Accounts of international energy affairs often present a divergence between geopolitical/realist and liberal market-based approaches. This article suggests that this state of affairs reflects the (often implicit) legacies of realist and rationalist international thought in the study of energy affairs and the corresponding political and economic ontological hierarchies of analytical frameworks employed in different accounts of energy politics. Consequently, this article recommends a greater explicit attention to scientific ontological foundations in studies of energy relations and, in line with the calls of Keating et al. and Strange, suggests an approach based in the literature on I/GPE, which merges political and economic ontological axioms, as most apposite for the study of energy affairs. Building on this framework, and giving particular examples from the context of Eurasian energy politics, this article then outlines a number of politico-economic heuristic models (structural diversity, territorial non-coincidence, milieu-shaping and market-authority bargains) that are particularly useful concepts in helping to explain the intricate interactions of international energy relations.