Magnetic Pig Positioning Through Distorted Steel Pipe Fields
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Magnet-based pig position detection systems in hydrocarbon pipelines face challenges due to magnetic field distortions caused by carbon steel pipes and external factors, leading to unreliable position measurements and limited measurement range.
Innovation Solution
A method and system using a magnetic field source attached to the pig, with magnetic field sensors outside the pipe to measure parameters, and a processor to compute the pig's position relative to a reference, employing magnetic field representation models and in-situ calibration to compensate for background noise and distortions, enhancing accuracy and range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If magnet-based detection systems are used to detect pig passage by measuring magnetic field strength changes, then the system avoids HSE issues associated with nucleonic devices, but the system becomes unreliable due to sensitivity to external distortions from carbon steel pipes, valves, junctions, and earth's magnetic field
Solution Approach 1:
The system transitions from measuring only magnetic field strength (one dimension) to measuring both magnetic field strength and direction (two dimensions). By detecting changes in magnetic field direction in addition to strength, the system can distinguish between pig passage signals and distortion signals from pipe components, thereby maintaining reliability in the presence of magnetic field distortions.
Solution Approach 2:
The system continuously monitors magnetic field parameters and uses this feedback to dynamically adjust detection thresholds and algorithms. By analyzing patterns in magnetic field strength and direction changes over time, the system can differentiate between genuine pig passage events and spurious signals caused by pipe valves, junctions, or earth's magnetic field variations.
2Productivity
If the arctan function method is used to calculate linear position of a magnet, then the calculation is simple and fast, but the position estimation deviates exponentially from true position when the magnet is displaced from the sensor
Solution Approach 1:
The system changes the mathematical parameters used for position calculation from simple trigonometric functions to more sophisticated models that account for magnetic field distortion by carbon steel pipes. By incorporating calibration data and using enhanced calculation algorithms, the system maintains computational efficiency while significantly improving position accuracy over larger displacement ranges.
Solution Approach 2:
The system performs preliminary calibration measurements to establish the relationship between magnetic field parameters and actual positions before operational use. This pre-established calibration data is then used to correct position calculations during actual pig tracking, allowing the system to maintain high accuracy without requiring complex real-time computations.
3Reliability
If multiple sensors are used in an array to increase measurement range, then the reliability range is improved, but the device size and complexity greatly increase, which is undesirable for subsea applications with limited installation space
Solution Approach 1:
Instead of adding multiple sensors spatially (increasing device size), the system enhances the measurement capability of a single sensor by detecting multiple parameters (magnetic field strength and direction). This dimensional expansion of measurement parameters allows the system to achieve extended reliable measurement range without increasing physical device size, making it suitable for subsea applications.
Solution Approach 2:
The system replaces the mechanical approach of using multiple physical sensors with a computational approach that uses advanced algorithms and multi-parameter measurement from a single sensor location. This substitution reduces device complexity and size while maintaining or improving measurement reliability through software-based signal processing and distortion compensation.
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 system provides accurate and reliable pig position measurement over a wider range, reducing sensitivity to magnetic distortions and enabling precise detection of pig type and movement, suitable for both subsea and land applications.
Implementation Method 1
a magnetic field source (1) creating a magnetic field (2) extending to the outside of the pipe (5)
Implementation Method 2
a magnetic field sensor (6) arranged on the outside of the pipe (5) and adapted to measure the magnetic field (2) provided by the magnetic field source (1)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
It is disclosed a system for determining the position of a pig (4) located inside a pipe (5) comprising: • a magnetic field source (1) attached to the pig (4); • at least one magnetic field sensor (6) provided on the outside of the pipe (5) and configured to measure magnetic field parameters; and • a processor configured to receive magnetic field parameters from the at least one magnetic field sensor (6) and computing a position of the magnetic field source (1) relative to a given reference position. The system is used in a method comprising the steps of: • establishing a magnetic field representation of the magnetic field (2) provided by the magnetic field source (1); • in-situ measuring at least two magnetic field parameters outside the pipe (5) by means of the at least one magnetic field sensor (6) at least at one given measuring position relative to the reference position; • computing the source position of the magnetic field source (1) relative to the reference position based on data comprising the in-situ measured magnetic field parameters and the magnetic field representation of the magnetic field (2) provided by the magnetic field source (1); and • outputting data on the source position of the magnetic field source (1) relative to the reference position.