The article considers the possibilities of fiber-optic thermometry systems for monitoring the operation of wells and downhole equipment, as well as their features of data recording. The potential ability of fiber-optic distributed thermometry sensors to measure the temperature field along the entire wellbore makes it possible to almost instantly register its changes. The experience of complex study of a multilateral horizontal well by fiber-optic thermometry and a geophysical instrument is presented. In the well, the inflow profile was determined and the working sections of the main wellbore and the places of fluid inflow from the second and third sidetracks were identified. Comparison of the results of thermometry recorded by systems of different types showed their good convergence only at the end of the horizontal section, which suggests the o slight inflow from the “toe” part of the wellbore. At the same time, both systems did not register extreme temperature changes during compression induction, which indicates the random nature of the measurements performed by the fiber optic system. The measurements did not coincide in time with transient processes. Despite the advantages of standard thermometry in terms of measurement accuracy and more reliable metrological support, measurement of temperature anomalies of fast local processes is possible only using fiber-optic distributed thermometry sensors or thermocouples with a significant number of point sensors. Long-term monitoring requires the use of corrosion-protected geophysical cables with fiber optic modules, usually reinforced (polymer-coated), which reduces its thermal conductivity. To improve the measurements accuracy it is necessary to use fiber-optic systems with the highest possible sensitivity, which is determined by thermal inertia and depends mainly on the specific heat capacity and thermal conductivity of the cable layers. It is shown the necessity of consideration of distorting factors influence, the correct choice of data recording parameters, as well as resolution and thermal inertia of the fiber-optic geophysical cable.
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