Abstract:
A template for use in positioning subsea wellbores that has a drop away funnel that extends laterally from the template. The drop away funnel is used to locate a piling adjacent the wellbores and is selectively detached from the template after installing the piling. A tang and clevis type assembly mounts the drop away funnel to the template, where the tang and clevis are coupled together with a main stud. The main stud is oriented substantially parallel with an axis of the drop away funnel; so that when the stud is removed, the drop away funnel can decouple from the template and slide axially downward along the piling.

Description:
BACKGROUND 
     1. Field of Invention 
     The invention relates generally to method and apparatus for forming a subsea wellbore. More specifically, the invention relates to forming a piling bore and a wellbore at respective designated locations subsea. 
     2. Description of Prior Art 
     Subsea drilling templates are sometimes located on the sea floor for drilling a cluster of wellbores in a confined area. Subsea drilling templates typically have a number of receptacles, also referred to as funnels, through which a well will be drilled. Using a floating drilling vessel, the operator may drill each well, cap it, then move to another. At a later date, a platform is generally installed over the template and a tie-back is installed between the wells and platform. Production tubing is then generally connected from the well to production trees installed at the platform. 
     SUMMARY OF THE INVENTION 
     Provided herein is an example of a template for use in forming a wellbore in a seafloor. In an example the template is made up of a frame, an annular wellbore alignment funnel coupled with the frame, an annular piling funnel substantially coplanar with the wellbore alignment funnel, and a coupling. The coupling of this embodiment is defined by an overlap between a portion of the frame and the piling funnel. A bore is in the overlap adapted to receive a main stud, so that when the main stud is selectively engaged in the bore, the piling funnel is coupled to the frame, and when the main stud is removed from the bore, the piling funnel is decoupled from the frame. Optionally, the portion of the frame overlapping the piling funnel is an elongated tang member and the portion of the piling funnel overlapped by the frame is a clevis member with a recess adapted to receive the tang member therein. The template may further have sidewalls on the clevis at lateral ends of the recess that extend along elongate sides of the tang member and may include vertical slots in the sidewalls. Alignment members are optionally included that extend laterally from elongate sides of the tang and project through the slots when the tang member is in the recess. The alignment members may be positioned to provide a contact force against the slot as long as the main stud is engaged in the bore. A cup may optionally be included that is on an upper end of the main stud adapted for engagement from a remotely operated vehicle. The piling funnel may in one example be a first piling funnel and the coupling can be a first coupling; in this example the template further includes a second piling funnel substantially coplanar with the wellbore alignment funnel and a second coupling defined by an overlap between a portion of the frame and the second piling funnel, a bore in the overlap, and a main stud, so that when the main stud is selectively engaged in the bore, the second piling funnel is coupled to the frame, and when the main stud is removed from the bore, the second piling funnel is decoupled from the frame. Alternatively, when a piling is inserted through an axial opening in the piling funnel and into the seafloor, and the piling funnel is decoupled from the frame, the piling funnel drops to the seafloor and beneath the frame. 
     Also described herein is a method of subsea operations. In the example method provided on a seafloor is a drilling template having a wellbore alignment funnel and a piling alignment funnel mounted in a frame. A drill bit is inserted through the wellbore alignment funnel, a wellbore is drilled, and a piling is inserted through the piling alignment funnel. The piling alignment funnel is decoupled from the frame. In the example method, the piling alignment may be lowered to the seafloor. Further, a platform above a surface of the sea can be set over the wellbore, where the piling is used to align the platform at a designated location. The method can further optionally include coupling the piling alignment funnel to the frame by a main stud that is engaged in a bore that intersects the piling alignment funnel and the frame, wherein the piling alignment is substantially parallel with an axis of the piling alignment funnel, and wherein the step of decoupling the piling alignment from the frame comprises disengaging the main stud from within the bore. In one example, the piling alignment funnel is decoupled from the frame while the piling remains inserted in the piling as the piling alignment funnel is dropped to the sea floor. In one example, horizontal alignment of the piling alignment funnel is maintained during the step of decoupling the piling alignment funnel from the frame thereby shielding the main stud from moment forces. Optionally, an alignment element is mounted onto the frame that slides within a vertically formed slot on the piling alignment funnel and maintains the horizontal alignment of the piling alignment funnel. 
     In another example embodiment, a template for use in forming bores on a seafloor is disclosed herein. In this example the template includes a frame on the seafloor, wellbore alignment funnels mounted to the frame, a piling alignment funnel, a means for selectively coupling the piling alignment funnel to the frame, and a means for retaining the piling alignment funnel in a plane that is substantially parallel with a plane in which the wellbore alignment funnels are disposed when the piling alignment funnel is coupled to the frame and when being decoupled from the frame. In this example, the means for selectively coupling the piling alignment funnel to the frame comprises a main stud that engages a threaded bore that vertically extends through a portion of the frame and a portion of the piling alignment funnel. Optionally, the portion of the frame is a tang member and the portion of the piling alignment funnel is a clevis member. In an alternate embodiment, the means for retaining the piling alignment funnel in a plane can be an alignment member on a lateral side of the frame that slides within a vertical slot provided on the piling alignment funnel. 
