In order to carry out successful intelligent inspections (ILI) in pipelines carrying high concentrations of paraffinic and/or asphaltenic crude as well as sands, carbonates and sulphate deposits, it is necessary to consider the presence of deposits on the internal wall which can prove to be hard and adherent.
These deposits are more likely to be present in subsea pipelines due the low temperatures they are exposed to. Such deposits make it challenging to obtain reliable inspection data for the following reasons:
- Reduced contact between sensors and the pipe wall limiting the inspection effectiveness
- Odometric wheels slippage due to wax
- Abnormal wear or failure of the sensors due to friction with hard scale
This paper concerns a 12" sealine that was first inspected in 2012 following a standard cleaning pig procedure. Presence of a large amount of deposits made the results of this first inspection partially unusable. Following this, it was important to develop a more effective pre-inspection cleaning methodology, which was adopted for the 2015 ILI and fine-tuned for the 2017 and 2019 ILI.
The improved cleaning system was not only more effective but also significantly increased the inspection program efficiency; the entire operation lasted 15 days as opposed to 30. Furthermore, the results of the intelligent pig inspection allowed a comprehensive assessment of the current integrity conditions and future integrity of the pipeline. The total MFL data loss in 2012 was around 50 %; in the most recent inspection over 97% of the pipeline was captured.
Reinhart Hydrocleaning SA’s technology, TECMA’s turn key operations experience and Baker Hughes ILI capabilities were successfully combined and deployed to achieve a reliable, high resolution, multi technology report giving the customer confidence in the integrity of their asset.