Summary
Coiled-tubing (CT) applications include drilling operations, hydraulic
fracturing, well completions, removing sand or fill from wellbore, and other
applications that involve pumping fluids at high temperatures and high
salinity. Because of curvature effects in CT, huge pressure losses occur,
limiting the maximum flow rate achieved. By adding specific chemicals known as
"friction reducers" or "drag reducers" to the fluids, these pressure losses can
be minimized to a great extent.
Previously, several authors have published their results for fluid flow
through CT, but only a limited number of studies have been reported that relate
to temperature and salinity effects on drag reduction in fluids flowing through
CT.
This paper discusses an experimental study of two commonly used drag
reducers--ASP-700 and ASP-820--flowing through CT with different salinities and
temperatures. Both small-scale and large-scale flow loops are used in this
study. The small-scale flow loop includes a 1/2-in.-outside-diameter (OD)
smooth CT, while the large-scale flow loop includes 2 3/8-in. rough CT.
Elevated temperature tests and salinity tests are conducted using optimum
concentrations of drag reducers in fresh water, 2% KCl, and synthetic
seawater.
The flow data gathered were analyzed and used to develop correlations that
can predict drag reduction at different salinities and temperatures. The
developed correlations show reasonable agreement with experimental data.
© 2011. Society of Petroleum Engineers
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History
- Original manuscript received:
14 April 2010
- Meeting paper published:
23 March 2010
- Revised manuscript received:
3 August 2010
- Manuscript approved:
3 September 2010
- Published online:
13 January 2011
- Version of record:
22 February 2011
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