Abstract:
A technique enables formation of connections between subsea well installations and compliant guides. The technique comprises deploying a compliant guide ( 22 ) from a surface vessel ( 26 ) toward a subsea well installation ( 24 ). A lower end of the compliant guide ( 22 ) is moved toward the sea floor in proximity to a subsea well installation. Subsequently, one or more submerged tools operate in cooperation with a lower end ( 32 ) of the compliant guide ( 22 ) to move the compliant guide ( 22 ) into engagement with the subsea well installation ( 24 ).

Description:
BACKGROUND 
       [0001]    The production and transfer of fluids from subsea wells relies on subsea installations, surface vessels or structures, subsea flow lines and other equipment. In some applications, compliant guides are deployed between a surface vessel and a subsea installation. Difficulties arise in landing the compliant guide onto the subsea installation due, at least in part, to the motion of the surface vessel relative to the seabed. 
         [0002]    The compliant guide can be directed by guide wires connected between the subsea installation and the surface vessel. At the surface vessel, the guide wires are connected to a wave motion compensating system. Other systems operate without guide wires run between the subsea installation and the surface vessel. For example, systems exist that detect the motion of the surface vessel via accelerometers. The information from the accelerometers is used by a control system that compensates for the surface vessel motion while attempting to land the equipment onto the subsea installation. 
       SUMMARY 
       [0003]    In general, the present invention provides a technique for forming connections between a subsea well installation and a compliant guide, such as a spoolable compliant guide. The technique comprises deploying a compliant guide toward a subsea well installation. Subsequently, one or more submerged tools operate in cooperation with a lower end of the compliant guide to land or otherwise move the compliant guide into engagement with the subsea well installation. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]    Certain embodiments of the invention will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements, and: 
           [0005]      FIG. 1  is a schematic front elevation view of a compliant guide system coupled between a surface vessel and a subsea well installation, according to an embodiment of the present invention; 
           [0006]      FIG. 2  is a schematic front elevation view of the compliant guide being moved into engagement with a subsea well installation by connection formation equipment, according to an embodiment of the present invention; 
           [0007]      FIG. 3  is a schematic front elevation view of the compliant guide being moved into engagement with a subsea well installation by connection formation equipment, according to an alternate embodiment of the present invention; 
           [0008]      FIG. 4  is a schematic front elevation view of the compliant guide being moved into engagement with a subsea well installation by connection formation equipment, according to an alternate embodiment of the present invention; 
           [0009]      FIG. 5  is a schematic front elevation view of the compliant guide being moved into engagement with a subsea well installation by connection formation equipment, according to an alternate embodiment of the present invention; 
           [0010]      FIG. 6  is a schematic front elevation view of the compliant guide being moved into engagement with a subsea well installation by connection formation equipment, according to an alternate embodiment of the present invention; 
           [0011]      FIG. 7  is a schematic front elevation view of the compliant guide being moved into engagement with a subsea well installation by connection formation equipment, according to an alternate embodiment of the present invention; 
           [0012]      FIG. 8  is a schematic front elevation view of the compliant guide being moved into engagement with a subsea well installation by connection formation equipment, according to an alternate embodiment of the present invention; 
           [0013]      FIG. 9  is a schematic front elevation view of the compliant guide being moved into engagement with a subsea well installation by connection formation equipment, according to an alternate embodiment of the present invention; 
           [0014]      FIG. 10  is a schematic front elevation view of the compliant guide being moved into engagement with a subsea well installation by connection formation equipment, according to an alternate embodiment of the present invention; 
           [0015]      FIG. 11  is a schematic front elevation view of the compliant guide being moved into engagement with a subsea well installation by connection formation equipment, according to an alternate embodiment of the present invention; and 
           [0016]      FIG. 12  is a schematic front elevation view of the compliant guide being moved into engagement with a subsea well installation by connection formation equipment, according to an alternate embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    In the following description, numerous details are set forth to provide an understanding of the present invention. However, it will be understood by those of ordinary skill in the art that the present invention may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible. 
