RESERVOIR ENERGY SOURCE
 Gas dissolved in oil.
 Free gas under pressure.
 Gas reservoir.
 Oil reservoir wet/free gas cap.
 Fluid pressure.
 Hydrostatic – hydrodynamic.
 Compressed water, gas, oil.
 Elastically compressed rock.
 Gravity
 Combination of the above.
RESERVOIR DRIVE
 Reservoir drive is the natural energy in a reservoir
that forces the fluids out of the rock and into the
well.
 Every oil field has at least one reservoir drive.
 Type of reservoir drives in oil field include:
RESERVOIR DRIVE (Cont.)
Former:
 Solution gas drive.
 Gas cap drive.
 Water drive.
 Gravity Drainage.
 Combination drive.
Now:
1. Fluid Extension drive
2. Gas-cap drive
3. Water drive
4. Compaction drive
5. Combination drive
DISSOLVED GAS DRIVE RESERVOIR
Characteristics
1.Reservoir pressure
2.Surface gas-oil ratio
3.Water production
4.Well behavior
5.Expected oil recovery
Trend
Decline rapidly and continuously
First low, then rises to maximum
and then drops.
Non
Requires pumping at early stage
5 to 30 % of OIP
GAS CAP DRIVE RESERVOIR
Characteristics
Trend
1. Reservoir pressure
Falls slowly and continuously
2. Surface gas-oil ratio
Rises continuously in up structure wells
3. Water production
Absent or negligible
4. Well behavior
Long flowing life
5. Expected OR
10 to 20-30 % of OIP
WATER DRIVE RESERVOIR
Characteristics
Trend
1. Reservoir pressure
Remains high
2. Surface gas-oil ratio
Remains low
3. Water production
Starts early and increases
appreciable amount
4. Well behavior
Flow until water
production gets excessive
5. Expected oil recovery 35 to 70 percent
GRAVITY DRAINAGE DRIVE RESERVOIR
Characteristics
Trend
1. Reservoir pressure
Remains in medium rates
2. Surface gas-oil ratio
Stable
3. Water production
Negligible
4. Well behavior
Requires pumping at
early stage
5. Expected oil recovery
15 to 20 percent