Low pressure responsive downhole tool with floating shoe retarding means
First Claim
1. An annulus pressure responsive downhole tool apparatus, comprising:
- a tool housing;
a power piston slidably disposed in said housing;
a first pressure conducting passage means for communicating a well annulus with a first side of said power piston;
a second pressure conducting passage means for communicating said well annulus with a second side of said power piston;
said tool housing including inner and outer concentric tubular members defining an annular cavity therebetween, said second pressure conducting passage means being at least partially defined by said annular cavity;
retarding means, disposed in said second pressure conducting passage means, for delaying communication of a sufficient portion of an increase in well annulus pressure to said second side of said power piston for a sufficient time to allow a pressure differential from said first side to said second side of said power piston to move said power piston from a first position to a second position relative to said housing, said retarding means including an annular floating shoe closely received in said annular cavity, said floating shoe including resilient friction means snugly engaging both said inner and outer tubular members of said tool housing; and
pressure relief means, communicated with a first portion of said second pressure conducting passage means between said second side of said piston and said retarding means, for relieving from said first portion of said second pressure conducting passage means a volume of fluid sufficient to permit said power piston to travel to its said second position.
1 Assignment
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Accused Products
Abstract
An annulus pressure responsive downhole tool includes a housing having a power piston slidably disposed therein. First and second pressure conducting passages communicate a well annulus with first and second sides of the power piston. A retarding device is disposed in the second pressure conducting passage for delaying communication of a sufficient portion of an increase in well annulus pressure to the second side of the power piston for a sufficient time to allow a pressure differential across the power piston to move the power piston from a first position to a second position relative to the housing. The retarding device is an annular floating shoe having a large number of O-rings frictionally engaging inner and outer tubular members of said housing. A pressure relief valve is communicated with the second pressure conducting passage between the power piston and the retarding device for relieving from the second pressure conducting passage a volume of fluid sufficient to permit the power piston to travel to its second position. A spring biased pin disposed in the housing engages an indentation in an actuating mandrel attached to said power piston to releasably hold the power piston in its second position.
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Citations
20 Claims
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1. An annulus pressure responsive downhole tool apparatus, comprising:
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a tool housing; a power piston slidably disposed in said housing; a first pressure conducting passage means for communicating a well annulus with a first side of said power piston; a second pressure conducting passage means for communicating said well annulus with a second side of said power piston; said tool housing including inner and outer concentric tubular members defining an annular cavity therebetween, said second pressure conducting passage means being at least partially defined by said annular cavity; retarding means, disposed in said second pressure conducting passage means, for delaying communication of a sufficient portion of an increase in well annulus pressure to said second side of said power piston for a sufficient time to allow a pressure differential from said first side to said second side of said power piston to move said power piston from a first position to a second position relative to said housing, said retarding means including an annular floating shoe closely received in said annular cavity, said floating shoe including resilient friction means snugly engaging both said inner and outer tubular members of said tool housing; and pressure relief means, communicated with a first portion of said second pressure conducting passage means between said second side of said piston and said retarding means, for relieving from said first portion of said second pressure conducting passage means a volume of fluid sufficient to permit said power piston to travel to its said second position. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An annulus pressure responsive downhole tool apparatus, comprising:
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a tool housing; a power piston slidably disposed in said housing; a first pressure conducting passage means for communicating a well annulus with a first side of said power piston; a second pressure conducing passage means for communicating said well annulus with a second side of said power piston; said tool housing including inner and outer concentric tubular members defining an annular cavity therebetween, said second pressure conducting passage means being at least partially defined by said annular cavity; retarding means, disposed in said second pressure conducting passage means, for delaying communication of a sufficient portion of an increase in well annulus pressure to said second side of said power piston for a sufficient time to allow a pressure differential from said first side to said second side of said power piston to move said power piston from a first position to a second position relative to said housing, said retarding means including a floating shoe closely received in said annular cavity, said floating shoe including friction means snugly engaging both said inner and outer tubular members of said tool housing; and pressure relief means, communicated with a first portion of said second pressure conducting passage means between said second side of said power piston and said retarding means, for relieving from said first portion of said second pressure conducting passage means a volume of fluid sufficient to permit said power piston to travel to its said second position; and releasable holding means, operatively associated with said power piston, for releasably preventing said power piston from returning to its first position, said releasable holding means including; indentation disposed in an actuating mandrel attached to said power piston; a holding pin radially slidably disposed in a radial bore of said tool housing; resilient pin biasing means for biasing said holding pin radially inward relative to said housing; and wherein said indentation and said pin are so arranged and constructed that when said power piston is in its said second position said indentation is aligned with said pin so that said pin is moved into said indentation by said pin biasing means so that said power piston is releasably held in its said second position.
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14. A method of operating an annulus pressure responsive downhole tool of the type including a power piston slidably disposed in a housing, a valve means operatively associated with said power piston, first and second pressure conducting passages communicating an annulus of a well with first and second sides of said power piston, and a pressure relief means disposed in said second pressure conducting passage, said power piston being movable between first and second positions relative to said housing and corresponding to closed and open positions, respectively, of said valve means, said method comprising the steps of:
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running said tool down into said well with said valve means in its said closed position closing a flow passage of said valve means, and with said power piston in its said first position; resiliently biasing said power piston toward its said first position with a resilient biasing means; sufficiently balancing well annulus pressure across said power piston as said tool is run into said well so that a pressure differential from said first side to said second side of said power piston is never sufficient to overcome said resilient biasing means and prematurely move said power piston to its second position as said tool is being run into said well; setting a packer means, connected to said tool, in said well to separate said well annulus into upper and lower portions, said first and second pressure conducting passages being communicated with said upper portion, and said flow passage of said valve means being communicated with said lower portion of said well annulus; applying an increase in annulus fluid pressure to an annulus fluid in said upper portion of said well annulus; communicating said increase in annulus fluid pressure to said first side of said power piston through said first pressure conducting passage; delaying communication of a sufficient portion of said increase in annulus fluid pressure to said second side of said power piston a sufficient time to allow a pressure differential from said first side to said second side of said power piston to move said power piston to its said second position, said delaying being accomplished by placing an annular floating shoe in an annular portion of said second pressure conducting passage defined in said housing, and by frictionally retarding movement of said annular floating shoe by means of a plurality of resilient O-rings disposed in grooves of said annular floating shoe, said O-rings snugly engaging a wall of said housing, said wall partially defining said annular portion of said second pressure conducting passage; opening said pressure relief means during said time of delayed communication; moving said power piston from its first position to its second position; relieving from said second pressure conducting passage, as said power piston moves from its first position to its second position, a volume of fluid sufficient to permit said power piston to travel to its said second position; and thereby moving said valve means to its said open position opening said flow passage of said valve means as said power piston is moved to its said second position. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification