Downhole tool for cementing a borehole

Abstract

A downhole tool. The downhole tool may include a tubular body and an inner sleeve that is slidable within the tubular body. The tubular body may include a port that allows fluid flow between a bore of the downhole tool and an area outside of the tubular body. The downhole tool may be sequentially positionable in a run-in position that blocks fluid flow through the port in the tubular body, then in an open position that allows fluid flow through the port in the tubular bod, and then in a closed position that blocks fluid flow through the port in the tubular body.

What is claimed is: 
     
         1 . A downhole tool comprising:
 a tubular body comprising a port that allows fluid flow between a bore of the downhole tool and an area outside of the tubular body;   an inner sleeve slidable within the tubular body; and   wherein the downhole tool is sequentially positionable in a run-in position that blocks fluid flow through the port in the tubular body, then in an open position that allows fluid flow through the port in the tubular bod, and then in a closed position that blocks fluid flow through the port in the tubular body.   
     
     
         2 . The downhole tool of  claim 1 , wherein the inner sleeve blocks fluid flow through the port in the tubular body when in the downhole tool is in the run-in position. 
     
     
         3 . The downhole tool of  claim 1 , wherein the inner sleeve is sequentially positionable in a run-in position, then in an open position, and then in a closed position. 
     
     
         4 . The downhole tool of  claim 1 , further comprising a seat disposed within the inner sleeve, the seat comprising a shoulder shaped to receive a plug to shift the inner sleeve to position the downhole tool in the open position. 
     
     
         5 . The downhole tool of  claim 1 , wherein the inner sleeve and the tubular body are shaped such that the downhole tool is shiftable into an open position via an unbalanced force acting on the inner sleeve, the unbalanced force due to fluid pressure within the downhole tool. 
     
     
         6 . The downhole tool of  claim 1 , wherein the inner sleeve comprises a shoulder shaped to receive a plug to shift the inner sleeve to position the downhole tool in the closed position. 
     
     
         7 . The downhole tool of  claim 1 , wherein the inner sleeve comprises a profile on an interior surface of the inner sleeve. 
     
     
         8 . The downhole tool of  claim 1 , further comprising a seat slidable within the inner sleeve, wherein:
 the inner sleeve further comprises a port that, when the downhole tool is positioned in the run-in position, is aligned with the port in the tubular body; and   the seat is positionable in a run-in position that blocks fluid flow through the port in the inner sleeve and an open position that allows fluid flow through the port in the inner sleeve.   
     
     
         9 . A cementing system for a borehole, the cementing system comprising:
 a casing string positionable within the borehole, the casing string comprising a downhole tool comprising:
 a tubular body comprising a port that allows fluid flow between a bore of the downhole tool and an area radially outside of the tubular body; and 
 an inner sleeve slidable within the tubular body; and 
   wherein the downhole tool is sequentially positionable in a run-in position that blocks fluid flow through the port in the tubular body, then in an open position that allows fluid flow through the port in the tubular bod, and then in a closed position that blocks fluid flow through the port in the tubular body.   
     
     
         10 . The cementing system of  claim 9 , wherein the inner sleeve blocks fluid flow through the port in the tubular body when in the downhole tool is in the run- in position. 
     
     
         11 . The cementing system of  claim 9 , wherein the inner sleeve is sequentially positionable in a run-in position, then in an open position, and then in a closed position. 
     
     
         12 . The cementing system of  claim 10 , wherein the downhole tool further comprises a seat disposed within the inner sleeve, the seat comprising a shoulder shaped to receive a plug to shift the inner sleeve to position the downhole tool in the open position. 
     
     
         13 . The cementing system of  claim 9 , wherein the inner sleeve and the tubular body are shaped such that the inner sleeve is shiftable into an open position via an unbalanced force acting on the inner sleeve, the unbalanced force due to fluid pressure within the downhole tool. 
     
     
         14 . The cementing system of  claim 9 , wherein the inner sleeve comprises a shoulder shaped to receive a plug to shift the inner sleeve to position the downhole tool in the closed position. 
     
     
         15 . The cementing system of  claim 9 , wherein the inner sleeve comprises a profile on an interior surface of the inner sleeve. 
     
     
         16 . The cementing system of  claim 9 , wherein:
 the inner sleeve further comprises a port that, when the downhole tool is positioned in the run-in position, is aligned with the port in the tubular body; and   the downhole tool further comprises a seat slidable within the inner sleeve, the seat positionable in a run-in position that blocks fluid flow through the port in the inner sleeve and an open position that allows fluid flow through the port in the inner sleeve.   
     
     
         17 . A method for cementing a casing string in a borehole, the method comprising:
 positioning a casing string comprising a downhole tool within a borehole, wherein the downhole tool is positioned in a run-in position that blocks fluid flow between a bore of the downhole tool and an annulus formed between the casing string and a wall of the borehole; then   shifting the downhole tool to an open position to allow fluid flow between the bore of the downhole tool and the annulus; and then   shifting the downhole tool to a closed position to block fluid flow between the bore of the downhole tool and the annulus.   
     
     
         18 . The method of  claim 17 , wherein shifting the downhole tool to the open position comprises shifting an inner sleeve of the downhole tool via an unbalanced force acting on the inner sleeve to shift the downhole tool to the open position, the unbalanced force due to fluid pressure within the downhole tool. 
     
     
         19 . The method of  claim 17 , wherein shifting the downhole tool to the open position comprises pumping a plug downhole to engage with a shoulder of a seat of the downhole tool to shift the downhole tool to the open position. 
     
     
         20 . The method of  claim 17 , wherein shifting the downhole tool to the closed position comprises pumping a plug downhole to engage with a shoulder of an inner sleeve of the downhole tool to shift the downhole tool to the closed position.