    
    
     
       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 perspective view of an example embodiment of a drilling template in accordance with the present invention. 
         FIG. 2  is a side view of an example of drilling a wellbore through the template of  FIG. 1  in accordance with the present invention. 
         FIG. 3  is a side partial sectional view of wellbores formed using the template of  FIG. 1  in accordance with the present invention. 
         FIG. 4  is a perspective view of a drop away funnel in accordance with the present invention. 
         FIG. 5  is a side sectional view of a coupling for an embodiment of the drop away funnel of  FIG. 4  in accordance with the present invention. 
         FIG. 6  is a perspective view of an embodiment of the drop away funnel of  FIG. 4  with a piling inserted therein in accordance with the present invention. 
         FIG. 7  is a side view of a platform positioned on the seafloor using an embodiment of the piling of  FIG. 5  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. Accordingly, the improvements herein described are therefore to be limited only by the scope of the appended claims. 
     An example of a template  20  for aligning bores on a sea floor is shown in a perspective view in  FIG. 1 . The template  20  of  FIG. 1  includes a series of annular wellbore alignment funnels  22  shown in a substantially coplanar arrangement and connected to one another by a series of elongate frame members  24 . In the example of  FIG. 1 , the frame members  24  define a frame  26 . In one example, the frame members  24  are structural members, such as I-beams, T-beams, channel members, and the like and can also be hollow and have a circular or rectangular cross section. In an example, the funnels  22  have a conical upward surface to define an upward-facing flange. A piling alignment funnel  28  is also shown in the example of  FIG. 1  and mounted on an end of the frame  26 . 
       FIG. 2  shows in a side view an example of the template  20  having been landed on a wellhead  29  set in the sea floor  30 . Also shown is a drill string  32  being lowered towards the template  20  for forming a wellbore through the sea floor  30 . Optionally, a drilling vessel (not shown) may be used for providing the rotating drill string  32 . An annular collar  34  is optionally shown disposed within one of the funnels  22  and extending vertically upward from an upper end of the funnel  22  and for receiving a lower end of the drill string  32  therein. Referring now to  FIG. 3 , illustrated in a side partial sectional view are wellbores  36  (in dashed outline) that extend from the sea floor  30  downward into a formation below the template  20 A. In  FIG. 3 , the example of the template  20 A is shown having a second piling arrangement funnel  28   2  in addition to a first piling alignment funnel  28   1 . Similarly, piling bores  38   1 ,  38   2  are shown formed in the formation  39  below the sea floor  30  and registering with the respective piling alignment funnels  28   1 ,  28   2 . In one example of operation, after the piling bores  38   1 ,  38   2  are formed, pilings  40   1 ,  40   2  are inserted within the bores  38   1 ,  38   2 . 
       FIG. 4  is a perspective view of an example of a coupling  42  that selectively mounts the piling alignment funnel  28  onto the frame  26 . In  FIG. 4 , the example of the coupling  42  includes a tang member  44 ; which as shown extends from the frame  26 . The example tang member  44  is depicted engaging a clevis member  46  illustrated mounted on an end of the piling alignment funnel  28 . The example of the tang member  44  of  FIG. 4  is generally elongate and includes generally parallel planar members that define opposing lateral sides of the tang member  44 . Further shown in the examiner of  FIG. 2  are set screw  48  that project outward from an outer surface of each of the lateral sides. Slots  50  are shown vertically oriented along outer lateral sides of the clevis member  46  and in the example of  FIG. 4 , formed to receive the set screws  48  therein. In an example embodiment, the set screws  48  are within the slots  50  when the piling alignment funnel  28  is engaged with the frame  26 . Also shown in  FIG. 4  are horizontally disposed support ribs  54  that connect on one end to a lateral side of the clevis member  46  and extend partially around an outer circumference of the piling alignment funnel  28 . Also a cup  52  is shown mounted on an upper side of the tang member  44  and as will be described in further detail below is useful for disengaging the piling alignment funnel  28  from the frame  26 . 
       FIG. 5  is a side sectional view of an example of disengaging the coupling  42  so that the piling alignment funnel  28  may be decoupled from and lowered away from the frame  26 . As shown, a forward portion of the tang member  44  is profiled to have a reduced height proximate its terminal end that defines a downwardly-facing shoulder  56 . The profiled end of the tang member  44  fits within a recess  58  formed on an outer end of the clevis member  46  so that the shoulder  56  lands on an upward facing surface defined by a bottom of the recess  58 . The outer terminal ends of the recess  58  extend outward proximate to an outer lateral surface of the clevis member  46  and define side walls  60  in which the vertical slots  50  are formed. A main stud  62  is shown vertically intersecting the tang member  44  and in the example of  FIG. 5  has a threaded portion on its lower end. The threaded portion engages a threaded bore  64  shown extending through a lower surface of the recess  58  in the clevis member  46 . Further illustrated in the example embodiment of  FIG. 5  is that an upper end of the main stud  62  couples with the cup  52  such that engaging and rotating the cup  52  can selectively engage and disengage the main stud  62  from the bore  64 . In the example of  FIG. 5 , the main stud  62  has been rotated out of engagement with the bore  64  so that the clevis member  46  can be vertically moved downward and away from the tang member  44 , thereby allowing disengagement of the piling alignment funnel  28  with the frame  26 . 
