The Monitoring Technique Of Suspended Subsea Pipeline Based Active-heating Method

The paper present a practical phenomenon in the produce of marine oil—the subsea pipeline gets crack due to the scour of ocean currents and the serious consequences,after that we describe several kinds of techniques about monitoring the subsea pipelines,finally we provide a new technique about monitoring the suspended subsea pipeline based active_heating method.Affix the sensors of temperature(such as FBG,DS18B20) to the heating-belt with the same distance and package them using soft tube,we can get a scour sensor,by which we can monitor the scour level of sand. Due to the large different thermal conductivity between water and sand,the heat have a different change trend in them.That is to say,the temperature of heating-belt in the water rises at once after the belt connects to the power and keeps steady along with continuing heat, however, the temperature of heating-belt in the sand keeps increasing slowly in the total way after it connects to the power;In addition,after cutting off the power the temperature of heating-belt in the water get back the initialization quickly,but the temperature of heating-belt in the sand comeback slowly.By this trends we can obviously distinguish the surroundings batween water and sand, then, we can carry out a monitoring about scour.The second section of the paper is theoretical basis, it analyses the phenomenon which the former point out from aspect of heat transfer.After that we do a large experiment about monitoring the subsea pipelines'suspension by scouring, in which we also apply the optical fiber tecchnique besides the traditional temperature sensor. Brillouin optical fiber is one of the techniques, which has a low cost,can transfer with optical signal and long distance. Due to its advantages,Brillouin optical fiber have been attached importmant by people more and more and attempted to apply in the marine oil engineering. The paper introduces principle of Brillouin technique simply,secondly,describes its application in the structure health monitoring,lastly,we put it into the monitoring technique of subsea pipelines. Put Brillouin optical fiber together with heating-belt and package them,we get a piece of test-specimen and test it in the experiment,finally,the result indicates that the Brillouin frequency of the fiber in the sand rises immediately after the heating-belt connects to the power and keeps increasing slowly in the process of heating,however,the Brillouin frequency of fiber in the part of suspension rises at a low value and keeps steady in the total process of heating.The final result indicates the monitoring technique of subsea pipelines'suspension based active-heating is feasible,in addition,because of this technique's application,the dream of monitoring hundreds of subsea pipelines at one time may come true.Form the other part in,our technoque can improve the safty of the production in the marine oil in thture...