Summary
The challenge of theoretical and numerical studies of annular fluid flow
with varying eccentricity is mainly a result of the required coordinate
systems. Computational-fluid-dynamics (CFD) modeling provides the
state-of-the-art approach of investigating fluid flow in such complex
geometries. In this study, results from a series of numerical simulations for
the fully developed laminar flow of non-Newtonian power-law fluids in
concentric and eccentric annular geometries are used to investigate the effect
of eccentricity, flow-behavior index, and diameter ratio (ratio of the outer
diameter of the inner tubing to the inner diameter of the outer tubing) on
axial frictional pressure losses.
The frictional pressure-loss gradients predicted by the CFD simulations were
verified by comparing with the published studies and flow data from a
field-scale experimental set-up. At a constant flow rate, it is confirmed that
frictional pressure losses decrease with increasing eccentricity. A good
agreement was obtained with the Haciislamoglu et al. correlation, and the
results of this study, especially at low values of eccentricity. At very high
eccentricities, data from the CFD model yield lower frictional pressure loss
compared to Haciislamoglu et al. correlation. This type of expression is
obtained and the improved data of this study is incorporated.
Next, this paper presents the results of an experimental study carried out
to investigate frictional pressure-loss behavior of drag-reducing polymer
solutions, flowing turbulently through an eccentric annulus. The experimental
setup includes 30 ft of 3 1/2 x 2 3/8-in., 200 ft of 3 1/2 x 1 3/4-in., 69 ft
of 5 1/2 x 4-in., and 79 ft of 5 x 3 1/2-in. fully eccentric annuli. Data
analysis enabled the development of a new correlation using fluid apparent
viscosity at 511 sec–1, generalized Reynolds number, and diameter
ratio, all of which can be easily determined in the field, as independent
variables. These new correlations for laminar and turbulent flow of
drag-reducing polymer solutions present an improvement to existing
correlations, and also permit undemanding hydraulic-program calculations for
varying annular configurations.
© 2011. Society of Petroleum Engineers
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History
- Original manuscript received:
26 March 2010
- Meeting paper published:
23 March 2010
- Revised manuscript received:
10 January 2011
- Manuscript approved:
28 March 2011
- Published online:
9 November 2011
- Version of record:
27 December 2011
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