Mudline riser-casing connecting assembly

Abstract

A mudline riser-casing connecting assembly for an underwater well, where the mudline riser-casing connecting assembly comprises a bore hole conductor casing adapted to be fixed in a bore hole in the mudline and terminating at its upper end at or in the region of the mudline and which is adapted to support a fluid conveying riser and well bore casing, the assembly further comprising an annular landing shoulder on the inner face of the bore hole conductor casing at a position spaced downwardly from the upper end of the bore hole conductor casing and an annular hanger assembly adapted to be mounted to the upper end of the well bore casing, the annular hanger assembly being engagable with the landing shoulder to support the well bore casing from the landing shoulder, the mudline riser-casing connecting assembly further comprising a connector adapted at one end to be connected with the hanger assembly and adapted to be connected at the other end to the lower end of the riser, the connector being capable of selective engagement and disengagement with the hanger, the connector being supported in the bore hole conductor casing in the region of the upper end of the bore hole conductor casing through a support assembly to prevent radial movement of the connector within the bore hole conductor casing, the upper end of the connector extending above the support assembly and including a stress joint which is adapted to be fixed to the lower end of the riser, the stress joint being adapted to accommodate the stress arising from the movement of the lower end of the riser relative to that part of the mudline riser-casing connecting assembly within the bore hole conductor casing.

The claims defining the invention are as follows:  
     
         1 . A mudline riser-casing connecting assembly for an underwater well, said mudline riser-casing connecting assembly comprising a bore hole conductor casing adapted to be fixed in a bore hole in the mudline and terminating at its upper end at or in the region of the mudline and adapted to support a fluid conveying riser and well bore casing, the assembly further comprising an annular landing shoulder on the inner face of the bore hole conductor casing at a position spaced downwardly from the upper end of the bore hole conductor casing and an annular hanger assembly adapted to be mounted to the upper end of the well bore casing, said annular hanger assembly being engagable with the landing shoulder to support the well bore casing from the landing shoulder, the mudline riser-casing connecting assembly further comprising a connector adapted at one end to be connected with the hanger assembly and adapted to be connected at the other end to the lower end of the riser, the connector being capable of selective engagement and disengagement with the hanger, said connector being supported in the bore hole conductor casing in the region of the upper end of the bore hole conductor casing through a support assembly to prevent radial movement of the connector within the bore hole conductor casing, the upper end of the connector extending above the support assembly and including a stress joint which is adapted to be fixed to the lower end of the riser, said stress joint being adapted to accommodate the stress arising from the movement of the lower end of the riser relative to that part of the mudline riser-casing connecting assembly within the bore hole conductor casing.  
     
     
         2 . A mudline riser-casing connecting assembly as claimed at  claim 1  wherein, said connector comprises a first portion extending between the hanger and the upper end of the bore hole conductor, said support assembly comprising an annular support provided at the upper end of the first portion and receivable in the upper end of the bore hole conductor casing to resist relative radial movement between the connector and the upper end of bore hole conductor, said connector comprising a second portion extending between the upper end of the first portion and the riser said second potion providing the stress joint.  
     
     
         3 . A mudline riser-casing connecting assembly as claimed at  claim 1  wherein, a stabiliser element is located between the outer radial face of the first portion and the inner face of the bore hole conductor casing at a position intermediate of the hanger and the upper end of the bore hole conductor, said stabiliser being adapted to resist relative radial movement between the first portion and the upper end of bore hole conductor at said position.  
     
     
         4 . A mudline riser-casing connecting assembly as claimed at  claim 2  wherein, a stabiliser element is located between the outer radial face of the first portion and the inner face of the bore hole conductor casing at a position intermediate of the hanger and the upper end of the bore hole conductor, said stabiliser being adapted to resist relative radial movement between the first portion and the upper end of bore hole conductor at said position.  
     
     
         5 . A mudline riser-casing connecting assembly as claimed at  claim 3  wherein, the stabiliser element comprises an annular element fixed to the first portion.  
     
     
         6 . A mudline riser-casing connecting assembly as claimed at  claim 4  wherein, the stabiliser element comprises an annular element fixed to the first portion.  
     
     
         7 . A mudline riser-casing connecting assembly as claimed at  claim 1  wherein, the mudline riser-casing connecting assembly incorporates a disconnect facility which enables remote interengagement and disengagement of the lower end of the connector with the hanger assembly.  
     
     
         8 . A mudline riser-casing connecting assembly as claimed at  claim 2  wherein, the mudline riser-casing connecting assembly incorporates a disconnect facility which enables remote interengagement and disengagement of the lower end of the connector with the hanger assembly.  
     
     
         9 . A mudline riser-casing connecting assembly as claimed at  claim 3  wherein, the mudline riser-casing connecting assembly incorporates a disconnect facility which enables remote interengagement and disengagement of the lower end of the connector with the hanger assembly.  
     
     
         10 . A mudline riser-casing connecting assembly as claimed at  claim 4  wherein, the mudline riser-casing connecting assembly incorporates a disconnect facility which enables remote interengagement and disengagement of the lower end of the connector with the hanger assembly.  
     
     
         11 . A mudline riser-casing connecting assembly as claimed at  claim 5  wherein, the mudline riser-casing connecting assembly incorporates a disconnect facility which enables remote interengagement and disengagement of the lower end of the connector with the hanger assembly.  
     
     
         12 . A mudline riser-casing connecting assembly as claimed at  claim 6  wherein, the mudline riser-casing connecting assembly incorporates a disconnect facility which enables remote interengagement and disengagement of the lower end of the connector with the hanger assembly.