Method and apparatus to selectively reduce wellbore pressure during pumping operations
First Claim
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1. A service tool for use in a well, comprising:
- a tubular having a central passageway therethrough;
a crossover through which fluid flowing down the central passageway can exit the central passageway and enter a lower annulus below a packer and fluid flowing up the central passageway can exit the central passageway and enter an upper annulus above the packer;
a valve mounted to the tubular, the valve comprising a valve housing and a piston slidably mounted in the valve housing to allow or block fluid flow from the lower annulus into the central passageway through an opening in a wall of the tubular, the valve housing comprising a chamber and the piston comprising a piston head extending into the chamber to divide the chamber into a first subchamber and a second subchamber on opposed sides of the piston head, the first subchamber and the second subchamber being at atmospheric pressure prior to actuation of the valve; and
in whichthe valve is actuated by a pressure-responsive member responsive to absolute pressure to expose the first subchamber to pressure in the lower annulus which moves the piston and opens the valve, the valve being located adjacent a screen in the well.
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Abstract
A downhole tool has at least one diverter valve. The at least one diverter valve is used to reduce pressure in a wellbore caused by frictional resistance to fluid flow during a gravel pack operation. The increased pressure tends to be created as the beta wave of the gravel pack operation makes its way up the wellbore.
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Citations
17 Claims
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1. A service tool for use in a well, comprising:
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a tubular having a central passageway therethrough; a crossover through which fluid flowing down the central passageway can exit the central passageway and enter a lower annulus below a packer and fluid flowing up the central passageway can exit the central passageway and enter an upper annulus above the packer; a valve mounted to the tubular, the valve comprising a valve housing and a piston slidably mounted in the valve housing to allow or block fluid flow from the lower annulus into the central passageway through an opening in a wall of the tubular, the valve housing comprising a chamber and the piston comprising a piston head extending into the chamber to divide the chamber into a first subchamber and a second subchamber on opposed sides of the piston head, the first subchamber and the second subchamber being at atmospheric pressure prior to actuation of the valve; and
in whichthe valve is actuated by a pressure-responsive member responsive to absolute pressure to expose the first subchamber to pressure in the lower annulus which moves the piston and opens the valve, the valve being located adjacent a screen in the well. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A system for use in a well, comprising:
a service tool configured to deliver a gravel slurry in a gravel packing procedure, the service tool having a wall formed in a tubular shape and a plurality of valve assemblies mounted in the wall, each valve assembly comprising; an upper housing having a port therethrough; a lower housing joined to the upper housing, the lower housing having a pressure-responsive member therein responsive to absolute pressure; a piston sealingly and moveably mounted within the upper and lower housings to form a chamber, the piston having a piston head extending into the chamber and sealingly dividing the chamber into an upper chamber and a lower chamber maintained at atmospheric pressure until actuation of the piston, the pressure-responsive member being adjacent to the upper chamber; and
in whichthe piston allows or prevents fluid communication through the port. - View Dependent Claims (11, 12, 13, 14)
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15. A method to reduce wellbore pressure during pumping operations, comprising:
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a) providing a service tool to which diverter valves can be mounted; b) spacing the diverter valves along the service tool'"'"'s length such that the diverter valves will land adjacent a screen in the wellbore when the service tool is placed in the wellbore; c) setting each diverter valve to actuate independently from the other diverter valves to an open state when the absolute wellbore pressure reaches some predetermined threshold; d) actuating each diverter valve by positioning a piston head in a valve housing chamber to divide the valve housing chamber into opposed subchambers acting on opposed sides of the piston head and maintaining the opposed subchambers at atmospheric pressure until the absolute wellbore pressure reaches the predetermined threshold; e) placing the service tool in the wellbore; and f) performing pumping operations. - View Dependent Claims (16, 17)
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Specification