The distributed acoustic sensor (DAS) uses a single optical cable as the sensing unit, which can capture the acoustic and vibration signals along the optical cable in real-time. So it is suitable for monitoring downhole production activities in the process of oil and gas development. The authors applied the DAS system in a gas production well in the South China Sea for in situ monitoring of the whole wellbore for the first time and obtained the distributed acoustic signals along the whole wellbore. These signals can clearly distinguish the vertical section, curve section, and horizontal production section. The collected acoustic signal with the frequency of approximately 50 Hz caused by the electric submersible pump exhibit a signal-to-noise ratio higher than 27 dB. By analyzing the acoustic signals in the production section, it can be located the layers with high gas production rates. Once an accurate physical model is built in the future, the gas production profile will be obtained. In addition, the DAS system can track the trajectory of downhole tools in the wellbore to guide the operation. Through the velocity analysis of the typical signals, the type of fluids in the wellbore can be distinguished. The successful application of the system provides a promising whole wellbore acoustic monitoring tool for the production of marine gas hydrate, with a good application prospect.

Xiang-ge He;Xue-min Wu;Lei Wang;Qian-yong Liang;Li-juan Gu;Fei Liu;Hai-long Lu;Yi Zhang;Min Zhang

Beijing International Center for Gas Hydrate,Peking University,Beijing 100871,China;School of Earth and Space Sciences,Peking University,Beijing 100871,China;Dongguan Institute of Optics and Electronics,Peking University,Dongguan 523000,China;Guangzhou Marine Geological Survey,China Geological Survey,Ministry of Natural Resources,Guangzhou 510075,China;Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou),Guangzhou 511458,China;School of Computer and Communication Engineering,University of Science and Technology Beijing,Beijing 100083,China;SinoProbe Center,Chinese Academy of Geological Sciences and China Geological Survey,Ministry of Natural Resources,Beijing 100037,China

中国地质（英文）

[1]Xiang-ge He;Xue-min Wu;Lei Wang;Qian-yong Liang;Li-juan Gu;Fei Liu;Hai-long Lu;Yi Zhang;Min Zhang-.Distributed optical fiber acoustic sensor for in situ monitoring of marine natural gas hydrates production for the first time in the Shenhu Area, China)[J].中国地质（英文）,2022(02):322-329

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