Sidetracking technology on ?177.8 mm casing for heavy oil wells

Sidetracking the matured wells could recover the productivity and obtain more benefit. But the sidetracking work on heavy oil well usually would bring the problem of long operation period, and high possibility of complex accidents. In accordance of the difficulties brought by heavy oil well sidetracking, as hard work of wellbore treating, weak quality of sidetracking and difficult control of well trajectory, some studies were carried out. By the wellbore preparation, improving casing window, controlling well trajectory, and key techniques of well completion, the optimization methods were proposed for pressure test pipe string, sidetracking tool assembly, and drilling tool assembly. The difficulties of sidetracking heavy oil wells were solved. Better results were obtained through field tests, which indicated the improvement of heavy oil well sidetracking techniques.