Indicating system for a downhole apparatus and a method for locating a downhole apparatus

Abstract

A system for locating a downhole apparatus includes a wellbore having an interior pressure cavity, wherein the apparatus is disposed in the pressure cavity, a magnetic device for generating a magnetic field in the pressure cavity, and a magnetic field indicator disposed external to the pressure cavity, the magnetic field indicator responsive to the magnetic field in the pressure cavity, wherein the magnetic field is indicative of a position of the apparatus in the pressure cavity.

We claim: 
     
         1 . A system for locating a downhole apparatus, the system comprising:
 a wellbore having an interior pressure cavity, wherein the apparatus is disposed in the pressure cavity;   a magnetic device for generating a magnetic field in the pressure cavity; and   a magnetic field indicator disposed external to the pressure cavity, the magnetic field indicator responsive to the magnetic field in the pressure cavity,   wherein the magnetic field is indicative of a position of the apparatus in the pressure cavity.   
     
     
         2 . The system according to  claim 1 , further comprising a pressure barrier disposed in the wellbore and defining the interior pressure cavity. 
     
     
         3 . The system according to  claim 2 , wherein the pressure barrier is formed from a magnetic material. 
     
     
         4 . The system according to  claim 2 , wherein the pressure barrier is formed from a non-magnetic material. 
     
     
         5 . The system according to  claim 2 , wherein the magnetic device is disposed external to the pressure cavity and generates the magnetic field through a wall of the pressure barrier. 
     
     
         6 . The system according to  claim 2 , wherein the magnetic device comprises an inductive coil disposed external to the pressure cavity and generates the magnetic field through a wall of the pressure barrier. 
     
     
         7 . The system according to  claim 2 , further comprising a permeable structure disposed adjacent the magnetic device and at least a portion of the pressure barrier, wherein the magnetic field is directed through at least a portion of the permeable structure 
     
     
         8 . The system according to  claim 1 , wherein the magnetic device is coupled to the apparatus. 
     
     
         9 . The system according to  claim 1 , further comprising a permeable structure disposed adjacent the magnetic device, wherein the magnetic field is directed through at least a portion of the permeable structure. 
     
     
         10 . The system according to  claim 1 , wherein the magnetic field indicator comprises at least one indicator visible external to the pressure cavity. 
     
     
         11 . The system according to  claim 1 , wherein the magnetic field indicator comprises at least one of a passive magnetic field detector, a Hall effect sensor, a magnetoresistance sensor, and a fluxgate magnetometer. 
     
     
         12 . The system according to  claim 1 , wherein the magnetic field indicator comprises a reed relay that is automatically actuated in response to a predetermined magnitude of the magnetic field. 
     
     
         13 . The system according to  claim 1 , wherein the magnetic device is disposed in the pressure cavity and in electrical communication with the magnetic field indicator to sense a change in the magnetic field generated by the magnetic device. 
     
     
         14 . A method for locating a downhole apparatus, comprising:
 generating a magnetic field in an interior pressure cavity of a wellbore;   passing the apparatus through the pressure cavity of the wellbore; and   monitoring at least one of a presence and a magnitude of the magnetic field, wherein the at least one of the presence and the magnitude of the magnetic field is indicative of a location of the apparatus in the pressure cavity.   
     
     
         15 . The method according to  claim 14 , wherein a magnetic device is coupled to the apparatus to generate the magnetic field. 
     
     
         16 . The method according to  claim 14 , wherein a magnetic device is disposed external to the pressure cavity to generate the magnetic field extending into the pressure cavity. 
     
     
         17 . A method for locating a downhole apparatus disposed in a pressure cavity of a wellbore, the wellbore including a pressure barrier defining the pressure cavity, the method comprising the steps of:
 generating a magnetic field in the pressure cavity of the wellbore, the magnetic field extending through the pressure barrier;   passing the apparatus through the pressure cavity of the wellbore; and   monitoring at least one of a presence and a magnitude of the magnetic field adjacent a pre-determined section of the pressure barrier, wherein the at least one of the presence and the magnitude of the magnetic field is indicative of a location of the apparatus in the pressure cavity.   
     
     
         18 . The method according to  claim 17 , wherein the pressure barrier is formed from a magnetic material. 
     
     
         19 . The method according to  claim 17 , wherein the pressure barrier is formed from a non-magnetic material. 
     
     
         20 . The method according to  claim 17 , wherein the step of monitoring at least one of the presence and the magnitude of the magnetic field adjacent a pre-determined section of the pressure barrier is executed by a toggling of a reed relay.