Author: Zachary Farrell
Combining Datasets From Challenging Inspections
Managing rivers, bends and multi-diameters
In a Nutshell:
We know that having a full picture of every asset and an understanding of its condition along the full pipeline length is essential to safe and efficient operation. In-line inspection (ILI) tools have proven effective for collecting this knowledge for over 50 years; however, it seems there are pipelines that just were not meant to be fully inspected, and the only way to gain any insight into their condition is to dig them up.
Or is it? Pipeline digs are expensive, and, as the industry advances, there are ways for ILI to inspect even the most complicated pipelines. Of course, only inspecting part of the pipeline is not sufficient. Clearly, pipeline digs are sometimes needed but gathering pipeline inspection data using ILI is essential for the safety, lifetime and performance of the asset.
The proposed inspection first came to ROSEN Canada from a Canadian operator. A decrease in diameter in the middle section of the pipeline was identified as a notable feature of concern, requiring inspection to further investigate and maintain details of the line as a whole. The specifications included a river crossing inspection with an 8" diameter (d) for 200 m; the line then transitioned down to a 6"d for 300 m, then back to the 8"d for the remaining 1600 m. The 8" sections of the line had previously been inspected, but due to the challenging nature of the multi-diameter pipe, the entirety of the line had never been inspected, providing the operator with very few details of this section. The operator was previously unable to reach a solution that would allow inspection of the subject segment without having to dig up the section under the river. ROSEN was approached in hopes of creating a solution that would allow the entire pipeline to be inspected.
Coming up with a plan
After having assessed the line in its entirety – which meant gaining an understanding not only of the characteristics of its routing but also its operational conditions – and surrounding areas, ROSEN experts discovered that the main challenges would not only include the various diameters but also access. The pipeline had such a low maximum operating pressure that a conventional ILI tool was not suitable. In addition, how would a tool suitable for gathering data in a smaller 6"d line make its way through the previous 8" section without proper sealing to be propelled through? And how would it not get stuck when transitioning to the smaller diameter? It also became clear that a single tool would not be sufficient, as the 6" tool would not be able to achieve full coverage or collect complete data in the bigger sections.
To face these challenges, ROSEN Canada worked to create a new pull unit design for the 6-inch tool. This new design allowed the tool to be run through the 8" pipeline to successfully inspect the 6" section by using ROSEN wireline truck along with the 6" and 8" bidirectional tools. In conjunction with the 6" tool, the 8" tool was prepared to capture the data within the first 200 m of the pipeline.
In order to provide a complete and effective report for the customer, the data evaluation experts then combined the data from the two sections. The team was able to combine the datasets from both tools by stitching together the data from each section. To ensure the sections were matched correctly, equivalent welds were used as matching points. The combined datasets then allowed the data evaluation team to evaluate the data as one whole pipeline and deliver a comprehensive report, providing the operator with valuable details to fill in the gaps in the details of the multi-diameter pipeline.