The document introduces EDFM (Embedded Discrete Fracture Model), a fracture simulation technique developed by Sim Tech LLC. EDFM can more accurately model complex fracture networks compared to traditional reservoir simulators. It overcomes limitations of local grid refinement and unstructured grids by embedding fracture descriptions directly into the reservoir grid. EDFM also allows for efficient coupling of fracture models from third-party software with any reservoir simulator. Case studies demonstrate EDFM can better history match production from fractured wells and evaluate enhanced oil recovery techniques involving refracturing or injection.

1. An Innovative Workflow for Complex Fracture
Modeling and Simulation Using EDFM
Sim tech, llc
March 2019
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2. Introduction
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3. ØWe are an independent consulting and software development company.
ØWe specialize in dealing with the complex fractured reservoirs.
ØWe develop EDFM fracture simulation software.
Gabbro, Fractured surface of
shale rock, Oklahoma, USA
Fracfocus
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4. Big challenges for traditional reservoir simulators to
simulate fractures accurately and efficiently
Local Grid
Refinement
(CMG/ECL)
Y. Wu, et al, 2014
DPDK
(ECL)
Hydraulic
fractures
Natural
fractures
v Create huge grids to
describe fractures
v Can't handle complex
fractures
v Computationally expensive
v Duplicate grid to represent
DFN
v Over simplified fracture
communication, low
accuracy
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5. Embedded Discrete Fracture Model(EDFM)
1. Adding fracture description to the existing grid
2. NNC-Non-neighboring connections
3. Transmissibility calculation
Wellbore
Matrix
Fracture 2
Fracture 1
Physical domain Computational domain
Q T P 
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6. Popular Fracture modeling technologies VS EDFM
• Overall, EDFM has the best performance in Accuracy, Computational
efficiency and flexibility.
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7. Study of LGR Grid vs EDFM Process
LGR • LGR grids more difficult to
create.
• LGR grids have more grid
cells in model.
• LGR grid simulations are
longer to run.
• EDFM: easy to implement,
faster running time, powerful
to handle complex geometry
complexity
EDFM
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8. Study of Unstructured Grid Comparison
EDFM
Unstructured
grids
• Unstructured grids more
difficult to create
• Unstructured grids have more/
different grid cells in model
• Unstructured grids simulations
are longer to run
• EDFM, handle complexity
easily and more powerful, it’s
efficient and practical than
unstructured grid
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9. EDFM Preprocessor
Reservoir simulators
(UTCOMP, UTCHEM,
CMG, ECLIPSE, …)
EDFM Preprocessor
- fracture properties
- matrix permeability
Detect geometrical
intersection between matrix
blocks and fractures
Cut fractures into segments
with matrix cell boundaries
Create virtual gridblocks in
computational domain
for fracture segments
Add non-neighboring
connections for fracture
blocks
Run simulator
NNC list
Fracture
grids
Matrix
grids

10. Game Changer --- EDFM Preprocessor
• EDFM as a bridge to couple realistic fracture models to any reservoir
simulation with true fracture geometry
Fracman
Fracflow
Petrel
Kinetix(Mangrove)
Gohfer
Stimplan
EDFM
Preprocessor
Eclipse
CMG
tNavigator
Intersect
Nexus
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3rd party fracture model 3rd party reservoir simulator
ØNo need to: build a new reservoir model, buy a new fancy expensive simulator,
purchase super computer. Save time and money!
ØData transfer module that streamlines the workflow. EDFM will import 3rd party’s
fractures directly into your existing simulator.
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11. EDFM case studies
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12. Vertical Well Refracturing (Wattenberg Field)
1st Refrac
2nd Refrac
1,000 days 2,000 days 3,000 days
Initial fractures 1st refractures (1,000 days)
2nd refractures
(2,000 days)
Cumulative gas production
Pressure profiles (1,000 days after fracture creations)

13. • Refracturing the 4 vertical wells and fracturing a new well
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0
1500
0 X, ft 1500
Y,ft
width, inch
0
0.1

14. Refracturing for Horizontal Well
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Pressure-dependent fracture conductivity
with restoration of fracture conductivity
Enlarged fracture geometry
Increased fracture height
Equal area

15. Influence of Different Refracturing Mechanisms
No refracturing
Refracturing
No refracturing
Horizontal growth
Vertical growth
q Key to a successful refracturing work: create fracture areas in unstimulated zones
q Create new fractures
q Extend existing fractures
q When fracture conductivity is sensitive to stress, enhancement of fracture conductivity through refracturing
could also effectively improve the ultimate recovery

