Wellbore temperature calculation model during light oil blending in electrical submersible pump wells

Key words:  heavy oil  electrical submersible pump  light oil blending  viscosity reduction  temperature distribution  calculation model

Abstract:

Electrical submersible pump (ESP) is efficient artificial lifting equipment, which has large discharge capacity and is convenient for application and management in different types of oil wells. An ESP combined with light oil blending technique was proposed to reduce oil viscosity and increase the mobility of fluid in the wellbore for deep and heavy oil reservoirs in Tahe Oilfield. A wellbore temperature model was established to calculate the fluid temperature in annulus after light oils were blended or injected into the wellbore for the ESP operated wells. The model was based on the energy conservation principles, considering the heating effects from ESP 's motor and cable as well as the blended light oils. The influences of the injection depth, the volume and temperature of the blended light oils on wellbore fluid temperature were analyzed. The results show that, at a certain injection depth,increasing the blending oil 's temperature can effectively increase the mixture 's temperature above the injection point and near the wellhead, while it has little effect on the fluid temperature near the injection point, which is beneficial to the operations of surface gathering and transportation. The increase of the blended oil 's volume can also increase the temperature of the mixed fluid near the wellhead, but can slightly decrease the fluid temperature near the blending depth. The temperature of the mixed fluid slightly increases with the increase of the blending depth.