         [0018]    The present invention generally relates to a technique for utilizing a compliant guide system, such as a spoolable compliant guide system, connected between a surface vessel and a subsea well installation. The technique utilizes one or more connection systems and methodologies that facilitate engagement of the compliant guide with the subsea installation. In some applications, for example, the connection systems and methodologies can be utilized in facilitating the connection of the lower end of a spoolable compliant guide with a corresponding connector of a lubricator on the subsea well installation. 
         [0019]    In deploying a spoolable compliant guide, the guide can be fully deployed into its compliant shape such that the lower end of the guide is at a shallower depth relative to a corresponding connector of the subsea well installation. The various connection techniques described below are used to move the lower, connector end of the spoolable compliant guide into proximity and engagement with the subsea well installation. The connector techniques can be utilized in creating a downward force strong enough to overcome the buoyancy of the compliant guide which naturally tends to bias the lower end of the compliant guide away from the subsea well installation. This biasing force can be useful, however, during various emergency disconnect procedures in which it is beneficial to separate the compliant guide from the subsea well installation. 
         [0020]    Referring generally to  FIG. 1 , a well system  20  is illustrated according to an embodiment of the present invention. In this embodiment, well system  20  comprises a compliant guide  22 , e.g. a spoolable compliant guide, coupled between a subsea well installation  24  and a surface vessel  26  located at a surface  28  of the sea. Subsea well installation  24  may be located on or at a seabed  30 . 
         [0021]    In the embodiment illustrated, compliant guide  22  is flexible and may be arranged in a variety of curvilinear shapes extending between a surface location, e.g. intervention vessel  26 , and subsea well installation  24 . This flexibility allows the compliant guide  22  to be arranged in a variety of compliant configurations, as desired, to facilitate deployment or retraction of tool strings. By way of example, compliant guide  22  may be constructed as a tubular member formed from a variety of materials that are sufficiently flexible, including metal materials of appropriate cross-section and composite materials. Regardless, compliant guide  22  comprises a connector end  32  by which the compliant guide is connected to the subsea well installation  24 . 
         [0022]    Although a variety of subsea installations  24  can be utilized depending on the particular environment and type of intervention operation or other well operation, one example is illustrated in  FIG. 1 . In this example, the subsea installation  24  comprises a subsea wellhead  34 , such as a Christmas tree style wellhead, coupled to a subsea well  36 . The subsea installation  24  also comprises a corresponding connector end  38  onto which connector end  32  is landed or otherwise engaged. By way of example, corresponding connector end  38  may be positioned at the upper end of a lubricator  40 . 
         [0023]    Subsea well installation  24  also may comprise a variety of other features and components. For example, subsea well installation  24  may comprise a subsea lubricating seal  42  deployed directly above subsea wellhead  34 . Lubricating seal  42  can be used to close the borehole of subsea well  36  during, for example, intervention procedures. Additionally, a blowout preventer  44  can be located in subsea well installation  24  above subsea lubricating seal  42 . Blowout preventer  44  may comprise one or more cut-and-seal rams able to cut the conveyance and seal off the subsea installation during an emergency disconnect. Other components, such as a subsea stripper assembly  46 , also can be included in subsea well installation  24 . Depending on the application, subsea well installation  24  may incorporate emergency disconnect devices and other components to enable its desired function. 
         [0024]    The compliant guide  22  also can be used in cooperation with a variety of additional or alternate components that facilitate deployment of the compliant guide, use of the compliant guide, and protection of the subsea well in various subsea operations. For example, an emergency disconnect  48  can be provided at surface vessel  26  proximate an upper end  50  of compliant guide  22 . Additionally, a clump weight  52  can be attached to a lower and  54  of compliant guide  22  to facilitate deployment of the compliant guide. Clump weight  52  is attached to lower end  54  by a tether  56  connected across a float  58  and provides weight to help overcome the buoyancy of compliant guide  22 . During deployment, clump weight  52  draws the lower end of compliant guide  22  downwardly toward seabed  30  in an area proximate to subsea well installation  24 . Connection systems also can be utilized with compliant guide  22  to facilitate engagement of the compliant guide with subsea well installation  24 , as discussed in greater detail below. 
