Research On Numerical And Physical Simulation Experiment Of Three-dimensional High Density Resistivity Method

As an important geophysical method, resistivity method is based on theconductivity difference of the rock mass, which is based on the distribution of currentfield artificially created through observational studies to achieve the purpose ofprospecting and geological problems. Because the rock and soil electricalconductivity differences are widespread, that makes the method widely used inmultiple areas of the mineral survey and hydrogeological, engineering geologicalinvestigation and environmental monitoring with very good results. Early, with thetheory of the method is mature, one-dimensional exploration techniques is used in theexploration and namely sounding, electrical profiling techniques, the use of thepremise is the default stratum is horizontal layered media, but the actual geologicalconditions is complex, for the reasons that it is so difficult to achieve the desiredresult. Later, with the development of computer technology and array data acquisitionthinking, the two-dimensional high density resistivity method has been widely used,achieving very good results, and bringing considerable economic benefits. Theproblem is that the geological structure and abnormal are usually three-dimensionalform and three-dimensional ground features, using the traditional two-dimensionalhigh density resistivity method for exploration often effected by the flanking and cannot be accurate positioning of the geological structure and abnormal thusthree-dimensional high density resistivity method have come into being. The methodfor data collection in the area, the laying of the first multi-channel electrodemulti-polar distance measurement, we can get rich underground resistivityinformation, analyze slices obtained by processing data from different angles, so as torealize the accuracy of the target body from comprehensive perspective.At present, numerical simulation of three-dimensional high density resistivitymethod is mainly concentrated in the forward algorithm for computing the speed ofand the most used in practical applications is the complete data survey of thepole-pole array. But so far no one has the a detailed study on resolution of thecomplete data survey of the pole-pole array for an algorithm, while the lack ofdiscussion on the resolution of the three data measurement (complete data survey,cross diagonal survey and Γ survey). And a detailed analysis of several other typesof arrays are also not compare.To solve the above problems, this paper take advantage of the forward modelingsoftware RES3DMOD of three-dimensional high density resistivity method. First, agroup of high resistivity spherical model is established, change the center of thesphere where the depth with changing the size of the sphere at the same time, so as to study on the resolution used complete data survey of the pole-pole array. Second,select a set of typical model to simulate the resolution of different data measurement.Third, the high resistivity rectangular and inclined tabular body model are establishedrespectively, using a different type of array for data acquisition, to study theadvantages and disadvantages of different types of arrays. Physical simulationexperiments to validate the conclusions of the numerical simulation experiments, host,data acquisition software, sinks, electrodes and battery composed of a data acquisitionsystem, balloons, plastic rods and rubber sheets were selected to simulate highresistance anomalies. Finally data are inversion by software RES3DINV of thethree-dimensional high density resistivity method f, the inversion results are visualdisplayed by3D mapping software Voxler.Through the study of numerical and physical modeling experiment, there are thefollowing conclusions: First, as for complete data survey of the pole-pole array, whenabnormal body resistivity is10times more greater than background field resistivity,with abnormal body size of the smallest electrode distance change from1:1to3:1ratio, then abnormal conditions may be distinguished in the depth ranging from1.5to2times of the electrode spacing,while abnormal body sizes and minimum electrodespacing ratio of greater than or equal to5:1, abnormal body status in the theory ofexploration depth range can be well reflected. Second, as for the three data collectionmethods of pole-pole array, obtained richer information, the other two measurementdata obtained by repeated inversion so that abnormal convergence, but the resolutionis much lower than the complete data survey, sometimes may resulted in the shape ofabnormal deformation, so cross diagonal survey can be used on the premise that itdoes not affect the exploration results. Third, selection for the arrays, the pole-polearray has the advantages of the deepest effective exploration depth, the widesteffective horizontal exploration width but low resolution compared to other arrays,pole-dipole and dipole-dipole arrays have a higher resolution to distinguish theabnormal, and because of less acquisition data points schlumberger and wennerarrays have a lower resolution. Four, according to the different needs one-dimensionalelectrical sounding and electrical profiling apparent resistivity rate curve, thetwo-dimensional resistivity contour map, as well as three-dimensional slices andabnormal body rendering map can be extracted from the body of data collected fromthe three-dimensional high density resistivity method.