Stage tool for wellbore cementing

Abstract

A stage tool for cementing a wellbore annulus, comprising: a main body including a tubular wall with an outer surface and an inner bore extending from a top end to a bottom end; a cementing port through the tubular wall providing fluidic access between the longitudinal bore and the outer surface; a valve for controlling flow through the cementing port between the outer surface and the inner bore; and a plug sealing a circulation path between the valve and the outer surface, the plug being expellable by pressure applied from the inner bore. The stage tool may be run in with the plug isolating annular pressure from the valve. After sufficient cement has been introduced to the annulus, the stage tool fluid port can be closed to hold the cement in the annulus.

1 . A method for cementing a tubing string in a wellbore, the method comprising: positioning the tubing string with a stage tool in the wellbore, an annulus being defined between the stage tool and the wellbore wall; expelling a plug from over a cementing port of the stage tool by pressuring up an inner bore of the stage tool; pumping cement into the annulus; and closing the cementing port to hold the cement in the annulus to provide time for the cement to set. 
     
     
         2 . The method of  claim 1  wherein expelling drives the plug into the annulus. 
     
     
         3 . The method of  claim 1  wherein during cementing, a check valve permits only one way flow through the cementing port. 
     
     
         4 . The method of  claim 1  wherein expelling includes exposing a check valve for the cementing port to annular pressure. 
     
     
         5 . The method of  claim 1  wherein closing includes pressuring up on the inner bore. 
     
     
         6 . The method of  claim 1  wherein closing includes locking a check valve into a closed and locked position. 
     
     
         7 . The method of  claim 1  wherein closing includes signaling to open an atmospheric chamber to tubing pressure to drive a closure to close the cementing port. 
     
     
         8 . A stage tool comprising: a main body including a tubular wall with an outer surface and an inner bore extending from a top end to a bottom end; a cementing port through the tubular wall providing fluidic access between the inner bore and the outer surface; a valve for controlling flow through the cementing port between the outer surface and the inner bore; and a plug sealing a circulation path between the valve and the outer surface, the plug being expellable by pressure applied from the inner bore. 
     
     
         9 . The stage tool of  claim 8  wherein the plug and the valve are open to the inner bore and the valve is normally inactive and is activated by removing the plug. 
     
     
         10 . The stage tool of  claim 8  wherein the plug is shear pinned to hold the valve in an inactive position retracted from the cementing port. 
     
     
         11 . The stage tool of  claim 8  wherein the valve is a check valve. 
     
     
         12 . The stage tool of  claim 11  the check valve permits one way flow through the cementing port in a direction from the outer surface to the inner bore, the check valve being normally inactive and only acting on fluid flows through the fluid port when activated. 
     
     
         13 . The stage tool of  claim 8  further comprising a lock for locking the valve in a closed and locked position. 
     
     
         14 . The stage tool of  claim 13  wherein the valve is responsive to pressuring up the inner bore to be driven to the closed and locked position. 
     
     
         15 . The stage tool of  claim 8  wherein the circulation path is defined through a chamber between the cementing port and the outer surface and the plug is shear pinned in the chamber between the cementing port and the outer surface and holds the valve in an inactive position retracted from the cementing port and positioned out of the circulation path. 
     
     
         16 . The stage tool of  claim 15  wherein the valve is a check valve permitting one way flow through the cementing port in a direction from the outer surface to the inner bore, the check valve being activated by removal of the plug such that it moves into an active position in the circulation path. 
     
     
         17 . The stage tool of  claim 16  further comprising a lock for locking the check valve in a closed and locked position, the lock being operable by pressuring up the inner bore to drive the check valve from the active position in the circulation path to the closed and locked position. 
     
     
         18 . The stage tool of  claim 8  further comprising an atmospheric chamber to hold the valve in an open position relative to the cementing port and a controller to open the atmospheric chamber to the inner bore to close the valve.