Canadian Operator Rehabilitates Pipeline Under Major Waterway in 7 Days
Date Installed:
September 2018
Location & Region:
NWT, Canada
Product Used:
8-inch MXL, 1500
Application:
Crude Oil
Project Overview
An Operator in the Northwest Territories, Canada, discovered massive wall loss on a crude line that forced a shutdown and caused economic loss to the nearby hamlet. Sub-freezing temperatures limited installation options for the portion of the pipeline running under the river. In just seven days, new FlexSteel pipe was pulled through the corroded pipeline to restore the line.
Key Points:
Long pull sections connectedthe islands to the mainland
All fittings were installedonshore
The new pipeline has real-time monitoring capabilities
The Challenge
In the early 1940’s an abundance of oil was found under the Mackenzie River in the Northwest Territories, Canada. This discovery led to the creation of man-made islands to facilitate drilling, with pipelines connecting the islands to each other and then to the mainland to get the oil to market. The adjacent hamlet of Norman Wells was thriving until late 2017 when an inline inspection showed massive wall loss in the primary 10-inch offtake pipeline.
The Canadian Energy Regulator (CER) forced the producer to shut down the line, threatening to cease operations for the entire area. A new directionally drilled pipeline would not be approved by regulator. An immediate solution was necessary to avoid stranding people and equipment due to dropping water levels.
The Solution
After careful calculations of the tension loads, it was determined that 8-inch FlexSteel pipe could be pulled through the 10-inch carrier pipe. The Operator chose flexible steel-reinforced pipe because it provides exceptional corrosion resistance and can be installed easily and quickly by pulling it through the old, corroded pipeline. The use of gauging pigs confirmed that the clearances in the carrier pipe would accommodate the new flexible steel pipeline.
However, upon review, it was noted that the resulting bell of a traditional midline fitting would not allow for adequate clearance at midline couplings. As the pull needed to be completed in one, continuous string, FlexSteel Engineering developed a unique solution.
By modifying various geometrical elements of the fitting design, FlexSteel was able to complete a near-complete swage of the fitting jacket during installation. In doing so, the contact area of the swage was increased, resulting in additional pressure sealing, and the outside diameter was consistent with the pipe, making it a near-flat profile. Once swaged, the fitting outer diameter matched that of the FlexSteel pipe, ensuring that clearance of the inserted pipeline would not prove limiting during installation.
The Result
Using the pipe-in-pipe installation method, CER permit approval was mitigated. FlexSteel engineering strategies eliminated the chances of a fitting diameter or bend that would prevent a successful pull. To size the line, tight-tolerance gauging pigs with plates mimicking the size and shape of the midline were run through the corroded line.
Installation began once it was confirmed that the new flexible steel-reinforced line could be pulled through the old, corroded line. Pipe packages were staged and deployed from the islands. Single coil packages were pulled into the carrier and then connected to a new coil by use of the midline fitting. This process was repeated until the pull head had made it out of the carrier on the other end on each of the four pull sections.
The final pull section from Goose Island to the mainland was completed and tied into the existing facility LACT unit. Deployment was completed by boat and at strategic areas on the islands. The tight workspace, rough water conditions, and extreme wildlife (e.g., bears, elk, moose) added complexity to the project.
ShieldSure® annulus testing confirmed the pipeline was free of shield damage from the installation. The entire installation process was completed in just 7 days. Real time monitoring using SCADA was connected to the FlexSteel pipeline to continually monitor the pipe’s performance for the life of the asset.
