Gaining Insight in Riser Movements

This case study highlights the collaboration between an independent oil & gas company, and 4Subsea, a provider of advanced digital monitoring solutions and analytics, to address lateral riser motions at the seabed.

Challenges

Since installation, the risers at the considered site in the North Sea have experienced unexpected lateral motions at the seabed, causing self-trenching of the risers. The self-trenching has raised concerns about the risk of contact with subsea structures, production shutdown, and the potential for leakage or burst.

Objectives

The primary goal of the project is to understand the riser motions through sensor data analysis and numerical model simulations. The insight gained through analysis enables mitigation and helps to enable continued safe operations.

Solution

To better understand the riser motions, 4Subsea’s engineers deployed a 4Subsea SMS Motion™ sensor on the riser near the touchdown area, aiming to capture the lateral riser motions. A current profiler was positioned on the seabed to monitor currents at varying depths in the area. The measurement campaign lasted 10 months, providing vast amounts of data that established a solid foundation for analysis.

Leveraging data from an additional motion sensor located further up on the riser, weather data, platform motion data and production data, a dedicated team of engineers from 4Subsea conducted a correlation and causation analysis. The analysis results were used to impose riser motions in a comprehensive numerical simulation study.

Conclusion

This case highlights the value of seamless end-to-end collaboration—from sensors and instrumentation to domain expertise and engineering. Working closely with the Client and leveraging a robust data foundation, 4Subsea’s team were able to deliver a comprehensive understanding of the observed riser motions. This collaboration demonstrates how a strong, analytical approach enables proactive management of complex challenges, ensuring long-term safety and integrity of assets.