Feasibility Study for Monitoring of Off-shore Pipelines Using BOTDA System

Abstract

On offshore oil transmission, off-shore pipelines system is the main pattern to send the oil from offshore to onshore terminal, and plays an important role. However, because the harsh and complicated working condition of offshore pipelines, failures may happen because of corrosion, impulse and free-spanning. The failures will cause oil leakage, environment pollution and economic losses; and the damage-cleanup is really difficult and need a long time. In this situation, pipeline health monitoring is an urgent need. In this study, the free-spanning is mainly focused on because there is no much study on this part. However, because working condition of pipeline is harsh, the conventional conductive sensors could not survive in the environment; and another important feature of pipeline is that the length usually extended hundreds of kilometers, which is one of the big challenges for monitoring it, because we have no ideal about when and where failures may occur. When the potential damage or leakage locations are unknown, it is difficult to pre-determine the places to put localized sensors, such as electric strain gauge. So, distributed fiber optic sensors should be used. BOTDA (Brillouin Optical Tine Domain Analysis) system which has a high measurement accuracy and wide range is a Brillouin-based optic fiber sensor .In this study, a feasibility study of optic BOTDA on off-shore pipeline monitoring is studied. Numerical simulation about off-shore pipeline and strain measurement experiment are carried on. Results tell us that BOTDA is an excellent tool to monitor the long-distance pipeline, and our BOTDA system in KRISS is possible for monitoring although improvement is needed to make.