More than 30% of well workover operations at Yambursky Field are done with the help of CT units (1 team working with M10 and 1 team with M20). The main types of service operations performed with CT units include:

• restoring artificial bottomhole by sand bridge removal with the help of M10;
• flow stimulation and restoring bottomhole after hydrofracturing (HF) with M20.

The artificial bottom-hole restoring technology envisages the following method. At first the technological liquid is produced on the basis of foamforming liquid (FFL). Calcium chloride (CaCl2) is added into the medium for augmenting the stability of a foam system and reducing the congelation temperature. CM cellulose, neonol, water and methanol are added as well. 25 m3 of FFL is prepared for Cenomanian gas wells. A CT unit is set on the well mouth. The unit is connected with compression facility (SDA-5/220) and pump unit (CA-320) via T-branch in the form of an ejector. The connection necessarily includes a heat-exchanging apparatus. Then CT is lowered into the shut-in well till the top of the sand-bridge. After that the well is passed through the flare-line. A nose-piece with the diameter of 20–25 mm is mounted on the end of the flare-line in order to maintain the required back pressure.

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