         [0025]    Referring generally to  FIG. 2 , one embodiment of a connection system  60  is illustrated. Connection system  60  is used to facilitate the engagement, e.g. landing, of compliant guide  22 , e.g. a spoolable compliant guide, onto subsea installation  24 . In the specific embodiment illustrated, connector end  32  of spoolable compliant guide  22  is brought into engagement with corresponding connector end  38  of subsea well installation  24 , e.g. a subsea lower intervention package. As illustrated, connection system  60  comprises a plurality of subsea winches  62  mounted to subsea well installation  24 . Each subsea winch  62  comprises a winch cable  64  that extends upwardly through a cable guide  66  and into engagement with connector end  32 . Each cable guide  66  is mounted on subsea installation  24  at a suitable location, such as corresponding connector end  38 . 
         [0026]    A remotely operated vehicle  68  is used to pick up the cables  64  from the winches  62  after clump weight  52  has been used to draw connector end  32  into proximity with subsea well installation  24 . The remotely operated vehicle  68  is then operated so as to connect these cables to the spoolable compliant guide  22 . Once the winch cables  64  are connected to spoolable compliant guide  22 , the subsea winches  62  are activated to draw in the winch cables and to move connector end  32  into engagement with corresponding connector end  38 . The subsea winches  62  can be activated electrically, hydraulically or by other suitable power sources. By way of example, the subsea winches  62  are activated by hydraulic power supplied through remotely operated vehicle  68  or through the subsea installation  24  via an appropriate control umbilical  70 . 
         [0027]    In the specific embodiment illustrated in  FIG. 2 , a pair of subsea winches  62  are used to draw connector end  32  into engagement with corresponding connector end  38 . However, a single subsea winch  62  can be mounted to subsea well installation  24  and used to draw the spoolable compliant guide  22  into engagement with subsea well installation  24 , as illustrated in  FIG. 3 . In the embodiment illustrated in  FIG. 3 , subsea winch  62  comprises a hydraulic wire spooling head  72  actuated by remotely operated vehicle  68  to induce pulling of winch cable  64 , thereby drawing connector end  32  into engagement with corresponding connector end  38 . 
         [0028]    One or more subsea winches  62  can be deployed in a variety of locations depending on the environment and/or the configuration of subsea well installation  24 , connection system  60 , and compliant guide  22 . For example, one or more subsea winches  62  can be mounted independently of subsea well installation  24 . As illustrated in  FIG. 4 , subsea winches  62  are mounted on seabed  30 . In this latter embodiment, remotely operated vehicle  68  is used to connect the one or more winch cables  64  to compliant guide  22  via, for example, connector end  32 . The subsea winches  62  are then activated via a suitable power supply, e.g. pressurized hydraulic fluid, provided by remotely operated vehicle  68  or subsea well installation  24 . 
         [0029]    Another embodiment of connection system  60  is illustrated in  FIG. 5 . In this embodiment, connector end  32  of compliant guide  22  is moved toward corresponding connector end  38  of subsea well installation  24  by directing a discharge of fluid, as represented by arrows  74 . The discharge of fluid is created by a jet assembly  76  having jets  78  through which the discharged fluid  74  is directed. After deploying compliant guide  22  into proximity with subsea well installation  24  via clump weight  52 , fluid is pumped down through the interior of compliant guide  22 , as represented by arrows  80 . The fluid is then directed into generally arcuate or u-shaped passages  82  which change the direction of fluid flow before the fluid is discharged through jets  78 . 
