1. Emerging Applications in Cryogenics
(NITROGEN INJECTION FOR
RESERVOIR ENHANCED OIL RECOVERY.)

2. The life of an oil well goes
through three distinct phases
 Primary recovery
 Secondary recovery
 Tertiary recovery

3. Primary recovery

4. Secondary recovery

5. Tertiary recovery

6. Enhanced Oil Recovery (EOR)
 they can substantially improve extraction
efficiency
 Much of these oils would be recovered by
various EOR methods which involve the
injection of a fluid, or series of fluids

7. Three major EOR methods
 Thermal injection
 Chemical injection
 Gas injection

8. Thermal injection

9. Chemical injection

10. Gas injection

11. Natural gas
-limited availability
-increasing value of natural gas
Inert nitrogen
-less expensive substitutes
-provides a higher reservoir displacement volume
per standard volume of nitrogen
-provides the lowest volume requirement for
pressure maintenance.
-non corrosive.

12. Cryogenic processes
 can produce 99.999% pure nitrogen
 Cryogenic processes can produce very pure
end products
 the most cost-effective choice
 Are more energy efficient

13. Non-cryogenic processes
 employ membranes or adsorbents
(PSA/VPSA) to remove the unwanted
components of air
 They produce nitrogen which is typically 95 to
99.5% oxygen-free
 Non-cryogenic plants are less energy efficient
than cryogenic plants
 Non-cryogenic plants are relatively quick and
easy to start up

14.  The cost of nitrogen is depending upon the
pressures, quantities and location
 Because of increasing cost of natural gas,
nitrogen injection is becoming more popular and
attractive
In 1983-over 500 million cubic feet per day was
being injected into thirty oil or gas reservoir
In 1985-becomes 600 million cubic feet per day
In 1990-this number grew to 800 million cubic feet
per day in forty oil gas reservoir

15. EOR METHODS
With varying degrees of success, for the recovery of
light and heavy oils.
Two major types of EOR method
Thermal methods
-supply heat to the reservoir, and vaporize some of
the oil.
-the major mechanisms involve a large reduction in
viscosity, and hence mobility ratio.
-best suited for heavy oils and tar sands.

16. Non-thermal methods
-are best suited for light oils.
-applicable to moderately viscous oils, which
are not suitable for thermal methods
Objective:
Lowering the interfacial tension and improving
the mobility ratio

17. There are two types of non-
thermal EOR gas injection
miscible gas injection
-the gas is injected at or above minimum
miscibility pressure
immiscible gas injection
-flooding by the gas is injected below MMP

18. Comparison of nitrogen with
other gas injectant
Hydrocarbon gas
-require less treatment than other gases
-a corrosion problem
-increasing natural gas price
Major factor limiting CO2 injection
-availability
-the cost to build pipelines to carry

19. Advantage of carbon dioxide flooding
-miscibility can be attained at low
pressures
-useful over a wider range of crude oils
than hydrocarbon
Disadvantage of using CO2
-availability of carbon dioxide resources
-transportation cost
-poor sweep and gravity segregation and
corrosion

20. Nitrogen
-most available and cheapest universal gas
-no pipeline are required
-no incremental cost and required for corrosion
control

21. Nitrogen application for EOR
 In 1970- it was first introduced
 In 1970 to 1977-almot all of the nitrogen for
the EOR projects was taken from onsite inert
gas plants
 In 1980-most of the EOR projects was
supplied by onsite air separation plants

22. Offshore Cantarell oilfield in
the gulf of Mexico
 The largest oilfield in Mexico and one of the
largest in the world
 PEMEX heavy oilfield
 Have high productivity due to presence of a
gigantic natural gas cap
 Rank second fastest producing oil field in the
world behind Ghawar field in Saudi Arabia

23. Cantarell oilfield

24. Factor affecting the cost of
nitrogen
 The cost of energy necessary to produce and
compress nitrogen
 The air compressors for generating nitrogen
can be operated with motors, gas turbines or
gas diesel engines

25. Membrane produced nitrogen can be used in
plants where natural gas is unavailable
Advantage of a membrane plant
-compactness
-simplicity
-reliability
Resulting is low capital cost at smaller
capacities
And moderate purities

26. CONCLUDING REMARKS:
Recent advances in technology and the current economic
climate have resulted an increased interest in EOR,
especially [N.sub.2] gas injection in the petroleum
reservoirs for improved recovery. While the use of
Thermal and Chemical EOR methods are decreasing, Gas
injection method in EOR is increasing. Because cryogenic
air separation plants can be constructed at or
near the field and no pipelines are required, nitrogen gas
injection is rapidly increasing both in onshore and
offshore application for reservoir enhanced oil recovery.
The inert and non-corrosive nature makes it a preferred
choice over other gases (i.e. [CO2.sub.2], Natural gas
etc.). The long term supply security of nitrogen also
makes preferable and reliable than other unsecured
gases.

27.  Nitrogen injection is believed to yield high recovery of
the lightest hydrocarbon components. Nitrogen use in
the oil field continues to grow as new opportunities are
recognized, the demand being mainly satisfied with large
scale cryogenic nitrogen plants. Perhaps the greatest
task of the cryogenic industry is to develop more cost
effective nitrogen producing plants and means for its
effective injection to the reservoirs. In the mean time the
Petroleum Industry needs to study the long term effect
of Nitrogen on the reservoirs, including determining any
side effects the nitrogen injection may have on the
sustainability of the enhanced recovery. One important
factor may be the study of the effect of nitrogen purity,
as well as consideration for injection of a mixture of
gases vs. pure nitrogen.