At the request of Rosneft Oil Company, theoretical substantiation, design and development of an electromagnetic tool based on a new configuration of a measurement system is carried out. Multiplesonde multi-frequency electromagnetic well logging instrument with toroidal generator and receiver coils is targeted at studying the macro-anisotropic properties of complex oil and gas reservoirs. With the application of the measurement system with toroidal coils, an electromagnetic field is excited in the near-wellbore environment, depending on both the horizontal and vertical electrical resistivity. We have developed complexes of algorithms and programs for simulation, processing and inversion of signals of the electromagnetic tool in spatially inhomogeneous anisotropic media. On the basis of large-scale numerical simulation in realistic models of geological environment, we have studied the electromagnetic signals, concluded about the high spatial resolution of the tool, and substantiated its optimal configuration, which includes sonde spacings, operating frequencies, types of measured signals and operating modes. The electromagnetic tool has been extensively tested on laboratory stands and in real borehole conditions. We have conducted successful pilot tests in terrigenous and carbonate reservoirs of the Volga-Ural petroleum province. Moreover, we have accomplished the quantitative interpretation of logs of the electromagnetic tool at intervals of sandy-argillaceous reservoirs, and have shown that taking account of clay content according to its data leads to an increase in the oil saturation factor up to 10 % compared to traditional electrologging methods.
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