Fluid Types Comparison
Phase diagrams
This diagram puts the phase diagrams for all five fluid types (Black oil, Volatile oil, Gas condensate, Wet gas, Dry gas) on the same scale, and shows quality lines, reservoir temperature, and conditions of the producing wellstream.
It’s important to note that all of these phase diagrams are not exactly right, except as snapshots in time showing what we’d see if we could keep the composition constant. In reality however, as pressure decreases, fluid breaks out, and the reservoir composition changes. The phase envelope should change too.
Guidelines for Determining Fluid Type (McCain, 1994)
| Black Oil | Volatile Oil | Gas Condensate | Wet Gas | Dry Gas | |
| Initial GOR, scf/STB | <2000 | 2000 - 3000 | >3200 | >50,000 | (>100,000) |
| Initial Oil °API | <45 | >40 | >40 | up to 70 | |
| Bo at bubble point | <2.0 | >2.0 | - | - | - |
| C7+, mole% | >20 +/-2 | 12.5 to 20 +/-2 | <12.5 | (<3) | (<0.7) |
| Phase change in reservoir | bubblepoint | bubblepoint | dewpoint | no phase change | no phase change |
| Color of Stock-tank Liquid | dark | colored | lightly colored | water white | - |
Dead and Live Oil
Dead Oil is the oil containing no natural gas. It is a Black Oil type when production conditions do not reach bubble point.
Live Oil is the oil with dissolved natural gas. It is a Black Oil type when production conditions cross bubble point.
External links
See also good overview of reservoir fluid types from Fekete Associates: http://www.fekete.com/san/webhelp/feketeharmony/harmony_webhelp/content/html_files/reference_material/general_concepts/reservoir_fluid_types.htm