Apparatus and method for dry injecting balls for wellbore operations

Abstract

A system and method are provided for storing and dry launching one or more balls into a wellbore having reduced ball drop height and ball drop stages relative to existing systems and methods. Balls are individually stored in cartridges of a ball launcher in communication with the wellbore via an axial bore, and are isolated from fluids and pressure in the axial bore by seals located on the cartridge. A selected ball can be injected into the wellbore by isolating the axial bore from the wellbore, establishing a launching pressure in the axial bore, actuating the cartridge of the selected ball to a launch position to stage the ball in the axial bore, retracting the cartridge to a sealing position, establishing a release pressure in the axial bore, and then re-establishing communication between the axial bore and wellbore to allow the ball to be injected.

We claim: 
     
         1 . A method for dry launching one or more balls into a wellbore under wellbore pressure, comprising:
 individually storing each of the one or more balls in a ball launcher, each ball being sealed from an axial bore of the ball launcher;   isolating the axial bore from the wellbore with an upper isolation valve;   establishing a launching pressure in the axial bore, the launching pressure being less than the wellbore pressure;   actuating the ball launcher to unseal a selected ball of the stored balls and release the ball to the axial bore and onto the upper isolation valve;   pressurizing the axial bore to a release pressure at about the wellbore pressure; and   opening the upper isolation valve to drop the selected ball into the wellbore.   
     
     
         2 . The method of  claim 1 , further comprising:
 closing the upper isolation valve;   selecting a subsequent selected ball; and   repeating the step establishing of the launching pressure, actuating the ball launcher to release the subsequent selected ball; pressurizing the axial bore and opening the upper isolation valve to drop the subsequent selected ball.   
     
     
         3 . The method of  claim 1 , wherein the pressurizing the axial bore to the release bore comprises pumping fluids into the axial bore. 
     
     
         4 . The method of  claim 1 , wherein the establishing the launching pressure in the axial bore comprises removing at least some fluids from the axial bore. 
     
     
         5 . The method of  claim 1 , wherein
 individually storing each of the one or more balls comprises storing each of the one or more balls in one or more corresponding cartridges, each of which is sealed from the axial bore; and   actuating the ball launcher to unseal the selected ball comprises actuating the cartridge corresponding to the selected ball from a sealed position to a launch position in the axial bore.   
     
     
         6 . The method of  claim 4 , wherein
 the establishing the launch pressure in the axial bore comprises removing fluids from the axial bore to a fluid level below a lowermost of the cartridges.   
     
     
         7 . The method of  claim 4 , wherein the removing of fluids from the axial bore comprises gravity draining fluids therefrom. 
     
     
         8 . The method of  claim 4 , wherein the removing of fluids from the axial bore comprises pumping fluids therefrom. 
     
     
         9 . The method of  claim 6 , further comprising introducing dry gas to the axial bore while removing fluids. 
     
     
         10 . The method of  claim 1 , wherein the launching pressure is at about atmospheric pressure. 
     
     
         11 . The method of  claim 1 , wherein pressurizing the axial bore further comprises increasing a fluid pressure in the axial bore to about the wellbore pressure. 
     
     
         12 . The method of  claim 1 , wherein opening the upper isolation valve further comprises pumping fluid into and through the axial bore to displace the selected ball into the wellbore. 
     
     
         13 . A system for storing and dry launching one or more balls into a wellbore, comprising:
 a ball launcher having an axial bore in fluid communication with the wellbore, and one or more radial bores, each radial bore having a distal end open to the axial bore for access thereto;   cartridges corresponding to at least two of the one or more radial bores, each cartridge storing a corresponding ball of one of the one or more balls and actuable between a sealing position residing in the radial bore, misaligned from the axial bore, and a launch position aligned with the axial bore through the open bore end;   an upper isolation valve for alternatively fluidly isolating the ball launcher from the wellbore and fluidly coupling the ball launcher and the wellbore; and   an equalization port in fluid communication with the axial bore for adjusting fluid pressure in the axial bore.   
     
     
         14 . The system of  claim 13 , wherein each cartridge is sealed to its respective radial bore in the sealing position with one or more cartridge seals adjacent at least a distal end of the cartridge for fluidly isolating the stored ball from the axial bore. 
     
     
         15 . The system of  claim 13 , wherein a pumper is connected to the equalization port and operable to selectably remove fluid from the axial bore or deliver fluid to the axial bore to adjust the fluid pressure in the axial bore. 
     
     
         16 . The system of  claim 13 , wherein each of the one or more cartridges has a flared distal end for engaging a corresponding flare seat at a bore interface at the open distal end of the cartridge's radial bore. 
     
     
         17 . The system of  claim 16 , wherein each cartridge's bore interface supports the cartridge in the sealing position against wellbore pressures. 
     
     
         18 . The system of  claim 16 , wherein each cartridge's bore interface forms a primary seal between the axial bore and the stored ball. 
     
     
         19 . The system of  claim 18 , further comprising one or more cartridge seals adjacent at least a distal end of the cartridge to form a secondary seal between the axial bore and the stored ball. 
     
     
         20 . The system of  claim 16 , wherein each of the one or more cartridges stores its corresponding ball in a ball-receiving cup intermediate the cartridge, the one of one or more cartridge seals comprise a distal seal adjacent the distal end of the cartridge and a swab seal adjacent a proximal end of the cartridge opposing the distal end for fluidly isolating the stored ball therebetween. 
     
     
         21 . The system of  claim 14 , further comprising a swab seal adjacent a proximal end of the cartridge opposing the distal end. 
     
     
         22 . The system of  claim 13 , wherein the equalization port is located between the upper isolation valve and the lowest of the one or more radial bores. 
     
     
         23 . The system of  claim 13 , further comprising:
 a first bleed port located between the upper isolation valve and the lowest of the one or more radial bores; and   a second bleed port is located above the one or more cartridges.