Ball seat system

Abstract

The system and method for hydraulic fracturing includes a downhole tool with a sub, a sleeve, a ball seat support, and a ball seat holder. A ball dropped through the wellbore sits on the ball interface of the ball seat holder. Fluid flowing through the system pushes the ball against the ball interface, causing the ball seat holder to slide through the ball seat support and the ball interface to clamp the ball. A ball matches only a particular ball interface. Additional pressure forms a seal of the ball, the ball seat holder, and the ball seat support and moves the sleeve to slide through the sub and expose the throughbore to the annulus for the fracturing. Contact distributed between the ball, ball interface of the ball seat holder, and ball seat support withstands the temperature and pressure of the fracturing without deformation or failure of the ball.

We claim: 
     
         1 . A system for hydraulic fracturing, comprising:
 a sub with an upper portion and lower portion, said sub having a throughbore extending longitudinally through said sub;   a sleeve within said sub, being axially slideable between said upper portion and said lower portion of said sub, said throughbore extending through said sleeve;   a ball seat support with a seating surface on one side and an anchoring surface on an opposite side, said anchoring surface being fixedly engaged to said sleeve, said ball seat support being comprised of a support throughbore in fluid connection with said throughbore and a seat support opening at an end of said seating surface; and   a ball seat holder disposed within said ball seat support adjacent said seating surface, said ball seat holder being comprised of a holder throughbore in fluid connection and in alignment with said support throughbore of said ball seat support, a mounting member, a ball interface, and a holder opening at an end of said ball interface, said ball interface having a size corresponding to a size of a ball to be received within said ball seat holder so as to form seals between said ball and said ball seat holder and said ball seat support.   
     
     
         2 . The system for hydraulic fracturing, according to  claim 1 , said sub comprising a plurality of port openings, said sleeve forming a sealed barrier between said throughbore and an annulus of a wellbore in a first sleeve position by covering said port openings, said sleeve forming a fluid connection between said throughbore and an annulus of said wellbore through said port openings, when said sleeve is in a second sleeve position exposing said port openings. 
     
     
         3 . The system for hydraulic fracturing, according to  claim 2 , said sleeve comprising:
 a plurality of sleeve ports, forming said fluid connection in said second sleeve position between said throughbore and said annulus through said port openings.   
     
     
         4 . The system for hydraulic fracturing, according to  claim 2 , said sleeve comprising:
 a shearing means removably attached to said upper portion of said sub and an exterior of said sleeve, said shearing means being ruptured for movement from said first sleeve position to said second sleeve position.   
     
     
         5 . The system for hydraulic fracturing, according to  claim 1 , wherein movement of said ball seat support towards said lower portion corresponds to movement of said sleeve toward said lower portion. 
     
     
         6 . The system for hydraulic fracturing, according to  claim 1 , said seating surface being comprised of a cylindrical portion and a tapered portion, said tapered portion decreasing in diameter from said cylindrical portion to said seat support opening, said seat support opening at an end of said tapered portion. 
     
     
         7 . The system for hydraulic fracturing, according to  claim 1 , said tapered portion being at least one of a group consisting of conical, arcuate, and curved. 
     
     
         8 . The system for hydraulic fracturing, according to  claim 1 , further comprising:
 a seat shearing means removably attached to said seating surface of said ball seat support and an exterior of said mounting member said ball seat holder, said shearing means being ruptured for movement of said ball seat holder towards said seat support opening.   
     
     
         9 . The system for hydraulic fracturing, according to  claim 1 , wherein said ball seat holder is comprised of a collet collar, said mounting member being a sleeve portion of said collet collar, said ball interface being a clamp portion of said collet collar, said holder opening being a collet opening at an end of said collet collar, said collet opening having a size corresponding to said size of said ball to be received with said ball seat holder. 
     
