Methodological justification of russian galvanic and electromagnetic logs joint two-dimensional inversion with vertical resistivity evaluation

Two-dimensional numerical inversion is widely used by leading foreign oilfield services companies to process electrical measurements from intervals of deposits with complex structure. However, its application for Russian electric logs processing is connected with difficulties caused by design features of the logging devices. Previously, we developed and presented software for joint two-dimensional inversion of high-frequency induction (VEMKZ/VIKIZ) and Russian lateral (BKZ) logs. This research is focused on methodological justification of the approach implemented in the software. Using high-precision numerical simulating of BKZ and VEMKZ/VIKIZ signals in three-dimensional models of anisotropic media, we determined the conditions of the two-dimensional piecewise-constant geoelectric model applicability and evaluated the effect of axial symmetry violation on the data processing results. The use of the approach is justified when the well deviates from the normal to the bedding surface up to 15 degrees. With the use of statistical modeling on synthetic and practical data, we have studied the accuracy of the model parameters evaluation. The results show good accuracy of practically significant parameters evaluation in typical for West Siberian terrigenous sections conditions. On the results of the practical data processing we show the advantage of the new approach over the traditional BKZ and VEMKZ/VIKIZ interpretation techniques.