March 2008 UTC The distinction is somewhat arbitrary depending on reservoir temperature more than anything and it s hotter in Venezuela However if heavy oil occurs in the designated oil sands areas of Alberta the government arbitrarily deems it to be bitumen and charges a lower royalty rate Hence Canadian companies are quite happy to call it bitumen rather than heavy oil The Venezuelan government would rather call it extra heavy oil and charge more money for it In either case if the API gravity is around 10 which is to say the density is about the same as water it doesn t sink but rather forms an oil water emulsion which is rather difficult to separate and accounts for many of the production problems and costs 19 12 18