Application of pneumatic pipe-rammer and pulley block in directional drilling towback

Three solutions are proposed against the sticking that may happen during pipeline towback, that is, releasing viajarring with a pipe-rammer, releasing with a pulley block, and releasing with both pipe hammer and pulley block. In theFuhe River crossover project at Lintou Village, for example, the pipe hammer and pulley block were combined to releasethe stuck pipe when both first two solutions were failed. The result indicates that after releasing operation for 4 days, thepipeline was completely pulled back to the surface from the hole, both the pipeline and anti-corrosion coating were intact, and only the anti-corrosion belt at the weld junction showed slight spalling. The combined pipe hammer and pulley blockmethod still needs to be improved, because there are some shortcomings with the pulley block stroke and no protections forthe wire rope.