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64 PROPERTIES OF RESERVOIR FLUIDS
Of these models, those for black oils and dry gas are the simplest. The pressure‐
dependent properties previously described for gas, oil, and water, including the
properties in Figures 3.4 through 3.6, are sufficient. If reliable fluid data are missing
for one or more of the reservoir fluids, fluid properties from analogous fields or from
correlations can be used.
3.9 ACTIVITIES
3.9.1 Further Reading
For more information about fluid properties, see Dandekar (2013), Satter et al.
(2008), Sutton (2006), Towler (2006), Ahmed (2000), and McCain (1990).
3.9.2 True/False
3.1 A black oil is always black in color.
3.2 Unlike a volatile oil, a black oil contains no gas.
3.3 Centipoise is a unit of viscosity.
3.4 Condensate exists in the liquid phase if reservoir pressure in a gas condensate
reservoir is greater than dew‐point pressure.
3.5 A hydrocarbon gas can have a dew‐point temperature but not a dew‐point pressure.
3.6 The mole fraction of methane is usually larger in oil reservoirs than in gas
reservoirs.
3.7 Most scientists believe that fossil fuels were formed from various biological
organisms that lived on the surface of the Earth millions of years ago.
3.8 The cricondentherm is the maximum pressure in the P–T diagram.
3.9 Oil and gas are carbon‐based materials.
3.10 Single‐phase oil becomes two‐phase gas/oil when pressure drops below the
bubble‐point pressure.
3.9.3 Exercises
3.1 A. The density of water is 1 g/cc or 62.4 lbm/cu ft. The density of air is
0.0765 lbm/cu ft. What is the density of air in g/cc?
b. What is the density of gas in g/cc if the specific gravity of the gas is 0.7?
Hint: The specific gravity of gas is the density of gas divided by the
density of air, or γ = ρρ .
/
g
g
air
3.2 Fluid density for a volume with oil and water phases can be estimated
using ρ = S o × ρ + S w × ρ where ρ , ρ refer to oil density and water density,
w
f
o
o
w
S , S refer to oil saturation and water saturation, and S + S = 1. Estimate
o w o w
