Loss of circulation, i.e. the continuous and significant process of losing drilling fluid to the formation, is one of the most common and costly problems one can experience during drilling. Loss of circulation can occur during any well procedure that involves pumping fluid down the well and it invariably results in higher costs for materials, services and additional rig time As years pass producing oil, offshore platforms will need to be decommissioned. This process is relatively new in Brazil, and the demand for qualified professionals to perform the decommissioning of these units that have reached the end of production is increasing.All stages of decommissioning are very complex and involve professionals from various areas. As these are high-cost projects with very specific logistics, professionals need to describe well each step of the project and take into account all the environmental impacts that may be caused in order to avoid fines and extra expenses with repairs to the marine environment.