Column stabilized stinger transition segment and pipeline supporting apparatus

Abstract

The stinger segment includes a base structure having a plurality of upstanding stabilizing columns on opposite sides of its pitch and roll axes and carrying pipeline supports which permit translational movement of the pipeline relative to the stinger segment. The stinger segment is pivotably secured behind the pipelaying barge and is ballasted from a low draft condition with the base structure having freeboard to a high draft condition with the mean waterline located at about one half the effective height of the stabilizing columns when in the pipeline supporting position. The pipeline supports progressively decrease in height above the base structure from the end of the segment nearest the barge toward the opposite end such that a line extending along the supports defines a radius of curvature at least equal to and preferably much greater than the minimum allowable radius of curvature for the pipeline. The stinger segment is preferably configured such that the combined natural frequency of the segment, pipeline, and stinger match the natural frequency of the pipelaying barge. A stinger is secured to the aft end of the stinger transition segment to guide and support pipeline aft of the segment and before disposition on the sea floor. .Iadd.

What is claimed and desired to be secured by United States Letters Patent is: 
     
       1. A transition segment for laying pipeline on an underwater surface from a floating vessel having a pipeline work deck elevated above the mean waterline comprising: an elongated base structure;   a plurality of elements upstanding from said base structure with at least a number of said elements comprised of buoyant stabilizing columns located on opposite sides of the pitch and roll axes of the segment;   buoyancy control means for submerging said base structure and portions of said upstanding elements below the waterline to obtain a high draft floating condition, the displacement of the submerged base structure and portions of said upstanding elements being sufficient to maintain the segment buoyant in a pipeline portion supporting condition with the mean waterline located intermediate the height of said columns;   means carried by said segment adjacent its forward end for pivotally coupling the latter to the pipelaying vessel;   and means carried by said segment for supporting a portion of a pipeline for translational movement therealong, said pipeline support means being located above said base structure at elevations of decreasing height relative to said base structure in a forward to aft direction along said segment, the pipeline support means being adapted to receive pipeline payed out from the elevated work deck of the pipelaying vessel.   
     
     
       2. Apparatus according to claim 1 together with a stinger, means carried by said stinger adjacent its forward end for pivotally coupling said stinger to said segment, and means carried by said stinger for receiving the pipeline payed out from the vessel and said segment. 
     
     
       3. Apparatus according to claim 1 including said vessel, said coupling means pivotally coupling the forward end of said segment to the aft end of said vessel. 
     
     
       4. Apparatus according to claim 2 wherein said submerging means includes means for ballasting and deballasting said segment, and control means carried by said vessel for selectively ballasting and deballasting said segment. 
     
     
       5. Apparatus according to claim 3 including a stinger, means for coupling said stinger to the opposite end of said segment, and means carried by said stinger for receiving the pipeline payed out from said vessel and said segment. 
     
     
       6. Apparatus according to claim 1 including means for varying the submergence of the segment in the high draft condition. 
     
     
       7. Apparatus according to claim 1 wherein said stabilizing columns have a substantially uniform cross sectional area throughout their effective height, the cross sectional area and configuration of the columns, the weight distribution of the segment and the geometry of the submerged base structure being such as to provide segment motion minimizing characteristics in the pipeline portion supporting high draft condition. 
     
     
       8. Apparatus according to claim 1 wherein said base structure includes a pair of elongated transversely spaced hull members, at least a pair of said columns being carried by each of said members, and means connecting said members one to the other. 
     
     
       9. Apparatus according to claim 8 wherein said submerging means includes means for selectively ballasting and deballasting said base structure. 
     
     
       10. Apparatus according to claim 8 wherein said hull members include a plurality of compartments, valve means associated with said compartments for introducing water ballast into and expelling water ballast from said compartments. 
     
     
       11. Apparatus according to claim 1 wherein said support means progressively decreases in height above the base structure from the end of the segment nearest the vessel toward the opposite end of the segment such that a line extending along said support means has a radius of curvature at least equal to the minimum allowable radius of curvature of the pipeline portion. 
     
     
       12. Apparatus according to claim 11 wherein said support means comprises a plurality of rollers disposed at longitudinally spaced positions along said segment and lying substantially coincident with the longitudinal centerline of the segment. 
     
     
       13. Apparatus according to claim 12 wherein said base structure includes a pair of elongated transversely spaced hull members, at least a pair of said columns being carried by each of said members, a plurality of support struts extending between laterally adjacent columns, said rollers being disposed on said support struts. 
     
     
       14. Apparatus according to claim 3 wherein said vessel includes a plurality of columns upstanding from a hull structure whereby said vessel is column stabilized in a high draft condition. 
     
