Distributed sensor for monitoring the integrity of flexible pipelines and risers

High pressure flexible pipes are increasingly used in the exploration for crude oil and gas. The environment in which the flexible pipes are required to operate is extremely aggressive and hazardous. Crude diphasic oil in contact with flexible polymeric materials can create severe problems. In operation the pipe must be stable under fluctuating pressure conditions. Excessive Torsion, Axial or Bending strains caused by internal pressure change are undesirable. The current lack of any credible inspection technology to warn of impending failure and the risks that this poses particularly with respect to the operation of high pressure gas flexible risers is of great concern. The development of inspection technologies even if successful will only allow periodic examination of a system. Longer term observation of flexibles is essential for comparison with fatigue testing and the development of methods of assessing residual life whilst in service.

This paper describes the investigation of the generic technology relating to ruggedisation, calibration, validation, manufacture and application of a distributed sensing system for flexible pipelines and risers. The nature of flexible pipeline systems and the problems they are likely to encounter, emphasised the suitability of this type of approach. The use of Optical Time-Domain Reflectometry techniques, it has been shown, could for the first time enable the realisation of a system capable of meeting the industries needs for improved standards of safety, efficiency and economic viability.