         [0030]    To move connector end  32  into engagement with corresponding connector end  38 , the discharge of fluid is directed upwardly, as illustrated in  FIG. 5 . However, jet assembly  76  may be rotatably or otherwise movably mounted on compliant guide  22  to enable adjustment of the discharge direction via, for example, remotely operated vehicle  68 . By adjusting the direction of discharge, jet assembly  76  can be used to separate connector end  32  and corresponding connector end  38  during a disconnection procedure. Additionally, the jet assembly  76  can be rotated to change the direction of the fluid discharge for adjusting the horizontal position of connector end  32  relative to connector end  38 . 
         [0031]    The discharge of fluid  74  also can be induced by a propeller assembly  84 , as illustrated in  FIG. 6 . In this embodiment, the discharge of fluid is induced by propellers  86  of propeller assembly  84 . After deploying compliant guide  22  into proximity with subsea well installation  24 , fluid is pumped down through the interior of compliant guide  22 , as represented by arrows  80 . The fluid is then directed into propeller assembly  84  to induce rotation of propellers  86 . Propellers  86 , in turn, provide the discharge of fluid that can be used to move connector end  32  of compliant guide  22 . 
         [0032]    As with the embodiment illustrated in  FIG. 5 , remotely operated vehicle  68  can be used to orient the direction along which fluid is discharged. Thus, propeller assembly  84  can be rotated by remotely operated vehicle  68  to selectively move connector end  32  in a downward direction for connection or in an upward direction for disconnection. Additionally, remotely operated vehicle  68  also can be used to assist in guiding compliant guide  22  down toward corresponding connector end  38  of subsea well installation  24 . In some applications, remotely operated vehicle  68  is used to turn off flow to propellers  86  or to close off jets  78  via jet isolation valves. As an alternative, the remotely operated vehicle  68  is employed to supply fluid flow in addition or as an alternative to fluid flow  80  directed downwardly through the interior of compliant guide  22 . In the embodiment of  FIG. 7 , for example, remotely operated vehicle  68  is connected to propeller assembly  84  by an appropriate control line able to provide a flow of fluid to propeller assembly  84  for driving propellers  86 . 
         [0033]    Referring generally to  FIG. 8 , another embodiment of connection system  60  is illustrated. In this embodiment, connection system  60  comprises a tensioning wire system  90  for drawing connector end  32  into engagement with corresponding connector end  38 . Tensioning wire system  90  comprises a tensioning wire  92  mounted along compliant guide  22  in a manner able to guide the landing of compliant guide  22  onto subsea well installation  24 . 
         [0034]    Following placement of the subsea well installation  24  at seabed  30 , compliant guide  22 , e.g. a spoolable compliant guide, is deployed toward the subsea well installation  24  with the aid of clump weight  52 . During deployment of compliant guide  22 , tensioning wire  92  is positioned to extend through the connector end  32  of compliant guide  22  to a location below the connector end. The tensioning wire  92  is then clamped to compliant guide  22  by tension wire clamp  94  and guided through one or more tension wire guides  96  as compliant guide  22  is deployed. The upper portion of tensioning wire  92  is spooled onto a wire tensioning assembly  98  able to selectively spool or unspool tensioning wire  92 . Once connected to wire tensioning assembly  98 , tension is placed on tensioning wire  92  until the spoolable compliant guide  22  is moved into a desired compliant shape. 
         [0035]    Subsequently, continued deployment of compliant guide  22  moves the compliant guide toward subsea well installation  24 . When connector end  32  is generally proximate to subsea well installation  24 , tensioning wire  92  is connected to subsea well installation  24  by remotely operated vehicle  68 . After connecting the tensioning wire  92 , the remotely operated vehicle  68  can again be used to loosen tension wire clamp  94  so that the stored energy in compliant guide  22  biases the compliant guide to a straighter shape. As a result, connector end  32  of compliant guide  22  is forced downwardly along tensioning wire  92  toward corresponding connector end  38  until a connection is made. Once connector end  32  and corresponding connector end  38  are engaged, the remotely operated vehicle  68  can be used to again tighten tension wire clamp  94 . Disconnection of the compliant guide  22  from subsea well installation  24  can be achieved by reversing the procedure. 
