Instrumented Strakes for Subsea Riser VIV Monitoring
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for measuring vortex-induced vibration (VIV) in deepwater risers are inadequate due to the inability to obtain accurate, timely data along the length of the riser and across the full water column, relying on modeling and requiring high safety factors in design.
Innovation Solution
A system of fiber-optic sensors installed directly within the strakes or fairings of the riser, capable of measuring strain, temperature, pressure, vibration, and fatigue, providing real-time data transmission to monitor structural responses effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fiber-optic sensors are installed directly within the strakes or fairings, then measurement precision and data reliability are improved, but device complexity increases
Solution Approach 1:
The patent combines the VIV suppression device (strake or fairing) with the measurement device (fiber-optic sensor) into a single integrated unit. The sensor is installed directly within the strake or fairing structure, merging the flow suppression function with the measurement function. This eliminates the need for separate sensor mounting apparatus and reduces overall system complexity while improving measurement accuracy by placing sensors directly in the flow field.
Solution Approach 2:
The strake or fairing structure serves dual purposes: it acts as both a VIV suppression device and as a mounting structure for the fiber-optic sensor. This multi-functionality reduces the number of separate components needed in the system, thereby reducing device complexity while enabling precise measurements of vortex-induced vibrations.
2Measurement precision
If multiple sensor stations are installed along the riser, then measurement precision along the water column is improved, but ease of manufacture deteriorates
Solution Approach 1:
The riser is divided into multiple segments, each equipped with its own strake or fairing containing a fiber-optic sensor. This segmentation allows measurements to be taken at multiple locations along the water column, improving spatial resolution and measurement precision. Each segment can be manufactured and installed independently, maintaining ease of manufacture through modular deployment.
Solution Approach 2:
The fiber-optic sensors are pre-installed within the strakes or fairings before these components are attached to the riser. This preliminary action simplifies the overall installation process, as the sensors are already integrated into the suppression devices and require no additional mounting steps during riser deployment.
3Reliability
If safety factors of 10-20 are used in design, then reliability is improved, but loss of substance increases due to over-design
Solution Approach 1:
The fiber-optic sensors provide real-time feedback data on the actual vortex-induced vibrations and structural responses of the riser. This empirical data allows operators to replace conservative safety factors with actual measured information, enabling more efficient design and operation. The feedback loop eliminates the need for excessive safety margins while maintaining reliability through continuous monitoring and data-driven decision-making.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate, near real-time monitoring of VIV effects, enhancing riser design efficiency and safety by providing reliable, timely data without disrupting the costly installation process.
Implementation Method 1
A system of fiber-optic sensors installed directly within the strakes or fairings of the riser, capable of measuring strain, temperature, pressure, vibration, and fatigue
Implementation Method 2
Vortex induced vibration (VIV) of offshore structure originates when fluid (either gas as in wind, or liquid as in seawater, for example) passes a bluff body and causes low pressure eddys or vortices to form downstream of the body. The vortices are shed periodically
Implementation Method 3
A helical strake consists of a number of fins wound as a helix around the periphery of the riser. The helical strakes shed the vortices into finite cells and length, both shortening and weakening the vortices
Implementation Method 4
Fairings are aerofoil-shaped structures that streamline flow and reduce the VIV by weakening vortices that are shed at that location
Implementation Method 5
This phenomenon affects a vast array of structures, particularly in offshore locations, and is due primarily to ocean current interacting with the riser
Data Source
AI summary
A vortex induced vibration suppression system for use on a subsea riser system having either a stake or fairing component includes at least one fiber optic sensor mounted on the component. The fiber optic sensor associated with the riser includes at least one sensor for producing a sensor signal. The system may include a plurality of sensors and the plurality of signals produced thereby are combined at a multiplexer for generating a single, composite sensor signal. The signal may be monitored in real time or near real time for observing and monitoring the reaction of the subsea riser to conditions inducing vibration.