Ultrasonic technique for tracking oil-water emulsion layer in separation vessels

Abstract

Ultrasonic based techniques have been explored to monitor emulsion layer and separation of oil and water phases from their emulsions. Creation of oil and water emulsions is a common occurrence in the petroleum and gas processing industry and several other commercial operations. This creates a multi-interface level measurement problem due to the presence of an emulsion layer in between oil and aqueous phase layers. The potential of ultrasonic-based methods has been tested by tracking the interphase position between the phases with suitably configured probes. The oil phase consisted of either crude or mineral oil while deionized water constituted the aqueous phase. The tests were conducted in a four inch diameter and twenty inch tall column mounted with acoustic probes. The measured acoustic parameters included, time of flight and energy content of the travelling wave at a selected frequency of 3.5 MHz. The ingress of emulsion phase layer at a sensor location could be easily detected since the probe design maintained a good signal-to-noise ratio even in highly attenuating emulsion phase. The observed attenuation losses in the emulsion phase are attributable to intrinsic losses and thermal effects. The simultaneous changes to acoustic velocity could be attributed to the fraction of water phase in the oil-water emulsions.