Method and Apparatus for Wellbore Fluid Treatment

Abstract

An apparatus for fluid treatment of a wellbore includes (a) a tubing string having (i) a wall defining an inner bore extending along a longitudinal axis, and (ii) a plurality of spaced apart ports in the wall; and (b) a plurality of axially spaced apart valves configured to permit fluid to flow therethrough. The valves are mounted along the tubing string. Each valve is (i) moveable in a downhole direction along the inner bore from a first position in which the one or more of the plurality of ports are closed, to a second position in which the one or more of the plurality of ports are open, and (ii) having a minimum inner diameter with respect to an innermost surface of the valve when the valve is in the first position. The minimum inner diameter of each valve is generally equal.

1 . An apparatus for fluid treatment of a wellbore, the apparatus comprising:
 a) a tubing string having (i) a wall defining an inner bore extending along a longitudinal axis of the tubing string, and (ii) a plurality of spaced apart ports in the wall; and   b) a plurality of axially spaced apart valves configured to permit fluid to flow therethrough, the plurality of axially spaced apart valves mounted along the tubing string, each valve: (i) moveable in a downhole direction along the inner bore from a first position in which the one or more of the plurality of ports are closed to inhibit fluid communication between the inner bore and the wellbore through the one or more of the plurality of ports, to a second position in which the one or more of the plurality of ports are open to permit fluid communication between the inner bore and the wellbore through the one or more of the plurality of ports, and (ii) having a minimum inner diameter with respect to an innermost surface of the valve when the valve is in the first position, wherein the minimum inner diameter of each valve is generally equal.   
     
     
         2 . The apparatus of  claim 1 , wherein each valve is moveable toward the second position based on increasing fluid pressure at an uphole side of the valve relative to a downhole side of the valve. 
     
     
         3 . The apparatus of  claim 2 , wherein each valve has a conduit extending along the axis between the uphole side and the downhole side of the valve for permitting fluid to flow therethrough, the conduit defining the minimum inner diameter and blockable to facilitate increasing fluid pressure at the uphole side of the valve relative to the downhole side of the valve. 
     
     
         4 . The apparatus of  claim 1 , wherein the plurality of valves are mounted in a common segment of the tubing string. 
     
     
         5 . The apparatus of  claim 1 , wherein the inner diameter remains constant when the valve moves from the first position to the second position. 
     
     
         6 . The apparatus of  claim 1 , wherein each valve is disposed in a corresponding groove formed in an inner surface of the tubing string. 
     
     
         7 . The apparatus of  claim 1 , wherein each valve is spaced apart from a corresponding stop surface in the inner bore when in the first position, and abuts the corresponding stop surface when in the second position to inhibit movement of the valve in the downhole direction. 
     
     
         8 . An apparatus for fluid treatment in a wellbore, the apparatus comprising:
 a) a tubing string including:
 (i) a wall defining an inner bore extending along a longitudinal axis, 
 (ii) at least one first port in the wall; and 
 (iii) at least one second port in the wall, the at least one second port spaced axially downhole from the at least one first port; 
   b) a first valve mounted in the inner bore and translatable along the axis in a downhole direction from a first position in which fluid communication between the inner bore and the wellbore through the at least one first port is blocked, toward a second position in which the at least one first port is open to provide fluid communication between the inner bore and the wellbore through the at least one first port, the first valve having a first conduit extending along the axis for permitting passage of fluid through the first valve, the first conduit defined at least in part by a minimum first radial extent measured transversely from the axis to a radially innermost surface of the first valve when the first valve is in the first position; and   c) a second valve mounted in the inner bore downhole of the first valve and translatable along the axis in the downhole direction from a third position in which fluid communication between the inner bore and the wellbore through the at least one second port is blocked, toward a fourth position in which the at least one second port is open to provide fluid communication between the inner bore and the wellbore through the at least one second port, the second valve having a second conduit extending along the axis for permitting passage of fluid through the second valve, the second conduit defined at least in part by a minimum second radial extent measured transversely from the axis to a radially innermost surface of the second valve when the second valve is in the third position,   wherein the second radial extent is generally equal to the first radial extent.   
     
