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Study On Controlled-source Electromagnetic Complex Resistivity 2.5-D Forward

Posted on:2009-03-11Degree:MasterType:Thesis
Country:ChinaCandidate:N ZhaoFull Text:PDF
GTID:2120360242484317Subject:Earth Exploration and Information Technology
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CSEM (Controlled-source electromagnetic) method is an efficient electromagnetic method; it is widely used in many domain of today's geophysical exploration, such as hydrology, petroleum, coalfield, terrestrial heat, and so on. 2.5-D forward problem has very important practicality, it mainly is used of complicated earth controlled-source electromagnetic data. Compared with the veriest 3-D medium, 2.5-D model reduces the computation quantity, which can be fulfilled easily on common computers. On the other hand, our country is a country with a lot of mountains area, it is easier for 2.5D model to approach field geologic setting. So the research on electromagnetic forward and inversion of 2.5D model has important theoretical and practical significance.During computing 2.5D electromagnetic response, we divide target area into many small parts according to the finite element method, then we deduce the independent functional of electric field component and magnetic field component according to Maxwell equation for this block homogeneous medium. And we substitute Cole-Cole model to the Maxwell equation.As a result, the calculation speed of 2.5D forward problem is improved quickly.We design two abnormal model(low resistivity model and high resistivity model), then change the complex resistivity parameters,such as polarizability(m), frequency correlation coefficient(c), time constant (Ï„) and work frequency(f).By this way,we can observe how the complex resistivity parameters above effect the real variable and imaginary variable of electric field on E y horizontal component.
Keywords/Search Tags:CSEM, 2.5-D forward problem, complex resistivity, Cole-Cole model, finite element method
PDF Full Text Request
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