A Method for Measurement of Electromagnetic Apparent Resistivity in Frequency Domain of Artificial Field Source

Abstract

The invention discloses an artificial field source frequency domain electromagnetic apparent resistivity measuring method; the method sets a horizontal electric dipole field source and electric fieldhorizontal component measuring system according to detection or exploration needs, and employs emission and reception fixed devices for lossless detection; the method uses electromagnetic signals of different frequencies f to record a multi-frequency point electromagnetic field Ex component of certain measuring point; the method employs a first order difference derivation approximation method to calculate an electromagnetic field Ex frequency point derivative (see description) of the corresponding frequency point combination, and storing the calculated derivation information; the method uses the electromagnetic field Ex component frequency point derivative (see description) to carry out the apparent resistivity transition. The method removes the limits of using Kania apparent resistivity definition norms for solving the apparent resistivity, and can reduce the unstable calculation result risks caused by a non-linear equation group in a normal whole region apparent resistivity solving process, thus effectively improving the apparent resistivity calculation efficiency and accuracy.

Description

technical field [0001] The present invention relates to an artificial field source frequency domain electromagnetic apparent resistivity measurement method in the field of exploration geophysics. Its special feature is that the method for calculating apparent resistivity in the whole area does not need to solve nonlinear equations, which reduces the inaccurate band of solving nonlinear equations. To define the error of apparent resistivity and improve the accuracy of traditional apparent resistivity calculation. Background technique [0002] In geophysical exploration, in order to describe the conductivity of underground rocks and ores, resistivity or conductivity is usually used to describe it. However, in actual work, the combined effect of collected underground rocks and ores is not the true resistivity of underground rocks and ores. , which is called the apparent resistivity, which is related to many factors such as the composition and structure of underground rocks and ...

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Problems solved by technology

For example, it still uses the conventional Carnia apparent resistivity definition method for calculation (such as or ), the premise of this definition is that electromagnetic waves propagate as plane waves, so it is necessary to place the observation area in the far area, and use the data in the far area to calculate the apparent resistivity, and the apparent resistivity calculated in the non-far area will produce serious distortion. Therefore, the data in the transition zone and the near zone are discarded, thereby reducing the scope of application of CSAMT

At the same time, working in the field needs to measure two orthogonal electric and magnetic fields in the far area, which reduces the efficiency of field work and increases the cost of field exploration

In addition, the conventional full-area apparent resistivity definition method adopts E_E x and To solve the problem, this definition method is applicable to most of the measurement areas, and it cannot solve the apparent resistivity obstacle in the non-planar area, but it needs to solve the nonlinear equations to define the corresponding apparent resistivity, resulting in the apparent resistivity accuracy depends on non-planar The solution of linear equations, which affects the accuracy and efficiency of apparent resistivity calculation

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