Locating a missing tool in a subsea pipeline can be particularly challenging, especially when there are no means of tracking through traditional methods such as electromagnetic transmitters and receivers. During a recent operation, a magnetic surveying system was deployed to locate an in-line inspection (ILI) tool quickly and effectively, offering a reliable solution in a challenging environment. This case study highlights how it was used and its potential application in subsea operations.
Project Background
Our client was performing an in-line inspection as part of a pre-commissioning scope of work in the Mediterranean. During this process, the ILI tool, which was part of a pig train, was received in a damaged condition and part of the tool was missing. This posed a significant challenge, as the batteries in the transmitters on the standard bi-directional pigs – supplied by a third party manufacturer – had depleted, leaving no active signals to locate the lost tool.
A quick solution was required as locating the Magnetic Flux Leakage (MFL) tool was critical to avoid ongoing vessel costs and potential project delays. With no functioning transmitters but the presence of a magnetic source available, IK Trax proposed using a magnetic surveying system to locate the tool, an option that was quickly approved by the end client.
Our team mobilised a technician and equipment to the vessel, where they worked with an ROV operator to survey a 50m section of the pipeline and surrounding manifold area. The system was mounted in the ROV manipulator, with its screen visible through the ROV camera. The technician monitored the live readings displayed on the screen and, despite magnetic interference in the area, detected a clear spike in the readings when the tool was within range. This hotspot was within an electric valve and the results were confirmed through repeated scans leading to the successful identification of the tool’s location.
Magnetic Surveying System
The magnetic surveying system provided real-time numerical or graphical representations of gauss readings.
The system functioned as follows:
- A live feed displayed variations in magnetic field as the ROV maneuvered through the pipeline area
- Readings indicated a spike in the magnetic field, which implied a potential magnetic signature from the pig
- The team used constant monitoring and fly-bys to confirm the location of the magnetic tool
Using this approach is most effective for shorter pipe sections where the approximate search area is already known. The system’s functionality demonstrates its versatility, proving its effectiveness in challenging subsea environments with potential magnetic interference from ROVs, manifolds and valves.
Future Applications
The successful deployment of the magnetic surveying system during this project highlights its potential for broader applications.
Contingency Planning
Operators can integrate this technology into their standard procedures as a contingency tool. It’s ability to detect magnetic fields without relying on active transmitters makes it an ideal backup solution for scenarios where transmitters are not available, for example when batteries are depleted.
Long-Term Subsea Operations
For operations requiring extended monitoring, such as when pigs are to remain in the pipeline for months or even years, this system can be used to track pigs equipped with powerful magnets instead of transmitters. This approach eliminates concerns about transmitter battery life while still providing reliable confirmation of the pig’s position, even after extended periods.
Real-Time Monitoring
The system’s real-time magnetic field readings offer operators a valuable tool for locating and identifying irregularities, enabling swift and accurate responses to unforeseen situations.
Conclusion
By using this magnetic surveying system, we were able to locate the missing tool quickly and accurately, saving the client both time and money by avoiding costly vessel time and project setbacks. This successful deployment highlights the versatility of the system and its potential to provide an effective solution in a wide range of operational scenarios.
Interested in hearing more about this or other applications? Contact our specialists today.
