Channel Characteristics of Acoustic Telemetry while Drilling
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摘要: 为给随钻声波传输系统的设计和研发提供理论和试验依据,对声波在钻柱中传输的信道特性进行了研究。首先以声波在周期性结构的传输理论模型为基础,编制了计算机仿真程序,仿真分析了钻柱结构、钻柱长度及钻管长度对单位脉冲响应的影响;然后采用88.9与127.0 mm钻杆,较系统地进行了声波传输试验,分析了钻柱长度、支撑方式、信号接收位置、钻柱曲率及钻柱尺寸对声波传输信道特性的影响。结果表明:钻柱信道呈梳状滤波特性;钻柱的信道特性不随支撑方式的改变发生较大变化;钻杆数量的增加导致时域波形衰减;钻柱的声波信道特性基本不受钻柱长度的影响,但单根钻杆的差异会引起通频带缩小;不同接收位置接收信号的通频带的位置及宽度完全一致,只是幅值不同;钻柱曲率不会对通频带的位置产生影响,但会对其宽度造成影响;钻柱尺寸基本不会对通频带结构产生影响。仿真分析结果与声波传输试验结果可为随钻声波传输系统的设计提供模拟及试验依据。Abstract: In order to provide theoretical and experimental basis for the design of acoustic telemetry system,we studied the channel characteristics of acoustic wave transmitting through the drill string.According to the principles of sound wave propagation in periodic structures,this paper adopted numerical simulation technology to perform analysis on sound waves propagating along drill string,the effects of drill string structure,drill string length and drill pipe length on unit impulse response were analyzed.According to the experimental study on 88.9 and 127.0 mm drill pipes,the effects of drill pipe length,supporting means,signal receiving location,drill string curvature and drill string size were investigated.The results show that:drill string channels take on comb-filtering characteristics,which does not vary from the support form significantly;increase in the number of drill pipes leads to time domain waveform attenuation;the channel characteristic is basically not affected by the length of the drill string,but the difference in one drill pipe would cause the narrowing in width of pass band;the positions and width of pass band of different receiving positions are exactly the same,but different in amplitude;drill string curvature has no impact on the pass band position,but would affect its width;drill string size has little effect on the pass band.The simulation and experimental results can provide bases for the design of acoustic telemetry system.
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Keywords:
- acoustic wave transmission /
- logging while drilling /
- drill string /
- information /
- numerical simulation /
- bab test
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