Field test on transporting diluted heavy oil by screw pump

Over years of service, parts of screw pump are worn to certain extent. In order to identify the variation of screw pump's characteristic curve, it is necessary to test and check the pump performance curve. As per relevant specifications, field test was conducted on the screw pump in a pump station of a crude oil pipeline, and the flowrate-differential pressure and efficiency-differential pressure characteristic curves formed at the time of transporting diluted heavy oil by screw pump were obtained. Based on the ex-factory flowrate-differential pressure and power-differential pressure performance curves of the screw pump for different viscosities as well as the results obtained from field test, the linear interpolation method was used to obtain the ex-factory performance curves of the screw pump at the viscosity corresponded by the test oil. The correlation results of measured performance curves and ex-factory performance curves of the screw pump show that, for a pump used for many years, its efficiency reduces by 1.1%-14.0%, moreover, at the same differential pressure, the flowrate also losses, possibly by 3.7%-15.6%, and as the differential pressure increases, the flowrate declines more largely. The screw pump performance curves obtained in field test can provide bases for the technologic calculation and energy consumption analysis for transporting diluted heavy oil by this crude oil pipeline in the future.