Coiled tubing is widely used in the petroleum industry to pump fluids in the well bore at high rates. The friction pressure losses occurring in the tubing at these high rates are an issue of immense concern to the industry. Most of this friction loss can be attributed to the section of the tubing reeled on the spool during the treatment. The dimension of the reel used in the treatment governs the degree of curvature of the tubing and in turn the corresponding pressure drop. These pressure losses apart from increasing the cost of the treatment due to increased energy requirements also reduce the life of the tubular used.Experimental and simulation study has been undertaken to determine friction pressure loss in 1 1/2 and 2 3/8-in. coiled tubings using water and 35 lb/Mgal guar as test fluids. Computational Fluid Dynamics software FLUENT has been used to generate simulations that have been validated with limited experimentation using a field-scale test setup. Previous experiments used limited flow rates and few curvature ratios due to high field-scale experimentation costs. But using CFD simulations friction pressure loss data have been gathered for a range of curvature ratios and flow rates that are comparable to the ones used in the field.Results obtained have been used to determine the effect of curvature ratio on friction pressure losses while pumping Newtonian and non-Newtonian fluids in 1 1/2-in. and 2 3/8-in. tubing.
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