The Experimental Study On Complex Electrical Frequency Dispersion Characteristics Of Coal Containing Water

In recent years,there has been a great deal of progress in assessing the porosity and permeability of the rock,It is very important to evaluate coal seam gas control by using coal seam electrical detection of coal seam pore water,evaluate coal seam hydraulic outburst prevention measures and gas enhanced drainage and seepage effect.Collection of four kinds of Metamorphic Grade primary structural coal samples from Pingdingshan mining area,Hebi mining area and Jiaozuo mining area,reference to rock electrical measurement and analysis method,use the IM3533-01 LCR meter manufactured in Japan,at room temperature and pressure,the in-phase resistivity R and the specific resistivity X of the different water-bearing coal bodies at the frequency of 1mHz-200 kHz alternating electric field were measured.The main conclusions are as follows:(1)The in-phase resistivity and the specific resistivity of the water-bearing coal have the dispersion characteristics.(2)The dispersion characteristic curve shows that the in-phase resistivity R of the water-bearing coal has a monotonically decreasing law with the increase of the frequency,which accords with Rock-induced polarization law.At the same time with the increase of water saturation,the specific resistivity X more and more show the first increase after the increase and then reduce the three-stage type.And the three-stage type corresponds to the in-phase resistivity.By analyzing the mechanism of the three-stage rule: The low frequency band is mainly excited by induced polarization,the middle band frequency band is mainly electromagnetic induction,the high frequency band is dominated by dielectric effect.(3)The Complex electricity of water-bearing coal has anisotropic characteristics,parallel surface cleat and parallel butt cleat of the electrical characteristics are similar and better law,while the vertical bedding surface of the law is relatively slightly worse.(4)The dispersion characteristic curve shows that the influence of dielectric polarization on Coal electricity cannot be neglected,and the complex resistivity decreases with increasing water saturation,the complex resistivity decreases significantly with the increase of water saturation in the band less than 1000 Hz,and the change is not obvious.So the low frequency band(f <1000HZ)can be used as a prediction of the coal seam water content advantage band.(5)The low frequency band is mainly by induced polarization,it points out that the coal seam aquosity is predicted by induced polarization.It is feasible to predict the water content of coal seam by complex resistance method,the results of the study are of significance to the development of complex resistance method for evaluating the dominant band selection of coal water aquosity and the method used.