Effects of High Oil Viscosity on Oil/Gas Flow Behavior in Horizontal Pipes

A capillary model is employed to study the slug flow behavior in pore structure. Oil-water system and oil-gas system are investigated in the experiments. During the flow process, it is observed that the wetting phase liquid will generate a thin liquid film on the inner surface of the tube wall, and the liquid film plays an important role in capillary flow. At the meantime, the pressure drop across the tube is recorded during the experiment, result shows that the pressure drop magnitude is proportional to the oil slug length, while it is not significantly affected by the liquid injecting velocity.

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Drift-flux parameters for high-viscous-oil/gas two-phase upward flow in a large and narrow vertical and inclined annular duct

Journal of Energy Resources Technology ◽

10.1115/1.4051397 ◽

2021 ◽

pp. 1-24

Author(s):

Marcel C. Barbosa ◽

Oscar M. H. Rodriguez

Keyword(s):

Flow Pattern ◽

Gas Flow ◽

Production Systems ◽

Outer Diameter ◽

Oil Viscosity ◽

Two Phase ◽

Drift Flux ◽

Viscous Oil ◽

Annular Duct ◽

Oil Gas

Abstract Proper sizing of flow lines in the upstream energy industry depends on accurate modeling of gas-liquid flow, which has a common occurrence in production wells and has been studied thoroughly for many decades. However, data of flow in duct geometries different from circular pipes and when the liquid viscosity is much higher than that of water are scarce. Proper prediction of pressure gradient, heat and mass transfer and corrosion depends on the accuracy of the model used to calculate the volumetric phase fraction. In pumped directional wells with inverted-shroud gravitational separators there is flow through an annular duct formed between the wells' casing and the separator itself that can have some tens of meters. The present work is an investigation on upward vertical/inclined high-viscous-oil/gas flow in a large and narrow annulus (30mm hydraulic diameter with an outer diameter equal to 155mm), using a radial geometry comparable to those found in real production systems. Air-water and air-oil mixtures, the latter with two oil viscosity ranges, were used as working fluids. The experimental test section used was 9.67m long positioned at 90° (vertical) and 45° and made of two concentric pipes. Flow pattern transitions from the literature were analyzed and compared to the collected experimental data. Drift-flux parameters were obtained from multiple working conditions. These drift-flux parameters were employed in the development of a novel flow-pattern-independent correlation, compared against the present data and other data sets from the literature in which other geometries and fluids were used. The predictions of the proposed drift-flux correlation are significantly superior in comparison to correlations selected from the literature in all cases.

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Study of Gas Flow in Micronozzles Using an Unstructured DSMC Method

ASME 2009 7th International Conference on Nanochannels, Microchannels and Minichannels ◽

10.1115/icnmm2009-82180 ◽

2009 ◽

Author(s):

Ehsan Roohi ◽

Masoud Darbandi ◽

Vahid Mirjalili

Keyword(s):

Boundary Layer ◽

Knudsen Number ◽

Gas Flow ◽

Subsonic Flow ◽

Flow Behavior ◽

Boundary Layer Separation ◽

Back Pressure ◽

Viscous Force ◽

Dsmc Method ◽

Wide Range

The current research uses an unstructured direct simulation Monte Carlo (DSMC) method to numerically investigate supersonic and subsonic flow behavior in micro convergent–divergent nozzle over a wide range of rarefied regimes. The current unstructured DSMC solver has been suitably modified via using uniform distribution of particles, employing proper subcell geometry, and benefiting from an advanced molecular tracking algorithm. Using this solver, we study the effects of back pressure, gas/surface interactions (diffuse/specular reflections), and Knudsen number, on the flow field in micronozzles. We show that high viscous force manifesting in boundary layers prevents supersonic flow formation in the divergent section of nozzles as soon as the Knudsen number increases above a moderate magnitude. In order to accurately simulate subsonic flow at the nozzle outlet, it is necessary to add a buffer zone to the end of nozzle. If we apply the back pressure at the outlet, boundary layer separation is observed and a region of backward flow appears inside the boundary layer while the core region of inviscid flow experiences multiple shock-expansion waves. We also show that the wall boundary layer prevents forming shocks in the divergent part. Alternatively, Mach cores appear at the nozzle center followed by bow shocks and an expansion region.

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Behavior of Radial Incompressible Flow in Pneumatic Dimensional Control Systems

Journal of Fluids Engineering ◽

10.1115/1.1598991 ◽

2003 ◽

Vol 125 (5) ◽

pp. 843-850 ◽

Cited By ~ 2

Author(s):

G. Roy ◽

D. Vo-Ngoc ◽

D. N. Nguyen ◽

P. Florent

Keyword(s):

Gas Flow ◽

Flow Behavior ◽

Pressure Gauge ◽

Axisymmetric Flow ◽

Low Pressure ◽

Industrial Applications ◽

Nozzle Geometry ◽

Machined Surface ◽

Flow Area ◽

Simpler Algorithm

The application of pneumatic metrology to control dimensional accuracy on machined parts is based on the measurement of gas flow resistance through a restricted section formed by a jet orifice placed at a small distance away from a machined surface. The backpressure, which is sensed and indicated by a pressure gauge, is calibrated to measure dimensional variations. It has been found that in some typical industrial applications, the nozzles are subject to fouling, e.g., dirt and oil deposits accumulate on their frontal areas, thus requiring more frequent calibration of the apparatus for reliable service. In this paper, a numerical and experimental analysis of the flow behavior in the region between an injection nozzle and a flat surface is presented. The analysis is based on the steady-state axisymmetric flow of an incompressible fluid. The governing equations, coupled with the appropriate boundary conditions, are solved using the SIMPLER algorithm. Results have shown that for the standard nozzle geometry used in industrial applications, an annular low-pressure separated flow area was found to exist near the frontal surface of the nozzle. The existence of this area is believed to be the cause of the nozzle fouling problem. A study of various alternate nozzle geometries has shown that this low-pressure recirculation area can be eliminated quite readily. Well-designed chamfered, rounded, and reduced frontal area nozzles have all reduced or eliminated the separated recirculation flow area. It has been noted, however, that rounded nozzles may adversely cause a reduction in apparatus sensitivity.

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