抄録
Temporary abandonment operations that led to the oil spill incident in Gulf of Mexico were analyzed focusing on temporary abandonment procedures and actual operations from the negative pressure test to blowout occurrence. Temporary abandonment plan went through remarkable transitions from original plan to actual plan. Especially cement in shoe track was the only active barrier when negative pressure test was conducted under considerable different risk factors associated with cement job. The plan was changed to efficiently perform temporary abandonment operations since there were delay of the process and cost increase. In this circumstance, the negative pressure test was done and all members on site believed that cement barrier has been successfully tested regardless of presence of strange pressure behavior due to overreliance on leader's judgment. During displacement SOBM (Synthetic Oil Base Mud) with sea water in marine riser, blowout occurred. Although there was a lot of opportunity to detect the kick during this operation, nobody could stop operation until gas came in marine riser.
