This presentation is discussing New Approach to Design Capillary Pressure Curves, which Would Improve Simulation Models Initialization and shorten History Match time consumed.

1. New Approach to Design Capillary Pressure Curves, which
Would Improve Simulation Models Initialization and Shorten
History Match Processes Time Consume.
Qatar 2012
SPE-ATW “Reservoir Modeling: Strategies for
Optimizing Business Decisions”
Faisal Al-Jenaibi
faljenaibi@adnoc.com

2.  Introduce new concept to design Pc’s curves which would contribute in
achieving:
 Less volumetric gaps between static and dynamic models in term of
hydrocarbon-in-place. i.e. (encouraged fluids saturation matched
laterally and vertically between static and dynamic models with gaps
below 1.0 %).
 Better match with initial water saturation logs data.
 Better description of hydrocarbon column thickness, top of transition
zone and Pc curves.
 Reduce computer timing and CPU’s.
 More realistic development plan & EOR applications and timing
Presentation Objective

3. Presentation Outline
 To address the current issues of main concern issues with
the simulation modeling.
 To address alternative Pc’s curves design to enhance
simulation models accuracy.
 History Case Studies.
 Finding and Conclusions.

4. Presentation Outline
 To address the current issues of main concern issues with
the simulation modeling.
 To address alternative Pc’s curves design to enhance
simulation models accuracy.
 History Case Studies.
 Finding and Conclusions.

5. Current Pc’s Curves Design Concern Issues
SW_PC (%)
HeightAboveFWLDepth(ft)
HeightAboveFWLDepth(ft)
RT’s
Top
Bottom
SW_LOG (%)
Krw << 0
Water is not allow to move below Swcr’s values … !!
Where is top of the transition Zone … !!

6. Current Pc’s Curves Design Concern Issues
Sw_log data are still scattered per geological rock type classification
Single Pc curve might not be able to present Sw_log data

7. Current Pc’s Curves Design Concern Issues
Top of the transition zones in the current simulation models, are
usually presented with high Pc’s curves values just to match
Sw_log wells profiles, although the water is considered as
immobile in the simulation models until cell Sw values reached
above selected Swcr or/and reasonable Krw’s values e.g.
(>0.00001)
Thus, is it possible that top of the transition zone is very low and
at higher Sw, with respect of existing many wells that produced
dry oil at high rate during production tests and for couple months
before started water cut, while they perforated at nearby FWL
depth.
Because of continued changing water saturation with depth
which might be due to wettability issue
Currently many engineers are using best fit or/and
height above FWL function or/and J-Function Pc’s
curves with high values, which assuming the whole
reservoir is in the transition zone ... !!?
Consequently, in order to slow down water
movement in transition zone, either by use:
(1) Unphysical Swcr’s “Simulator Parameter”
(2) Very low Krw’s values
(3) Unsupported permeability multiplier
FWL depth
100% water
Krw
Kro
Swirr Sor
Top of transition zone i.e. (oil dry limit)
0.0
1.0
Swcr
Is this part of the transition zone??
where no water is allow to move
between Swirr & Swcr ranges!!

8. Current Pc’s Curves Design Concern Issues
The shape of the imbibition curves in the current simulation models are
participating in unnecessary additional calculations
Sw
Pc (psi)
0
(-)
(+)
0 1

9. Current Pc’s Curves Design Concern Issues
Main Questions:
• How to generate drainage Pc’s curves that would replicate wells
Sw_log profiles in the dynamic models at high resolution level?
• How to introduce thin transition zone definition into dynamic
models while honoring wells Sw_log profiles?
• How to slowdown water movement in dynamic in transition
zone model without using Swcr’s values or lowering Krw’s
values or applying permeability multipliers?
• and how to improve dynamic models running performance and
stability?

10. Presentation Outline
 To address the current issues of main concern issues with
the simulation modeling.
 To address alternative Pc’s curves design to enhance
simulation models accuracy.
 History Case Studies.
 Finding and Conclusions.