       FIG. 6  illustrates an example embodiment of the piling alignment funnel  28  vertically dropping away from the frame  26  in a side perspective view. In this example moment forces M F  are exerted to the coupling  42  from the weight of the piling alignment funnel  28 . The moment forces M F  may fluctuate during operations as contact with the piling  40  may cause the alignment funnel  28  to tilt with respect to the piling  40 . The engagement of the slots  50  and set screws  48  largely absorb the moment forces M F  thereby shielding the main stud  62  from what can be damaging bending moments from the weight of the piling alignment funnel  28 . Moreover, strategic positioning of the set screws  48  and slots  50  shields the main stud  62  from the bending moments during disengagement of the piling alignment funnel  28  from the frame  26 . In an example, the set screws  48  and slot  50  are positioned so that the set screws  48  maintain contact with the slot  50  until a lowermost threaded portion of the main stud  62  has disengaged from an uppermost threaded portion of the threaded bore  64 . Still referring to  FIG. 6 , the piling  40  is shown inserted within the piling alignment funnel  28  such that disengaging the piling alignment funnel  28  from the frame  26  allows the piling alignment funnel  28  to slide axially downward while still circumscribing the piling  40 . 
       FIG. 7  shows a side view of an example of a fixed platform  66  that shown having legs  68  whose lower ends are in contact with the sea floor  30 . Alignment tubulars  70   1 ,  70   2  are shown coupled with the legs  68  that in the example of  FIG. 7  are provided for positioning the platform  66  in a designated location and/or orientation with respect to the wellbores  36 . In the example of  FIG. 7 , the alignment tubulars  70   1 ,  70   2  engage the strategically positioned the pilings  40   1 ,  40   2  to dispose the platform  66  at the designated location. Although the piling alignment funnels  28   1 ,  28   2  are shown on distal ends of the template  20 A, the piling alignment funnels  28   1 ,  28   2  may be disposed from the same or adjacent the sides of the template  20 A. Wellhead assemblies  72  are shown provided on an upper end of the platform  66  and that are in fluid communication with the wellbores  30  via risers  74  that extend from the wellbores  30  and up to the wellhead assemblies  72 . An advantage of disengaging the piling alignment funnels  28   1 ,  28   2  from the rest of the template  20 A is that when the platform  66  is deployed, in the unintended axial forces transferred to the pilings  40   1 ,  40   2  will not be transferred to the template  20 A and/or the risers  74 . As such, potential damage to the template  20 ,  20 A and wellhead assemblies can be prevented by the optional step of decoupling the piling alignment funnels  28   1 ,  28   2  from the rest of the template  20 ,  20 A. 
     Still referring to  FIG. 7 , an example of a remotely operated vehicle (ROV)  76  is schematically illustrated, wherein the ROV  76  includes mechanical arms  78  for performing functions subsea. A control line  80  may be used for control commands that can in turn direct the ROV  76  subsea so the ROV  76  may manipulate the cup  52  ( FIG. 5 ) and for enabling a remote and subsea decoupling of the piling alignment funnels  28   1 ,  28   2  from the template  20 A. It necessarily follows that the ROV  76  can be used to decouple funnel  28  from template  20  of  FIG. 1 . One of the advantages of the engagement of the main stud  62  is that disengaging the main stud from the threaded bore  64  can be accomplished with a lower torque than that might otherwise be required for couplings that exert an axial and a torsional force to retain the piling alignment funnels  28  to the frame  26 . 
     In one example of operation, an embodiment of the template  20  of  FIG. 2  or template  20 A of  FIG. 3  is set at a location on the seafloor  30  and a drill string  32  is used to form wellbores  36  into the seafloor  30  beneath the template  20 ,  20 A as well as bores  38 ,  38   1 ,  38   2 , for insertion of pilings  40 ,  40   1 ,  40   2 . An ROV  76  can be deployed subsea for manipulating the coupling(s)  42  that releasably fasten the piling alignment funnel(s)  28 ,  28   1 ,  28   2  to the template(s)  20 ,  20 A. As discussed above, unscrewing the main stud  62  allows the piling alignment funnel(s)  28 ,  28   1 ,  28   2  to vertically drop down from the template(s)  20 ,  20 A and decouple the template(s)  20 ,  20 A from the pilings  40 ,  40   1 ,  40   2 . As such, subsea deployment of the platform  66  can take place with reduced risk of damage to the template(s)  20 ,  20 A or any other hardware that may be coupled with the template(s)  20 ,  20 A. If the platform impacts the piling while the funnel is attached to the template, the impact can transfer through the funnel and damage the template or misalign the templates and interfere with tieback to the rig once in position. Thus an advantage exists by detaching the funnel from the template. 
     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.