Pressure activated cyclical valve apparatus and method

Abstract

A pressure activated cyclical valve assembly includes a first sub, a second sub, a piston, and a biasing member. The first sub has a first passageway therethrough. The second sub is coupled to the first sub and has a second passageway therethrough. The piston is positioned within the second passageway and is shiftable between a deactivated position in which a bypass port is closed and an activated position in which the bypass port is open. The piston has a piston orifice and the first passageway is in fluid communication with the second passageway through the piston orifice. The biasing member exerts a force against the piston to maintain the piston in the deactivated position. The piston orifice is sized to restrict the flow of fluid therethrough such that the piston can be shifted between the deactivated and activated positions by changing flowrate of fluid in the first passageway.

What is claimed is: 
     
         1 . A pressure activated valve assembly, comprising:
 a sub having a sidewall extending between a first open end and a second open end, the sidewall defining a cavity between the first open end and the second open end and also defining at least one port passing through the sidewall and in communication with the cavity, wherein the sub is configured to allow a fluid to flow through the cavity from the first open end toward the second open end;   a piston disposed at least partially within the cavity, the piston having an orifice through which the fluid can flow; and   a biasing member exerting a force on the piston directed toward the first open end;   wherein the piston is movable between a first position and a second position, in the first position the piston covers the at least one port, thereby preventing the fluid from flowing through the at least one port, and in the second position the at least one port is uncovered and at least a portion of the fluid can flow through the at least one port, and   wherein the piston is configured to be in the first position when the fluid flows at a first flowrate and in the second position when the fluid flows at a second flowrate, wherein the second flowrate is greater than the first flowrate.   
     
     
         2 . The assembly as recited in  claim 1 , wherein in the second position, the piston is below the at least one port in the sidewall. 
     
     
         3 . The pressure activated valve assembly as recited in  claim 1 , wherein the orifice of the piston has a smaller cross-sectional area than at least a portion of the cavity. 
     
     
         4 . The pressure activated valve assembly as recited in  claim 1 , wherein the piston includes a removable nut defining the piston orifice. 
     
     
         5 . A pressure activated cyclical valve assembly configured to control a flow of a fluid, comprising:
 a first sub having a first passageway therethrough;   a second sub coupled to the first sub and having a second passageway therethrough;   a piston positioned within the second passageway and shiftable between a deactivated position in which a bypass port is closed and an activated position in which the bypass port is open, the piston having a piston orifice, wherein the first passageway is in fluid communication with the second passageway through the piston orifice; and   a biasing member to exert a force against the piston in a direction opposite the direction of the flow of the fluid through the first and second passageways to maintain the piston in the deactivated position,   wherein the piston orifice is sized to restrict the flow of the fluid between the first passageway and the second passageway such that the piston can be shifted between the deactivated and activated positions by changing flowrate of the fluid in the first passageway.   
     
     
         6 . The assembly as recited in  claim 5 , wherein an increase of the flowrate of fluid in the first passageway to a predetermined level increases pressure in the first passageway sufficient to overcome the force exerted by the biasing member and thereby shift the piston to the activated position. 
     
     
         7 . The assembly as recited in  claim 5 , wherein the first passageway and the second passageway have the same diameter. 
     
     
         8 . The assembly as recited in  claim 7 , wherein the piston orifice terminates a tapered passageway that extends between the first passageway and the second passageway. 
     
     
         9 . The assembly as recited in  claim 5 , wherein the first sub is threadedly coupled to an upper section of a drillstring, and the second sub is threadedly coupled to a lower section of the drillstring, and wherein the drillstring is deployed in a wellbore that penetrates a hydrocarbon bearing reservoir. 
     
     
         10 . The assembly as recited in  claim 5 , further comprising at least one shear screw coupled to the second sub and to the piston, wherein the at least one shear screw restricts translation of the piston with respect to the second sub, and wherein an increase of the flowrate of fluid in the first passageway to a predetermined level causes the at least one shear screw to breakaway to allow translation of the piston with respect to the second sub. 
     
     
         11 . The assembly as recited in  claim 5 , wherein the piston includes a removable nut defining the piston orifice. 
     
     
         12 . The assembly as recited in  claim 5 , further comprising a seal insert, wherein the seal insert is in contact with an exterior surface of the piston when the piston is in the deactivated position, and wherein the seal insert includes an inner wall and an outer wall, wherein the inner wall is tapered and a spring biases the inner wall toward a central axis of the assembly. 
     
     
         13 . The assembly recited in  claim 5 , wherein the piston includes an expandable seat defining the orifice, wherein the expandable seat is configured to transform from a first configuration wherein the orifice defines a first diameter to a second configuration wherein the orifice defines a second diameter which is larger than the first diameter, such that in the first configuration a plug is unable to pass through the orifice and in the second configuration the plug is able to pass through the orifice. 
     
     
         14 . The assembly of  claim 13 , wherein the expandable seat is translatable from a first position in which the expandable seat is constrained from transforming to the second configuration to a second position in which the expandable seat is able to transform to the second configuration, the assembly further comprising a biasing member exerting a force on the expandable seat in a direction opposite the direction of fluid flow through the first and second passageways to maintain the expandable seat in the first position. 
     
     
         15 . A method of bypassing fluid in a drillstring assembly, comprising:
 providing a pressure activated cyclical valve assembly in a drillstring, the pressure activated valve assembly comprising:
 a sub having a sidewall extending between a first open end and a second open end, the sidewall defining a cavity between the first open end and the second open end and also defining at least one port passing through the sidewall and in communication with the cavity, 
 a piston disposed at least partially within the cavity, the piston having an orifice; and 
 a biasing member exerting a force on the piston directed toward the first open end; and 
   moving the piston from a deactivated position to an activated position by increasing flowrate of a fluid through the cavity and the orifice to increase pressure on the piston to counteract the force exerted by the biasing member and move the piston from the deactivated position to the activated position.   
     
     
         16 . The method of  claim 15 , further comprising decreasing the flowrate of the fluid such that the piston moves from the activated position to the deactivated position. 
     
     
         17 . The method of  claim 15 , further comprising deploying a plug in the drillstring so that the plug blocks the orifice while the piston is in the activated position. 
     
     
         18 . The method of  claim 17 , wherein the plug is made of a deformable material, and further comprising further increasing the flowrate of the fluid to move the deformable plug through the orifice; and then decreasing the flowrate of the fluid such that the piston moves from the activated position to the deactivated position.