Pressure sensitive cover for a fluid port in a downhole tool

Abstract

A fluid port cover for a fluid port includes a disc-shaped body having a weakened material line to render the body tearable.

1 . A fluid port cover for a fluid port comprising:
 a fluid port cover for a fluid port comprising a disc-shaped body having a weakened material line to render the body tearable, and at least one leak aperture formed through the body, the leak aperture intersecting the weakened material line from which tearing of the body along the weakened material line is initiated when a pressure differential across the body is reached.   
     
     
         2 . The cover of  claim 1 , wherein the body is formed of an erodible material. 
     
     
         3 . The cover of  claim 1 , wherein the body has a material strength at the weakened material line that varies from one portion of the weakened material line to a second portion of the weakened material line to permit a progressive opening of the body along the weakened material line when a pressure differential across the body is reached. 
     
     
         4 . The cover of  claim 3 , wherein the body comprises a first face, an opposite face, and edges between the first face and the opposite face and the body has a thickness from the first face to the opposite face varies and the thickness varies from the one portion of the weakened material line to the second portion of the weakened material line to cause the variance in the material strength of the body. 
     
     
         5 . The cover of  claim 4  wherein the first face is substantially planar and the opposite face is concave with a tapering inner diameter that tapers toward a substantially central point between the edges and the weakened material line extends along a length of the first face opposite the tapering inner diameter. 
     
     
         6 . The cover of  claim 1 , wherein the weakened material line is a score and the score has a depth that varies along its length to cause the variance in the material strength of the body. 
     
     
         7 . The cover of  claim 6 , wherein the perimeter of the opposite face is recessed relative to the central portion to receive the mounting ring or the sealing ring. 
     
     
         8 . The cover of  claim 1 , wherein the weakened material line includes a plurality of score lines crossing at an intersecting point on at least one side face of the body, the body adjacent the intersecting point having a strength weaker than a portion of the body distanced from the intersecting point. 
     
     
         9 . The cover of  claim 1 , wherein the weakened material line is a V-shaped score. 
     
     
         10 . The cover of  claim 9 , wherein the body is formed of aluminum or steel. 
     
     
         11 . A downhole tool assembly comprising:
 a tubular body including a wall forming an inner diameter and an outer surface;   a fluid port through the tubular body;   a closure installed to be configurable between a position covering the fluid port and a position exposing the fluid port; and   the fluid port cover of  claim 1  installed in the fluid port.   
     
     
         12 . The assembly of  claim 11 , wherein the fluid port cover is sealed against the fluid port by a seal compressed in the fluid port between an annular insert and the perimeter of the fluid port cover. 
     
     
         13 . The assembly of  claim 12 , wherein the annular insert is selected to meter fluid flow through the port. 
     
     
         14 . The assembly of  claim 12 , wherein the annular insert comprises a nozzle defining a flow path for fluid therethrough. 
     
     
         15 . The assembly of  claim 12 , wherein the fluid port comprises a gland in its wall for receiving a retaining ring for securing the insert against the seal and the fluid port cover. 
     
     
         16 . The assembly of  claim 11 , wherein the closure comprises a sliding sleeve. 
     
     
         17 . A method for operating a downhole tool comprising:
 providing a downhole tool including a tubular body including a wall forming an inner diameter and an outer surface; a fluid port through the tubular body; a closure installed to be configurable between a position covering the fluid port and a position exposing the fluid port; and the fluid port cover of  claim 1  installed in the fluid port;   positioning the downhole tool within a wellbore; and   creating a pressure differential across the fluid port cover to initiate a tear in the fluid port cover.   
     
     
         18 . The method of  claim 17 , wherein the closure comprises a sliding sleeve. 
     
     
         19 . The method of  claim 17 , further comprising metering fluid flow through the fluid port.