Experimental Study On Induced Polarization Method Based On Dual Mode Parallel Electrical Acquisition System

As an effective geophysical prospecting method,the induced polarization method has been widely used in metal mine search,oil and gas exploration,coalfield exploration and geological survey.Based on the unique advantages of dual mode parallel data acquisition system in terms of acquisition method,device form and acquisition efficiency,the experimental study of excited polarization method is carried out by combining electronic circuit simulation,physical simulation and practical application.(1)The charge and discharge process of induced polarization is studied in this paper.It is found that the induced polarization completes 50% and 90% after the power supply in 0.1s in 0.5s,under the condition that the copper is used to simulate the high polarization medium.Therefore,when calculating the apparent amplitude frequency of induced polarization method,the apparent resistivity whose current injection time is 0.5s can be selected as the low frequency resistivity and the high frequency apparent resistivity can be selected according to background noise level,which are able to significantly improve the efficiency of IP exploration with high polarization body;(2)The circuit model is established to simulate the negative polarization phenomenon appearing in the induced polarization.According to the Cole-Cole model,the earth is considered as a complex partial pressure network composed of multiple polarization units.The simulation results is shown as following.When there is a high polarization body,polarization leads a dominant position.When there is no high polarization body,partial pressure leads a dominant position.A low polarization body can be used as a resistor with a fixed resistance after polarization is completed,while the other polarization is still charging and its resistance and voltage are keeping rising,which causes that the voltage of the low polarization body become low and leads to the negative polarization phenomenon;(3)The two pole-dipole devices(AMN&MNB)and Wenner devices(wenner ? device,wenner ? device and wenner ? device)can be extracted from the AM data of dual mode parallel electrical collection system,which increases the diversity of acquisition devices and obviously improves the collection efficiency at the same time.The wenner data synthesized from AM data is compared with the original wenner data.The results display that the root mean square errors of apparent resistivity difference are 0.01,0.02 and 0.24,respectively for wenner ? device,wenner ? device and wenner ? device;the root mean square errors of apparent amplitude frequency difference are 3.4,13.8 and 8.7,respectively for wenner ? device,wenner ? device and wenner ? device;The inversion results of apparent resistivity and apparent amplitude frequency can accurately reflect the abnormal body position;(4)As a kind of effective method to monitor with the excavation floor,the double mode parallel electric acquisition system can be applied to the monitoring of the bottom of the excavated coal roadway.By using its advantage in the induced polarization data acquisition,apparent amplitude frequency can be used as an auxiliary means for the interpretation of the apparent resistivity data which explain the insensitive region of the apparent resistivity method.