     
       15. Apparatus according to claim 1 wherein said base structure includes a pair of elongated transversely spaced hull members, at least a pair of said columns being carried by each of said members, said base structure having sufficient displacement to float the segment in a low draft condition with the base structure having freeboard, said submerging means including means for ballasting said hull members to change the draft of the segment from said low draft condition to said high draft condition. 
     
     
       16. Apparatus for laying pipelines on an underwater surface comprising: a floating vessel having a pipeline work deck elevated above the mean waterline;   a transition segment having an elongated base structure;   a plurality of elements upstanding from said base structure with at least a number of said elements comprised of buoyant stabilizing columns located on opposite sides of the pitch and roll axes of said segment;   means carried by said segment for supporting a portion of a pipeline for translational movement therealong and adapted to receive pipeline payed out from the elevated work deck of the pipelaying vessel;   means for ballasting and deballasting said segment to selectively obtain high and low draft floating conditions with said base structure and portions of said upstanding elements located below the waterline in the high draft condition, the displacement of the submerged base structure and portions of said upstanding elements being sufficient to maintain the segment buoyant in the high draft pipeline portion supporting condition with the mean waterline located intermediate the height of said columns;   means for pivotally coupling the forward end of said segment to the aft end of said vessel;   and buoyancy control means carried by said vessel for selectivey ballasting and deballasting said segment.   
     
     
       17. Apparatus according to claim 16 together with a stinger, means carried by said stinger adjacent its forward end for pivotally coupling said stinger to said segment, and means carried by said stinger for receiving the pipeline payed out from the vessel and said segment. 
     
     
       18. A transition segment for laying pipelines on an underwater surface from a floating vessel having a pipeline work deck elevated above the mean waterline comprising: an elongated base structure;   a plurality of elements upstanding from said base structure with at least a number of said elements including buoyant stabilizing columns located on opposite sides of the pitch and roll axes of the segment;   said stabilizing columns extending above said base structure a predetermined height;   said segment having a displacement sufficient to locate said base structure and portions of said upstanding elements below the waterline with the mean waterline located above the base structure intermediate the height of said stabilizing columns;   the cross sectional area and configuration of the columns, the weight distribution of the segment and the geometry of the submerged base structure being such as to provide segment motion minimizing characteristics in the pipeline portion supporting condition;   means carried by the base structure for pivotally coupling the segment to the pipelaying vessel;   and means carried by said segment for supporting a portion of a pipeline for translational movement therealong, said pipeline support means being located above said base structure at elevations of decreasing height relative to said base structure in a forward to aft direction along said segment, the pipeline support means being adapted to receive pipeline payed out from the elevated work deck of the pipelaying vessel.   
     
     
       19. Apparatus according to claim 18 including means for varying the draft of the segment in the pipeline supporting condition. 
     
     
       20. Apparatus according to claim 18 wherein said stabilizing columns have a substantially uniform cross sectional area throughout their height. 
     
     
       21. Apparatus according to claim 18 wherein said base structure includes a pair of elongated transversely spaced hull members, at least a pair of said columns being carried by each of said members, and means connecting said members one to the other. 
     
     
       22. Apparatus according to claim 18 together with a stinger, means carried by said stinger adjacent its forward end for pivotally coupling said stinger to said segment, and means carried by said stinger for receiving the pipeline payed out from the vessel and said segment. 
     
     
       23. Apparatus according to claim 18 including said vessel, said coupling means pivotally coupling the forward end of said segment to the aft end of said vessel. 
     
     
       24. Apparatus according to claim 23 including a stinger, means for coupling said stinger to the opposite end of said segment, and means carried by said stinger for receiving the pipeline payed out from said vessel and said segment. 
     
     
       25. A transition segment for laying pipelines on an underwater surface from a floating vessel having a pipeline work deck elevated above the mean waterline comprising: an elongated base structure comprised of a pair of transversely spaced hull members and an elongated keel spaced below said hull members, means connecting said hull members and said keel each to the other;   a plurality of elements upstanding from said base structure with at least a number of said elements including buoyant stabilizing columns located on opposite sides of the pitch and roll axes of the segment, at least a pair of said columns being carried by each of said hull members;   said stabilizing columns extending above said base structure a predetermined height;   said segment having a displacement sufficient to locate said base structure and portions of said upstanding elements below the waterline with the mean waterline located above the base structure intermediate the height of said stabilizing columns;   means carried by the base structure for pivotally coupling the segment to the pipelaying vessel;   and means carried by said segment for supporting a potion of a pipeline for translational movement therealong, said pipeline support means being located above said base structure at elevations of decreasing height relative to said base structure in a forward to aft direction along said segment, the pipeline support means being adapted to receive pipeline payed out from the elevated work deck of the pipelaying vessel.   
     
