1. DEVELOPMENT THEORYAND TECHNOLOGYOF
OIL AND GAS FIELD
PrimaryRecovery Drive Mechanisms
Presented : China university of Geosciences (WUHAN)
Presenters:
Prof. Congjiao Xie
Mr.Nsulangi, P.T ( MScinONGE,Major Reservoir Engineering)
E-mail:nsulangi@gmail.com
Date: April 05, 2016

2. Contents
Introduction
 Primary Drive Mechanisms
Types of Primary Recovery Drive Mechanisms
 Solution gasdrive
 Gas cap drive
 Water drive
 Gravity drainage
 Combination or mixed drive
ProductionwellDesign undermixed Drive
Worked Examples

3. Primary RecoveryDriveMechanisms
During primary recovery the natural energy of the reservoir is used to
transport/push hydrocarbons towards andout of the production wells.
These naturalenergies are called Primary Recovery Drive Mechanisms,
which includes;
 Solution gasdrive
 Gas cap drive
 Water drive
 Gravity drainage
 Combination or mixed drive

5. SOLUTION GAS DRIVE
This drive mechanism requires the reservoir rock to be completely
surrounded by impermeable barriers.
As production occurs the reservoir pressure drops, and the expansion of
solution and that of the dissolved gases in the oil and water provide
most of the reservoirs drive energy.

6. SOLUTION GAS DRIVE cont…
TYPES OFSOLUTIONGAS DRIVE MECHANISMS
A solution gas drive reservoir can be categories into two major groups
depending on the reservoir pressure.
These groups are;
– Undersaturated Reservoir, and
– Saturated Reservoir

7. SOLUTION GAS DRIVE cont…
Undersaturated Reservoir
For an undersaturated reservoir no free gas exists until the reservoir pressure falls below the
bubblepoint. In this regime reservoir drive energy is provided only by the bulk expansion
of the reservoir rock and liquids (water and oil).
Production trends；
– ReservoirPressure> BubblePointof Oil
– ReservoirPressurefallsQuickly
– Gas Oil Ratio(GOR) remains Consatant
This type of reservoir is the best Candidates for Secondary Oil Recovery by Waterflooding.

9. SOLUTION GAS DRIVE cont…
SaturatedReservoir
For a saturated reservoir there is a free gas liberated due to the decreases in Reservoir
pressure. In this regime reservoir drive energy is provided by the bulk expansion of the
liberated gas from the Oil surface.
Production trends；
– Reservoir Pressure <= Bubble Point of Oil
– Reservoir Pressure falls Slowly
– Gas Oil Ratio (GOR) increases
This type of reservoir is the best Candidates for Secondary Oil Recovery by Gas injection.

11. Gas Cap Drive
In a gas cap drive reservoir, the primary source of reservoir energy is an
initial gas cap, which expands as the reservoir pressure drops .
Additional energy is provided by the expansion of solution gas
released from the oil.
Production trends;
-Reservoir pressure fall slowly
-GOR rises
-Oil production rate fall quickly

13. Water drive
In a water drive reservoir, the oil zone is in communication with an aquifer
that provides the bulk of the reservoir's drive energy. As oil is produced, the
water in the aquifer expands and moves into the reservoir, displacing oil to
theproductionwell.
Productiontrends;
-Reservoir pressure remains fairly constant
-GOR remain fairly constant
-WOR increases as Oil-water-contacts move upward

15. Gravity drainage
Gravity drainage, or gravity segregation, is the tendency of oil, gas,
and water to segregate in a reservoir during production due to their
differing densities.
Sometimes gravity drainage is called as a Secondary drive
mechanism, because it occurs only in combination with one or
more of the primary oilreservoir drive mechanisms.

17. Combination or mixedDrive
Combined drive, the reservoir consists of more than one drive
mechanisms. These drives are responsible for transport/push
hydrocarbons towards andout of the production wells.
Can be either of the following combination;
-Water Drive - GasCap- Solution Gas Drive
-Solution GasDrive-Water Drive- Gravity Segregation ,etc.

19. Production well Design under mixedDrive
The design of Production well under combined drives
mechanisms it involves recognize the size and strength
of the dominant primary driving energy of the reservoir.
Example: Oil Production well Design
- Dominant Water Drive- Perforation should be as far as
possible above the Oil-Water contact.
- Dominant Gas Cap Drive- Perforation should be as far as
possible below the gas-oil contact.

20. Dominant Water Drive

21. Dominant Gas Cap Drive

22. Worked Examples
Study thefigurebelow;Calculate
1. ValueofQ0
2. Timeperiodfor wellWtoproduce 80% ofLayer_03
If naturaldrivemechanismofthe fieldis capabletoonly produce
72% ofLayer_01.
Calculate;
4.Timeperiodfor secondary recovery methodtostart.
5.Recovery ofthePrimary Drivemechanisms.

24. REFERENCES
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http://www.weatherford.com/dn/WFT194606