Unconventional Oil and Gas
Very heavy oil
Oil sands (>100m)
Oil sands (<100m)
Oil and Gas
"Unconventional" oil and gas are not chemically different from "conventional" oil and gas. The difference stems from their position underground or from the unusual nature of their reservoirs. After being formed very deep down in source-rock, oil and gas migrate towards the surface, accumulating in reservoir rocks that are porous and permeable when sequestration conditions are favorable.
Conventional extraction has focused on the "easy" reservoir rocks, i.e. the most porous and permeable. More recently, the oil industry has turned its attention to reservoir rocks that are harder to deal with (tight gas reservoirs) or to oil and gas that is close to the surface but more viscous (heavy and very heavy oil, oil sandsUnconventional oil deposits containing extremely viscous... ), and finally to the very heart of the source rock itself (shale gasShale gas is found in deeply buried clayey sedimentary rock that is both the source rock and the reservoir for the gas... and, in a few fields in the United States, shale oilRefers to liquid hydrocarbons extracted from oil shale (see definition) by heating, pyrolysis or hydrogenation. ).
Unconventional oilOil that cannot be extracted using current technology or that entails additional technology or costs to produce... and gas also include the methane (ch4)The main component of natural gas deposits and oil deposit gas caps. Methane is produced naturally by landfills... gas trapped in coalCoal is ranked by its degree of transformation or maturity, increasing in carbon content from... seams, which causes the powerful firedamp explosions so often feared by coal miners. In a separate category, methane hydrates build up in sediment near the ocean floor and in Arctic permafrost. This graphic presents the main types of unconventional oil and gas being produced today, along with the most commonly used production methods.