Key words: thermometry, cross flows behind casing, thermal tag, well output, well injectivity.
Thermal processes, occurring in the well during column induction heating, are studied. The data, obtained in the course of theoretical and laboratory experiments, are considered. Results of testing the method of active thermometry in the conditions of fields of the Ural-Volga and the Surgut regions are analyzed. The efficiency of the thermal tags application at defining cross flows behind casing from the top, wells outputs and injectivities, during the study of multi layered objects and marginal wells, is shown.