基于正交频分复用(OFDM)技术的高速测井遥传系统

High Speed Telemetry System for Well Logging Based on OFDM

采用传统的曼彻斯特等编码调制方式的遥传系统所获得的低传输率已成为制约测井仪器发展的瓶颈。正交频分复用技术(OFDM,Orthogonal Frequency Division Multipexing)利用子载波间的正交性很好地解决了频带利用率和码间干扰问题,具有较强的抗干扰能力和自适应能力,可以在带宽有限的测井电缆上实现数据的高速传输。LEAP800测井系统在分析七芯测井电缆传输特性的基础上,结合测井的实际情况,开发出基于正交频分复用技术的兆级高速测井遥传系统,已完成多次井场测试工作,各项指标满足设计要求。系统具有全双工通信能力,可提供上行1000 kbit/s、下行50 kbit/s的数据传输速率,并具有建立时间短、工作稳定可靠、自适应不同测井电缆等特点,可在175℃连续工作2 h以上。该系统已经在油田测井服务中投入使用。

By analyzing the frequency characteristics of the well logging wireline, a high speed well logging telemetry system is developed based on the Orthogonal Frequency Division Multiplexing（OFDM）. This system with high environment noise immunity and adaptive data rate according to the noise environment is a full duplexer communication system and has achieved upstream data rate above 1 000 kbit/s and downstream data rate above 50 kbit/s over the 7 000 meters long well logging cable with the bit error rate less than 10E-7. As part of the LEAP800 well logging system, the telemetry system, with the features of short communication establishing time, high reliability and adapting to different lengths of wireline automatically, can work at 175 degree centigrade for two hours continuously and has been successfully used in the oilfield operation.