What share of global oil resources is made up of heavy oils and tar sands?

Of the world’s total oil resources, approximately 21 percent are classified as heavy oils, while about 30 percent are categorized as tar sands.1

It is important to note that these figures represent total resources rather than recoverable reserves, as not all of these deposits are considered economically or technically viable to extract. The exploitation of these resources presents significant challenges; for instance, the costs associated with mining and upgrading tar sands are considerably higher than those for conventional oil production. Furthermore, heavy oils are often more costly to process, and their extraction requires substantial energy expenditure, which can reduce the net recoverable volume from a reservoir.12

Despite these constraints, the development of these fossil fuel resources has become increasingly important as producers seek to replace depleted conventional reserves.31