Abstract bp's Wells Organization manages its operational risks through what is known as the ‘Three Lines of Defense’ model. This is a three-tiered approach that starts with self-verification as the first line of defense which Wells assets apply to prevent or mitigate operational risks. The second line is conducted by its Safety and Operational Risk function using deep technical expertise. The third line of defense is provided by Group Audit. This paper will discuss the Wells self-verification programme evolution from its first implementation; results, lessons learned, and further steps planned as part of the continuous improvement cycle will be also shared. The company's Wells organization identified nine major accident risks which have the potential to result in significant HSE impacts. Examples include loss of well control, offshore vessel collision and dropped objects. The central Risk team developed bowties for these risks, with prevention barriers on cause legs and mitigation barriers on consequence legs. Detailed risk bowties are fundamental to Wells self-verification, adding technical depth to allow more focused verification to be performed when compared with the original bowties, as verification is now conducted using checklists targeting barriers at their component level – defined as critical tasks and equipment. Barriers are underpinned by barrier enablers – underlying supporting systems and processes such as control of work, safe operating limits, inspection and maintenance and others. Checklists are standardized and are available through a single, global digital application. This permits the verifiers, typically wellsite leaders, to conduct meaningful verification conversations, record the resulting actions, track them to closure within the application and gain a better understanding of any cumulative impacts, ineffective barriers and areas to focus on. Self-verification (SV) results are reviewed at rig, region, Wells and Upstream levels. Rigs and regions analyze barrier effectiveness and gaps and implement corrective actions with contractors at the rig or region level. Global insights are collated monthly and presented centrally to Wells leadership. Common themes and valuable learnings are then addressed at functional level, shared across the organization or escalated by the leadership. The self-verification programme at the barrier component level proved to be an effective risk management tool for the company's Wells organization. It helps to continuously identify risks, address gaps and learn from them. Recorded assessments not only provide the Wells organization with barrier performance data, but also highlight opportunities to improve. Leadership uses the results from barrier verification to gain a holistic view of how major accident risks are managed. Programme evolution has also eliminated duplicate reviews, improved clarity of barrier components, and improved sustainability through applying systematic approach, standardization, digitization and procedural discipline.