Application of vertical drilling technology to the sidetracking of vertical well

During the drilling of the vertical section of Well HSH2 in the piedmont tectonic belt, pipe sticking happened due to downhole drop. After fishing operation was carried out many times, the accident was not settled and downhole fish was formed. In this case, sidetracking is the only solution. In this paper, the adaptability of different sidetracking schemes was analyzed. Then, the sidetracking scheme based on the hole straightening ability of vertical drilling system were eventually selected and optimized after the sidetracking difficulty and the well trajectory after the sidetracking were analyzed comprehensively. The sidetracking of the well with pipe sticking caused by the fish in the vertical section was successfully fulfilled by controlling the drilling parameters (e.g. weight on bit) in the process of construction. The deviation angle of the first spud in is controlled within 0.1° by decreasing the hole angle of the subsequent hole section by means of the vertical drilling system. Field application shows that this technology provides a new scheme for the vertical well sidetracking in igneous rocks and can be used as the important reference for the treatment of drilling accidents in the future.