Patent ID: 6084403
Filing Date: 2000-07-04
Classification: E21B,G01B

Abstract:
A slim hole induction collar locator tool for detecting the location of collars in a casing string, comprising:a transmitter coil disposed within a high-strength metallic pressure housing, the transmitter coil connected to receive an oscillating current input and to transmit an oscillating magnetic field external to said pressure housing;a first receiver coil disposed within said pressure housing at a location spaced from said transmitter coil;a second receiver coil disposed within said pressure housing at a position spaced from said transmitter coil and proximate said first receiver coil;phase detection circuitry connected to said first receiver coil and to said second receiver coil;said first and second receiver coils being constructed to detect said oscillating magnetic field and to provide corresponding signals to said phase detection circuitry;whereby the presence of collars in the casing string are indicated by changes in the phase relationship of signals received by first receiver coil and second receiver coil;wherein the pressure housing is dimensioned to be insertable through a tubing string operatively positioned within the casing string, such that the tool can detect the location of collars in the casing string beyond a distal end of the tubing string; andwherein the outside diameter of the pressure housing is less than 2.75 inches.