Landing string

Abstract

A landing string for use in deploying equipment between a surface vessel and a subsea well comprises a separation assembly configured to permit relative movement of upper and lower regions of the landing string upon exposure to a predetermined load.

1 . A landing string for use in deploying equipment between a surface vessel and a subsea well, comprising a separation assembly for permitting relative movement of upper and lower regions of the landing string upon exposure to a predetermined load. 
     
     
         2 . The landing string according to  claim 1 , wherein, in use, the separation assembly permits a controlled relative movement of the upper and lower regions of the landing string at or around the predetermined load. 
     
     
         3 . The landing string according to  claim 1 , wherein controlled relative movement of the upper and lower regions of the landing string controls transmission of load between said regions and along the landing string. 
     
     
         4 . The landing string according to  claim 1 , wherein the predetermined load comprises a predetermined axial load. 
     
     
         5 . The landing string according to  claim 1 , wherein the predetermined load comprises a predetermined tensile load. 
     
     
         6 . The landing string according to  claim 1 , wherein the predetermined load comprises at least one of a compressive load, a torsional load and a pressure induce load. 
     
     
         7 . The landing string according to  claim 1 , wherein the separation assembly defines a linkage or connection between the upper and lower regions of the landing string. 
     
     
         8 . The landing string according to  claim 1 , wherein the separation assembly defines a weak link or connection arrangement. 
     
     
         9 . The landing string according to  claim 1 , wherein the separation assembly defines a rigid connection between the upper and lower regions of the landing string prior to exposure to the predetermined load. 
     
     
         10 . The landing string according to  claim 1 , wherein the separation assembly permits relative movement between the upper and lower regions upon exposure to the predetermined load while still defining a connection therebetween. 
     
     
         11 . The landing string according to  claim 1 , wherein the separation assembly defines a compliant connection between the upper and lower regions following exposure to the predetermined load. 
     
     
         12 . The landing string according to  claim 11 , wherein the compliant connection retains the upper and lower regions of the landing string in general engagement with each other while minimising the load transference between said regions. 
     
     
         13 . The landing string according to  claim 1 , wherein the separation assembly damps relative movement between the upper and lower regions of the landing string following exposure to the predetermined load. 
     
     
         14 . The landing string according to  claim 13 , wherein the separation assembly comprises a fluid damping arrangement for damping relative movement between the upper and lower regions of the landing string. 
     
     
         15 . The landing string according to  claim 1 , wherein the separation assembly permits complete separation of the upper and lower regions of the landing string. 
     
     
         16 . The landing string according to  claim 15 , wherein the separation assembly permits complete separation of the upper and lower regions from a rigid connection configuration upon exposure to the predetermined load. 
     
     
         17 . The landing string according to  claim 15 , wherein the separation assembly permits complete separation of the upper and lower regions from a compliant connection configuration upon exposure to a predetermined load. 
     
     
         18 . The landing string according to  claim 15 , wherein the separation assembly defines an initial rigid connection, and then a compliant connection upon exposure to the predetermined load, followed by complete separation upon exposure to the same, or a different predetermined load. 
     
     
         19 . The landing string according to  claim 1 , wherein the predetermined load is selected in accordance with operator preference. 
     
     
         20 . The landing string according to  claim 1 , wherein the predetermined load is selected to be lower than a defined safety load associated with the remainder of the landing string. 
     
     
         21 . The landing string according to  claim 1 , wherein the predetermined load is selected to be lower than a safety bad associated with a vessel. 
     
     
         22 . The landing string according to  claim 1 , wherein the separation assembly comprises a release arrangement for initially securing the upper and lower regions of the landing string together and for permitting or initiating relative movement of said regions upon exposure to the predetermined load. 
     
     
         23 . The landing string according to  claim 22 , wherein the release arrangement comprises one or more frangible members which are configured to break and permit relative movement of the upper and lower regions upon exposure to the predetermined load. 
     
     
         24 . The landing string according to  claim 1 , wherein the separation assembly comprises first and second separable components, wherein the first component is associated with the upper region of the landing string and the second component is associated with the lower region of the landing string. 
     
     
         25 . The landing string according to  claim 24 , wherein one or both of the first and second separable components are integrally formed with a respective upper and lower landing string region. 
     
     
         26 . The landing string according to  claim 24 , wherein one or both of the first and second separable components are separately formed and connected to a respective upper and lower landing string region. 
     
     
         27 . The landing string according to  claim 24 , wherein the first and second separable components are secured together to permit connection between the upper and lower regions of the landing string. 
     
     
         28 . The landing string according to  claim 24 , wherein the first and second components are rigidly secured together until exposure to the predetermined load. 
     
     
         29 . The landing string according to  claim 24 , wherein the first and second separable components are secured together by a release arrangement. 
     
     
         30 . The landing string according to  claim 24 , wherein the first and second separable components permit a telescoping movement therebetween. 
     
     
         31 . The landing string according to  claim 24 , wherein one of the first and second separable components comprises or defines a projection which is received within a recess formed within the other of the first and second separable components. 
     
     
         32 . The landing string according to  claim 31 , wherein the projection and recess define tapered surfaces. 
     
     
         33 . The landing string according to  claim 24 , wherein the first and second separable components are configured to transmit bending between the upper and lower regions of the landing string. 
     
     
         34 . The landing string according to  claim 24 , wherein one or both of the first and second separable components comprise one or a plurality of land-out plates or ribs to permit transmission of bending. 
     
     
         35 . The landing string according to  claim 1 , comprising at least one valve assembly. 
     
     
         36 . The landing string according to  claim 1 , comprising a lower valve assembly located within the lower region of the landing string. 
     
     
         37 . The landing string according to  claim 36 , wherein the lower valve assembly comprises or defines a sub sea test tree (SSTT). 
     
     
         38 . The landing string according to  claim 1 , comprising an upper valve assembly located within the upper region of the landing string. 
     
     
         39 . The landing string according to  claim 38 , wherein the upper valve assembly comprises or defines a retainer valve. 
     
     
         40 . The landing string according to  claim 1 , comprising a shear-sub component configured to be sheared by external equipment. 
     
     
         41 . A method for controlling load transmission along a landing string, comprising:
 providing a separation assembly between upper and lower regions of a landing string;   configuring the separation assembly to permit relative movement between the upper and lower regions of the landing string upon exposure to a predetermined load.