EXPERIMENTAL ESTIMATION OF TEMPERATURE NOISE CAUSED BY FREE THERMAL CONVECTION IN WATER-FILLED BOREHOLES

Abstract

The relevance of the research. Temperature measurements in boreholes are used for solving a wide range of exploration, geophysical, environmental, hydrogeological, and geodynamic problems. The development of new temperature sensors and registration systems significantly expands the capabilities of borehole thermometry. This raises the requirements for measurement accuracy. However, these requirements often cannot be satisfied in real borehole conditions due to the influence of temperature noise caused by free thermal convection of the fluid. For effective planning of equipment and methods of temperature measurements in boreholes, it is necessary to evaluate the amplitude of temperature noise. The main aim of the research is to develop mathematical models for estimation the level of temperature noise caused by free thermal convection. Methods: statistical analysis of temperature records obtained from laboratory experiments, temperature logging and temperature monitoring in boreholes. Results. The optimal parameter for estimating temperature noise is the standard deviation of temperature fluctuations. Models of varying complexity have been developed that make it possible to estimate the amplitude of convective noise depending on the geothermal gradient, the internal radius of the borehole, and the Rayleigh number. The proposed models allow choosing the equipment and methods of temperature logging and temperature monitoring in boreholes, depending on the ratio of useful signal/temperature noise.

Keywords

• borehole
• temperature logging
• temperature monitoring
• free thermal convection
• temperature noise