VRMT Sensors for Drilling Riser Tension Monitoring
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Solution Overview
Problem
Drilling risers and riser towers face increased stresses and pressures due to longer lengths and deeper subsea installations, leading to potential structural failures from compressive stresses and buckling, necessitating a system to monitor forces and ensure timely servicing.
Innovation Solution
The implementation of variable reluctance measurement technology (VRMT) sensors to remotely monitor tension, compression, and bending moments on drilling risers and riser towers, utilizing optimized sensor configurations with increased wire turns and mechanical amplifiers, allowing for real-time health assessment of the riser system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If riser length is increased to reach deeper subsea installations, then operational capability is improved, but compressive stresses and buckling risks increase
Solution Approach 1:
The patent applies preliminary action by installing VRMT sensors and mechanical amplifiers on the riser before deployment to deeper waters. This allows pre-configured monitoring capability that can detect compressive stresses and buckling risks from the outset, enabling proactive intervention before structural failure occurs.
Solution Approach 2:
The patent implements feedback through the VRMT sensor system that continuously monitors forces and stresses on the riser in real-time. The mechanical amplifiers amplify subtle deformations, and this feedback information is used to assess riser health and trigger servicing operations when thresholds are approached, resolving the contradiction between increased length and maintained strength.
2Length of moving object
If riser length is increased, then deeper water access is enabled, but tension forces and unsupported weight increase
Solution Approach 1:
The VRMT sensor system provides continuous feedback on tension forces along the riser length. By monitoring these forces in real-time, the system can identify high-stress zones and trigger buoyancy module deployment or other countermeasures to redistribute loads, enabling deeper water operation while managing increased tension forces.
Solution Approach 2:
The patent employs buoyancy modules as counterweights to offset the increased unsupported weight of longer risers. The VRMT monitoring system identifies when tension forces exceed thresholds, triggering buoyancy module deployment to provide upward counterforce, thereby enabling extended riser length without proportional increase in net tension forces.
3Measurement precision
If VRMT sensors are optimized with increased wire turns, then measurement precision is improved, but sensor complexity increases
Solution Approach 1:
The patent applies parameter changes by increasing the number of wire turns in the VRMT sensors to enhance measurement precision. This parameter modification increases the sensitivity of the sensors to subtle forces and deformations on the riser. The added complexity is justified by the critical need for precise force monitoring in deepwater riser applications.
Solution Approach 2:
The patent introduces mechanical amplifiers as intermediaries between the riser structure and the VRMT sensors. These amplifiers magnify subtle deformations, allowing the sensors to achieve high measurement precision without requiring excessively complex sensor configurations. The mechanical amplifiers serve as mediators that translate minute structural changes into measurable sensor signals.
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 reliable, real-time monitoring of forces on drilling risers and riser towers, enhancing their structural integrity by detecting changes in stress and tension, thereby preventing failures and facilitating timely maintenance.
Implementation Method 1
Variable reluctance measurement technology ('VRMT') sensors to monitor forces and stresses on drilling risers and riser towers
Data Source
AI summary
The invention involves utilizing variable reluctance measurement technology (“VRMT”) sensors to monitor forces and stresses on drilling risers and riser towers. The tension monitoring system described herein includes an optimized configuration of variable reluctance measurement technology sensors, wherein the sensors have increased wire turns around each end of their C-cores or alternatively are mounted on mechanical amplifiers or both. An array of optimized variable reluctance measurement technology sensors can be configured at multiple points on a riser system. The VRMT sensors may be integrally attached to the risers or flexible joints for the risers, or may be installed on existing riser or flexible joint systems.