A fluid mixture of mid-density and/or high-density alkanes that stays mostly A mixture of hydrocarbons that stay liquid or semi-solid in subsurface reservoir at Normal Surface Conditions (NTP).
The usual composition ranges from C1 to C32 and API gravity is between 4° and 42° (Specific Gravity is 0.816 ÷ 1.0).).
It may also include minor organic and inorganic chemical substances chemical substances (usually < 7% in weight).
The total range of oil density densities is often classified in narrow ranges:into the following sub-ranges (see also Fig 1):
Fig. 1 – A range of different gravity oil compositions from heavy (with dark brown colour at the left side of a bar) to the light (with yellow colour at the right side of a bar). | Heavy Oil | Extra Heavy Oil (Bitumen) |
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In case it oil does not contain dissolved gas it it is called Dead Oil otherwise it is called Live Oil.
The heavier oils are usually met in Black Oil Reservoirs and lighter oils are in Volatile Oil Reservoirrs.
See also
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Natural Science / Physics / Chemistry / Chemical Substance
Petroleum Industry / Upstream / Subsurface E&P Disciplines / Petroleum Geology / Petroleum fluids