Static shift correction of magnetotelluric data using time domain electromagnetic data (case study: an oil field located in southwest of Iran)

The purpose of this study is to correct the static shift of magnetotelluric (MT) data in one of the oil fields located in southwest of Iran using time domain electromagnetic (TEM or TDEM) data. Acquisition of the MT data has been made in the same area as the TEM data was acquired at the frequency range of 0.0005-320 Hertz. . A major problem in the MT method that occurs due to distribution of surface electrical anomalies and causes the displacement of resistivity curves, is called the static shift. In this paper, the TEM data have been used to remove the static shift effects. First, both modes of MT data have been corrected statically by reconciling the data with resistivity curves (especially in high frequencies). Then, one-dimensional (1D) and two-dimensional (2D) modeling of the corrected MT data has been made using WinGlink software. Based on the results obtained from dimensional analysis done on the MT data, it can be concluded that the resistivity distribution in the study area is mainly in 2D and three-dimensional (3D) forms. Thus, 1D modeling is unlikely to be the solely correct approach. However, the two-dimensional modeling results are highly valid considering the precise study and determination of geoelectrical directions or trends of the subsurface structures. In this paper, to obtain an exact 2D resistivity model, the static shift correction of the MT data has been carried out for all stations of the A survey line using the TEM data. The results show that the surface static shift correction is very effective in modeling the results and efficiently removes the surface galvanic effects.