16. Pressure Profiles
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Top layer
Middle layer
Fracture growth in horizontal direction Fracture growth in vertical direction

17. Field Application in Niobrara Tight Gas
URTeC 2901327
Well interference due to long fracture hits

18. Field Application in Niobrara Tight Gas
Well 1 Well 2
Well 3 Well 4
Well 5 Well 6
Fracture Conductivity from History Matching

19. Field Application in Niobrara Tight Gas
Simulation
model
Number of
gridblocks
Number of time
steps
CPU time
(second)
The ratio of CPU
time (LGR/EDFM)
EDFM 291,900
733 (history) 1,589
14 (history)
20 (forecasting)
670 (forecasting) 1,763
LGR 855,750
1420 (history) 21,720
1378 (forecasting) 33,619
LGR EDFM
Pressure Profiles (middle layer) after 40 yearsPressure in the fractures

20. Field Application in Niobrara Tight Gas
Fractures in the
simulation
Number of
wells
Three-well
production/ Six-
well production
HF + 4000 NF
(0.02 md-ft)
3
68%
6
Six wells Three wells

21. Comparison of Simple and Complex Fractures
36%
Complex hydraulic fractures 5 md-ft
Activated natural fractures 0.03 md-ft
Non-activated natural fractures 0.001 md-ft
Marcellus shale
Simple hydraulic fractures 5.5 md-ft

22. Impact of complex fractures(Marcellus Shale)
• Traditional fracture simulation method underestimates the impact of
natural fracture and the complexity of fractures.
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After HM
period
Simple fractures
After 10 years
Complex fractures

23. 3rd party import-Kinetix
Kinetix Frac
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24. 3rd party import-Gofher
Gofher Frac
New grid model generated with
frac integrated in
Display reservoir simulator
outputs with EDFM frac
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25. Field Case Study of Well Interference in Eagle Ford
LWD Ultrasonic imager to identify fractures Well spacing 250-550 ft and cluster spacing 20-70 ft
IPTC 19468

26. Field Case Study of Well Interference in Eagle Ford
W1H W2H W3H W4HW5H W6H W7H W8H W9H
2168 hydraulic fractures
28 long fractures (fracture hits)
L1
L2
L3
L4
L5
L6
L7

27. Field Case Study of Well Interference in Eagle Ford
History matching results for
4 parent wells and 5 child wells

28. Field Case Study of Well Interference in Eagle Ford
28 long fractures 750-3750 ft
Fracture conductivity 0.5 md-ft
2168 hydraulic fractures with conductivity of 3-360 md-ft, half-length of 55-100 ft, height of 30-75 ft
W1H W2H W3H W4HW5H W6H W7H W8H W9H

29. EOR Study in Eagle Ford with Fracture Hits
Gas injector Gas injectorWater injector
2 Gas injectors
• Full model - 15 MMscf/d
• Sector model
900,000 MMscf/d (6%)
• One cycle of 30 days
• 50 cycles
1 water injector
• Full model – 4320 bpd
• Sector model
260 bpd (6%)
• One cycle of 30 days
• 10 cycles
• Injection BHP – 3500 psi

30. EOR Study in Eagle Ford with Fracture Hits
Child
Wells
Primar
y
Huff-n-Puff (7-
12%)
Water
Injection(10-15%)
Containment Opt
(20-30%)
Parent Wells
Production Strategy
Cumulative Oil Prod
(6% Sector model)
Incremental Oil
recovery
Primary 143,255 BBLS -
Huff-n-Puff 153,802 BBLS 7%
Huff-n-Puff+ Water 160,420 BBLS 12%
2 Gas Huff-n-Puff + Pressure containment 184,000 BBLS 29%
SPE 195240
Field operation of
gas Huff-n-Puff in Eagle Ford

31. 3rd party import --- Petrel with massive natural fractures
Natural Frac
Reservoir Model
EDFM Processor
Embed fracture/Calculate Non-
Neighboring Connections &
Transmissibility
New grid model generated with
frac integrated in
Matrix Grid 146*96*50 Treatment
frac Number 12,958 EDFM
frac number 267,756 EDFM+DPDK
Challenges：
• Full field with 15 wells
• Huge massive natural fractures
• Accurate modeling and simulation
Solution：
• EDFM couples with DPDK
• 3 years history matching
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32. Summary
üEDFM can overcome the limitations of all the existing
mumerical methods
üMultiple refracturing scenarios considering natural fractures can
be examined for optimization of refracturing strategies for a
multi-well pad
üTested & Validated on multiple reservoir types and scenarios.
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33. Thanks for your time!
Appreciate your comments!
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