Method for installing an external line on a deployed drilling riser

Abstract

A method for assembling a marine drilling riser includes assembling a predetermined number of sections of the marine drilling riser and extending them into a body of water from a drilling platform. The assembling including affixing a selected number of external line guides to the riser at selected longitudinal positions. The line guides are initially closed to be substantially at most equal a diameter of buoyancy devices on the riser. The line guides are subsequently opened to extend beyond the buoyancy device diameter. A predetermined length of fluid external line is moved to adjacent the assembled riser and the fluid conduit is coupled to the external line guides. The external line guides are locked and assembly of the riser is completed and tension is applied thereto.

What is claimed is: 
     
         1 . A method for assembling a marine drilling riser, comprising:
 assembling a predetermined number of sections of the marine drilling riser and extending the assembled sections into a body of water from a drilling platform, the assembling including affixing a selected number of external line guides to the riser at selected longitudinal positions along the riser, the external line guides initially in a folded position traversing a dimension at most substantially equal to a diameter of buoyancy devices affixable to the riser;   moving the external line guides to an open position such that a line clamp on each line guide extends beyond the diameter of the buoyancy devices;   moving a predetermined length of external line to adjacent the assembled riser and coupling the external to a line clamp on each of the external line guides;   closing the line clamp on each of the external line guides; and   completing assembly of the riser and applying tension thereto.   
     
     
         2 . The method of  claim 1  wherein the external line comprises a mud return line in fluid communication at one end to an outlet of a subsea mudlift pump. 
     
     
         3 . The method of  claim 2  wherein the one end of the mud return line is coupled to a connector affixed to an exterior of the riser proximate the subsea mudlift pump, and wherein the subsea mudlift pump is coupled to an exterior of the riser on a modified riser joint. 
     
     
         4 . The method of  claim 2  wherein the coupling the mud return line to the connector comprises lifting the riser to engage the mud return line with the connector. 
     
     
         5 . The method of  claim 1  wherein the assembling the predetermined length of external line is performed at a selected lateral distance from a main well center on the drilling platform. 
     
     
         6 . The method of  claim 5  wherein the moving the predetermined length of external line comprises moving a pipe cart or subsea tree carrier laterally toward the predetermined number of sections of riser. 
     
     
         7 . The method of  claim 1  wherein the external line guides are affixed to the riser in a closed position such that the external line guides extend laterally from the riser at most to an outer diameter defined by buoyancy cans. 
     
     
         8 . The method of  claim 7  wherein the external line guides are operated to an open position after being lowered through a drilling deck on the drilling platform, the open position extending a pipe retaining line clamp on each external line guide to beyond the outer diameter defined by the buoyancy cans. 
     
     
         9 . The method of  claim 8  wherein the operating the external line guides is performed either above a water surface in a moon pool of the drilling platform or below a water surface by a remotely operated vehicle.