11. New PC’s Curves Design Concept (SPE-117894)
Facts:
• Many wells which reported with high
Sw_log data have produced dry oil during
production test although they were
completed nearby water zone.
• High porosity & permeability rock type will
have lower capillarity force i.e. (Pc curve)
than low porosity & permeability rock type.
• Due to high heterogeneity in carbonate
reservoir, single Pc curve per rock type
might not be enough to reflect Sw_log data.

12. New PC’s Curves Design Concept (SPE-117894)
SW
HeightaboveFWLdepth(ft)
0 1
Water Zone
Transition Zone
Oil Zone
High PORO
High PERM
Low PORO
Low PERM
Oil Dry Limit
FWL Depth

13. New PC’s Curves Design Concept (SPE-117894)
PC’s Curves Should:
• address the thickness of the
transition zone.
• provide excellent match with
initial Sw_log data.
• assist in achieving better history
match.
• contribute in model stability.
• optimize saturation tables.
• eliminate Swcr’s usage.
• address wettability issues.
SW
HeightaboveFWLdepth(ft)
0 1
Water Zone
Transition Zone
Oil Zone
High PORO
High PERM
Low PORO
Low PERM
Oil Dry Limit
FWL Depth

14. PC’s Curves Design Setup
1 Water Zone Transition Zone Oil Zone2 3
1
2
Sw
PC
Sw
Kr’s
Used Swc
Number of Saturation Tables = 162 (case study)
Use Swc’s & permeability multipliers to control water movement
Current
Approach
1
2
3
Sw
PC
oil dry limit
Sw
Kr’s
Swirr1
Swirr2
Swirr3
Swirr2 Swirr3Swirr1
Number of Saturation Tables = 14 (case study)
Good match with Sw_log @ time zero
New
Approach

15. New PC’s Curves Design Concept
Wettability Change with Depth
Hydrocarbon
Zone
Water
Zone
Many simulation studies showed improvement in history
match profiles after introduced wettability change with depth
concept.
Used “Try & Error” to define each interval depth, then used cut-
off depth approach to signed Pc’s curves to each interval.

16. New PC’s Curves Design Concept
Wettability Change with Depth
Hydrocarbon
Zone
Water
Zone
KrwKro
Sw Sw
Pc Kr’s
KrwKro
Sw Sw
Pc Kr’s
KrwKro
Sw Sw
Pc Kr’s
Oil Wet System
Mix Wet System
Water Wet System
“RRT- X”
Many simulation studies showed improvement in history
match profiles after introduced wettability change with depth
concept.
Used “Try & Error” to define each interval depth, then used cut-
off depth approach to signed Pc’s curves to each interval.

17. New PC’s Curves Design Concept
Wettability Change with Depth
Hydrocarbon
Zone
Water
Zone
SWHeightaboveFWLdepth(ft) 0 1
Water Zone
Transition Zone
Oil Zone
Oil Wet
System
Water Wet
System
Oil Dry Limit
FWL Depth
With the new Pc design concept, the wettability changes with
depth can be used as optional to reflect difference wet system
in the simulation model with minimum number of saturation
table.

18. Presentation Outline
 To address the current issues of main concern issues with
the simulation modeling.
 To address alternative Pc’s curves design to enhance
simulation models accuracy.
 History Case Studies.
 Finding and Conclusions.

19. Sw Matching @ Initialization
Reservoir-A Case Study, (Average Zonal Sw Map)
Current Simulation
Model using 164 Saturation Tables
Updated Simulation Model with New
Approach using 14 Saturation Tables
Excellent match was achieved with implement new approach to design Pc’s
curves which contributed in model enhancement and boost model
reliability. The difference gap between the current simulation and the new
simulation models is less than 1.0 %.

20. Stability Test
Reservoir-A Case Study
Simulation model running time
the lower is better
Time steps performance
the higher is better
Convergent problems indicator, less
frequency is better.
Time consumed per each time step,
the lower is better.

