Downhole detection tool
First Claim
1. A downhole tool for the detection of downhole cable or control lines, the downhole tool comprising:
- an eddy current sensor, the eddy current sensor being arranged to be proximate to an internal wall of a well casing,wherein the eddy current sensor includes a receiver coil and a transmitter coil, where the receiver coil and the transmitter coil are configured in a nested arrangement, andwherein the eddy current sensor is arranged for pulsed operation whereby an electrical pulse is generated in the transmission coil so as to generate eddy currents in the internal wall of the well casing and the downhole cable or control lines, the receiver coil being arranged to detect a magnetic field generated by the eddy currents,a rotational mechanism to rotate the eddy current sensor, with an axis of rotation parallel with the longitudinal axis of the well casing, anda control unit including a processing unit arranged to;
process readings taken by the eddy current sensor, monitor a decay of the magnetic field induced by the eddy currents generated by the electrical pulse, analyse a tail end of a response curve of the receiver coil readings obtained during the decay, andprovide an indication of where downhole cable or control lines are detected at an outer wall of the well casing on the basis of the decay of the magnetic field.
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Accused Products
Abstract
The present invention concerns a downhole cable or control line detection tool. More particularly, but not exclusively, this invention concerns a method and apparatus for the downhole detection of a cable or control line associated with the external wall of a well casing. A downhole tool for the detection of downhole cable or control lines is provided. The downhole tool comprises an eddy current sensor, the eddy current sensor being arranged to be proximate to the internal wall of a well casing. The eddy current sensor is arranged for pulsed operation. The downhole tool further comprises a mechanism for rotating the eddy current sensor, with an axis of rotation parallel with the longitudinal axis of a well casing.
12 Citations
23 Claims
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1. A downhole tool for the detection of downhole cable or control lines, the downhole tool comprising:
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an eddy current sensor, the eddy current sensor being arranged to be proximate to an internal wall of a well casing, wherein the eddy current sensor includes a receiver coil and a transmitter coil, where the receiver coil and the transmitter coil are configured in a nested arrangement, and wherein the eddy current sensor is arranged for pulsed operation whereby an electrical pulse is generated in the transmission coil so as to generate eddy currents in the internal wall of the well casing and the downhole cable or control lines, the receiver coil being arranged to detect a magnetic field generated by the eddy currents, a rotational mechanism to rotate the eddy current sensor, with an axis of rotation parallel with the longitudinal axis of the well casing, and a control unit including a processing unit arranged to; process readings taken by the eddy current sensor, monitor a decay of the magnetic field induced by the eddy currents generated by the electrical pulse, analyse a tail end of a response curve of the receiver coil readings obtained during the decay, and provide an indication of where downhole cable or control lines are detected at an outer wall of the well casing on the basis of the decay of the magnetic field. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of detecting a downhole cable or control line running along an external wall of a well casing, comprising the steps of:
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providing an eddy current sensor and locating the eddy current sensor in proximity to an internal wall of the well casing, wherein the eddy current sensor includes a receiver coil and a transmitter coil, where the receiver coil and the transmitter coil are configured in a nested arrangement, sending a pulse of current to the eddy current sensor, thereby generating a magnetic field, and creating eddy currents in the well casing, measuring, using the eddy current sensor, the magnetic field generated by the eddy currents induced within the downhole cable or control line, moving the eddy current sensor around the circumference of the internal wall of the well casing, repeating the generating and measuring steps, analysing the measurement results of the eddy current sensor, including; processing the readings taken by the eddy current sensor, monitoring a decay of the magnetic field induced by the eddy currents generated by the electrical pulse, analysing a tail end of the magnetic field response curve of the eddy current sensor readings during the decay, wherein the analysis identifies any readings which present a profile suggestive of the downhole cable or control line; and providing an indication of where the downhole cable or control lines are detected at an outer wall of the well casing on the basis of the decay of the magnetic field created by the eddy currents, and recording the location corresponding to any such indications of where the downhole cable or control lines are detected. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23)
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Specification