Development and application of distributed optical fiber acoustic vibration sensor system

In view of the problem that the exploration and development of oil and gas fields need to obtain the complete waveform of micro acoustic disturbance signal, the research and development of distributed optical fiber acoustic sensor (DAS) technology and supporting system based on the scheme of double pulse heterodyne modulation and arctangent heterodyne demodulation were carried out. Combined with the indoor vibration simulation experiment of characteristic parameters, the response frequency range of the new DAS system is 20 Hz~25 kHz, the maximum dynamic range is 60 dB, and the signal-to-noise ratio is 49 dB, which can meet the detection requirements of micro acoustic wave of the amplitude, frequency and phase of the complete waveform. Meanwhile, the system has been successfully applied in the detection of underground steam cavity in heavy oil development of Xinjiang Oilfield. The actual effective sound pressure intensity is −195 dB, which verifies the reliability of the system and has a good application prospect.