Analyzing the case of France, this article aims to explain how the development of enhanced oil recovery (EOR) techniques over the last decade contributed to politicizing the subsurface-that is, putting underground resources at the center of social unrest and political debates. France faced a decline of its oil and gas activity in the 1990s, followed by a renewal with subsurface activity in the late 2000s using EOR techniques. An industrial demonstrator for carbon capture and storage was developed between 2010 and 2013, while projects targeting unconventional oil and gas were pushed forward between 2008 and 2011 before eventually being canceled. We analyze how the credibility, legitimacy and governance of those techniques were developed and how conflicts made the role of the subsurface for energy transition the target of political choices. The level of political and industrial support and social protest played a key role in building project legitimacy, while the types of narratives and their credibility determined the distinct trajectories of hydraulic fracturing (HF) and carbon capture and storage (CCS) in France. The conflicts over EOR techniques are also explained through the critical assessment of the governance framework that tends to exclude civil society stakeholders. We suggest that these conflicts illustrated a new type of politicization of the subsurface by merging geostrategic concerns with social claims about governance, ecological demands about pollution and linking local preoccupations to global climate change.Read less <