井下无线微小信号识别技术研究

Donwhole Wireless Tiny Signal Identification Technology

低频电磁场虽然具有穿透性强、传输距离远和导向能力强的优点,但由于其受功率限制和工频噪声的干扰,所以难以推广。鉴于此,对似稳恒电磁场在油管-套管-大地介质中的传播规律进行分析,采用金属导通工具提高上部套管分压,井下发射器采用自适应技术发射信号,提高信号稳定性,采用扩频技术等手段提高低阻抗、高噪声环境下井筒内微小信号分辨率,增强抗干扰能力。现场试验结果表明,这些技术手段能有效提高低频电磁场传输性能,有助于推动基于似稳恒电磁场的信号传输技术在深井中的推广应用,为智能完井工具、智能测试工具和地面直读系统的研制奠定技术基础。

Low frequency electromagnetic field is characterized by strong penetrability, long transmission dis?tance and good directing capacity?However, it can not be promoted effectively because of its power limitation and frequency noise interference?In this paper, the propagation law of the quasi?static electromagnetic field in tubing?casing?earth medium was analyzed?Specifically, conducting metal tools were used to increase the partial pressure of upper casings, adaptive transmitter technology was used to improve signal stability, and spread spectrum technolo?gy and other means were used to improve the distinguishability of tiny signals in low?impedance and high noise envi?ronment, so as to realize anti?interference capability?Field tests show that these techniques can improve the trans?mission performance of low frequency electromagnetic field, thereby promoting the application of the signal trans?mission technology based on quasi?static electromagnetic field in deep wells, and laying a technical foundation for the development of smart completion tools, intelligent test tools and surface read systems.