基于FBGF-P的全光纤井下声波传感器

An All-fiber Optical Acoustic Sensor for Sonic Logging Based on FBG F-P

研究了应用于油井井下流噪声探测的FBG F-P干涉仪。结合空气腔芯轴耦合的高灵敏度全光纤声波传感器,光纤FBG F-P干涉仪设计为弱反射的长腔长结构,以提高传感器声压相移灵敏度;对空气腔芯轴内外层骨架材料优化选取,结合质量控制改善其固有频率,提高传感器的频率响应特性。实验结果表明,传感器探测灵敏度约为-147dB,频率响应范围50Hz^20kHz。传感器为全光纤结构,进行耐压与防水封装后,能满足高温高压井测量工作环境的应用要求。

In this paper, combining all-fiber bragg grating Fabry-Perot（FBG F-P） interferometer with air-backed mandrel coupling, a highly sensitive sensor for sonic noise signal detecting in sonic logging is presented and demonstrated experimentally as well. In order to improve the acoustic pressure phase sensitivity of sensor, the FBG F-P interferometer is designed in weak reflection long cavity length structure. Then through the selection of air-backed mandrel inner and outer layer skeleton materials is optimized and quality is controlled, the frequency response characteristics of sensor have been improved. The experimental results show that the sensor＇s sensitivity is about --147 dB, the frequency response range is 50 Hz-20 kHz. The sensor is of all-fiber structure, so with pressure and waterproof package designing, it can be applied to the sonic logging condition characterized by high temperature and high pressure.