Downhole Eddy Current Sensor for Cable Detection
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Solution Overview
Problem
Downhole cables or control lines are at risk of damage during well perforation due to explosive charges, which can render the well inoperable or make operations more difficult.
Innovation Solution
A downhole tool equipped with an eddy current sensor that rotates around the inner wall of the well casing to detect the presence of cables or control lines on the external wall, using pulsed alternating current to generate magnetic fields and analyze the response for metal presence, allowing for precise location and avoidance during perforation planning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If explosive charges are fired through the well casing for perforation, then flow path for oil and gas is created, but downhole cable or control line on the outside may be damaged or broken
Solution Approach 1:
The eddy current detection tool is deployed before perforation operations to map the location of downhole cables and control lines on the well casing exterior. This preliminary detection enables operators to plan perforation patterns that avoid these sensitive components, preventing damage before it occurs while still achieving the desired flow path creation
2Measurement precision
If eddy current sensor is placed close to well casing for detection, then detection precision is improved, but risk of sensor damage or interference increases
Solution Approach 1:
The well casing itself serves as an intermediary medium between the eddy current sensor and the downhole cables. The sensor detects changes in the casing's electromagnetic properties caused by the presence of cables on the exterior, allowing indirect detection without requiring the sensor to contact or come close to the cables, thus avoiding direct exposure to harmful factors
3Use of energy by moving object
If pulsed operation is used for eddy current sensor, then energy consumption is reduced, but detection time increases
Solution Approach 1:
The eddy current sensor operates in pulsed intervals rather than continuously, emitting electromagnetic pulses and measuring the resulting eddy currents during each pulse cycle. This periodic operation significantly reduces energy consumption compared to continuous operation while maintaining adequate detection capability through signal averaging and filtering across multiple pulses
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The tool effectively detects and maps the location of downhole cables or control lines, enabling the planning of perforation patterns that avoid damaging these components, thereby ensuring well operation integrity.
Implementation Method 1
The eddy current sensor may be arranged to produce an alternating electrical current. This alternating electrical current creates an alternating magnetic field, which results in the creation of eddy currents in the target material.
Implementation Method 2
This alternating electrical current creates an alternating magnetic field, which results in the creation of eddy currents in the target material. In turn, the eddy currents produce a magnetic field which opposes the field that has been created by the eddy current sensor.
Data Source
AI summary
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.