Droplet shear in oil/water emulsion produced by centrifugal pump and gear pump

Abstract

Before being fed into the separators, a pump is often used to maintain adequate flowing pressure of oil/ water emulsion in a production conduit, especially in a depleted or matured reservoir. Droplet shearing and size reduction due to the pump highly affect the separation performance. This paper aims to present an experimental investigation on the shearing of oil droplets in an oil/water production fluid passing through a high rpm single-stage centrifugal pump (C-pump) and a lower rpm gear pump. A cross polarizer microscope has achieved sample analyses. The experiments have been carried out at various water/oil ratios, from 70/30 to 90/10, with two different temperatures of 50 o C and 80 o C. Further, the viscosities of the fluid sample from both pump outlets are correlated with the water cuts. The results are presented in a graphical format showing the droplet size distributions of different cases from the two tested pump types. There is a general trend of higher shear intensity and smaller mean oil droplets with the C-pump than the gear pump. Water cut and the temperature seem to have a small effect on the shearing of the droplets. Further, the viscosity correlation for the fluid collected from two pump outlets at different temperatures and water cuts shows a slight decrease in viscosity with the shear rate. However, it is highly affected by the water cut and temperature.