基于光纤磁传感的套损检测技术研究

Study on the technology of casing damage detection based on optical fiber magnetic sensing

报道一种FBG F-P磁敏感结构结合光相干检测的光纤磁场传感器,应用于套损检测技术领域。光纤FBG F-P干涉仪设计为弱反射的长腔长结构,以提高磁传感器相移灵敏度;基于差动抗干扰探测结构消除磁场与温度的交叉敏感性,采用双层封装结构,可适应与恶劣环境。搭建套损检测试验平台,制定试验方案,实验结果表明磁传感器测量结果与实际模型缺陷基本一致。光纤磁传感器为全光纤结构,进行耐压与防水封装后,能满足实际井下测量工作环境的应用。

A fiber optic magnetic field sensor with FBG F-P magnetically sensitive structure combined with optical coherence detection is reported and applied in the field of casing loss detection. The fiber optic FBG F-P interferometer is designed with a long cavity structure with weak reflection to improve the phase shift sensitivity of the magnetic sensor. Based on the differential anti-interference detection structure to eliminate the cross-sensitivity between magnetic field and temperature, the double-layer packaging structure can adapt to the harsh environment. The test platform for casing damage detection was built and the test scheme was formulated. The experimental results showed that the measured results of the magnetic sensor were basically consistent with the actual model defects. The fiber optic magnetic sensor is an all-fiber structure, which can meet the application of underground measurement working environment after being sealed with pressure-proof and water-proof.