015]    Referring now to FIG. 2, a reel schematic is shown. Spool  32  is shown mounted on the central shaft  50  which is supported by conventional bearings (not shown). On the left end of the central shaft  50  is mounted a swivel  51  having an outer body  52  and a mandrel  53 . connection  54  attaches the swivel  33  to central shaft  50 .  
         [0016]    Hydraulic lines  60 - 63  are attached to the swivel outer body  52  to deliver pressurized fluids to the swivel from the non-rotating hydraulic supply (not shown). Within the spool, line  70  connects with line  60  and exits the main shaft  50  and goes directly to the hose bundle  80  going to the ocean floor. This line is characteristic of the lines which need the pressure to be maintained during the rotating operations. Gage  81  is provided on this line to monitor the pressure in this line. Line  71  connects with line  61  and also goes directly to the hose bundle and is characteristic of a return line which would not require the high pressure during rotation. Line  72  and  73  connect with lines  62  and  63  respectively and supply a multi-valve panel  82  on the side  83  of the spool  32  for individual control of a multiplicity of lines to subsea equipment.  
         [0017]    Stab Plate  84  engages receptacle plate  85  to give individual hydraulic supply to various selected lines when the reel is not rotating. Control box  86  provides for operational control of the spool  32 , failsafe brakes  87  provide stopping power for the spool  32 , locking pin  88  provides positive position stopping for the spool  32 , and motor  89  provides operations power for the spool  32  thru chain  90 .  
         [0018]    Referring now to FIG. 3, a half section of the swivel of this invention can be seen. Inner mounting plate  100  is attached to the main shaft  50  by bolts  101 . Outer mounting plate  102  is mounted to the mandrel  103  by bolts  104 . Outer mounting plate  102  is attached to the inner mounting plate  100  by bolts  105 .  
         [0019]    Mandrel  103  is an cylindrical member with 8 seal surfaces  110 - 117  and locating shoulders  120  and  121 . Fluid pressure communicates thru port  130 , thru seal sub  131 , drilled hole  132 , and out port  133 . Similar flow paths occur in ports  134 ,  135  and  136  at 90 degree spacings around the mandrel  103 .  
         [0020]    Body  140  provides a central locating shoulder  141 , and end thread  143  which engaged by a gland  144 , and an end thread  145  which is engaged by gland  146 . The space between the central locating shoulder  141  and the glands  144  and  146  provides cavities for the insertion of seals  150  and  151  on one end and  152  and  153  on the other end. This provides that when high pressure is in the area between these seals, the outward force is directed by an appropriate shoulder or gland to resist the force. By providing the threaded gland design, seals made of hard plastic like material are able to be installed to give superior wear life in comparison to the life afforded by softer seals which can be stretched into grooves.  
         [0021]    Similarly, Body  160  provides a central locating shoulder  161 , and end thread  163  which is engaged by a gland  164 , and an end thread  165  which is engaged by gland  166 . The space between the central locating shoulder  161  and the glands  164  and  166  provides cavities for the insertion of seals  170  and  171  on one end and  172  and  173  on the other end. This provides that when high pressure is in the area between these seals, the outward force is directed by an appropriate shoulder or gland to resist the force.  
         [0022]    The shoulder is indicated in the preferred embodiment to be a threaded gland. In practicality, lock rings, bolted flanges, and other style shoulder means can be used to achieve the goal of retaining the seals within the cavity. Literally, the end of the other body can provide the means to retain the seal within the cavity.  
         [0023]    In this way each of 2 bodies has provided a central shoulder and a gland on each end to trap 2 sets of seals each, for a total of 4 sealed ports. The mandrel  103  has been made from a single piece of metal and provides a straight continuous flow path for the porting. The outer body is not continuous but is rather made of 2 independent bodies  140  and  160 . Mating shoulders  180  and  181  keep the bodies  140  and  160  accurately aligned and bolts  182  keep them attached together for rotary operation. In this way we can install four sets (pairs) of seals which are not amenable to deforming and insertion into grooves. This allows a single swivel to have 3, 4, or more channels of high pressure service.  
         [0024]    Port  190  is an air inlet port which can be used to flow air thru port  191  to allow for cooling of the mandrel  103  of the swivel. Ports  200 - 204  provide for leak detection from the seals. Thread  210  provides for an anti-rotation means to stop the rotation of the bodies while the mandrel is being rotated.  
         [0025]    In this way swivels with 3, 4, 5 or even more fluid channels can be provided.  
         [0026]    The foregoing disclosure and description of this invention are illustrative and explanatory thereof, and various changes in the size, shape, and materials as well as the details of the illustrated construction may be made without departing from the spirit of the invention.