2-D Resistivity Section Sounding Inversion In 3-D Terrain

Dc IP method is a kind of very effective geophysical prospecting method,can be applied to all kinds of complex terrain,harsh natural conditions,it has strong anti-interference ability,high efficiency,high stability and precision of advantages,and widely applied in the exploration of mineral resources in our country.For a long time,the research under the condition of rolling terrain geoelectric anomaly has always been a difficult problem in electrical prospecting,the reason is not only because the problem is more complex,also is limited by different era in the development of science and technology level,it's hard to do a complete solution.Undulating terrain imaging of 2-d resistivity forward modeling and inversion problem in geophysical experts under the unremitting efforts of both at home and abroad,has been basically solved and widely used in the actual production;And undulating terrain 3 d forward modeling and inversion imaging also has a bigger progress,the research methods mainly include integral equation method,the finite element method,finite difference method,and conjugate gradient method,etc.In the field of dc excitation electrical prospecting,we get the measured resistivity data generally with the 2 d or 3 d inversion of terrain.Two-dimensional topography inversion speed,but the accuracy is relatively low,because the only correct the topographic relief on a single profile of anomaly,while ignoring the side profile anomalies caused by terrain;Three-dimensional topography of the inversion accuracy is higher,but the inversion speed slow,and when only a few measurement section,because too much data is not suitable for making 3 d inversion.In this paper,in view of the working mode of the dc IP field,puts forward a three-dimensional terrain under the restriction of two-dimensional IP sounding inversion profiles can not only improve the inversion speed,also consider the terrain of the two-dimensional profile side profile constraints.First for three dimensional ladder sweep in different terrain and symmetric four-pole sounding do the relevant numerical simulation analysis,and the symmetric four-pole sounding topographic correction method for resistivity data,and then do the correction of data after the two-dimensional profile inversion,and then restore the terrain.