基于动电效应的震电测井方法研究进展*

与双电层和孔隙流体渗流有关的声波-电磁场耦合效应(动电耦合波)在油气储层勘探、地震电磁场等领域有着潜在应用价值。该文简述动电耦合波在理论模型以及井孔动电耦合波的实验测量、模拟计算方面的研究进展,并对油气储层测井领域进一步的动电耦合波研究进行了展望。基于动电信号的探测方法同时接收声波和电磁场两类信号,可避免单一类别信号方法的不足。实验获得了岩心的动电耦合系数,但其表征的孔隙岩石物理性质还有待进一步认识。基于耦合控制方程,开展了震电波场的计算和分析。结果表明,声源激发后,可接收到伴随声波的电磁信号和早于声波的电磁首波。这两类信号都既对影响声波特性的岩石模量、孔隙度和渗透率等参数敏感,又与电导率等岩石电学性质密切相关。非饱和岩石动电耦合波理论和基于动电耦合波的参数反演方法等问题有待进一步研究。

Research advances of electrokinetic well logging for oil and gas reservoir

The electrokinetic coupling effects between elastic wave and electromagnetic field due to the electric double layer and the fluid flow in porous rocks have potential application in oil-gas exploration and coseismic electromagnetic field. In this study, we give a sketch of the theoretical model of electrokinetic waves and the experimental measurement and simulation of the borehole electrokinetic waves. In addition, we outlook the further research directions of the electrokinetic waves in oil-gas reservoir logging. The electrokinetic exploration method receives both the seismic (acoustic) and electromagnetic signals, which avoids the shortcoming of the seismic and electromagnetic method and possesses the advantages of both of them. The electrokinetic coupling coefficient has been measured in laboratory, however, the porous rock physical parameters characterized by the electrokinetic coupling coefficient need to be further understand. The seismoelectric wavefields have been calculated and analyzed based on the electrokinetic governing equations. The results show that an acoustic source excites both the electromagnetic field accompanying the acoustic signals and the electromagnetic wave arrives earlier. These two kinds of signals are not only sensitive to the elastic moduli, porosity and permeability affecting the elastic wave characteristics, but also relates to the electric characteristics, such as the conductivity. Some issues to be further studied are discussed, such as the electrokinetic wave theory for unsaturated rocks and the parameter inversion method based on electrokinetic waves.