     
         10 . The system for hydraulic fracturing, according to  claim 9 ,
 wherein said collet collar has an extended position for receiving said ball, said sleeve portion disposed in a front end of a cylindrical portion of said seating surface,   wherein said collet collar has a transitioning position to reduce fluid flow through said holder throughbore, said ball engaging said collet collar, said ball exerting pressure from fluid flow on said collet collar, said ball seat holder shearing from said ball seat support, said ball seat holder moving along said seating surface toward said seat support opening, and   wherein said collet collar has a retracted position for sealing said ball, said ball seat holder, and said ball seat support, said holder throughbore being sealed from fluid flow, said collet opening being sealed by said ball, said seat support opening sealed by said collet collar and said ball, said sleeve portion being abutted against said seating surface where said cylindrical portion meets a tapered portion of said seating surface.   
     
     
         11 . The system for hydraulic fracturing, according to  claim 1 ,
 wherein said ball interface is comprised of tapering collet petals, each petal being separated by slits,   wherein fluid flows through said slits, said holder opening, and said seat support opening in an extended position of the collet petals,   wherein fluid flow through said slits, said holder opening, and said seat support opening, reduces in a transitioning position of the collet petals, said slits of adjacent collet petals being narrowed, and   wherein fluid flow through said slits, said holder opening, and said seat support opening, stops in a retracted position of the collete petals, said slits being closed being adjacent collet petals, so as to form a seal with said ball, the collet petals, and said seat support opening.   
     
     
         12 . The system for hydraulic fracturing, according to  claim 11 , wherein said tapering collet petals radially overlap, each slit being positioned between and over adjacent petals, and wherein side space between adjacent petals and lateral space between surfaces of adjacent petals are reduced and closed to form said seal. 
     
     
         13 . A system for multi-stage hydraulic fracturing, comprising
 a first sub with a first upper portion and first lower portion, said first sub having a first throughbore extending longitudinally through said first sub;   a first sleeve within said first sub, being axially slideable between said first upper portion and said first lower portion of said first sub, said first throughbore extending through said sleeve;   a first ball seat support with a first seating surface on one side and a first anchoring surface on an opposite side, said first anchoring surface being fixedly engaged to said first sleeve, said first ball seat support being comprised of a first support throughbore in fluid connection with said first throughbore and a first seat support opening at an end of said first seating surface;   a first ball seat holder disposed within said first ball seat support adjacent said first seating surface, said first ball seat holder being comprised of a first holder throughbore in fluid connection with said first support throughbore of said first ball seat support, a first mounting member, a first ball interface, and a first holder opening at an end of said first ball interface, said first ball interface having a size corresponding to a size of a first ball to be received within said first ball seat holder so as to form seals between said first ball, and said first ball seat holder, and said first ball seat support;   a second sub with a second upper portion and second lower portion, said second sub having a second throughbore extending longitudinally through said second sub;   a second sleeve within said second sub, being axially slideable between said second upper portion and said second lower portion of said second sub, said second throughbore extending through said sleeve;   a second ball seat support with a second seating surface on one side and a second anchoring surface on an opposite side, said second anchoring surface being fixedly engaged to said second sleeve, said second ball seat support being comprised of a second support throughbore in fluid connection with said second throughbore and a second seat support opening at an end of said second seating surface; and   a second ball seat holder disposed within said second ball seat support adjacent said second seating surface, said second ball seat holder being comprised of a second holder throughbore in fluid connection with said second support throughbore of said second ball seat support, a second mounting member, a second ball interface, and a second holder opening at an end of said second ball interface, said second ball interface having a size corresponding to a size of a second ball to be received within said second ball seat holder so as to form seals between said second ball, and said second ball seat holder, and said second ball seat support,   wherein the first and second throughbores, the first and second support throughbores, and the first and second holder throughbores are in fluid connection to said wellbore,   wherein the first and second subs are associated with different downhole tools at different locations in the wellbore, and   wherein positions of the first and second subs relate to an order of dropping the first and second balls to respective first and second ball interfaces.   
     
