Asphaltene Gradients, Connectivity and Tar Mats All Treated by Simple Chemistry and Reservoir Fluid Geodynamics - Oliver Mullins

1. 1
Primary funding is provided by
The SPE Foundation through member donations
and a contribution from Offshore Europe
The Society is grateful to those companies that allow their
professionals to serve as lecturers
Additional support provided by AIME
Society of Petroleum Engineers
Distinguished Lecturer Program
www.spe.org/dl

2. Society of Petroleum Engineers
Distinguished Lecturer Program
www.spe.org/dl
2
Oliver C. Mullins
Schlumberger
Asphaltene Gradients, Connectivity, Tar Mats
All Treated by Simple Chemistry and Reservoir Fluid Geodynamics
1) Reservoir Fluid Geodynamics
2) DFA & Asphaltene Thermodynamics
3) Connectivity Analysis
4) Tar Mats
5) Conclusions

3. 3
Petroleum System
FILLS Reservoir
Reservoir Fluid Geodynamics
Redistributes Fluids and Yields Tar Formation During, After Charge
Time Line
Geologic Past Present Day
Current
Simulation
Produces Reservoir

4. Asphaltene Nanoscience
Asphaltene Thermodynamics
Diffusion
Fluid Mechanics
Reservoir Fluid Geodynamics Requirements:
Comprehensive
Science
DFA Data
of Reservoir
40 RFG Oil Reservoir
Evaluation Case Studies
Fluid Gradients
in Reservoir
Reservoir
Fluid Geodynamics
DS Reports
and We Took the Charter!
4
Service Co.
Geochemistry

5. F = mg. Newton’s 2nd Law
Peng-Robinson EoS 1976
HC
Liquids
Gas-Liquid Fluid- (dissolved) Solid
Flory-Huggins-Zuo EoS 2010
Yen-Mullins Model 2010
Gas
Cubic EoS Gas-Liquid
Crude Oil Thermodynamics: Asphaltenes Now Included.
Equilibrium (static) vs Disequilibrium (dynamic)
Asphaltenes:
Van Der Waals EoS 1873
5
Molecule
Nanoaggregate Cluster
Sizes
of
Asphaltenes
Light Oil Black Oil Heavy Oil

6. Asphaltenes have THREE Aggregation Thresholds, not One.
Nanoaggregate ~2nm Cluster ~5nm
1 2 3
Molecules ~1nm
Light Oil
Bulk
Asphaltenes
Add Asphaltene
George A. Olah Award in Hydrocarbon or Petroleum Chemistry. American Chemical Society., 2018
Yen-Mullins Model of Asphaltenes
Bulk Phase Separation
Light Oil Model Black Oil Model Heavy Oil Model
Black Oil Heavy Oil Heavy Oil & Tar
Add Asphaltene Add Asphaltene

7. 7
Asphaltene Concentration.
Crude Oil Solvency. (GOR).
Well Solvated Solvated
Add Asphaltene
Poorly
Solvated Unstable
Tar Mat
Nanoaggregate
Cluster
Molecule
Less Solvated
Light Oil Heavy Oil
Heavy Oil
& Tar Mat
Tar Mat
“Condensate”
& Tar Mat
Phase-
Separated
Add GasAdd Asphaltene Add Asphaltene
Add Asphaltene/ Gas
Asphaltenes Particles in Reservoir Crude Oils
Black Oil
Black Oil
w/ Heavy Oil

8. 8
Ivar Aasen
Charged from
Viking Graben
from West
Ivar Aasen

9. 0 0.5 1.51.0OD DFA
X360
X400
X440
TVDss(meters)
(B) (C)
Ts
(Ts+Tm)
Equilibrated Asphaltenes  Connected. Proven in Production
Maturity Variation in Charge. GOC Deep Near Charge Point.
Charge
FHZ EoS
Ivar Aasen
Light Oil Model
Asphaltenes Geochemistry
High Maturity,
Low Asphaltene Low Maturity,
High Asphaltene

10. 10
Heavy Oil Isolated by FractureTVDss(m)
DFA Color (asphaltenes)
Connected
Isolated
‘Heavy’ Oil
Fracture

11. 11
Simple Charge
and
Geodynamics.
(Structure & Fluid)
gas
gas
gas
gas
oil
Timeline
HIGH Maturity LOW Maturity
1st Charge
2nd Fracture
gas
gas
gas

12. B6UB6L
Well 2 Well 1 DFA: Both Wells
Lower
Sand
FHZ EoS
(2 nm)
Upper
Sand
TVD
DFA: Asphaltenes
0 0.3 0.6 0.9 1.2
Upper
Sand
Shale
Break
Lower
Sand
Shale
Pinchout
Seismic Imaging Isopachs
Upper
Lower
Upper
Lower
DFA: Asphaltenes Equilibrated  Connected.
Match Seismic Isopach Imaging.
Lateral Connectivity. Vertical Baffle.
Black Oil
Model

13. All Fluid Measurements Consistent with Equilibrated Asphaltene Analysis
Geochem Maturity

14. 14
T1ST T1 T2
Asphaltene Gradient
FHZ Modeling
Fault Throw ~380ft
T1ST
T1
T2
Fault Block Migration, Asphaltene Gradients & Connectivity
B6L
B6U
FHZ Modeling

15. 15
T1ST T1 T2
Asphaltene Gradient
FHZ Modeling
Fault Throw ~380ft
T1ST
T1
T2
1st Asphaltenes Equilibrated. 2nd Fault Threw.
B6L
B6U
FHZ Modeling

16. 16
T1ST T1 T2
FHZ Modeling
DFA Density
B6L
B6U
Isotope
Lab API
Lab GOR
Asphaltene Gradients, API Gravity Consistent. GOR, CH4 Isotope Different.

