Effect of Viscosity on Pressure Drop of Oil-Water Two Phase Flow in 6” Horizontal and Inclined Stainless Steel Annulus Pipe
Keywords:multiphase flow, viscosity, oil-water flow, pressure drop, water-cut, inclined pipe, annular flow
Two phase annular fluid flow (oil in water) commonly found in petroleum industry and is generally used for the lubricated transportation of highly viscous oil. Despite their importance, behavior of such flows has not been explored to an appreciable extent. Liquid viscosity may change considerably because of changes in temperature as in deep-water oil production. The variations in liquid viscosity have a remarkable influence on flow characteristics. In this experimental work, attention has been focused on effect of viscosity on pressure drop measurements of oil-water annular two-phase flow in a horizontal and inclined 6-inch diameter stainless steel pipe at different flow conditions. Two different mineral oils Exxsol D80 and Exxsol D130 along with water were used as working fluids in the present experimental study. Experiments were carried out for different inclination angles including: 0° - 90° and for different water cut (WC) ratios (0 to 100% in steps of 20 %). Inlet oil-water flow rates were varied from 2000 to 12000 barrels-per-day (BPD). For a given flow rate the frictional pressure drops (FPD) has been found to decrease from WC = 0 to WC 20%. Further increase in WC, FPD has been found to increase up to WC 40%. For WC more than 40%, the decrease in FPD is not appreciable. This could be due to phase inversion or change in flow pattern regime. For a given case with WC 40% (horizontal, ? = 0° case, flow rate = 10000 BPD), the FPD of Oil (D130) is more than FPD of Oil (D80) by 7%. This implies Oil (D80) is more suitable for transportation of oil-water two phase flows. For a given case (with WC 40%, 10000 BPD), for D80 oil, for increase in angle from zero degree to 90 degree, the increase in FPD is not appreciable. However, for the above scenario, for D130 oil, for increase in angle from zero degree to 90 degree, the percentage increase in FPD has been found to be 27%.