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本文提出的瞬态感应测井是一种以瞬变电磁激发为基础的感应测井方法.其工作波形是瞬态的:有一个主频并有一定的带宽.发射探头是线圈,激发的感应电动势与感应测井一样沿圆周方向.具体激发频谱取决于与其配合的声波测井压电换能器参数.当换能器是宽带时,激发的瞬变电磁场是宽带的,激发波形的电震荡周期比较少,测量的电磁感应波形的震荡周期也比较少.这些震荡波形从激发时刻便开始出现,只能够用同轴的线圈进行接收.同样,接收信号中也包含直接耦合信号和二次场信号,两者相差90°.当地层的电导率随频率改变时,接收波形中二次场的响应波形幅度和相位均发生改变.对接收波形可以参考感应或阵列感应测井的处理方法,用Doll几何因子进行设计.但是,需要面对不同频率的幅度和相位,增加解耦处理方法.相对于阵列感应测井,该测井方法有两个优点:能够测量一个频带内地层的电阻率,能够与阵列声波测井从探头结构上进行组合,便于测井系统的集成.
The transient induction logging proposed in this paper is a kind of induction logging method based on transient electromagnetic excitation.The working waveform is transient: there is a main frequency and a certain bandwidth.The transmitting probe is a coil, the induced induction The electromotive force is the same as the induction logging in the circumferential direction.The specific excitation spectrum depends on the parameters of the acoustic logging piezoelectric transducer with which it is matched.When the transducer is broadband, the transient electromagnetic field excited is broadband and the electrical shock of the excitation waveform The cycle is relatively small, the measured electromagnetic induction waveform oscillation period is relatively small.These shock waveforms began to emerge from the moment of excitation, can only be used to receive a coaxial coil Similarly, the received signal also includes a direct coupling signal and the secondary field Signal, the difference between the two 90. When the conductivity of the ground layer changes with frequency, the receiving waveform of the second field response waveform amplitude and phase are changed.For the receive waveform can refer to induction or array induction logging processing method, with Doll geometry, however, there is a need to add decoupling to the amplitude and phase at different frequencies, which has two advantages over array-sensing logging: The resistivity was measured one band interior layer, it can be combined with the structure from the probe array acoustic logging, the logging system to facilitate integration.