Valve assembly

Abstract

A downhole valve assembly ( 10 ) comprises a tubular body ( 12 ), and a valve comprising a valve member ( 18 ) and a fluid actuated valve control mechanism ( 14 ) adapted to be selectively actuated to move the valve member between an open and a closed configuration, for selectively allowing fluid flow through the body ( 12 ). A first hydraulic control conduit ( 41 ) is in fluid communication with the valve control mechanism ( 14 ) for permitting actuation of the control mechanism to move the valve member ( 18 ) to the open configuration, by application of a first control fluid. A second hydraulic control conduit ( 41 ) is in fluid communication with the valve control mechanism ( 14 ) to move the valve member ( 18 ) to the closed configuration, by application of a second control fluid.

1 . A well operating method comprising: 
 providing a valve in a tubing string;    running the tubing string into a cased bore;    sealing the tubing string in the cased bore;    closing the valve to isolate a lower end of the bore;    uncoupling the tubing string from the valve;    retrieving the tubing string above the valve;    running a replacement tubing string into the bore;    coupling the replacement tubing string to the valve; and    opening the valve to permit fluid communication between the lower end of the bore and the tubing string.    
     
     
         2 . The method of  claim 1 , further comprising running the valve into the bore with the tubing.  
     
     
         3 . The method of  claim 1 , wherein the tubing string is a production tubing string.  
     
     
         4 . The method of  claim 1 , further comprising locating the valve towards the lower end of the tubing string.  
     
     
         5 . The method of  claim 1 , further comprising sealing the tubing string in the cased bore using a packer.  
     
     
         6 . The method of  claim 5 , further comprising locating the valve in the bore above a packer.  
     
     
         7 . The method of  claim 5 , further comprising locating the valve in the bore below a packer.  
     
     
         8 . A bore-drilling method comprising: 
 mounting a valve in casing lined with a bore;    advancing the bore by drilling using a drill string passing through the valve;    retrieving the drill string through the valve;    closing the valve to isolate a lower end of the bore; and    opening the valve to re-establish fluid communication with the lower end of the bore.    
     
     
         9 . The method of claim  10 , further comprising the step of monitoring the bore for conditions indicative of the formation of a problem the bore is about to encounter.