Regarding the Thermal Behaviour of a Centrifugal Pump for Oil Recovery

Abstract

The modern world is characterized by increasing consumption of oil and its products. Oil production and consumption is an indicator of the economic level of development. However, there is a depletion of oil reserves in the field. New fields are not productive. Oil production in these fields leads to complications. Centrifugal pumps, which account for about 95% of the world's production, are particularly susceptible to such operational complications. Electric submersible pumps for oil well operation are the most flexible way, easily controlled and automated. Therefore, in low-productive fields, electric submersible pumps are widely used. However, in recent years, the operation of electric centrifugal pumps began to observe complications in the form of failures due to a decrease in the electrical resistance of the "cable – motor" system. Another complication in the operation of the electric centrifugal pump is a decrease in productivity. The third and most widespread complication is salt deposits in the inner cavity of the centrifugal pump. Studies conducted to identify the cause of salt deposition show that the original cause is the properties of reservoir water. However, it was not clear why salts were formed in some cases and not in others. Тhe state of Affairs remained unclear until the investigation of the thermal condition of the electric submersible pump began. It turned out that the centrifugal pump when pumping strongly carbonated liquids rapidly reduce the efficiency. It has been shown that the pump temperature is determined by the properties of the formation fluid and the properties of the centrifugal pump. Salt deposition begins when formation water inside the pump begins to boil. Analytical expressions were obtained to calculate the pump temperature. It turned out that the temperature of the pump also depends on the coefficient of heat transfer from the metal to the gas-liquid mixture and the coefficient of thermal conductivity of the gas layer on the surface of the pump. This work is devoted to obtaining an analytical expression for determining the heat return coefficient. The ability to calculate the pump temperature and determine the boiling pressure of reservoir water at this temperature will predict the deposition of salts in the centrifugal pump.