Separation of a marine riser from a subsea wellhead

Abstract

A subsea well system includes a safety assembly connected between a marine riser and a subsea wellhead, and an ejector bollard connected with the safety assembly and having a piston operable from a retracted position to an extended position to push an upper portion and a lower portion of the safety assembly apart and thereby physically separate the marine riser from the subsea wellhead.

What is claimed is: 
     
         1 . A subsea well system, comprising:
 a safety assembly connected between a marine riser and a subsea wellhead; and   an ejector bollard connected with the safety assembly and comprising a piston operable from a retracted position to an extended position to push an upper portion and a lower portion of the safety assembly apart and thereby physically separate the marine riser from the subsea wellhead.   
     
     
         2 . The system of  claim 1 , further comprising hydraulic pressure source connected to the ejector bollard to actuate the piston to the extended position. 
     
     
         3 . The system of  claim 2 , further comprising a hydraulic pressure accumulator connected to the ejector bollard to actuate the piston to the extended position. 
     
     
         4 . The system of  claim 1 , wherein the safety assembly comprises a blowout preventer. 
     
     
         5 . The system of  claim 1 , wherein the safety assembly is connected between a blowout preventer and the marine riser. 
     
     
         6 . The system of  claim 1 , wherein the safety assembly comprises a connector operable to an unlatched position thereby disconnecting the marine riser from the subsea wellhead. 
     
     
         7 . The system of  claim 6 , further comprising a hydraulic pressure accumulator connected to the ejector bollard to actuate the piston to the extended position. 
     
     
         8 . The system of  claim 6 , further comprising hydraulic pressure source connected to the ejector bollard to actuate the piston to the extended position; and
 the safety assembly further comprising a connector operable to an unlatched position thereby disconnecting the marine riser from the subsea wellhead.   
     
     
         9 . The system of  claim 8 , wherein the safety assembly comprises a blowout preventer. 
     
     
         10 . The system of  claim 8 , wherein the safety assembly is connected between a blowout preventer and the marine riser. 
     
     
         11 . A method, comprising physically separating a marine riser from a subsea wellhead in response to actuating an ejector bollard connected at a safety assembly between the marine riser and the subsea wellhead. 
     
     
         12 . The method of  claim 11 , wherein the physically separating comprises physically pushing the marine riser away from the subsea wellhead. 
     
     
         13 . The method of  claim 11 , wherein the ejector bollard comprises a piston and the actuating the ejector bollard comprises hydraulically extending the piston and thereby physically pushing the marine riser away from the subsea wellhead. 
     
     
         14 . The method of  claim 11 , wherein the safety assembly comprises a blowout preventer. 
     
     
         15 . The method of  claim 11 , wherein the safety assembly is connected between a blowout preventer and the marine riser. 
     
     
         16 . The method of  claim 11 , further comprising actuating a latch located with the safety assembly to an unlatched position prior to the physically separating the marine riser from the subsea wellhead. 
     
     
         17 . The method of  claim 16 , wherein the physically separating comprises physically pushing the marine riser away from the subsea wellhead. 
     
     
         18 . The method of  claim 16 , wherein the ejector bollard comprises a piston and the actuating the ejector bollard comprises hydraulically extending the piston and thereby physically pushing the marine riser away from the subsea wellhead. 
     
     
         19 . The method of  claim 18 , wherein the safety assembly comprises a blowout preventer. 
     
     
         20 . The method of  claim 18 , wherein the safety assembly is connected between a blowout preventer and the marine riser.