Coiled tubing applications include drilling operations, hydraulic fracturing, well completions, removing sand or fill from wellbore, etc. These applications involve pumping fluids at high temperatures and salinity. Due to curvature effects in coiled tubing, huge pressure losses occur limiting the maximum flow rate achieved. By adding specific chemicals known as 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 coiled tubing but only a limited number of studies have been reported related to temperature and salinity effects on drag reduction in fluids flowing through coiled tubing.

This paper discusses experimental study of two commonly used drag reducers ASP-700 and ASP-820 flowing through coiled tubing with different salinities and temperatures. Both small-scale and large-scale flow loops have been utilized in this study. The small-scale flow loop includes a ½-in. OD smooth coiled tubing while the large-scale flow loop includes 2⅜-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 thus 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.

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