Casing Defect Detection via Alternating Current Magnetic Field
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Solution Overview
Problem
Existing measurement tools for oil and gas exploration in boreholes face challenges due to pressure and temperature conditions, which affect their accuracy in detecting anomalies in metal casings, such as corrosion or cracks, within the borehole environment.
Innovation Solution
A tool with two electric connectors and a magnetic sensor is used to excite an alternating current in the casing, generating a magnetic field that changes when anomalies are present, allowing for precise location and sizing of defects through signal processing, with the connectors maintaining contact via brush or bow-spring types and the sensor detecting the induced magnetic field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If permanent magnets are used to generate magnetic flux in the casing, then magnetic field changes can be detected to locate anomalies, but the primary magnetic field interferes with the detection signal reducing measurement precision
Solution Approach 1:
The patent removes the permanent magnet component that generates the primary magnetic field, extracting only the necessary function of inducing eddy currents through an alternating magnetic field generated by a coil, thereby eliminating the harmful primary magnetic field interference while maintaining anomaly detection capability
Solution Approach 2:
The patent replaces the static permanent magnet system with a dynamic coil-based alternating magnetic field system, substituting a mechanical/magnetic system with an electromagnetic induction system that does not produce harmful primary field interference
2Reliability
If high pressure and temperature conditions are present in the borehole, then measurements can be taken in situ, but the extreme conditions affect the operation and accuracy of measurement tools
Solution Approach 1:
The patent replaces mechanical contact-based measurement systems with electromagnetic induction and magnetic field detection systems that have no moving parts and are inherently more resistant to high pressure and temperature effects, thereby maintaining measurement reliability in extreme borehole conditions
3Measurement precision
If coil antennas are used to induce eddy current in the casing, then casing properties can be measured, but the measurement precision and quality of information derived may be limited
Solution Approach 1:
The patent extracts and eliminates the interfering primary magnetic field component from the measurement system, allowing the magnetic field sensor to detect only the secondary magnetic field generated by eddy currents at anomaly locations, thereby significantly improving measurement precision and information quality
Solution Approach 2:
The patent uses magnetic field sensors to detect changes in the magnetic field caused by eddy currents, processing these feedback signals to locate and characterize anomalies with high precision, thereby recovering and enhancing the quality of measurement information
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
This method provides high accuracy and low-cost measurements by avoiding interference from primary magnetic fields, enabling effective detection and imaging of anomalies with high signal-to-noise ratio, allowing for precise determination of anomaly size and thickness.
Implementation Method 1
two electric connectors...to excite an alternating current in the casing flowing in a longitudinal direction...generating a magnetic field
Implementation Method 2
a magnetic sensor...to detect the magnetic field at the site of interest
Implementation Method 3
excite an alternating current in the casing flowing in the longitudinal direction of the casing to generate a magnetic field
Data Source
AI summary
Various embodiments include apparatus and methods to inspect casing defects in a pipe such as a casing associated with a drilling operation. Electrical connectors contacting the inside wall of the pipe can be used to generate a current in the pipe. Magnetic fields correlated to an anomaly or anomalies that alter the current can be sensed to identify the presence of the anomaly or anomalies. Additional apparatus, systems, and methods are disclosed.