User Experience (UX) Design of Artificial Intelligence (AI) applications that assist knowledge-intensive tasks are usually the result of an iterative and fuzzy process. Although the combination of state-of-the-art technology with human expertise is undoubtedly valuable in the industry context, designing a user-centered tool that fits in the everyday activities of knowledge workers - supporting and augmenting their potential - is not a trivial work. User research uncovers pain points and opportunities, bringing the insights that inspire designers and Human Computer Interaction (HCI) experts. It allows a clear understanding of the context, which is the essence of a consistent interaction experience. Nevertheless, revealing the UX of the application and how AI in this context reshapes knowledge workers' everyday tasks is not straightforward and might also be an iterative process. In this paper, we present findings from a case study of the use of a storytelling method to design and validate the UX of AI assistants for the Oil & Gas industry by using an animated sketch-based video.