fluid property and reservior engineering

1. Lec.9
Introduction to
Petroleum Reservoir
Fluids and Phase
Behavior

2. Petroleum Reservoir Fluids
 The hydrocarbons existing in petroleum reservoirs are
primarily a mixture of different types of chemical
compounds made up of carbon and hydrogen.
 the hydrocarbons in petroleum reservoirs may exist in
either the gaseous or the liquid phase.

3. Classification of Reservoir Gases and Oils
 generally be classified according to their chemical
characteristics and their physical properties.

4. Chemical Classification of
Reservoir Oil Or Crude
Oils

5. Physical Classification of
Reservoir Oil Or Crude Oils

6. Five Reservoir Fluids
1. Black oils
2. Volatile oils
3. Gas condensates or retrograde gases
4. Wet gases
5. Dry gases

8. Unconventional Oils
 heavy oils and tar sands: in most cases may be commonly
associated with biodegradation in reservoirs, which
obviously means lost or depleted low molecular weight
hydrocarbon components compared to normal crude oils.

9.  heavy oil and tar sands are generally dominated by a large
proportion of asphaltenes and resins that can range from
25% to 75%, which means very low API gravities and very
high viscosities. the average range being 10°–12° to 20°API
and 100 to 10,000 cP and less than 10°–12°API and greater
than 10,000 cP, respectively

10. Phase Behavior
 Petroleum reservoir fluids may exist solely in gas phase,
liquid phase, equilibrated gas–liquid phases, or in some
rare cases as a solid phase, depending upon the prevalent

11. pressure and temperature conditions in addition to
chemistry and composition of a given system
Definition of Terms used in Phase Behavior
 Phase
 Intermolecular Forces, Pressure, and Temperature
 Equilibrium

12.  Component and Composition
 Distinction between gases and liquids
 Types of Physical Properties
Phase
 can be defined as any homogenous and physically
distinct part of a system having uniform chemical and

13. physical characteristics. Common examples are gas
phase, liquid phase, or solid phase
Intermolecular Forces, Pressure, and Temperature
 Gas, liquid, and solid phases are basically made up of
molecules, and the forces of attraction and repulsion
between them are intermolecular forces.

14.  The pressure in a system (e.g., gas phase enclosed in a
container) arises from the number of times the
molecules collide with the walls of the container.
 Temperature is a measure of the average kinetic energy
of the molecules, which means if heat is added to the
system, the average kinetic energy increases and thus

15. the molecules hit the container walls more frequently,
which again increases the pressure.

16. Equilibrium
Defined as a condition at which a given phase appears
to be at rest if it is maintained at a constant
temperature and pressure.

17. Component and Composition
A component is defined as an entity, for example,
methane, ethane, and propane. Composition or
concentration means the relative amount (fraction or
percent) in which a particular component is present in
a given mixture.

18. Distinction between gases and liquids
 In a gas phase, molecules are relatively far apart, a gas
phase adopts the container shape or fills it up completely.
 In liquids, molecules are fairly close together, and liquids
also adopt the container shape but to the extent of its
volume.

19. Types of Physical Properties
 Intensive properties are independent of the system
size or amount, for example, density, viscosity,
temperature, and pressure.
 Extensive properties are dependent on the system size
or amount, for example, mass and volume.

20.  Phase Behavior of Pure (Single) Component
 Phase Behavior of Two Component (Binary
System)
 Phase Behavior of Multicomponent Mixtures