Abstract: Well 12X3 is an important exploration well drilled in Jidong Oilfield, with an actual total depth of 4415m. During the drilling of ?215.6mm hole, well collapse, cutter lost, lost circulation and gas invasion frequently occur, and an irregular hole profile is build, which is very bad for cementing operation. In this case, a lot of preparation work is carried out, and the cementing program, as well as cement slurry properties, are modified to meet the actual downhole condition. During the field operation, the procedures are strictly followed, and a successful cementing job is completed.