Restoring of casing strings integrity during wells workover, is relevant for most fields operated for 15 years and more. Corrosion processes, high injection pressures lead to an increase in the number of cases of loss of production strings tightness. Depending on the operating conditions, a number of negative factors affect to a certain extent the service life of the casing string, the main ones being external and internal corrosion, mechanical wear of the production string during tripping operations.
At present, replacement of the defective part of the production string, located in the free, i.e. uncemented and unstuck casing section, includes a set of works, involving the dismantling and installation of the lifting unit and the working platform, digging the pit and unscrewing of the leaky pipe with the help of machine keys, that significantly complicates the repair of the well.
To facilitate the replacement of the upper part of the production string, a new device UOEK-146 (168) for the unscrewing of the production string, allowing the production string to be separated precisely at the given joint without the use of machine keys, hydraulic anchor, rotor, drill pipes, was designed and introduced. The device is intended for the unscrewing of the production string in the wells cased with casings 146 and 168 mm in diameter. The operation of the device is based on converting the translational motion of the tubes into rotation using a screw with a large pitch. In this case, the torque is transmitted to the production string through hydraulic anchors. The main components and the operating principle of UOEK-146 (168) are considered.
The device under consideration is applied in six wells in Oil and Gas Production Department Lyantorneft. The results of field trials confirmed the efficiency and reliability of the device.
References
1. Spravochnik mastera po dobyche nefti, gaza i kondensata (Handbook for the farm boss): edited by Batalov D.A., Surgut: Neft' Priob'ya Publ., 2010.
2. Garifov K.M., Kadyrov A.Kh., Rakhmanov I.N. et al., New methods of protection and sealing of flow tubing (In. Russ.), Neftyanoe khozyaystvo = Oil Industry, 2003, no. 8, pp. 82–84.
