Basement reservoirs are a subset of naturally fractured reservoirs and owe their hydrocarbon storage capacity and productivity to the presence of naturally permeable fractures. The fractures have developed through a variety of geological processes and are so distributed that they provide a connected network of void space. The rocks hosting such fractures are typically igneous and metamorphic rock such as granite, basalt and gneiss.

Fractured basement reservoirs are typically associated with structures which, over time, have been uplifted in relation to the source (sedimentary) rock such that hydrocarbons are able to migrate into the basement fractures.