Drilling riser release method

Abstract

The method of releasing a drilling riser depending from a surface vessel from a subsea installation, comprising unlatching a connector on the primary conduit of the drilling riser, allowing the tension in the drilling riser to cause a separation between the portion of the primary conduit above the connector and the portion of the primary conduit below the connector, and the separation causing one or more control lines to be cut into an upper portion and a lower portion.

1 . The method of releasing a drilling riser depending from a surface vessel from a subsea installation, comprising:
 unlatching a connector on the primary conduit of said drilling riser,   allowing the tension in said drilling riser to cause a separation between the portion of said primary conduit above said connector and the portion of said primary conduit below said connector, and   said separation causing one or more control lines to be cut into an upper portion and a lower portion.   
     
     
         2 . The method of  claim 1  further comprising detecting the loss of one or more signals from said surface vessel. 
     
     
         3 . The method of  claim 1  further comprising initiating a signal from said subsea installation to said surface vessel warning of impending release. 
     
     
         4 . The method of  claim 1  further comprising said separation causing one or more auxiliary fluid lines to be separated into an upper portion and a lower portion. 
     
     
         5 . The method of  claim 1  further comprising sealing the lower end of the upper portion of said one or more auxiliary lines. 
     
     
         6 . The method of  claim 1  further comprising sealing the lower end of the upper portion of said primary conduit. 
     
     
         7 . The method of  claim 1  further comprising activating a cutter to cut any pipe which is within said primary conduit. 
     
     
         8 . The method of  claim 7  further comprising said cutter is an explosive cutter. 
     
     
         9 . The method of  claim 7  further comprising said cutter is a chemical cutter. 
     
     
         10 . The method of  claim 7  further comprising said cutter is not activated when engaging a circular body of a first diameter and is activated when engaging a circular body of a second diameter smaller than said first diameter. 
     
     
         11 . The method of releasing a drilling riser depending from a surface vessel from a subsea installation, comprising:
 unlatching a connector on the primary conduit of said drilling riser,   allowing the tension in said drilling riser to cause a separation between the portion of said primary conduit above said connector and the portion of said primary conduit below said connector, and   activating a cutter to cut any pipe which is within said primary conduit.   
     
     
         12 . The method of  claim 11  further comprising said cutter is an explosive cutter. 
     
     
         13 . The method of  claim 11  further comprising said cutter is a chemical cutter. 
     
     
         14 . The method of  claim 11  further comprising said cutter is not activated when engaging a circular body of a first diameter and is activated when engaging a circular body of a second smaller diameter 
     
     
         15 . The method of  claim 11  further comprising detecting the loss of one or more signals from said surface vessel. 
     
     
         16 . The method of  claim 11  further comprising initiating a signal from said subsea installation to said surface vessel warning of impending release 
     
     
         17 . The method of  claim 11  further comprising said separation causing one or more auxiliary fluid lines to be separated into an upper portion and a lower portion. 
     
     
         18 . The method of  claim 11  further comprising sealing the lower end of the upper portion of said one or more auxiliary lines. 
     
     
         19 . The method of  claim 11  further comprising sealing the lower end of the upper portion of said primary conduit. 
     
     
         20 . The method of  claim 11  further comprising cutting one or more control lines or hoses which are outside said primary conduit. 
     
     
         21 . The apparatus of releasing a drilling riser depending from a surface vessel from a subsea installation, comprising:
 a connector for unlatching the primary conduit of said drilling riser,   allowing the tension in said drilling riser to cause a separation between the portion of said primary conduit above said connector and the portion of said primary conduit below said connector, and   one or more cutters for cutting said one or more control into an upper portion and a lower portion.   
     
     
         22 . The apparatus for releasing a drilling riser depending from a surface vessel from a subsea installation, comprising:
 a connector for unlatching the primary conduit of said drilling riser,   allowing the tension in said drilling riser to cause a separation between the portion of said primary conduit above said connector and the portion of said primary conduit below said connector, and   a cutter to be activated by said separation and then explosively or chemically cut any pipe which is within said primary conduit.