Summary
Cuttings transport in highly deviated wellbores is more challenging and
critical than in vertical wells. In inclined wells, the fluid velocity has a
reduced vertical component that may not be sufficient to transport all the
cuttings to the surface. When cuttings returns do not appear to be sufficient
for the drilling rate, hole-cleaning sweeps are applied to clean the borehole
or reduce cuttings-bed thickness. Fiber-containing sweeps have been very
effective in cleaning highly deviated and extended-reach wells. In addition,
substantial torque and drag reduction has been reported when fiber-containing
drilling fluids are used in the field. Although field observations are
encouraging, very little is known currently about flow behavior, hydraulics,
and cuttings-transport efficiency of fiber sweeps.
There is a great need for understanding how fiber particles enhance the
cleaning capabilities of fiber-containing sweeps. The interaction between fiber
particles and drilling fluid is still not understood fully, although the
improvement in cuttings and solids transport is attributed to the formation of
a fiber mat network that enhances the carrying capacity of drilling fluids.
This article presents results of experimental investigations conducted to
study hole-cleaning performance of a fiber sweep. Flow-loop experiments have
been carried out to evaluate and compare sweep efficiencies of the fiber sweep
[0.47% Xanthan gum (XG) and 0.04% synthetic fiber] and the base fluid (0.47%
XG). Equilibrium bed heights were measured at different sweep flow rates in
horizontal and inclined configurations. Results from this study indicate that a
fiber-containing sweep has better hole-cleaning capabilities than the base
fluid, even though these two sweep fluids have very similar rheological
properties. Moreover, adding fiber slightly reduces annular pressure loss at
the same average bed height.
© 2009. Society of Petroleum Engineers
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History
- Original manuscript received:
28 January 2008
- Meeting paper published:
1 April 2008
- Revised manuscript received:
16 December 2008
- Manuscript approved:
5 January 2009
- Published online:
29 October 2009
- Version of record:
23 December 2009
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