OFFSHORE OIL WELLS INTEGRITY: SAFETY ANALYSIS OF AN OFFSHORE OIL WELL AT THE PRODUCTION PHASE USING STPA (SYSTEM-THEORETIC PROCESS ANALYSIS)

Despite the growing share of renewable sources, the world energy matrix still depends heavily on fossil fuels, especially oil. The exploration of this product brings severe challenges and risks which must be managed during all phases of an oil well's lifetime. Analysis methodologies have already been developed and established to contribute to safety; however, with the growing complexity of the system, these methodologies may need a more structured way to identify some arising loss scenarios. The System-Theoretic Accident Model and Process (STAMP) deals with this problem. STAMP is a causality model that, attacking the problem from different paradigms, treats safety as a control problem, shifting emphasis from preventing failures to enforcing safety constraints. Based on a system model that spells out the control levels of a system and the control and feedback interactions between them, named SCS (Safety Control Structure), it focuses on preventing those interactions that lead the system to a hazardous condition, making it vulnerable to losses. This paper presents an analysis technique built on STAMP named System Theoretic Process Analysis (STPA), applied in the case of a submarine oil well at the production phase to highlight the benefits of using STAMP as a complement to more traditional analysis methodologies. The results conclude that STPA analysis can identify safety breaches from different sources. The first relevant source relates to the component failure events - also covered by more conventional methods such as PRA (Probabilistic Risk Assessment). The most significant contribution relates to safety breaches related to components interaction, managerial decisions, organizational factors, and others. The latter are manageable by structuring the loss scenario generation, which is the primary goal of STAMP.