线圈法岩心复电阻率扫频测量系统研究

为了研究用不同测量方法所测得的岩石电阻率或电导率的异同及其关系 ,在实验室内研制了线圈法岩样复电阻率扫频测量系统。该系统可改变传统感应测井中以发射电流直接作为参考的方法 ,将发射电流移相一定的角度 ,从而解决了虚部小信号的检测问题。发射电流在低频时 ,短线圈距的线圈系对介质电导率的灵敏度低于长线圈距的 ;而在高频时结果则相反。试验表明 ,在室内用线圈法测量岩心复电阻率是可行的 ,而且被测信号幅度和相位均与岩石的电阻率有很好的对应关系 ,也更能真实地反映岩石的频散特性。同时 ,用线圈法测量的岩心复电阻率也可用来探测岩石中地层水的饱和度。

Development of sweep-frequency measurement system for rock complex resistivity with coil antenna

In order to study the relationship between the resistivities of rock measured using electrode and coil methods, a sweep-frequency measurement system for measuring complex resistivity of core was developed using coil antenna setup in laboratory. The emit current was directly used to be a reference in the traditional induction well logging. This system makes the emit current a phase shift to improve the detection accuracy of the component signal of weak imagery. The sensitivity of short sonde coils to the media conductivity is less than that of the long sonde coils in low frequency, but the result is contrast in high frequency. The test shows that the measurement of complex resistivity of core in laboratory with coil method is possible. The measured amplititude and phase of signal are good corresponding to the resistivity of core and can indicate the electrical dispersion of rock. The measured complex resistivity of core can be used to investigate the saturation of formation water in rock.