基于单光子探测的极端环境下水质低浊度和小粒径测量方法研究

The high precision synchronous measurement of low turbidity and small particle size with is very important to improve productive efficiency and promote petroleum resource exploitation. In order to meet the requirement of high performance water quality online detection in the exploiting fields of low permeability reservoir .etc, the project proposed a new water quality measurement method based on single-photon detection. By using high sensitive Geiger-mode APD detector and combining the time-correlated single-photon counting (TCSPC) technique with photon correlation spectroscopy (PCS) technique, we can synchronously measure of low turbidity and small particle size with high precision, which can overcome many deficiencies of those traditional water quality detecting technologies, such as poor detection accuracy, low measurement speed and weak anti-interference capability. Moreover, by studying the design of high integrated transceiving fiber-optics probe, we can detect backscattering light with high efficiency in remote narrow space, which can overcome the problem that the low turbidity and small particle size cannot be measured in extreme conditions with high temperature and pressure. Last, by combining the light scattering theory with single-photon detecting theory, we will investigate the high sensitive detection mechanism of weak light scattering by the particle in water and built a signal-to-noise ratio (SNR) theory model of water quality detecting system based on single-photon detection, which will be used to guide the optimized design of measurement system. The optimized measurement system is finally used to carry out the field experiment and application demonstration. The effective implementation of this project can contribute to expanding the application of traditional water quality detection technique in the extreme environment and providing theoretical basis and technical support for developing new multi-parameter laser water quality detecting method and building high performance laser water quality system.

水质低浊度和小粒径的高精度同步测量对提高生产效能和促进能源开发意义重大。本项目针对低渗透油藏等资源开发中对高性能水质在线检测需求，提出一种基于单光子探测的水质测量新方法，通过利用盖革模式下APD高灵敏的单光子探测性能，将时间相关单光子计数法和光子相关光谱法有机结合，实现低浊度和小粒径的高精度同步测量，克服传统检测方法精度低、实时性差、抗干扰能力弱等不足；通过探索高集成度收发一体式光纤探头设计方法，实现远端狭小空间内后向散射光的高效探测，解决高温高压极端条件下低浊度和小粒径无法测量的问题。同时将光散射理论与单光子探测理论结合，探索水体颗粒物微弱散射光的高灵敏探测机理，建立单光子水质测量系统性噪比模型，实现测量系统的优化设计，并开展外场实验和应用示范。本项目的实施将有助于拓展现有水质测量技术在极端环境下的应用，为发展新型多参数激光水质检测方法，构建高性能激光水质检测系统提供理论基础与技术支撑。

对于水质中的低浊度和小粒径参数进行高精度、同步测量在提高生产效率和促进能源高效开发方面意义重大。在项目执行的四年时间内，我们发展了一种基于单光子探测技术的水质测量新方法，先后探索了在盖革工作模式下的高灵敏度单光子接收特性，研究了时间相关单光子计数法和光子相关光谱法有机结合的高灵敏度水质检测方法，实现了高集成度收发一体式光纤探头设计，构建了光散射理论与单光子探测理论结合的信噪比SNR模型，并研制了水质浊度和小粒径同步实时检测系统原理样机，在0～1000NTU内，可实现采样时间优于10ms且分辨率高达0.01NTU的低浊度测量；在100nm-1μm宽粒径范围内，可实现精度优于20nm的小粒径高精度测量；同时，设计的光纤探头接收端信噪比高达50dB，耐温高于100℃，抗压大于50Mpa，外径尺寸小于4cm。相关研究结果先后发表论文13篇（其中SCI收录5篇，EI收录7篇），申请国内专利6项（其中发明3项，实用新型3项）。本项目的研究成果可为发展新型、多参数激光水质检测方法，构建高性能激光水质同步实时检测系统提供理论基础与技术支撑。