We apply a mixed-method design centred on the deployment of metaphors to explore the role that language plays in the structuring of the public discourses of unconventional hydrocarbon development (UHD) across three major developed economies. We analyse UHD-related metaphorical devices deployed in broadsheet newspapers in Australia, the UK and the USA between January 2006 and May 2018. We develop an innovative Type Hierarchy Approach to metaphors by mapping through directed graph hierarchies. These allow concept-mapping analysis in terms of supertypes and subtypes, i.e. concepts ordered in terms of generality and inclusion as in “rapid expansion” → “explosion”. We find two broad discourses, each containing metaphorical constructions: economic gain across temporal horizons (incorporating boom, bonanza, revolution and death metaphors); and risk tolerance and decision-making (incorporating gamble and insanity metaphors). At the level of individual metaphors, deployment trends and patterns can be mapped along country borders rather than for example political alignment. Boom and bonanza appear most widespread in the USA, whereas UHD as a revolution is more closely associated with UK newspapers. Over time, UHD-related metaphor use decreases in all three countries, potentially reflecting an increasing public acceptance of UHD and moving shale gas from unconventional to conventional hydrocarbon development.