Hydraulic fracturing through coiled tubing (CT) has become an effective and economical stimulation technique for wells with multiple zones to be fractured. Yet, prediction of friction pressure losses of fracturing slurries in coiled tubing presents a unique challenge in the fracturing job design.

This paper presents an experimental study of friction pressure losses of fracturing slurries in coiled tubing using a full-scale coiled tubing test loop which consists of 1000 ft 2–3/8″ coiled tubing and 200 ft 2–3/8″ straight tubing sections. The fracturing slurries were prepared with guar-based gels at various polymer and sand concentrations. Based on the experimental results, the characteristics of the flow behavior of fracturing slurries as affected by sand concentration, base gel rheology and centrifugal forces are discussed. A new correlation has been developed and can be used to predict the friction loss increase over base gel friction.

The coiled tubing erosion mechanisms (sliding abrasion, random particle impact, and directional particle impact) have been discussed. The abrasion by sliding sand bed is believed to be the dominant erosion mechanism.

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