Fugro GEOS jacket monitoring systems provide a cost-effective means of monitoring the integrity of many jacket structures.
Systems for design verification allow the performance of structures to be evaluated in service by comparing measured data with design.
Online Monitoring (OLM)
The Fugro GEOS On Line Monitoring (OLM) system provides a cost-effective means of monitoring the integrity of many jacket structures.
OLM measures the acceleration response of platforms to the wave motion. Significant damage is identified by a change in the natural frequencies exhibited by the platform.
The OLM system can be used to monitor:
- Low redundancy structures
- Structures with low fatigue lives
- Structures operating beyond design life
- Critical members of high redundancy structures
- Structures operating in regions with less well-developed inspection infrastructure
- Structures in seismically active areas
- Unmanned structures
Oil is considered a valuable but finite resource it is therefore vitally important to explore every opportunity to increase productivity and maximise the utilisation of assets.
Fugro GEOS can quantify the level of conservatism in design parameters to demonstrate that a platform is not being subjected to the maximum loading considered at the design stage. This knowledge can be used to make cost saving decisions such as:
- Increasing deck mass
- Increasing conductors and risers
- Extending operating life
- Optimising inspection programmes
- Platform loading / wave relationship
The actual natural frequencies of jackets can be significantly higher than those used in the design, this can be due to the foundations being stiffer than predicted. The effect of the higher natural frequencies is to reduce the dynamic amplification of the design wave forces by the structure, resulting in lower stresses.
Fugro GEOS can measure the platform natural frequencies by using accelerometers fixed to the deck for a period of a few hours.
Repair & Damaged Structure Monitoring
Structural monitoring can also enhance safety on damaged platforms and demonstrate the effectiveness of repairs. Examples include:
- Measuring the effectiveness of re-grouting leg connections
- Monitoring motion levels of damaged structures before, during and after repair
- Monitoring damaged structures to permit safe abandonment
Collision Detection System
Collisions between vessels and offshore oil and gas platforms and infrastructure are a major problem, particularly on unmanned structures. They are reported to cause more damage to structures than the natural environment in some regions.
Fugro GEOS’ collision detection system provides a cost-effective means of monitoring vessel impacts on offshore structures.
The accelerometer based system continually measures the dynamic displacement of the platform. A sudden change in measurement will indicate possible impact on the structure.
Air Gap Measurements
A permanent or temporary deck-mounted wave radar is used to measure tidal cycles. Oceanographic analysis of the data allows the platform LAT to be calculated, and air gap estimated. This service is often supplemented with a platform tilt survey.