Most of the Brazilian oil and gas (O&G) production comes from offshore operations. With the discovery of the Pre- Salt basin, the O&G production increased dramatically from 41 thousand in 2010 to 1,5 million barrels per day in 2018. On average, Pre-Salt wells are more than seven kilometres deep; therefore, its exploration faces a challenging environment. Only systems with high complexity levels in different aspects can overcome these challenges. This complexity spreads in various aspects – technical, managerial, legal, operational, and others. In such a system, risks are always present and may be pervasive, even in fields already well known and in undergoing exploration. In November 2011, Brazil experienced a blowout in Frade oilfield, located in Campos Basin. An accident with a very high probability of high severity in the O&G industry is a blowout, which is an uncontrolled flow of formation fluids into the wellbore, along the wellbore, into another reservoir, or the environment. The consequence of this blowout was a leakage of 3,700 barrels of crude oil into the sea. The Brazilian National Petroleum, Natural Gas and Biofuels Agency (ANP) analysed this accident. Using the ANP analysis as a departure point, we carried out a Causal Analysis using Systems Theory (CAST), one of the System-Theoretic Accident Modelling Process (STAMP) tools. One crucial point in analysing such a complex system is to integrate all actors' levels - Government, Regulators, Associations, Company, Management, Staff, and Work - in one single model that represents the most relevant tradeoffs in the industry. We developed a preliminary System Dynamics model to have an integrated vision of the question at study. This paper comments on the CAST analysis and SD model and shows how this analysis is encompassed in the preliminary SD model generating relevant insights. Results show and reinforce the perception that high-level decisions may hugely affect both the performance and the system safety, resulting in unintended consequences.