Abstract A pipe joint locator for use in drilling underwater wells for locating pipe joints of a drill string. The locator including a ring magnet for producing a magnetic field for magnetizing pipe joints passing through the ring. A plurality of Hall effect detectors circularly positioned in a plane parallel to and spaced from the plane of the ring magnet and equally spaced apart for measuring quantitative amounts of ferrous objects. Means connected to the detectors for determining the location of any pipe joints moving through the locator. A second set of plurality of Hall effect detectors positioned in a plane parallel to the plane of the ring and spaced on a second side of a ring magnet. Preferably, each set of detectors includes four detectors spaced approximately ninety degrees apart. A tubular housing positioned internally of said magnet and detectors. The output of each set of detectors being combined for avoiding errors due to non-axial movement of the pipe through the locator. Measuring means connected to the detector combining the difference between the output of the first set of detectors and the second set of detectors.
A pipe joint locator for well pipe comprising, a tubular housing through which pipe and connecting joints may be moved, a ring magnet positioned about the housing for producing a magnetic field axially through the housing, a first set of four Hall effect detectors circularly positioned about the outside of said housing and spaced on one side of the ring magnet for measuring a deflection of the magnetic field caused by the movement of a pipe joint through the magnetic field, a second set of four Hall effect detectors circularly positioned about the outside of said housing and spaced on the second side of the ring magnet for measuring a deflection of the magnetic field caused by the movement of a pipe joint through the magnetic field, the output of the first set of detectors being combined, the output of the second set of detectors being combined, and means connected to said outputs for determining the location of any pipe joints moving through the locator.
Claim 2
Dependent Claim
165 words
A pipe joint locator for well pipe comprising, a tubular housing through which pipe and connecting joints may be moved, a ring magnet positioned about the housing for producing a magnetic field axially through the housing, a first set of four Hall effect detectors circularly positioned about the outside of said housing and spaced on one side of the ring magnet for measuring a deflection of the magnetic field caused by the movement of a pipe joint through the magnetic field, a second set of four Hall effect detectors circularly positioned about the outside of said housing and spaced on the second side of the ring magnet for measuring a deflection of the magnetic field caused by the movement of a pipe joint through the magnetic field, the output of the first set of detectors being combined, the output of the second set of detectors being combined, and means connected to said outputs for determining the location of any pipe joints moving through the locator.
Claim 3
Dependent Claim
30 words
The apparatus of claim 1 wherein the difference between the combined output from the first set of detectors and the combined output of the second set of detectors is measured.