17. 17
T1ST T1 T2
FHZ Modeling
DFA Density
B6L
B6U
Isotope
Lab API
Lab GOR
Biogenic Methane Charge AFTER Fault Block Migration.
Color
lines up.
API
lines up.
GOR
Doesn’t
Line Up
Isotopes
Don’t
Line Up

18. 18
T2ST Formation Pressure profile
4 ft of shale
between upper
and lower B6
XX XX
intervening shale isopach
T2ST
T1ST
T1
• Seismic cannot detect 4ft shale barrier
• DFA Offset upper Sand – Lower Sand Predicts Limited Connectivity
Pressure Depletion Proves Shale Baffle/Barrier Predicted from DFA
Pressure
DP = 150 psi
Scissors
Fault

19. 1st Anticline Forms
& Fills with Oil;
Asphaltenes Equilibrate.
Oil-Bearing Sand
2nd Fault Block Migration.
Asphaltene Equilibrium
Preserved.
Reservoir Fluid and Structural Geodynamics: Pliocene Reservoir !
3rd Gas Charge into Upper Block.
GOR, Isotopes off.
Gas
Charge
Wells
Understanding RFG Essential for Extending Reservoir

20. 20
Heavy Oil
and
Tar Rim
Side View
Top View
oil
Equilibrated Asphaltenes  Connected.
Known in Production.
HUGE Asphaltene & Viscosity Gradients Matches FHZ exactly over 100 km.





 D

kT
hgV
OD
hOD 
exp
)0(
)(
50 km
TVD (feet)
x700
x800
x900
x000
x100
x200
Tar Mat

21. 21
Heavy Oil and Tar in this Giant Field from Reservoir Fluid Geodynamics
Tar from Incompatible Charge, Asphaltene Migration.
Tar Tar
RFG Sequence:

22. 100 300 500
Psat
7700
7800
7900
8000
8100
0.15 0.2 0.25
Ts .
(Ts+Tm)
Psat (psi) Ts/(Ts+Tm)
Reservoir Concerns: Viscosity, Tar Mat, Water Injection.
FHZ EoS
5.1 nm
Clusters
7700
7800
7900
8000
8100
0 10 20 30 40
%Asphaltenes
8 Well
Locations
ONLY Asphaltene Gradients Define Reservoir Concern.
Tar Mat
%Asphaltenes
FHZ EoS
5.1 nm
Cluster
Only Asphaltenes Tell the Story.
Geochem Maturity

23. 23
CH4 Enters from Top
SingleOilColumn
dC13 ~ -64
dC13 ~ -57
Gas Diffusion into Oil and Asphaltene Migration.
Methane Isotopes. Primary Biogenic Gas.
1
2
3
4
Gas Charge into Oil

24. 2424
Recent Charge of Gas into Oil Reservoir.
Huge GOR Gradient. Asphaltene Expulsion, Migration to OWC.
Quasi-Equilibrium near Base of Oil Column
Cluster
Gradient

25. 3 Adjacent Fault Blocks. Same Petroleum System.
3 Entirely Different Realizations.
RFG Validated !
25

26. 1st Movie of Tar Mat Formation!
Different Gradients Due to Baffling. Production Differs by 10x.
Well 1. Baffled. NOT Equilibrated
Low DST Production Rate
Well 2. Equilibrated.
High Production.
Asph GOR Core Ex
Equilibrated; Tiny Fluid Gradients
Tar Mat.
Late Gas
Charge
Into Oil
Reservoir
Initial
Gas
Asphaltene
1 2
OD
120 180
GOR m3
/m3
Asphaltenes GOR
TVD
Not Equilibrated; Huge Gradients
0
OD
Tar
Tiny
Asphtn
FHZEoS
TAR
600
%AsphGOR
200180
SLOW Diffusion FAST Diffusion

27. 27
Oil
Core
Extract
Well 2.
0
OD
Tar
Tiny
Asphtn
FHZEoS
TAR
600
%AsphGOR
200180
Asph GOR
Scanning Electron Microscopy: Tar Mat
Trapped
Oil
Tar Mat is Two-Phase System.
Asphaltene and Trapped Oil.

28. 28
Shale
Baffle
Asphaltenes
On Baffle
Methane diffusionAsphaltene
Diffusion
(Slow)
Lateral
Gas
Sweep
H2O
Core %Asphaltene
Tar on
Shale
Well #3
Vertical Gas Sweep
Shale
Tiny amount,
Equilibrated
Asphaltenes
Below Shale: Asphaltenes Deposited Throughout Due To Lateral Sweep.
0 OD
DFA

29. 29
Conclusions:
1) Reservoir Fluid Geodynamics follow Structural Geodynamics
Huge improvement in reservoir / basin analysis.
2) RFG is founded on
DFA & Asphaltene Thermodynamics,
Geochemistry
40 RFG Oilfield projects
3) Single asphaltene framework broadly applicable for light oils,
black oils, heavy oils, for connectivity, viscosity, tar mats and more.

30. 30
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31. 31
Multiple Charge:
Light oil plus Black oil
Single Charge;
Black Oil
High Asphaltene Onsent Pressure from Incompatible Charge
from Gulf of Mexico (high pressure, high solution gas)

32. 32
GCs, Same Thus Equilibrated.
Sample 5 and 15 on trend.
Except 8 slightly more biodegraded. And At OWC.
Deepest and slightly
more Biodegraded.