随钻声波测井的正弦脉冲激励方法和实验研究

Sine-wave Pulse Excitation Circuit Method and Experiment Study for LWD Acoustic Logging

多极子随钻声波测井受钻铤直达波干扰影响严重,将声源激励频率控制在隔声体阻带内是获得高信噪比数据的重要方法。传统单脉冲激励源因其谐振点工作和宽频特性难以满足要求。针对这一问题,设计了基于推挽式功率放大结构的门控正弦波脉冲激励电路,包括发射主控制器、信号发生、半波整流、功率放大、脉冲变压器及高压储能等电路单元。通过实验研究,激励同一换能器的声源频率、相位和带宽均可控,实现了多极子模式的发射,并给出了声源周期数量设计的参考依据。

Multipole LWD acoustic logging are affected seriously by direct waves along the drill collar.In order to obtain high SNR data,it is an effective method to control the frequency of excitation sources into the attenuation domains of the isolator.However,the traditional single pulse signals cannot meet the above demands for their broad frequencies and resonance working status.Therefore,this paper designs a gate sine-wave pulse excitation circuit based on push-pull power amplification structure to solve this problem.The circuit consists of an excitation controller,a signal generator,a detector,a power amplifier,a pulse transformer and a power storage circuit.Through experimental research,the frequency,phase and bandwidth of the sound source of the same transducer are all adjustable,which realizes the multi-pole mode emission and obtains the reference basis for the design of the number of sound source cycles.