Formation Anisotropy Characterization Method Based on Micro-Resistivity Imaging Logging

Anisotropy is an inherent property of the formation. In highly deviated wells and horizontal wells, the anisotropy coefficient can be calculated by using the difference information of electromagnetic wave logging curves while drilling. In slightly deviated wells, anisotropy has no obvious influence on resistivity. The traditional method of calculating formation anisotropy coefficients by using difference information is no longer applicable. In this paper, the high-resolution characteristics of micro-resistivity imaging logging and local measurement characteristics in different directions were used to divide the image gray scale, and the equivalent resistivity volume model was established to further calculate the equivalent horizontal resistivity and vertical resistivity, so as to obtain the anisotropy coefficient of the reservoir. The obtained anisotropy coefficient was compared with the anisotropy coefficient calculated with the resistivity while drilling of drilled wells, and the two were in good agreement. In addition, the resolution of the anisotropy coefficient calculated by the micro-resistivity imaging was higher, which could well reflect the anisotropy characteristics of fractures, holes, and heterogeneous well sections, and provide a new method for evaluating the formation anisotropy.