         [0036]    In other applications, the remotely operated vehicle  68  is used directly in moving the compliant guide  22  into engagement with subsea well installation  24 . As illustrated in  FIG. 9 , once compliant guide  22  is deployed into proximity with subsea well installation  24 , remotely operated vehicle  68  is attached or anchored to the lower end of compliant guide  22  by an appropriate handle  100 . After attachment, remotely operated vehicle  68  can be operated to guide connector end  32  along both horizontal and vertical planes to properly position compliant guide  22  for engagement with subsea well installation  24 . This technique is useful, for example, in applications utilizing a spoolable compliant guide that is not excessively stiff or subject to excessive motion. 
         [0037]    Operation of the remotely operated vehicle  68  also can be assisted by a variety of cooperating mechanisms. For example, remotely operated vehicle  68  can be aided by a winch  102  connected between subsea well installation  24  and the remotely operated vehicle, as illustrated in  FIG. 10 . In the embodiment illustrated, winch  102  is mounted to remotely operated vehicle  68  and comprises a cable that extends to and is connected with corresponding connector end  38 . By way of example, winch  102  may be a hydraulically operated winch operated by remotely operated vehicle  68 . Thus, winch  102  is able to assist remotely operated vehicle  68  draw connector end  32  into engagement with corresponding connector end  38 . 
         [0038]    In another example, remotely operated vehicle  68  is aided by a hydraulic cylinder  104  connected between subsea well installation  24  and the remotely operated vehicle, as illustrated in  FIG. 11 . In this embodiment, hydraulic cylinder  104  comprises a cylinder and piston arrangement which cooperate to selectively expand and contract the length of the hydraulic cylinder upon the appropriate hydraulic input from remotely operated vehicle  68 . Hydraulic cylinder  104  is mounted between remotely operated vehicle  68  and corresponding connector end  38 . Thus, the hydraulic cylinder  104  can be selectively actuated to assist remotely operated vehicle  68  draw connector end  32  into engagement with corresponding connector end  38 . 
         [0039]    Another embodiment of connection system  60  is illustrated in  FIG. 12 . In this embodiment, connector end  32  of compliant guide  22  is moved toward corresponding connector end  38  of subsea well installation  24  with the assistance of a controlled buoyancy module  106 . The controlled buoyancy module  106  is installed at a lower end of compliant guide  22 , and the actual buoyancy of module  106  can be controlled by remotely operated vehicle  68  via a fluid line  108 . Fluid line  108  is used to add or remove a selected fluid able to change the buoyancy of controlled buoyancy module  106 . Following deployment of compliant guide  22  into proximity with subsea well installation  24  via, for example, clump weight  52 , the remotely operated vehicle  68  is engaged with a lower portion of compliant guide  22 , e.g. connector end  32 , via handle  100 . In this embodiment, the remotely operated vehicle  68  is used to guide connector end  32  in a horizontal plane while controlling the buoyancy of module  106  to appropriately move connector end  32  along a vertical plane until engaged with corresponding connector end  38 . The controlled buoyancy module  106  also can be used to facilitate disconnection of compliant guide  22  from subsea well installation  24 . 
         [0040]    Connection system  60  is used to facilitate engagement of compliant guides, e.g. spoolable compliant guides, with a variety of subsea well installations that can be used for intervention procedures or other procedures. The overall well system  20  and connection system  60  also can incorporate a variety of additional or alternate components depending on the specific environment and procedure undertaken. Additionally, one or more remotely operated vehicles can be utilized in connecting and disconnecting many types of components at the subsea location. The connection system and procedures also can be used with a compliant guides extending downwardly from many types of surface vessels and surface structures. 
         [0041]    Although only a few embodiments of the present invention have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of this invention. 
