ABSTRACT
The well in the northern part of the Tarim Basin is a four-open horizontal well. The completion depth of the third opening is 7538.5 m. The well was drafted before the electric test, but the well wall collapsed in the section below 7450 m, so it was decided to backfill and sidetrack. After two backfills, five sidetracks failed. Aiming at the difficulties of ultra-deep well, ultra-long open holes, complex downhole situations, and serious drag pressure, a method of optimizing sidetracking point and drilling tool assembly and strengthening control during sidetracking was proposed. The drilling tool combination was a 215.9 mm PDC bit and a 172 mm rotary steering tool. When drilling to a well depth of 7200 m, time-controlled sidetracking was started, and the sidetracking was successful. This study can provide a reference for long open-hole sidetracking in ultra-deep wells in the same block.
