SPE Drilling & Completion
Volume 24,
Number 4,
December 2009,
pp. 553-563
Summary
The flow of non-Newtonian fluids through eccentric annuli is prevalent
during drilling and cementing operations of directional and horizontal wells.
The flow pattern in an eccentric annulus can differ greatly from that in a
concentric annulus, and this difference affects both the pressure drop and the
flow rate at which the laminar-turbulent transition occurs. Errors resulting
from ignoring the effect of eccentricity on frictional pressure drop and
equivalent circulating density can lead to formation fracture or well-control
problems in some situations.
In this paper, a new method is presented for calculating pressure losses in
eccentric annuli. The method is based on an effective diameter that accounts
for the effects of both conduit geometry and fluid rheology. Predictions of the
method are compared with an extensive set of data for drilling fluids obtained
from a large-scale flow loop. The results demonstrate that the new method is
capable of reliably predicting the pressure drop of most drilling fluids in
both laminar and turbulent flow regimes for eccentric annular geometries of
practical interest.
Introduction
The flow of non-Newtonian fluids through eccentric annuli occurs during
drilling and cementing operations for oil and gas wells. Approximate and exact
(numerical) solutions to the fundamental flow equations in this geometry have
been published for Bingham plastic, power-law, and yield-power-law fluids. The
purpose of this article is to present a generalized method for computing
frictional pressure losses in eccentric annuli that is applicable to a wide
variety of drilling fluids. Predictions obtained with the new method are
compared with experimental data from a large flow loop that are available in
the literature.
© 2009. Society of Petroleum Engineers
View full textPDF
(
481 KB
)
History
- Original manuscript received:
30 May 2007
- Revised manuscript received:
25 November 2008
- Manuscript approved:
22 January 2009
- Published online:
17 September 2009
- Version of record:
23 December 2009
View Cart
