More and more pipelines operate at pressures lower than 34 bar (500 psi), especially in the gas or multiphase service, and operators are looking to vendors to provide inspection solutions. In low pressure pipelines, though many other obstacles may also exist, a dominant challenge is to overcome speed excursions during the inspection. Though the factors that contribute to speed excursions, such as excessive girth welds, bends, dents, diameter changes, riser stations, etc., exist in most pipelines, the effects are increased in a low flow or low pressure environment. In this particular case the following challenges were found in the operators 10” pipeline:
- Sour gas pipeline
- Operating pressure of ~10 bar (145 psi)
The operator’s needs were clear, provide a solution that ensures tool velocity is within optimal data quality specifications without any disruptions to normal pipeline operations, and deliver metal-loss analysis. With that in mind ROSEN’s Challenging Pipeline Diagnostics engineers set forth to optimize the dynamic behavior of the inspection solution, concentrating on three core objectives:
- Minimize overall friction to keep the differential pressure changes as low as possible
- Establish constant friction to avoid changes in differential pressure when passing certain pipeline features
- Minimize difference between static and dynamic friction to avoid the ILI system from stopping and to avoid pressure release after buildup to continue the inspection
The solution uses ROSEN’s high resolution MFL technology, supplemented with the following elements:
- Low friction pull and sensor unit
- Ultra-compact design On-site analysis of operating conditions
- Pipeline data logger analysis
- Recommendations to manage pressure levels
Inspection can be performed during standard operation eliminating pipeline downtime.
Low flow / low pressure tailored system avoids the need for costly onsite support equipment and additional mediums such as nitrogen.
Safety and Compliance
System design reduces probability of speed excursions thus ensuring a complete data set.