地球物理学进展 ›› 2018, Vol. 33 ›› Issue (4): 1438-1443.doi: 10.6038/pg2018BB0165

• 固体地球物理及空间物理学(大气、行星、地球动力学、重磁电及地震学、地热学) • 上一篇    下一篇

基于拉曼散射的深孔测温技术研究

张青1,2,郝文杰1,2,*(),蒿书利1,2,李胜涛1,2,王新杰1,2,蒋凡1,2   

  1. 1. 国土资源部地质环境监测技术重点实验室,河北保定 071051
    2. 中国地质调查局水文地质环境地质调查中心,河北保定 071051
  • 收稿日期:2017-09-29 修回日期:2018-06-23 出版日期:2018-08-20 发布日期:2018-09-13
  • 通讯作者: 郝文杰 E-mail:haowenjielove@163.com
  • 作者简介:张青,男,1965年生,教授级高工(技术二级),主要从事地质环境监测仪器研发和技术方法研究.(E-mail: zhqn123@163.com)
  • 基金资助:
    国土资源部公益性行业科研专项资金(201511056);自然科学基金(青年)(41402322);地质调查项目(DD20179033,DD20179621,DD20160192)

Research of deep-hole temperature measurement technology base on Raman scattering

ZHANG Qing1,2,HAO Wen-jie1,2,*(),HAO Shu-li1,2,LI Sheng-tao1,2,WANG Xin-jie1,2,JIANG Fan1,2   

  1. 1. Key Laboratory of Geological Environment Monitoring Technology, Ministry of Land and Resource, Hebei Baoding 071051, China
    2. Center for Hydrogeology and Environmental Geology, CGS, Hebei Baoding 071051, China
  • Received:2017-09-29 Revised:2018-06-23 Online:2018-08-20 Published:2018-09-13
  • Contact: Wen-jie HAO E-mail:haowenjielove@163.com

摘要:

孔中测温作为一种原位测试方法,是地热资源勘察、开发中重要的研究内容.分布式光纤传感测温技术,能够弥补传统点式测温耗时与漏测的不足,同时传感光纤具有耐高温、高压和抗(钻井液)腐蚀性等特点,可实现钻孔恶劣环境下的分布式温度测量.本文利用拉曼散射和光时域反射技术,设计了深井分布式光纤温度测试系统.该系统采用波分复用技术,将后向拉曼散射光中的斯托克斯光与反斯托克斯光分离,利用反斯托克斯光的温度敏感特性感知环境温度,结合同源斯托克斯光,解调温度信息;根据光纤中光的传输速率和背向拉曼散射光的回波时间,可以对温度点进行定位,实现对光纤温度场的分布式测量.通过多点数字累加平均技术的微弱信号处理方法,并引入光纤突变损耗修正系数、光电采集影响系数等,借助光纤环基准参考,实现测温数据的解算.同时本文设计的深孔耐高温铠装测试光缆,可实现-65~350 ℃范围内的温度测试;结合GH_DR2号地热孔野外测试实验,完成测深800m,孔内最高温度54.8 ℃,证明此种测温方法的有效性和潜在的推广价值.

关键词: 分布式测温, 干热岩勘察, 光纤传感技术, 后向拉曼散射

Abstract:

As an in-situ measurement technique,borehole temperature is an important research area in geothermal exploration. In recent years, fiber-optical Distributed Temperature Sensing(DTS) can achieve borehole temperature distribute measure with high temperature and pressure resistance, anti-corrosive and other unique advantages, suitable for geothermal, especially deep boreholes of Hot Dry Rock(HDR) resources exploration and research. Combined with field work of HDR exploration, temperature effect of optical fiber backwards Raman scatter and Optical Time Domain Reflecting(OTDR) technology were applied to research Distributed Optical Fiber Temperature measurement System(DTS) for deep-hole. Uses Wavelength-Division-Multiplexing(WDM), Raman wavelength filters separated anti-stokes and stokes light of the backscattering light. Through the analysis of the intensity ratio of anti-stokes and stokes light, a digital multi-point average method(Digital BOXCAR) of signal weak-signal detection has been proposed base on the characteristic and sort of fiber-optical sensor and the feature of Raman-scatter. Base on fiber optic mutation loss correction coefficient and photoelectric signal acquisition response coefficient, with practical measure temperature in fiber coil, analysis results indicate that the modified temperature demodulation formula can efficient improve measurement precision of the system temperature. Designed a kind of fiber-optic cable for deep borehole high temperature test, which can realize distributed temperature measurement from minus 65 ℃ to 350 ℃. Selecting the GH-DR2 HDR prospecting hole in Qinghai province Gonghe County to conduct the field tests, completed sounding 800 m, the maximum temperature of 54.8 ℃, which can improve the work efficiency and potential application value.

Key words: distributed temperature measurement, hot dry rock, optical fiber sensing technology, Raman back-scattering

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