The photo is sourced from toptransoil.ru
Treatment with a hot heat transfer fluid takes place in several stages. First, the liquid is pumped into hollow rods placed inside the tubing. After a certain period of time, the liquid leaves the flow coupling and mixes with the oil flow, rising up along the pipe. However, due to the large area of the pipe space, the flow rate of the heat transfer fluid decreases, causing the liquid to gradually cool down. This is why oil workers usually apply a thermal insulation layer to the inner surface of hollow rods for optimal heating of the well.
“The presence of a thermal insulation layer on the inner surface of the hollow rods significantly affects temperature distribution on the wall of the well. In the presence of a thermal insulation layer, the temperature at the level of the coupling (1,200 m) reaches 56 °C, growing by 36 °C compared to the case without thermal insulation. This is due to the fact that the heat transfer fluid has a higher temperature at the outlet of the coupling, which is equal to 63 °C. When it moves along the rods without an additional layer, the fluid has time to cool down to 20.7 °C at the coupling level,” Evgeny Goltsov, one of the authors of the study and postgraduate student at the Design and Technologies in Electrical Engineering Department, is quoted as saying by Perm Polytechnic University.
The scientists used two different heat transfer fluids (oil and water) to flush the well after a preliminary assessment of their efficiency via a mathematical model. The experiment showed that when the well was flushed with hot oil for five hours (at a flow rate of 150 m3/day and a temperature of 120 °C), the deposits were removed completely. However, when the well was flushed with hot water (at a flow rate of 150 m3/day and a temperature of 90 °C) for the same period of time, the results proved unsatisfactory. This was caused by water quickly cooling down on the pipe wall (to no more than 58 °C), as a result of which the removal of paraffin did not occur in the entire column of the well.
The results of the study could be used to combat paraffin deposits, which is especially important during production in regions with a subarctic climate.
