The paper discusses the problem of casing string deformation in TATNEFT’s injection wells drilled in Kynovian mudstones, which results in connectivity interruption and, as a consequence, in severe problems during well workover operations. Conventional workover procedure involving milling of a deformed section with its further cementing proves to be inefficient due to complexity of milling the deformed section and the necessity for operation reiteration.
A new method of drilling using a casing liner has been developed by TatNIPIneft’s research engineers as an alternative solution. This method allows cutting drilling costs and time due to simultaneous well drilling and casing operations, elimination of non-metreage works and well-logging operations prior to the liner running, and using of water-based mud instead of oil-based one. This technology uses casing pipes with buttress thread, and it proved effective during trial sidetracking in the Vostochno-Suleevskaya Area and in the Tat-Kandyzsky field.
The results of the trial sidetracking support demonstrate high efficiency of this drilling method: higher rate of drilling, zero deformation of threads, reduction of wellbore inclination resulting in better passability and lower deformation risk. By March 2024, this technology has been successfully applied in five wells. It was awarded the status of the Best Practice in PJSC TATNEFT and was recommended for injection well repairing which underlines its substantial potential and contribution to development of new drilling technologies and workover techniques.
