On 21st August 2009, the crucial blowout was occurred on the Montara wellhead platform in the Timor Sea at the northern coast of Western Australia. It was just eight months before the Macondo blowout. The uncontrollable state continued until 3rd November 2009 and countermeasure operations continued until 3rd December 2009. The immediate cause was considered as the failure of well integrity caused by poor cement job. The mishandling of well barriers is the primary cause of the blowout. Recently, the Macondo is mainly highlighted due to large-scale damages. However, these two blowouts are significant issues for the oil industry to learn lessons because of many similarities between both incidents.