1. RESERVOIR ENGINEERING

2. Overview of Reservoir Engineering
Outcome:
Data in put:
PVT
Scale
Reservoir Simulation:
Natural depletion
Water Injection
Reservoir Management:

3. Reservoir Fluid Studies
There are several laboratory tests that being conducted to characterize the reservoir fluid. The test results are then being used as input for Petral software analysis:
Compositional Analysis
Constant composition expansion test
Differential liberation test
Separator test
Swelling test for CO2 and N2

4. Compositional Analysis
Samples of oil and gas are taken from test separator or from stock tank. The fluid then combined in laboratory on the basis of the produced GOR.
The method is by flashing the sample from reservoir to atmospheric condition to obtain oil and gas at equilibrium condition

5. Result of Compositional Analysis
Gas Chromatography
Component
Mole %
Molecular
Separator Oil
Separator Gas
Wellstream
Weight
60°F
CO2
0.08
1.49
0.91 N2
0.00
0.27
0.16 C1
1.91
60.66
36.47 C2
1.60
15.32
9.67 C3
2.40
10.14
6.95
i-C4
0.81
1.88
1.44
n-C4
2.66
4.82
3.93
i-C5
1.45
1.43
n-C5
1.57
1.30
1.41 C6
6.81
2.59
4.33
C7+
80.71
0.09
33.29
218 
0.8515 
TOTAL
100.00
Wellstream composition calculated based on GOR of 130 scf/stb

6. Constant Composition Expansion Test (CCE)
The objectives of the CCE test are:
Determine the saturation pressure.
Compressibility factor of gas phase.
Total hydrocarbon volume as a function of
pressure.

7. CCE Test Result
Pressure (psig)
Relative Volume
5000
0.9453
2516
1.0001
4500
0.9541
2401
1.0243
4000
0.9638
2253
1.0599
3500
0.9746
2090
1.1066
3000
0.9867
1897
1.175
2900
0.9893
1698
1.2655
2800
0.992
1477
1.4006
2700
0.9948
1292
1.5557
2620
0.997
1040
1.8696
2605
0.9974
830
2.2956
2591
0.9978
640
2.9457
472
3.9877

8. Reported Reservoir Conditions Constant Composition Expansion
Reservoir Characterization & PVT information data
Reported Reservoir Conditions
Reservoir Pressure
2516 psia
Reservoir Temperature
220 degF
Constant Composition Expansion
Bubble point Pressure
psia

9. Differential Liberation Test (DL)
Based on the DL test it is possible to determine
amount of gas in solution, the shrinkage in the
oil volume, density of the remaining oil as a
function of pressure.
Therefore, the gas compressibility factor and specific gravity can also be determined.

10. DE Test Result Pressure (psig) Vapor Z-Factor Liquid Density (lb/ft3)
Gas-Oil Ratio (Mscf/stb)
Oil Relative Volume (rb/stb)
Gas Gravity
Gas FVF (rb/Mscf)
2516.7
45.11
1.1342
1.7493
2350
0.8686
45.669
1.0526
1.7095
0.7553
1.2574
2100
0.8692
46.502
0.9378
1.6535
0.7547
1.407
1850
0.8719
47.331
0.8309
1.6013
0.7565
1.6006
1600
0.8767
48.16
0.7307
1.5523
0.7614
1.8586
1350
0.8836
48.992
0.6361
1.5057
0.7704
2.2164
1100
0.8926
49.835
0.546
1.4609
0.7859
2.7411
850
0.9036
50.699
0.4591
1.4171
0.8121
3.5773
600
0.9167
51.608
0.3732
1.3726
0.8597
5.105
350
0.9324
52.632
0.2824
1.3234
0.9618
8.7518
159
0.9481
53.673
0.196
1.272
1.1726
18.685
56.323
1.1228
1.8901

11. Differential Vaporization Test (at 2014 psig and 155 °F)
Reservoir Characterization & PVT information data
Differential Vaporization Test (at 2014 psig and 155 °F)
Oil Formation Volume Factor
1.1 bbl/stb
Solution Gas Oil Ratio
1.1342scf/stb
Oil Density
45.11lb/ft3
Reservoir Fluid Viscosity (at 2014 psig and 155°F)
Oil Viscosity
1.33 CP

12. Separator Testing
Tested to determine the changes in volumetric behavior of reservoir fluid as fluid pass through separator then into stock tank.

13. Swelling Test
Performed for very specific applications where if a reservoir is to be depleted under miscible gas injection or a gas cycling scheme
Swelling Test of (CO2)
Swelling Test of (N2)
Mole Fraction
Gas Added
Saturation
Pressure (psig)
Swell Factor
(Relative Volume)
2519 1 5
2607
1.024 10
2705
1.0504 20
2913
1.1136 30
3159
1.1949 40
3285
1.3031
Mole Fraction
Gas Added
Saturation
Pressure (psig)
Swell Factor
(Relative Volume)
2521 1 5
3216.6
1.0117 10
4019
1.0242 20
5784
1.0528 30
8057
1.0879