The horizontal flow of equal density oil‐water mixtures was investigated in a 1‐inch diameter laboratory pipeline. Oils of viscosities 6.29, 16.8 and 65.0 centipoise were used in the experiments. Flow patterns, holdup ratios and pressure gradients were investigated for a range of superficial oil velocity from 0.05 to 3.0 ft./sec. and a range of superficial water velocity from 0.1 to 3.5 ft./sec, with input oil‐water ratios ranging from 0.1 to 10.0. Similar series of flow patterns were observed for each oil and were found to be largely independent of the oil viscosity. At high oil‐water ratios oil formed the continuous phase and a water‐drops‐in‐oil regime was noted. As the oil‐water ratio was decreased the flow patterns concentric oil‐in‐water, oil‐slugs‐in‐water, oil‐bubbles‐in‐water and oil‐drops‐in‐water in which water was the continuous phase were observed. The most viscous oil did, however, exhibit anomalous behavior at low superficial water velocities and this is attributed to different interfacial properties. The pressure drops measured indicated that for a given oil flow rate the pressure gradient was reduced to a minimum by the addition of water provided that the oil was not in turbulent flow. Maximum pressure gradient reduction factors varied from 1.7 for the 6.29 centipoise viscosity oil to 10 for the 65.0 centipoise viscosity oil at input oil‐water ratios of 4.5 and 1.0 respectively.
The flow characteristics of the two‐phase system —white mineral oil and water—were examined in a horizontal, smooth, one‐inch pipe. Flow conditions were investigated over a range of input oil‐water volume ratios from 0.1 to 10 at thirteen superficial water velocities ranging from 0.116 ft./sec. to 3.55 ft./sec. A theoretical analysis of the laminar flow of two immiscible liquids between wide parallel plates yielded a modified parallel plate friction factor based on the water properties and the superficial water velocity. It was evaluated for a number of input oil‐water volume ratios and plotted against the superficial water velocity. The experimental pressure drop data that were obtained were correlated using a modified Fanning friction factor which was evaluated for the range of input ratios studied and correlated with the superfical water velocity. A flow pattern correlation was obtained for visually observed types of flow—bubble, stratified and mixed—and it was shown that these patterns occurred in laminar, transitional or turbulent conditions of flow. The theoretical analysis for flow between wide parallel plates was adapted to obtain hold‐up relationships, and a plot of the hold‐up ratio HR (the input divided by the in situ oil‐water volume ratio) versus the input oil‐water ratio was constructed. This plot indicated that in the laminar region of flow the hold‐up was not dependent on the superficial water velocity but was only a function of liquid viscosity and input ratio. Experimental results for flow in the pipe conformed with this prediction while indicating that in the turbulent region superficial water velocity was also a factor.
The upward vertical flow of oil‐water mixtures has been investigated in a 37‐ft. length of cellulose acetate butyrate tubing of inside diameter 1.038‐in. Flow pattern, holdup and pressure drop data were obtained for water mixtures with 0.936, 20.1 and 150 centipoise oils at superficial water velocities ranging from 0.10 to 10.0 ft./sec. The oil‐water mixtures exhibited a behavior similar to that of air‐water mixtures studied previously. The flow patterns observed at constant superficial water velocity with increasing oil‐water ratio were: drops of oil in water, slugs of oil in water, froth, and drops of water in oil. Holdup of the phase forming the continuous medium was observed but to a much lesser extent than with the air‐water system. Curves of pressure drop versus oil‐water ratio exhibited a minimum, a maximum and a second minimum at low water velocities; a single minimum at intermediate water velocities; and a steady increase at superficial water velocities above about 5 ft./sec. A friction factor based upon the properties and the superficial velocity of the water is correlated with the superficial velocity of the oil and a Reynolds number based on the properties and superficial velocity of the water. This shows that the pressure drop due to friction and other irreversibilities is essentially independent of the viscosity of the oil except under conditions where the oil is the continuous phase.
Using a mechanistic approach, equations are developed to describe the stratified cocurrent flow of gas‐liquid mixtures in horizontal pipes. An iterative method is suggested for their solution. Experimental data were collected using air‐oil mixtures in a one inch 1. D. by 101 ft. long acrylic pipe. Pressure drop and average in situ liquid volume fraction are presented as a function of the superficial gas velocity and are compared with predicted results from this study and other models reported in the literature. Visual observation of flow patterns and their transitions are indicated on the tentative flow pattern map of Govier and Aziz(1).
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