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. The unit managed from the control desk in the cabin. The unit drive is made from hydraulic actuation station, powered by diesel or electric engine. In order to make the units more self-sustainable they also equipped with high pressure triplex pump for supplying technological fluid into the well and power generator. Besides, many units have a positioning crane for easer installation of the equipment on the well. It is located in the back side of the unit. Small size of the unit allows locating it on one chassis, semi-trailer or skid.