Method and apparatus for reducing impact force in a ball-seat assembly

Abstract

A method of restricting fluid flow includes: releasing a ball into a fluid conduit and receiving the ball in a ball receiving element disposed at the fluid conduit and at least partially restricting fluid flow; and at least partially reflecting one or more pressure waves resulting from an impact between the ball and the ball receiving element by a reflective boundary disposed in the fluid conduit.

1 . A method of restricting fluid flow, comprising:
 releasing a ball into a fluid conduit and receiving the ball in a ball receiving element disposed at the fluid conduit and at least partially restricting fluid flow; and   at least partially reflecting one or more pressure waves resulting from an impact between the ball and the ball receiving element by a reflective boundary disposed in the fluid conduit.   
     
     
         2 . The method of  claim 1 , wherein the fluid conduit includes a first fluid having a first characteristic. 
     
     
         3 . The method of  claim 2 , further comprising injecting a second fluid into the fluid conduit, the second fluid having a second characteristic different than the first characteristic and configured to form an interface between the first fluid and the second fluid, the interface forming the reflective boundary. 
     
     
         4 . The method of  claim 3 , wherein the characteristic is selected from at least one of a polarity, a viscosity, a chemical composition and a physical composition. 
     
     
         5 . The method of  claim 3 , wherein the first characteristic is a first density and the second characteristic is a second density. 
     
     
         6 . The method of  claim 1 , wherein at least partially reflecting includes generating at least one reflected wave that destructively interferes with the one or more pressure waves. 
     
     
         7 . The method of  claim 3 , wherein the second fluid is injected at a time that is dependent on a release time of the ball so that the interface is located at a selected distance relative to the ball at impact. 
     
     
         8 . The method of  claim 3 , wherein the second fluid is injected at a time that is dependent on a release time of the ball so that the interface is located at least one of upstream and downstream of the ball receiving element at impact. 
     
     
         9 . The method of  claim 7 , further comprising injecting an additional fluid after the second fluid, the additional fluid having a characteristic different than the second characteristic so that the interface is located both upstream and downstream of the ball receiving element at impact. 
     
     
         10 . The method of  claim 1 , further comprising disposing a carrier including the actuator assembly in a borehole. 
     
     
         11 . An apparatus for restricting fluid flow, comprising:
 a ball receiving element disposed in a fluid conduit and configured to receive a ball that has been advanced through the fluid conduit and at least partially restrict fluid flow; and   a reflective boundary disposed in the fluid conduit at least partially reflecting one or more pressure waves resulting from an impact between the ball and the ball receiving element.   
     
     
         12 . The apparatus of  claim 11 , wherein the boundary at least partially reflects one or more pressure waves resulting from an impact between the ball and the ball receiving element, and generates at least one reflected pressure wave that destructively interferes with the one or more pressure waves. 
     
     
         13 . The apparatus of  claim 11 , wherein the fluid conduit is configured to receive a first fluid having a first characteristic. 
     
     
         14 . The apparatus of  claim 13 , wherein the fluid conduit is configured to receive a second fluid, the second fluid having a second characteristic different than the first characteristic and configured to form an interface between the first fluid and the second fluid, the interface forming the reflective boundary. 
     
     
         15 . The apparatus of  claim 14 , wherein the characteristic is selected from at least one of a polarity, a viscosity, a chemical composition and a physical composition. 
     
     
         16 . The apparatus of  claim 14 , wherein the first characteristic is a first density and the second characteristic is a second density. 
     
     
         17 . The apparatus of  claim 14 , further comprising a processor configured to inject the second fluid at a time that is dependent on a release time of the ball so that the interface is located at a selected distance relative to the ball at impact. 
     
     
         18 . The apparatus of  claim 14 , further comprising a processor configured to inject the second fluid at a time that is dependent on a release time of the ball so that the interface is located at least one of upstream and downstream of the ball receiving element at impact. 
     
     
         19 . The apparatus of  claim 18 , wherein the processor is configured to inject an additional fluid after the second fluid, the additional fluid having a characteristic different than the second characteristic so that the interface is located both upstream and downstream of the ball receiving element at impact. 
     
     
         20 . The apparatus of  claim 11 , further comprising a carrier including the ball receiving element and the fluid conduit, the carrier configured to be disposed in a borehole.