Method and apparatus for wellbore fluid treatment

Abstract

An apparatus for treatment of a wellbore is described. The apparatus includes a tubing string having a wall that defines an inner bore and a plurality of ports spaced apart along the wall. The apparatus includes a plurality of port-closure sleeves each covering a corresponding port. The apparatus also includes a movable sleeve initially positioned uphole from the port-closure sleeves. There is an interference fit between the movable sleeve and the port-closure sleeve, enabling the movable sleeve to engage a port-closure sleeve, displace the port-closure-sleeve to open the corresponding port, and then pass past the port-closure sleeve to engage and displace the next downhole port-closure sleeve.

What is claimed is: 
     
         1 . An apparatus for treatment of a wellbore comprising:
 a tubing string having a longitudinal axis, a wall defining an inner bore, a first port extending through the wall, and a second port extending through the wall and positioned downhole along the axis from the first port;   a first port-closure sleeve proximate to the first port, and adapted to slide within the tubing string from a closed position covering the first port, to an open position uncovering the first port;   a second port-closure sleeve proximate to the second port, and adapted to slide within the tubing string from a closed position covering the second port, to an open position uncovering the second port; and   a movable sleeve located uphole from the first port-closure sleeve and the second port-closure sleeve, the movable sleeve having a seat adapted to receive a sealing device, and the movable sleeve being adapted to slide downhole to engage and displace the first port-closure sleeve from the closed position to the open position, upon receipt of the sealing device at the seat and upon a first application of pressure to the uphole side of said sealing device.   
     
     
         2 . The apparatus of  claim 1  wherein the movable sleeve is further adapted to:
 disengage from the first port-closure sleeve after displacing the first port-closure sleeve from the closed position to the open position; and, 
 slide downhole past the first port-closure sleeve to engage and displace the second port-closure sleeve from the closed position to the open position, upon a second application of pressure to the uphole side of said sealing device. 
 
     
     
         3 . The apparatus of  claim 1 , wherein the sealing device is one of a plug and a ball. 
     
     
         4 . The apparatus of  claim 2 , wherein an outer surface of the movable sleeve and an inner surface of the first port-closure sleeve, are adapted to engage in an interference fit with each other. 
     
     
         5 . The apparatus of  claim 4 , wherein the outer surface of the first movable sleeve comprises a movable-sleeve engaging profile, the inner surface of the first port-closure sleeve comprises a first engaging profile, and the movable-sleeve engaging profile is adapted to engage with the first engaging profile. 
     
     
         6 . The apparatus of  claim 2  further comprising a first port-closure sleeve pin for maintaining the first port-closure sleeve in the closed position, said first port-closure sleeve pin adapted to be sheared after the movable sleeve engages with the first port-closure sleeve and before the movable sleeve displaces the first port-closure sleeve from the closed position to the open position. 
     
     
         7 . The apparatus of  claim 2 , wherein the first port-closure sleeve is installed in a cylindrical groove provided within the tubing string, which restricts movement of the first port-closure sleeve between the closed position and the open position. 
     
     
         8 . The apparatus of  claim 8 , wherein the cylindrical groove has a downhole end that stops displacement of the first port-closure sleeve in the downhole direction. 
     
     
         9 . A method for fluid treatment of a wellbore using a tubing string having a longitudinal axis, a wall defining an inner bore, a first port extending through the wall covered by a first port-closure sleeve, and a second port extending through the wall covered by a first port closure sleeve and positioned downhole along the axis from the first port, the method comprising:
 displacing a movable sleeve in the tubing string under a first application of hydraulic pressure;   engaging the first port-closure sleeve with the movable sleeve to displace the first port-closure sleeve from a first port closed position to a first port open position;   disengaging the first port-closure sleeve from the movable sleeve and further displacing the movable sleeve downhole past the first port-closure sleeve; and   engaging the second port-closure sleeve with the movable sleeve to displace the second port-closure sleeve from a second port closed position to a second port open position.   
     
     
         10 . The method of  claim 9 , further comprising displacing the movable sleeve under a second application of hydraulic pressure to successively engage a third port-closure sleeve that is positioned in the tubing string downhole from the second port-closure sleeve. 
     
     
         11 . The method of  claim 10 , further comprising displace the third port-closure sleeve from a third port closed position to a third port open position. 
     
     
         12 . The method of  claim 9 , further comprising circulating treatment fluid from surface through the tubing string and through the first and second ports to treat a formation. 
     
     
         13 . The method of  claim 9  wherein displacing a movable sleeve in the tubing string under a first application of hydraulic pressure comprises launching a plug from surface to land on a seat that is part of the movable sleeve. 
     
     
         14 . The method of  claim 13 , wherein the plug forms a pressure seal with the seat. 
     
     
         15 . The method of  claim 14 , further comprising pressure-isolating a stage of the tubing string with packers positioned outside the tubing string adjacent the first port-closure sleeve. 
     
     
         16 . An apparatus adapted to be installed in a tubing string for treatment of a multi-port stage of a wellbore comprising:
 a port closure for each port in the stage; and   a movable sleeve adapted to receive a plug, slide downhole along with the plug under hydraulic pressure applied from surface, and displace each port closure to enable circulation of treatment fluid through each port of the stage.   
     
     
         17 . The apparatus of  claim 15 , wherein each port-closure is a cap extending into the tubing string. 
     
     
         18 . The apparatus of  claim 16 , wherein the movable sleeve has a cutting downhole end, adapted to displace the caps from their respective ports as the movable sleeve slides past the caps. 
     
     
         19 . The apparatus of  claim 15 , wherein the movable sleeve is provided with a seat at an uphole side of the movable sleeve, adapted to receive a plug for pressure-sealing the tubing string. 
     
     
         20 . The apparatus of  claim 15 , wherein an outer surface of the movable sleeve and an inner surface of each port-closure sleeve are adapted to engage with each other in an interference fit.