Magnetotelluric static correction of two-dimensional model based on the highest frequency phase method and spatial filtering method

Static effect is one of the main reasons for affecting the accuracy of magnetotelluric sounding. In this paper, a static correction method, the highest frequency phase method, is proposed on the basis of the phase correction method, which is more suitable for geological conditions with smooth electrical changes. Its principle is to eliminate the error accumulation in the phase correction method by replacing the apparent resistivity value of the previous frequency point in the recurrence formula with the arithmetic mean of the highest frequency apparent resistivity of the measuring points on both sides of the measuring points that need to be corrected and are less affected by the static effect. Taking the forward and inversion of two-dimensional model as an example, the effectiveness and superiority of the highest frequency phase method are proved by comparing the forward and inversion results from spatial filtering method, phase correction method and highest frequency phase method before and after static correction for different models. It also shows that for the horizontal layered formation model with sharp resistivity difference and severe static shift, the static correction effect of joint correction which combines highest frequency phase method with spatial filtering method is much better.