     
       26. Apparatus according to claim 25 wherein said hull members, keel and connecting means define a generally open framework, said hull members and said keel being arranged in a generally triangular configuration in a plane generally normal to the longitudinal centerline of the segment. 
     
     
       27. Apparatus according to claim 1 wherein said base structure includes a pair of elongated transversely spaced hull members and a keel, at least a pair of said columns being carried by each of said members, means connecting said hull members and said keel each to the other and defining a generally open framework, said hull members and said keel being arranged in a generally triangular configuration in a plane generally normal to the longitudinal centerline of the segment. 
     
     
       28. Apparatus according to claim 2 wherein said stinger comprises a plurality of articulated stinger segments. 
     
     
       29. Apparatus according to claim 17 wherein said stinger comprises a plurality of articulated stinger segments. 
     
     
       30. Apparatus according to claim 23 wherein said vessel has a longitudinal centerline, said segment having a longitudinal centerline laterally offset from the vessel centerline when said vessel and segment are coupled one to the other. 
     
     
       31. Apparatus according to claim 3 wherein said vessel includes a base structure; a working platform;   a plurality of elements upstanding from the base structure of said vessel with at least one portion of said elements being connected to said platform to support the platform in spaced relation above said base structure;   at least a portion of the upstanding elements of said vessel including at least six stabilizing columns disposed on the base structure of said vessel and upstanding therefrom a predetermined height, a pair of the columns of said vessel being located adjacent opposite ends of said base structure on opposite sides of the pitch axis of said vessel, at least three columns of the vessel being located on opposite sides of the roll axis of the vessel;   the base structure of said vessel having a displacement sufficient to float the vessel in a low draft condition;   means for ballasting and deballasting the vessel to respectively submerge its base structure and portions of its elements below said platform below the waterline thereby to provide a high draft, otherwise unsupported, floating condition and return the vessel to the low draft condition;   the displacement of the submerged base structure and portions of said elements of said vessel being sufficient to maintain the vessel buoyant in the high draft floating condition; the combined water plane areas of the columns of said vessel forming at least the major portion of the total water plane area of said vessel in the high draft condition; the cross-sectional area and configuration of the columns of said vessel, the weight distribution of the vessel, and the geometry of the submerged base structure and portions of said elements of said vessel being such that the vessel obtains motion minimizing characteristics in the high draft condition;   and means carried by the vessel for conducting pipelaying operations while the vessel is maintained in the high draft floating condition. .Iadd. 32. Apparatus for laying pipe on an underwater surface comprising:   a floating vessel including a pair of elongated hulls disposed in spaced side-by-side relation;   a working platform including a pipeline workdeck spaced above said hulls a predetermined height;   means for supporting said platform in fixed spaced relation above said hulls including columns connected to said hulls and said platform, at least three of such columns being connected with each of the hulls on opposite sides of the roll axis of the vessel with pairs of such columns being located near opposite ends of each of said hulls on opposite sides of the pitch axis of the vessel and another of said columns being located at an intermediate position on each hull;   the distance between the extremities of said vessel along its longitudinal centerline being substantially greater than the distance between the extremities of said vessel along its transverse centerline;   said hulls having ballast compartments for ballasting said vessel to alter its draft between a low draft hull supported floating condition and a high draft semisubmerged column stabilized floating condition with said pipeline workdeck elevated above the mean waterline a distance at least about fifteen feet;   said columns having predetermined cross-sectional areas and being located on the hulls to provide righting moments about the pitch and roll axes of said vessel when in high draft condition; the centroid of the cross-sectional area of each of said columns lying transversely outboard the centerline of the hull to which said column is connected;   means including an elongated segment adjacent one end of said vessel and extending generally longitudinally therefrom for supporting at least the portion of the pipeline payed out from said elevated pipeline workdeck which extends through the air between said one vessel end and a location spaced from said vessel at which the pipeline enters the water;   means carried by said segment and said vessel for pivotally connecting said support segment to said vessel, said support segment including means for maintaining the radius of curvature of the pipeline greater than the radius of curvature which would permit bending stresses on the pipeline in   
     