     
         9 . The apparatus of  claim 8 , wherein the at least one first port comprises a plurality of first ports and the at least one second port comprises a plurality of second ports. 
     
     
         10 . The apparatus of  claim 9 , wherein the first ports are spaced circumferentially apart from one another about the axis, and wherein the second ports are spaced circumferentially apart from one another about the axis. 
     
     
         11 . The apparatus of  claim 8 , wherein the tubing string includes a first stop surface between the first and second valves, the first valve spaced axially uphole from the first stop surface when in the first position, and the first valve in engagement with the first stop surface when in the second position for inhibiting further translation of the first valve in the downhole direction, and wherein the tubing string includes a second stop surface downhole of the second valve, the second valve spaced axially uphole from the second stop surface when in the third position, and the second valve in engagement with the second stop surface when in the fourth position for inhibiting further translation of the second valve in the downhole direction. 
     
     
         12 . The apparatus of  claim 8 , wherein the bore is defined at least in part by a bore inner radius measured from the axis to a radially inner surface of the wall, and wherein the first radial extent is generally equal to the bore inner radius. 
     
     
         13 . The apparatus of  claim 8 , wherein the second valve is directly downhole of the first valve, and the first and second valves are in a common segment of the tubing string. 
     
     
         14 . The apparatus of  claim 8 , wherein the apparatus is free of any packers axially intermediate the at least one first port and the at least one second port. 
     
     
         15 . The apparatus of  claim 8 , further comprising:
 (d) a port-opening sleeve in the bore uphole of the first and second valves, the port-opening sleeve drivable through the tubing string into engagement with the first valve to urge translation of the first valve toward the second position, and when the first valve is in the second position, the port-opening sleeve is drivable past the first valve and into engagement with the second valve to urge translation of the second valve toward the fourth position, the port-opening sleeve having a sleeve conduit extending along the axis for permitting passage of fluid through the port-opening sleeve, and drivable by plugging the sleeve conduit with a sealing device and applying fluid pressure to an uphole side of the port-opening sleeve.   
     
     
         16 . An apparatus for fluid treatment in a wellbore, the apparatus comprising:
 a) a tubing string including: (i) a wall defining an inner bore extending along a longitudinal axis, and (ii) a plurality of axially spaced apart ports in the wall; and   b) a plurality of axially spaced apart valves mounted in the inner bore, each valve independently translatable along the axis in a downhole direction, each valve translatable from a closed position in which fluid communication through at least one of the plurality of ports is blocked, toward an open position in which the at least one of the plurality of ports is open to provide fluid communication between the inner bore and the wellbore through the at least one of the plurality of ports, each valve having a conduit for permitting passage of fluid through the valve, the conduit extending along a centerline generally parallel with the axis, and the conduit having a minimum radial extent measured from the centerline to a radially innermost surface of the valve when the valve is in the closed position, wherein the minimum radial extent of each valve is generally equal.   
     
     
         17 . The apparatus of  claim 16 , wherein each valve is drivable toward the open position by increasing fluid pressure at an uphole side of the valve relative to a downhole side of the valve. 
     
     
         18 . The apparatus of  claim 17 , wherein the conduit is blockable to facilitate increasing fluid pressure at the uphole side relative to the downhole side of the valve. 
     
     
         19 . The apparatus of  claim 17 , wherein the plurality of axially spaced apart valves are mounted in a common segment of the tubing string. 
     
     
         20 . An apparatus for fluid treatment of a wellbore, the apparatus comprising:
 a) a tubing string having: (i) a wall defining an inner bore extending along a longitudinal axis of the tubing string, and (ii) a plurality of spaced apart ports in the wall; and   b) a plurality of axially spaced apart valves configured to permit fluid to flow therethrough, the plurality of axially spaced apart valves mounted along the tubing string, each valve actuable by a common plug movable through the tubing string, each valve actuable by the plug to move the valve from a first position in which the valve is configured to cover one or more of the plurality of ports to a second position in which the valve is configured to open one or more of the plurality of ports to permit fluid communication between the inner bore and the wellbore, and each valve having a minimum inner diameter with respect to an innermost surface of the valve when the valve is in the first position, wherein the minimum inner diameter of each valve is generally equal, and wherein each valve is configured to permit passage of the plug therethrough when in the second position.