21. History Match Performance Profiles of 50 Years
Reservoir-A Case Study
Simulation model running
time the lower is better
Time steps performance
the higher is better
Convergent problems indicator,
less frequency is better.
Time consumed per each time step,
the lower is better.

22. History Match Performance Profiles of 50 Years
Reservoir-A Case Study
Comparable water breakthrough
time was met

23. General Remarks:
 There is no history match processes
were implemented during model
update i.e. (no permeability multipliers
have been used), the only change take
place was in saturation tables setup.
 The history match profiles have not
been lost or changed after introduced
the new PC’s curves design approach,
which support the newly approach
capability in reducing convergences
problems and speed-up running time.
 Simple with very optimized saturation
tables input data that can be applied to
any model.
Summary Results Table

24. Sw Matching @ Initialization
Reservoir-B Case Study, (Sw at Layer#1, Cross-Section)
Current
Simulation
Model
Updated
Simulation
Model with
New
Approach

25. History Match Performance Profiles
Reservoir-B Case Study
Water cut production with new
approach is demonstrating better
match profiles to the field
observed data.

26. General Remarks:
 The simulated water cut using new
approach is presenting more match
with field observed data.
 With using new approach, less number
of saturation tables were used that
demonstrate similar history match
trends.
Summary Results Table

27. Current Approach
New Approach
Sw Matching @ Initialization
Reservoir-C Case Study, (Sw at Layer#1, Cross-Section)

28. History Match Performance Profiles
Reservoir-C Case Study
Field water cut production reported
low. The new approach demonstrate
better match with measured data.

29. General Remarks:
 Although, the reservoir transition zone
was estimated very thick, however; the
simulated water cut with new approach
was more reflect to field measurement.
 The injected water rate was improved
with implement new approach, where
the original model didn’t achieve it.
Summary Results Table

30. Sw log Profile Sw Pc Profile
Geological
Model
(Sw Map)
Simulation
Model
(Sw Map)
Sw Matching @ Initialization
Reservoir-D Case Study

31. SW Model
Static Model
SW Model
Dynamic Model
Sw Matching @ Initialization
Reservoir-E Case Study
A-634 H-201 K-312
N-144 K-423 B-542
Sw log
Sw_pc

32. Sw_log vs. Sw_Pc Matching
Reservoir-F Case Study
The new methodology, which was applied to redesign the saturation model has
contribute in achieving excellent match between Sw_logs data and Sw_pc that enhance
simulation model in terms of fluids distribution and fluids in place calculation i.e.
(OIP’s & GIP’s), and reduce the volumetric gap in between the static and the dynamic
models to less than 1.0 %.

33. Presentation Outline
 To address the current issues of main concern issues with
the simulation modeling.
 To address alternative Pc’s curves design to enhance
simulation models accuracy.
 History Case Studies.
 Finding and Conclusions.

34. Finding and Conclusions (1/2)
 The new approach to design Pc’s curves can provide and contribute in
the following points:
 Efficient and practical procedure that can be easily implemented and updated while
achieving high quality match with observed measured data.
 Excellent match with logs-derived water saturation profiles per well and per layer.
 Excellent match with less volumetric gaps (OIP & GIP) between the static and
dynamic models that can be reduced to below 1.0 %.
 More representative definition to the top transition zone thickness which would
assist further to control water and gas breakthroughs timing and trends.
 Eliminate using unsupported parameters such as permeability multipliers and usage
of unmeasured Swcr’s values.
 Allow to implement more ideal relative permeability curves shapes.

35. Finding and Conclusions (2/2)
 Improve simulation model stability which would accelerate computer running time
and reduce convergences problems.
 Practical to address the wettability change with depth. (Assign oil-wet wettability to
top of structure and water-wet wettability nearby transition zone interval).
 Minimize the number of saturation table that can be managed in the simulation
model.
 More reliable results for predicted reservoir production potential required for
management decisions in order to select the most optimum development scheme
based on techno-economic evaluation with enhanced oil recovery methods (EOR)
for long term full field development plan.

36. Thank You