BASIC STRATEGY OF HEALTH MONITORING ON SUBMARINE PIPELINE BY DISTRIBUTED OPTICAL FIBER SENSOR

摘要

Submarine pipeline system is a main pattern in collection and transmission of offshore oil and gas, which sends oil and gas from offshore oil/gas field to land, and it plays an important role in the production of oil and gas. Because of the complicated and harsh condition in which pipeline system works, such as impulsion, corrosion and free-spanning vibration, failure of submarine pipeline system occurs occasionally, it causes oil leakage, environment pollution and economic losses. Health monitoring is a feasible and effective manner to ensure submarine pipeline safe and reliable during service, especially when all factors affecting pipeline failure are not still entirely realized or controlled. The basic strategy of a new real-time monitoring system for long distance submarine pipeline is introduced in this paper, which has the function of diagnosis and auto-alarm. In this system, a new distributed optical fiber sensor (DOFS), which uses optical time domain reflectometry theory based on Brillouin backscatter, is applied to monitor the strain and temperature along the pipeline. To be used for long distance submarine pipeline, this system applies Wavelength Division Multiplex (WDM) technology and series DOFSs in series so as to extend the measure scope for long distance submarine pipeline. By using signal processing system to analyze the outcome data of sensor, the strain along the pipeline can be obtained. If the strain reaches the alarm setting, the system will send out caution and meanwhile accurately give the damage position, The system can also analyses vibration frequency of pipeline, if free-spanning vibration occurs, caution will also be given, so that the operator can take some measures in time to avoid the failure of pipeline. In this paper, the makeup of distributed optical fiber sensor and developing principle are specified, system development, application and construction in engineering are analyzed as well. The brand new practical system can not only be used for submarine oil and gas pipeline but also for land oil and gas transfer system, city coal gas transfer system, electricity-transmission cable and so on. This system can be widely used in many prospects of other industries.