EXPERIMENTAL STUDY OF THE THERMAL FIELD IN THE WELLBORE DURING INDUCTION

One of the promising methods of geophysical survey of existing wells is active thermometry. The technology for conducting studies by this method includes artificial heating of a section of a metal casing (for example, induction), registration and analysis of temperature changes in the range of thermal exposure. As a result of heat exchange with the heated section of the column, a thermal disturbance is created in the fluid flow moving inside the column or in the behind-the-casing flow channel. The analysis of non-stationary temperature in the process of induction action allows solving actual practical problems, for example, determining the presence of fluid overflows in the space behind the casing string. The paper presents the results of an experimental study of the temperature field in a well with an artificial heat source in relation to the determination of behind-the-casing fluid flows. The azimuth-localized behind-the-casing flow "from bottom to top" in the well sump to the lower working formation is considered. It is shown that the temperature of the metal string itself, which is recorded by temperature sensors pressed against the string and distributed along the azimuth, provides the most information in terms of detecting behind-the-casing fluid movement, the sensitivity of the temperature of the fluid in the casing string to the presence of overflow is much lower. On the curves of the azimuthal temperature distribution of the column, the sector with overflow is marked by a lower temperature relative to other sectors, which is due to the removal of heat from the column due to the behind-the-casing fluid movement. The results of experimental studies have shown that it is possible to determine the behind-the-casing flow by measuring the temperature field directly in the heating interval, as well as upstream of the heater, and both measurements during heating and after the heater is stopped are informative. It has been established that the magnitude of the temperature anomalies formed due to the flow is about several degrees, in this regard, the results of temperature measurements can be confidently used to determine the intervals of behind-the-casing fluid movement in the well.