System and method for well workover with horizontal tree

Abstract

A workover system for use with a subsea horizontal tree provides an economical solution when it is not necessary to pull the production tubing out of the well and/or when a subsea drilling BOP is not required. The system utilizes a riser and riser adaptor. An annulus flow line for connection to the annulus is provided with the riser. The workover system is adaptable to multiple configurations for connecting the lower end of the annulus flow line to the subsea horizontal tree for communication with the annulus. For instance, the annulus flow line may be connected to the adapter, or may be connected between the well cap and tubing hanger, or below the tubing hanger. An isolation sleeve may or may not be utilized in various embodiments and may be constructed for sealing and/or latching with different components depending on the embodiment. One or more control valves for the annulus flow may be provided in several different/alternative positions including within the tubing hanger and outside of the subsea horizontal tree.

1 . A workover system for a subsea horizontal tree wherein a subsea drilling BOP is not utilized and a riser extends from the subsea horizontal tree towards the surface, the subsea horizontal tree comprising a tubing hanger, the tubing hanger supporting a production tubing string in a well, the well further comprising a casing string with an annulus defined between the casing string and the tubing string, the workover system comprising: 
 an adapter for connecting the riser with the subsea horizontal tree;    an annulus line for communication with the annulus;    a lower end of the annulus line being connected to a port leading into the subsea horizontal tree for communication with the annulus; and    at least one valve mounted between the lower end of the annulus line and the annulus for controlling fluid flow between the annulus line and the annulus, the at least one valve being mounted in at least one of either a position external to the subsea horizontal tree or a position within the tubing hanger.    
   
   
       2 . The system as defined in  claim 1 , further comprising: 
 a receptacle mounted externally to the subsea horizontal tree for receiving and guiding a lower end of the annulus line into fluid communication with the port, the at least one valve being mounted adjacent to the receptacle.    
   
   
       3 . A system as defined in  claim 1 , further comprising: 
 a tree cap, and    an insertable isolation sleeve insertable through the tree cap, the isolation sleeve having an end for sealing engagement with the tubing hanger.    
   
   
       4 . The system as defined in  claim 3 , wherein the port is spaced axially above the tree cap and communicates with the annulus along a flow path adjacent to the insertable isolation sleeve through the tree cap.  
   
   
       5 . The system as defined in  claim 1 , wherein the port is defined within the adapter.  
   
   
       6 . The system as defined in  claim 1 , further comprising a tree cap, and wherein the port is defined between the tree cap and the tubing hanger.  
   
   
       7 . The system as defined  claim 1 , wherein the port is defined below the tubing hanger.  
   
   
       8 . The system as defined in  claim 1 , further comprising a tree cap, the tree cap and the tubing hanger being formed as separate components axially spaced apart with respect to each other.  
   
   
       9 . A system as defined in  claim 1 , further comprising: 
 the tubing hanger defining a tubing hanger central bore therethrough in communication with the production tubing string, the tubing hanger also defining a substantially straight vertical flow path which is radially offset from the tubing hanger central bore, and the at least one valve is positioned along the vertical flow path for controlling fluid flow between the annulus line and the annulus.    
   
   
       10 . A workover system for a subsea horizontal tree wherein a subsea drilling BOP is not utilized and a riser extends from the subsea horizontal tree towards the surface, the subsea horizontal tree comprising a tubing hanger, the tubing hanger supporting a production tubing string in a well, the well further comprising a casing string with an annulus defined between the casing string and the tubing string, the workover system comprising: 
 an adapter for connecting the riser with the subsea horizontal tree;    a tree cap defining a central tree cap bore therethrough;    an annulus line for communication with the annulus;    the annulus line being connected to a port for communication with the annulus; and    an insertable isolation sleeve insertable through the tree cap central bore, the isolation sleeve having an end thereof for sealing engagement with the tubing hanger.    
   
   
       11 . The system as defined in  claim 10 , wherein the isolation sleeve seals with the adapter.  
   
   
       12 . The system as defined in  claim 10 , wherein the isolation sleeve does not seal with the tree cap central bore.  
   
   
       13 . The system as defined in  claim 10 , wherein the isolation sleeve seals with the tree cap central bore.  
   
   
       14 . The system as defined in  claim 10 , wherein the port is defined within the adapter.  
   
   
       15 . The system as defined in  10 , wherein the port is defined between the tree cap and the tubing hanger.  
   
   
       16 . The system as defined  claim 10 , wherein the port is defined below the tubing hanger.  
   
   
       17 . The system as defined  claim 10 , wherein the insertable isolation sleeve insertable through the tree cap central bore is available but is not utilized or has been removed.  
   
   
       18 . A workover system for a subsea horizontal tree wherein a subsea drilling BOP is not utilized and a riser extends from the subsea horizontal tree towards the surface, the subsea horizontal tree comprising a tubing hanger, the tubing hanger supporting a production tubing string in a well, the well further comprising a casing string, the casing string and production tubing defining an annulus therebetween, the system comprising: 
 an adapter for connecting the riser with the subsea horizontal tree;    a tree cap defining a central tree cap bore therethrough;    an annulus line for communication with the annulus; and    the annulus line being connected to a port for communication with the annulus between the casing string and the production tubing string, the port being formed at a position below the tree cap.    
   
   
       19 . The workover system of  claim 18 , wherein the port is defined below the tubing hanger.  
   
   
       20 . A system as defined in  claim 18 , further comprising: 
 an insertable isolation sleeve insertable through the tree cap, the isolation sleeve having an end for sealing engagement with the tubing hanger.    
   
   
       21 . The system of  claim 18 , further comprising a centrally positioned tubing hanger flow passageway, and a vertically extending flow passageway in the tubing hanger radially spaced from the tubing hanger flow passageway and in communication with the annulus and the port.  
   
   
       22 . The system as defined in  claim 18 , further comprising a tree cap, the tree cap and the tubing hanger being formed as separate components axially spaced apart with respect to each other.  
   
   
       23 . A workover system for a subsea horizontal tree wherein a subsea drilling BOP is not utilized, the subsea horizontal tree comprising a tubing hanger, the tubing hanger supporting a production tubing string in a well, the well further comprising a casing string with an annulus defined between the casing string and the tubing string, the workover system comprising: 
 an annulus line for communication with the annulus;    a lower end of the annulus line being connected to a port leading into the subsea horizontal tree for communication with the annulus; and    at least one valve mounted between the lower end of the annulus line and the annulus for controlling fluid flow between the annulus line and the annulus, the at least one valve being mounted in at least one of either a position external to the subsea horizontal tree or a position within the tubing hanger; and    a riser which extends towards the surface from the subsea horizontal tree, the riser comprising a smaller internal diameter than an outer diameter of the tubing hanger.    
   
   
       23 . The system as defined in  claim 22 , further comprising a tree cap, the tree cap and the tubing hanger being formed as separate components axially spaced apart with respect to each other.