     
        excess of its allowable bending stress. .Iaddend. .Iadd. 33.  Apparatus according to claim 32 wherein said elevated pipeline workdeck extends longitudinally substantially along one side of the centerline of said vessel, said pipeline support means extending longitudinally from said one end of the vessel and from said one side of the vessel. .Iaddend..Iadd. 34. Apparatus according to claim 32 wherein said pivotal connecting means includes a pivotal connection between said vessel and said support segment carried by at least one of said hulls. .Iaddend. .Iadd. 35. Apparatus according to claim 32 wherein at least one of said columns on each said hull has a longitudinal dimension in the direction of the longitudinal centerline of said vessel greater than its transverse dimension. .Iaddend. .Iadd. 36. A column stabilized semisubmersible pipelaying barge and pipeline support apparatus comprising: a pair of elongated hulls disposed in spaced side-by-side relation;   a working platform spaced above said hulls a predetermined height including a pipeline work deck on which pipe sections can be secured in end-to-end relation one to the other to form a pipeline longitudinally extending generally in the direction of the longitudinal centerline of said barge;   means for supporting said platform in spaced relation above said hulls including at least three columns connected to each of said hulls and said platform on opposite sides of the barge roll axis, with pairs of columns disposed on opposite sides of the barge pitch axis and located near opposite ends of the barge;   the distance between the extremities of said barge along the longitudinal centerline thereof being substantially greater than the distance between the extremities of said barge along its transverse centerline;   said hulls having ballast compartments for ballasting said barge to alter its draft between a low draft hull supported floating condition with the hulls having freeboard and a high draft semisubmerged column stabilized floating and pipelaying condition with the pipeline work deck elevated a substantial distance above the mean waterline, so that pipeline payed out from said elevated pipeline work deck when said barge lies in said high draft condition curves downwardly toward the water as it extends through the air between said elevated pipeline work deck and a location at which the pipeline enters the water,   said columns having predetermined cross-sectional areas and being located on the hulls to provide righting moments about the pitch and roll axes of said barge when in said high draft condition;   pipeline support means connected to said barge and extending generally longitudinally of the barge and in a predetermined attitude relative to said barge work deck for supporting at least the downwardly curved portion of the pipeline payed out from said elevated work deck which extends through the air between said barge and the location at which the pipeline enters the water, and   means for maintaining said pipeline support in said predetermined attitude relative to said barge thereby to maintain the radius of curvature of the downwardly curved pipeline portion greater than the radius of curvature which would permit bending stresses on the pipeline in excess of its   
     
     
        allowable bending stress. .Iaddend. .Iadd. 37.  Apparatus according to claim 36 wherein: each of said hulls has top and bottom substantially planar horizontally disposed surfaces extending substantially perpendicular to a vertical plane through the longitudinal centerline of said vessel with the transverse horizontal dimension of each hull being greater than its vertical dimension for a major portion of the length of said hulls; said columns are substantially constant in cross section for substantially their entire effective height between said platform and said hulls; and said work deck is located at an elevation at least 15 feet above the mean waterline when said barge lies in said high draft column stabilized pipelaying condition. .Iaddend..Iadd. 38. Apparatus according to claim 37, wherein said columns have their centroids located transversely outboard of the centerline of the hull to which said column is connected. .Iaddend..Iadd. 39. Apparatus according to claim 38, wherein each of said columns on each said hull has a dimension in the longitudinal direction greater than its dimension in the transverse direction. .Iaddend..Iadd. 40. Apparatus according to claim 37, wherein said means for maintaining said pipeline support include a plurality of discrete supports longitudinally spaced one from the other along said pipeline support and arranged such that a curved line through successive ones of said supports has a radius of curvature greater than the radius of curvature which would permit bending stresses on the pipeline in excess of its allowable bending stress. .Iaddend. .Iadd. 41. Apparatus according to claim 37 wherein said pipeline support is pivotally connected to the stern of said barge at an elevation below said work deck. .Iaddend..Iadd. 42. Apparatus according to claim 37 wherein said pivotal connection lies at an elevation below the elevation of said top hull surfaces. .Iaddend..Iadd. 43. Apparatus according to claim 36 wherein said pipeline work deck is generally horizontally disposed; and said work deck and said columns are relatively disposed such that pipeline is payed out from said pipeline work deck at an elevation no lower than the juncture of the upper ends of the columns and the underside of said platform. .Iaddend..Iadd. 44. Apparatus according to claim 36 wherein: one pair of said columns is disposed near the aft end of said vessel; said work deck and said columns are relatively disposed such that pipeline is payed out from said pipeline work deck and from the aft end of said vessel at an elevation no lower than the juncture of the upper ends of the aftmost columns on said hulls and the underside of said platform; said pipeline support being pivotally connected to said barge adjacent its aft end and extending generally longitudinally therefrom for supporting at least the downwardly curved portion of the pipeline payed out from said elevated pipeline work deck and the aft end of said vessel which extends through the air between said barge and the location at which the pipeline enters the water. .Iaddend. .Iadd. 45. Apparatus according to claim 36 including means for adjusting the elevation of said pipeline support means relative to said work deck. .Iaddend..Iadd. 46. Apparatus according to claim 36 including means for adjusting the elevation of said pipeline support means relative to the mean waterline. .Iaddend.