Self-supported drilling riser
First Claim
1. A riser pipe assembly for use in drilling a well into a submerged bottom from a floating vessel, comprising:
- a riser pipe extending between said vessel and said well, said riser pipe having an upper section and a lower section;
connector means for releasably connecting the lower section of said riser to the upper section of said riser;
buoyancy means attached to the lower section of said riser having sufficient buoyancy to make the lower section of said riser positively buoyant;
cable means extending between said submerged bottom and the upper end of said lower section of said riser pipe;
means for fastening said cable means to said riser pipe near the upper end of the lower section thereof to restrain vertical movement of said riser pipe relative to said cable means;
lateral restraint means attached to the lower section of said riser pipe at spaced intervals along the length thereof and coupling said riser pipe to said cable means to restrain lateral movement of said riser pipe relative to said cable means.
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Accused Products
Abstract
Apparatus and method for drilling a well into a submerged bottom from a floating drilling vessel while employing a riser pipe having positive buoyancy is disclosed. The riser pipe extends between the vessel and the well and is comprised of an upper and a lower section. Means are connected to the lower section for imparting a buoyant force to it of sufficient magnitude to render it positively buoyant. Means are provided extending between the submerged bottom and the upper end of the positively buoyant riser section for restraining the lower section against upward movement. The upper section of the riser pipe may be disconnected from the lower section so that the vessel may abandon the well site. The lower riser section is left self-standing, connected to the wellhead.
65 Citations
14 Claims
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1. A riser pipe assembly for use in drilling a well into a submerged bottom from a floating vessel, comprising:
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a riser pipe extending between said vessel and said well, said riser pipe having an upper section and a lower section; connector means for releasably connecting the lower section of said riser to the upper section of said riser; buoyancy means attached to the lower section of said riser having sufficient buoyancy to make the lower section of said riser positively buoyant; cable means extending between said submerged bottom and the upper end of said lower section of said riser pipe; means for fastening said cable means to said riser pipe near the upper end of the lower section thereof to restrain vertical movement of said riser pipe relative to said cable means; lateral restraint means attached to the lower section of said riser pipe at spaced intervals along the length thereof and coupling said riser pipe to said cable means to restrain lateral movement of said riser pipe relative to said cable means. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. In a riser pipe assembly for use in drilling a well into a submerged bottom from a floating vessel, the improvement comprising:
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a riser pipe extending between said vessel and said submerged bottom; buoyancy means connected to a span of said riser pipe;
said buoyancy means imparting a sufficient buoyant force to said span of riser pipe to render it positively buoyant;cable means fastened to the submerged bottom and to said riser pipe above said span of said riser pipe to restrain said span of riser pipe against upward movement; lateral restraint means connected to said riser pipe at spaced-apart locations along the length thereof, said lateral restraint means coupling said riser pipe to said cable means to restrain said riser pipe against lateral movement relative to said cable means.
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9. In a method for installing a riser pipe between an underwater well and a surface vessel, the improvement comprising:
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interconnecting the lower section and the upper section of the riser pipe with a connector that can be selectively parted so that the upper section of the riser can be removed from the drilling location, leaving the lower section in place; supporting the lower section of the riser pipe with buoyancy means disposed along the length thereof, said buoyancy means making the lower section of said riser pipe positively buoyant; restraining said lower section of said riser pipe against upward movement by means of at least one elongated tension member connected between the location of the underwater well and the upper end of said lower section of said riser pipe; restraining said lower section of said riser pipe against lateral movement relative to said elongated tension member by means connected to said lower section of said riser pipe at spaced apart locations along the length thereof and coupling said riser pipe to said elongated tension member. - View Dependent Claims (10, 11)
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12. A method for installing a riser pipe between a surface vessel and a well on a submerged bottom, comprising:
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interconnecting the lower section of said riser pipe with the upper section of said riser pipe by means of a connector that can be selectively parted to separate said upper section from said lower section; installing a shear ram in said riser pipe near said connector; connecting a frame member to the upper end of the lower section of said riser pipe, said frame member having holes to slidingly receive a plurality of restraint cables; connecting said restraint cables to said well on a submerged bottom, said cables extending from said well to said surface vessel; guiding said riser pipe to said well utilizing said restraint cables and connecting said riser pipe to a wellhead positioned atop said well; supporting the lower section of the riser pipe with buoyancy means disposed along the length thereof, said buoyancy means making the lower section of said riser pipe positively buoyant; securing said restraint cables to said frame to restrain the lower section of said riser pipe from vertical movement; and applying substantially constant tension to said riser pipe at said surface vessel to maintain the upper section of said riser pipe in tension. - View Dependent Claims (13, 14)
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Specification