PR-670-183826-R01 Assessment of Science Behind LSM for Pipeline Integrity

Integrity assessment of pipelines is vital to ensure that oil and gas pipes have adequate strength to prevent leaks and ruptures. Regular inspections are conducted to confirm safe operation conditions of pipelines. The industry's principle method for assessing pipelines is in-line inspection (ILI), involving the passing of a device along the inside of a pipe to assess the condition of the pipeline. ILI devices can be fitted with a number of sensors allowing various measurement parameters to be obtained simultaneously.

Not all pipelines are suited to ILI for reasons such as small diameter, obstructions within the pipe, or insufficient access to deploy or retrieve the ILI tools. These pipelines are sometimes referred to as 'difficult to inspect'. Alternative methods for examining pipeline condition are required, with a range of technologies collectively known as Large Standoff Magnetometry (LSM) offering a promising solution for detection of pipe defects from a distance, reducing the need for excavation.

LSM utilises the coupling between defects and changes in the magnetic properties of the pipeline material as a method for evaluation of pipe walls to identify the location of areas that require repair or further monitoring. Trials of existing commercial instruments by the pipeline industry have shown sufficient promise to investigate the technologies further. However, vendors have supplied limited information on the underpinning physics of both the materials being tested and the instrument technology.

The purpose of the project is to establish the ability of LSM to detect corrosion in API 5L pipe grades B to X70. The aim of Work Package 02 is to review the physics of the agreed pipeline defects and fluxgate type magnetic sensors. The properties of pipeline-specific soft magnetic materials are investigated to understand corrosion, how this alters the material properties and how this can affect the associated magnetic fields surrounding the material. The physics of fluxgate magnetometers and gradiometers are also reviewed to assess the ability of LSM to detect these two features.