A fluid mixture of mid-density and/or high-density alkanes that stays mostly Medium density hydrocarbon that stay liquid or semi-solid liquid in subsurface reservoirsolid at Normal Surface Conditions (NTP).
The usual composition ranges from C1 to C1632 and API gravity is between 10° 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). |
In case oil does not contain dissolved gas 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