This study traces the emergence of a multinational project for hydrocarbon extraction off the Mediterranean shores of Lebanon and the different knowledge claims and expertise that are made public in the process. Significantly, a lot of knowledge about and claims to certain forms of expertise concerned with Lebanon’s offshore petroleum fields remain in the realm of speculation. These epistemic practices of speculation are very much linked to the creation of value within financialised capitalist economies. For example, the question as to how much gas is there to be discovered is ultimately linked to another question pertaining to how much profit is there to be made. And, in the vision of making another oil-rentier state in the region, the issue of governmental reform and techniques of transparency are central dimensions to these speculative practices.