流体饱和孔隙介质中震电效应机理与震电波场特征的实验研究

Seismoelectric effect is in fact the conversion between machine energy and electromagnetic energy. Because of the complexity of the seimoelectric conversion,we still lack enough knowledges and quantitative investigation about the seismoelectric conversion in fluid-saturated porous media.We studied both seismoelectric waves properties and seismoelectric conversion mechanism experimentally with various physical models, and outlined the effective procedure to reduce noise and identify the seismoelectric signals in experiments, specially in high EM noise environment, we received successfully the two kinds of electromagnetic fields generated by seismic waves(ultrasonic) in a fluid-saturated porous medium. Our experiments confirm that the electric double layer on the interfaces between solid and fluid is the dominating mechanism generating the seismoelectric fields in fluid-saturated porous medium. Based on the model of the double layer, we studied and discussed various possible reasons generating the seismoelectric fields and their microsmic electrochemical factors. The results show that the movement differences between ions and anions in fluid electrolyte (brine) may induce the seismoelectric signals, and the received seismoelectric signals are derived from the streaming potential effect in fluid-saturated porous mediums..The analytical solution of borehole seismoelectric model suggests that the measurements of the stoneley-wave-induced electrical fields can yield information about the interconnected porosity and possibly about the permeability of the formation around the borehole. Our experiments also demonstrated that the amplitude of the seismoelectric signal is high in fractured zones and low in unfractured zones. The results proved that the borehole seismoelectric method can be used to detect and characterize the fractured(permeable) zones intersecting a borehole.

实验发现震电信号与介质及流体参数间的定量关系；研究震电波场的频率、振幅、传播特征，分析探讨不同介质条件下的震电转换机理，建立起能正确全面描述流体饱和孔隙介质中震电波场特征的震电方程；开展层状井孔介质模型震电场特征研究。该项目的实施对发展新的有效的石油地球物理勘探理论与方法具有重要意义。