Radial drilling operations currently involve capillary coiled tubing units, actually being smaller copies of usual CT units, the so-called “small coiled tubing”. The units are meant for working with coiled tube of stainless steel. The diameters of the tubing are ½ inch (12.7 mm), ¾ inch (19.05 mm) or 1 inch (25.4 mm). As in “big” coiled tubing, the tube is reeled on spool, equipped with a levelwind swivel and a manifold for supplying fluid into the tubing.

A differential characteristic of the capillary CT units is a possibility of running low depth (2,000- 2,500 m) round-trip operations without injectors. In such cases the spool acts as a winch of logging truck hoist. In case of deep operations small CT units are necessarily equipped with an injector with the pulling force of up to 5,000 kg.

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