Experimental investigation of gas-liquid separation for two-phase flow within annular duct of an ESP skid

Abstract

Although common in several sectors of the industry, undeveloped two-phase flow in annular ducts has yet to receive attention from researchers. This work investigates experimentally the gas-liquid separation phenomenon in the two-phase flows inside annular ducts. The experimental setup enables flow visualization and analysis through high-speed cameras. This experimental setup's design is based on a non-dimensional and similarity analysis with a real device (Electric Submersible Pump Skid or ESP Skid) in operation at an offshore oilfield in Brazil. The experiments were performed in 5°, 15°, 30° 45° and 60° slopes, horizontally. Flow patterns in the annulus were observed and analyzed. Also, vortices were observed in the intake region. The gas-liquid separation tests enabled the association of the measured separation efficiency with mixture velocities and, consequently, with dimensionless parameters (Froude number) and no-slip void fraction. As observed in the literature, the separation decreases as the mixture velocity increases. The results were qualitatively correlated with literature models, but with high quantitative discrepancies, mainly due to the disregard for radial slip in the models. Also, changes in the trend of separation efficiency were observed and these were caused by flow pattern changes.