中国科技核心期刊
(中国科技论文统计源期刊)
  Scopus收录期刊

石油科学通报 ›› 2025, Vol. 10 ›› Issue (6): 1330-1349. doi: 10.3969/j.issn.2096-1693.2025.02.031

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基于分布式光纤声传感技术的水泥环流体泄漏工况诊断

李晓蓉1,*(), 苏飞宇2, 李仨兴2, 赵杨3, 司晓宇1, 冯永存2   

  1. 1 中国石油大学(北京)安全与海洋工程学院北京 102249
    2 中国石油大学(北京)石油工程学院北京 102249
    3 中国石油大学(北京)非常规油气科学技术研究院北京 102249
  • 收稿日期:2024-10-08 修回日期:2025-01-16 出版日期:2025-12-30 发布日期:2025-12-30
  • 作者简介:李晓蓉(1986年—),副教授,博导,长期从事复杂油气井井壁稳定性和井筒完整性基础理论、方法和技术研究,主持国家自然科学基金项目等多项基础科研项目和工程技术服务项目,在《SPE Journal》等期刊发表科技论文30余篇。授权发明专利10余项。任中国岩石力学与岩石工程学会国际秘书处兼职副秘书长;国际岩石力学大会(IGS)论文委员会联合主席等,xiaorongli@cup.edu.cn
  • 基金资助:
    国家自然科学基金面上项目“应力—腐蚀耦合作用下CCUS井水泥环密封失效机理研究”(5247040354);国家自然科学基金青年项目“分布式光纤声传感(DAS)监测水泥环完整性研究”(52004298)

Diagnosis of cement sheath fluid leakage based on distributed optical fiber sensing

LI Xiaorong1,*(), SU Feiyu2, LI Saxing2, ZHAO Yang3, SI Xiaoyu1, FENG Yongcun2   

  1. 1 College of Safety and Ocean Engineering, China University of Petroleum, Beijing 102249, China
    2 College of Petroleum Engineering, China University of Petroleum, Beijing 102249, China
    3 Unconventional Oil and Gas Science and Technology Institute, China University of Petroleum, Beijing 102249, China
  • Received:2024-10-08 Revised:2025-01-16 Online:2025-12-30 Published:2025-12-30
  • Contact: * xiaorongli@cup.edu.cn

摘要:

水泥环完整性对油气井安全高效生产至关重要。随着油田开发的深入,增产增注等作业可能导致水泥环产生微裂隙,削弱其封隔油气水层的能力。传统固井检测方法只能提供单点或瞬时状态,难以实现全井段的实时监测。分布式光纤声传感技术为水泥环泄漏的实时监测提供了全新方法。基于自主搭建的分布式光纤监测井筒完整性实验平台,开展了不同泄漏通道尺寸、位置和泄漏量下的水泥环失效监测实验,获取了光纤监测数据。在传统谱减降噪方法中引入过减因子,有效解决了谱减过程的负值问题,通过结合短时傅里叶变换和连续小波变换提取泄漏信号的时频域特征,从而确定泄漏位置。同时,通过计算光纤信号的功率谱分布和声压级,建立了泄漏流量与声波能量之间的关系。最后,提出了一种基于卷积神经网络(Convolutional Neural Networks, CNN)和双向门控循环单元(Bidirectional Gated Recurrent Unit, BiGRU)的特征识别方法,实现了对泄漏工况的精准分类。研究结果表明,改进的谱减法在低频区域(0~100 Hz)能有效抑制宽频带噪声和脉冲噪声,抑制幅度可达 100 dB 至 120 dB。泄漏流量与声波能量呈正相关,流量仅改变特征频率的峰值,不影响频率分布特征。构建的CNN-BiGRU模型能有效识别光纤信号的空间和时序特征,表现出较高的准确性和良好的泛化能力,为分布式声光纤监测水泥环完整性的数据解释提供了支持。

关键词: 分布式声光纤传感器, 水泥环完整性, 时频分析方法, CNN-BiGRU, 深度学习模型

Abstract:

The integrity of cement sheath plays a decisive role in ensuring the safe and efficient production of oil and gas wells. However, the micro-cracks inside the cement sheath make the interlayer isolation fail with the further development of the oil field. The state of cement sheath at a certain measuring point or at a certain moment is provided by traditional detection methods, which cannot meet the needs of the whole well section real-time monitoring. Distributed acoustic optical fiber sensing provides a new method for real-time monitoring of fluid leakage in micro-cracks of cement sheath. In this paper, the data of fluid leakage under different leakage sizes, leakage locations and leakage flow rates are obtained based on the distributed optical fiber monitoring wellbore integrity experimental platform. The over-subtraction factor is introduced into the traditional spectral subtraction noise reduction method, which effectively solves the negative value problem of the spectral subtraction process. The time-frequency domain characteristics of the leakage signal are extracted by combining the Short-Time Fourier Transform and the Continuous Wavelet Transform to determine the leakage location. Then, the relationship between fluid leakage flow and acoustic energy is determined by calculating the power spectrum distribution and sound pressure level of the signal. Finally, a feature recognition method based on Convolutional Neural Network (CNN) and Bidirectional Gated Recurrent Unit (BiGRU) is proposed to achieve accurate classification of leakage conditions. The results show that the improved spectral subtraction effectively suppresses broadband noise and impulse noise in the low frequency region (0-100 Hz), and the suppression amplitude reaches 100 dB to 120 dB. The acoustic energy captured by the fiber is positively correlated with the fluid leakage, and the flow rate does not change the frequency distribution characteristics, but only changes the peak value of the frequency. It is found that the CNN-BiGRU model has high accuracy and good generalization ability, which effectively identifies the spatial and temporal features of the signal. The information of interlayer isolation failure of cement sheath is effectively obtained by distributed acoustic sensor, which has certain guiding significance for cementing operation.

Key words: distributed acoustic sensor, cement sheath integrity, time-frequency analysis, CNN-BiGRU, deep learning model

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