Considering the importance of different sectors of the oil industry, especially the upstream sector and the drilling industry, risk assessment and management, and moving towards new methods and technologies are inevitable in order to reduce costs and increase the profitability and credibility of the National Iranian Oil Company. The drilling industry is one of the most important upstream sectors, and its processes usually have higher risks than other activities in this industry.The main objective of this article is to make a comparative comparison of deviant and multi-branch drilling risks. For this purpose, first, the literature on the research topic was thoroughly reviewed using library sources, and a research gap was identified. At the next step, Experts' opinions and drilling documents related to the topic were used to identify various risks in technical and non-technical sectors. Then, A paired questionnaire was distributed among experts in the oil industry, and finally the analytical hierarchy process was used to rank technical and non-technical risks. The results showed that formation-fluid influx into the well (Kick), which can lead to blowout if not controlled, and stuck pipe had higher priority than other technical risks. Therefore, the causes, control measures, and consequences of these risks were analyzed using Bow-Tie diagrams. In the non-technical section, a lack of specialists was identified and ranked as the most important risk.