     
         14 . The system for multi-stage hydraulic fracturing, according to  claim 13 , each sub comprising a plurality of port openings, each sleeve covering said portion openings and forming a respective sealed barrier between each throughbore and an annulus of a wellbore when each sleeve is in a respective initial sleeve position, each sleeve exposing said port opening and forming a respective fluid connection between each throughbore and said annulus of said wellbore when each sleeve is in a respective actuated sleeve position, wherein port openings of each sub for a fluid connection are exposed by respective sleeves at different times. 
     
     
         15 . The system for multi-stage hydraulic fracturing, according to  claim 13 , wherein each ball seat holder is comprised of a respective collet collar, each mounting member being a respective sleeve portion of each collet collar, each ball interface being a respective clamp portion of each collet collar, each holder opening being a respective collet opening at an end of each collet collar, a first collet opening of said first ball seat holder having a size corresponding to said first ball, a second collet opening of said second ball seat holder having a size corresponding to said second ball, each size of each ball to be received with each ball seat holder being different. 
     
     
         16 . A method for multi-stage hydraulic fracturing, comprising the steps of:
 installing a downhole tool in a wellbore, said downhole tool being comprised of a sub with an upper portion and lower portion, said sub having a throughbore extending longitudinally through said sub; a sleeve disposed within said sub, being axially slideable between said upper portion and said lower portion of said sub; a ball seat support with a seating surface on one side and an anchoring surface on an opposite side, said anchoring surface being engaged to said sleeve, said ball seat support being comprised of a support throughbore in fluid connection with said throughbore and a seat support opening; and a ball seat holder disposed within said ball seat support adjacent said seating surface, said ball seat holder being comprised of a holder throughbore in fluid connection with said support throughbore of said ball seat support, a mounting member, a ball interface, and a holder opening at an end of said ball interface;   flowing fluid through said throughbore of said sub, said support throughbore and said seat support opening, and said holder throughbore and said holder opening;   dropping a ball of a set size through said wellbore;   seating said ball on said ball interface of said ball seat holder, said set size of said ball corresponding to said ball interface;   flowing additional fluid through said throughbore of said sub, said support throughbore, said ball interface and said holder throughbore, increasing pressure of said ball on said ball interface;   moving said ball seat holder within said ball seat support toward said seat support opening to a retracted position of said ball seat holder;   sealing said ball to said ball interface and said ball seat holder to said ball seat support so as to stop fluid flow through said holder opening, said ball interface, and said seat support opening;   flowing more fluid through said throughbore of said sub, increasing pressure of said ball seat support on said sleeve;   sliding said sleeve between said upper portion toward said lower portion by fluid pressure on said ball, said ball seat holder, and said ball seat support, said ball seat support abutting against said sleeve;   opening access of frac ports in said wellbore to said throughbore; and   fracturing hydraulically through said frac ports at a pressure maintained by sealing said ball to said ball interface and said ball seat holder to said ball seat support   
     
     
         17 . The method for multi-stage hydraulic fracturing, according to  claim 16 , further comprising the steps of:
 completing a fracturing at said downhole tool;   dropping another ball of another set size through said wellbore, said set size of said ball being different from said another set size of said another ball;   seating said another ball on another ball interface of another ball seat holder of another downhole tool in another location in said wellbore, said another set size of said another ball corresponding to said another ball interface;   fracturing hydraulically through another frac port at a pressure maintained by sealing said another ball to said another ball interface and said another ball seat holder to another ball seat support of said another downhole tool.   
     
     
         18 . The method for multi-stage hydraulic fracturing, according to  claim 16 , wherein said set size of said ball corresponds to only one ball interface of any ball seat holder in said wellbore. 
     
     
         19 . The method for multi-stage hydraulic fracturing, according to  claim 16 , wherein the step of sealing said ball to said ball interface and said ball seat holder to said ball seat support comprises:
 reducing fluid flow through said ball interface by narrowing slits in said ball interface; and   stopping fluid flow through said ball interface by closing said slits in said ball interface.   
     
     
         20 . The method for multi-stage hydraulic fracturing, according to  claim 19 , wherein said slits of said ball interface are arranged in a collet formation.