Effect of inclination and water cut on venturi pressure drop measurements for oil-water flow experiments

Abstract

This study presents an experimental investigation of pressure drop measurements in a Tercom flanged machined venturi meter of 0.5 beta ratio for oil-water two-phase flow in a 0.0762m (3-in.) pipe. Two-phase large scale inclinable flow loop was used to acquire data for different water cuts and fluid mixture flow rates. Mineral oil D80 and portable water were used for the single phase and two-phase oil-water experiments. The experiments were conducted for flow rates ranging from 2000 to 12000 bpd, water cuts varying from 0% to 100% in steps of 20%, for four flow loop inclinations (0, 40, 60, and 90 degrees) from horizontal to vertical positions. The range of liquid flow rates were selected to match the actual flow rates in real oil wells to reflect field conditions. The results show that the venturi pressure drop varies parabolically with fluid flow rate for given water cut. However, the venturi pressure drop varies linearly with water cut for given fluid flow rate. The corresponding slopes increase slightly with flow rates. The flow loop inclination has no effect on the venturi pressure drop measurements at the considered flow conditions. A new modified venturi coefficient, k, which is a function of pressure losses and geometry, was defined and its value obtained from the oil-water two-phase flow experiments. The mixture venturi pressure coefficient was also defined and determined, and the average value found to be around 15.5 for all flow loop inclinations. The results indicate that the venturi pressure drop and the determined venturi coefficients are unaffected by the flow loop inclination for selected oil-water two-phase flow conditions. In this paper, attention was focused on the variables affecting the performance of the venturi meter for oil-water flow under real oil well operating conditions.