         [0042]    The present invention provides a method of connecting a compliant guide at a subsea location, comprising:
       deploying a compliant guide toward a subsea well installation;   mounting a winch proximate the subsea well installation;   coupling a cable between the winch and a lower end of the compliant guide; and   pulling the cable with the winch to draw the lower end into engagement with the subsea well installation.       
 
         [0047]    Preferably, said deploying step comprises deploying a spoolable compliant guide. Also, the deploying may comprise utilizing a clump weight to pull the spoolable compliant guide toward a seabed. The mounting step may comprise mounting a plurality of winches proximate the subsea well installation. The winch may be mounted on the subsea well installation or on a seabed. Coupling may comprise using a remotely operated vehicle to pick up the cable from the winch and to attach the cable to the lower end of the spoolable compliant guide. Pulling may comprise operating the winch via hydraulic power. 
         [0048]    In another embodiment of the present invention a method is provided which comprises:
       deploying a compliant guide toward a subsea well installation;   moving a connector end of the compliant guide toward a corresponding connector end of the subsea well installation by directing a discharge of fluid; and   connecting the connector end and the corresponding connector end.       
 
         [0052]    Deploying may comprise deploying a spoolable compliant guide and/or utilizing a clump weight to pull the spoolable compliant guide toward a seabed. Moving may comprise directing a flow of fluid downwardly through the spoolable compliant guide and out through a directional jet assembly to create the discharge of fluid. Alternatively, moving may comprise directing a flow of fluid downwardly through the spoolable compliant guide to power a propeller used to direct the discharge of fluid. Moving may also comprise operating a remotely operated vehicle to power a propeller to create the discharge of fluid. A remotely operated vehicle may be used to change the direction in which fluid is discharged. 
         [0053]    The inventive method may also comprise: disconnecting the connector end from the corresponding connector end; and changing the direction along which the fluid is discharged to move the connector end away from the corresponding connector end. 
         [0054]    Yet another embodiment of the present invention provides a method, comprising: 
         [0055]    connecting to tensioning wire along a compliant guide; 
         [0056]    deploying the compliant guide toward a subsea well installation; 
         [0057]    connecting the tensioning wire to the subsea installation; and 
         [0000]    using the tensioning wire to guide a lower connector end of the compliant guide into engagement with the subsea well installation. 
         [0058]    The tensioning wire may be connected to a spoolable compliant guide. The tensioning wire may be connected so a lower end of the tensioning wire extends below the spoolable compliant guide. Said connecting step may further comprise temporarily clamping the tensioning wire to the spoolable compliant guide via a tension wire clamp and tensioning the tensioning wire to cause the spoolable compliant guide to move into a compliant shape. Using the tensioning wire comprises releasing the tension wire clamp so the spoolable compliant guide straightens and moves the connector end toward the subsea well installation. Releasing may comprise using a remotely operated vehicle to release the tension wire clamp. The tensioning wire may be clamped at the tension wire clamp after engagement of the lower connector with the subsea well installation. The method as recited in claim  18 , wherein connecting comprises using a remotely operated vehicle to connect the tensioning wire to the subsea well installation. 
         [0059]    Yet another embodiment of the present invention comprises:
       deploying a compliant guide toward a subsea well installation;   coupling a remotely operated vehicle proximate a connector end of the compliant guide; and   operating the remotely operated vehicle to move the connector end into alignment with the subsea installation for connection of the connector end with the subsea installation.       
 
         [0063]    Deploying may comprise deploying a spoolable compliant guide. Also the method may further comprise assisting the remotely operated vehicle with a winch actuated by the remotely operated vehicle, the winch being connected between the subsea well installation and the remotely operated vehicle. The method further may comprise assisting the remotely operated vehicle with a cylinder actuated by the remotely operated vehicle, the cylinder being connected between the subsea well installation and the remotely operated vehicle. Alternatively, assisting the remotely operated vehicle with a controlled buoyancy module able to move the connector end vertically may also be used.