Approximately 55% of Russia's oil reserves consist of high-viscosity oil, which is more difficult to extract than low- or medium-viscosity oil due to its complex composition and high concentrations of impurities and heavy hydrocarbons. Electric submersible centrifugal pumps are commonly used for high-viscosity crude production, but high viscosity can overload equipment and cause failure at critical values. Installing special heating devices in the bottom-hole zone to reduce crude viscosity is key to ensuring stable pump operation. At the same time, maintaining the required temperature and controlling heat distribution are essential to prevent pump failures and ensure flow rates.
Against this background, scientists at Perm National Research Polytechnic University (PNRPU) conducted relevant research as part of the Priority 2030 Strategic Academic Leadership Program. The paper was published in the Journal of Computational Continuum Mechanics.
To analyze heat and mass transfer processes in oil wells equipped with bottom-hole heaters, the scientists employed mathematical modeling to create a 3D computer model encompassing the well, perforated pump-compressor tubing, and a connected cylindrical heater. The model accounts for oil temperature distribution, velocity, viscosity, and heater parameters.
Using this model, the scientists investigated heaters of different power levels (1, 1.75, 2.25kW) and lengths (1, 3, and 5m) while maintaining a temperature of 122°C (experiments showed that 125°C is the maximum operating temperature for such devices; higher temperatures cause overheating and failure). Natalia Trufanova, Head of the Electrical Engineering Design and Technology Department at PNRPU, explained that with a 1-meter device, oil heats most intensely in the first two meters of the tubing due to higher specific power, and temperature changes are nearly identical across all devices—rising to a maximum before gradually cooling.
The model also determines how heater parameters affect oil temperature at the pump inlet. A 1m, 1kW device raises oil temperature to 39.11°C; a 3m, 1.75kW device to 52.39°C; and a 5m, 2.25kW device to 60.18°C. Higher temperatures reduce oil viscosity, though the reduction also depends on pump power; for some pumps, a 1-meter heater is ineffective, while 3–5m lengths are more effective.
PNRPU graduate student Dmitry Pinyagin noted that using the highest-power (2.25kW) electric heater in the bottom-hole zone can increase oil temperature by 60°C, reducing viscosity 14-fold.
The technology developed by Perm Polytechnic University scientists helps oil production specialists determine the temperature and properties of hydrocarbon flow in known well sections, calculate the required heater length to reduce oil viscosity, ensure stable operation of electric submersible centrifugal pumps, improve equipment durability, and lower material costs in field development.
