1. Hydraulic Fracturing Design for Optimum Well Productivity
Frank E. Syfan, Jr., PE, SPEE
Syfan Engineering, LLC
February 26, 2015

2. Outline Critical Fracture Design Parameters Case Histories: Summary
GoFrac, LLC
Outline
Critical Fracture Design Parameters
Rock Mechanics
Fracture Mechanics
Fluid Systems
Proppant Selection
Case Histories:
Case A: Marcellus Shale
Case B: Eagle Ford Shale
Case C: Bakken
Case D: Cotton Valley
Summary
Conclusions

3. Critical Fracture Parameters Rock Mechanics
Mineralogy
Content: Quartz, calcite, clay (??)
Shales: Many are not in strictest geological sense!
Poisson’s Ratio
𝒗=− 𝝏 𝜺 𝒕𝒓𝒂𝒏𝒔 𝝏 𝜺 𝒂𝒙𝒊𝒂𝒍
Modulus of Elasticity (Young’s Modulus)
 𝒎 ≝ 𝑺𝒕𝒓𝒆𝒔𝒔 𝝈 𝑺𝒕𝒓𝒂𝒊𝒏 𝜺 =𝑬
In-Situ Stress
𝝈 𝑯 = 𝒗 𝟏−𝒗 𝝈 𝒗 − 𝑷 𝒑 + 𝑷 𝒑 + 𝝈 𝝉

4. Critical Fracture Parameters Fracture Mechanics
Fracture Face Skin
𝑺 𝑭𝒂𝒄𝒆 = 𝝅 𝒀 𝒙 𝑿 𝒇 𝒌 𝒓 𝒌 𝑫 −𝟏
Choked Fracture Skin
𝑺 𝒄𝒉 = 𝒉 𝑿 𝒇 𝟏 𝑪 𝒇𝑫 𝒍𝒏 𝒉 𝟐 𝒓 𝒘 − 𝝅 𝟐
Half-Length & Width
What is optimum length?
Perkins & Kern (1961)
Fracture Conductivity!!!
wkf
CfD

5. Critical Fracture Parameters Fluid Systems
Fluid & Additive Design
Slickwater DOESN’T Work Everywhere!
Chemical and Fluid Compatibility
Gel Stability and Breaker Tests
Temperature Ranges
Nano-Fluid Non-Emulsifiers
Polyacrylamide Breakers
ISO , ,

6. Critical Fracture Parameters Proppant Selection
Ceramic
Resin Coated
a-Qtz

7. Critical Fracture Parameters Proppant Selection
Ceramics
RC Ceramics
Bauxite
13+ 12 8 5 4
Intermediate
RC a-Qtz
LWC
Premium
Incr. Closure Pressure, Kpsi
Economy
Intermediate
a-Qtz
Incr. Cost & Performance

8. Critical Fracture Parameters Proppant Selection
The Ideal Proppant
Crush resistance / high strength
Slightly deformable, not brittle
No embedment
Low specific gravity
Chemical resistance
No flowback
Complete system compatibility
Ready availability
Cost effective
Reality: The Ideal Proppant Doesn’t Exist!!

9. Critical Fracture Parameters Proppant Selection
Infinite vs. Finite Conductivity
Formation Permeability
Depth/Closure Stress
Formation Ductility/Embedment
What is Brinell Hardness?

10. Critical Fracture Parameters Proppant Selection
Median Particle Diameter
Cyclic Stress
Multi-Phase Flow
Proppant Flowback
Non-Darcy Effects
Beta Factor

11. Critical Fracture Parameters Conductivity
Fracture Conductivity – Wkf
Single Most Important Factor to Achieve!
Dimensionless Conductivity
Fracture Flow Capacity Divided by Reservoir Flow Capacity.
Considered “Infinite” the fracture deliverability exceeds reservoir deliverability with negligible pressure loss.

12. Critical Fracture Parameters Conductivity: McGuire & Sikora (1960)
GoFrac, LLC
Critical Fracture Parameters Conductivity: McGuire & Sikora (1960)
Dimensionless Productivity Index vs. Dimensionless Conductivity
(Square Reservoir)
Dimensionless Productivity Index vs. Dimensionless Conductivity
(Rectangular Reservoir – 1/10)

13. Critical Fracture Parameters Fines
Intermediate Strength Ceramic – 8,000 psi
12/20 Hickory/Brady – 6,000 psi
RC Proppant – 8,000 psi
StimLab Proppant Consortium, 1997 – 2006

14. Critical Fracture Parameters Depth/Closure Stress
Brown vs. Northern White?
API 19C (ISO ) Guidelines Are Specific!!
Sieve Distribution
Krumbein Factors
Turbidity
Acid Solubility
K-Value (Also Called Crush Resistance)
Point Where Fines >10.0%
Relative Number Only!!

15. Critical Fracture Parameters Median Particle Diameter
SPE (2003)
Particle Sieve Distribution Variations
Field Samples – 20/40 N. 25X
0.545 mm
0.703 mm
Courtesy: PropTester – Houston TX

16. Critical Fracture Parameters Median Particle Diameter
Each Proppant Sample Passes ISO Guidelines!
Flow Capacity Decreases
MPD = mm
MPD = mm
Courtesy: PropTester – Houston TX

17. Critical Fracture Parameters Median Particle Diameter
100
1,000
10,000
Published Data
MPD = mm
Conductivity (md-ft)
Actual Data
MPD = mm
2,000
4,000
6,000
8,000
10,000
Closure Stress (psi)
Courtesy: PropTester – Houston TX

18. Critical Fracture Parameters Beta Factor
A Quantity Relating Pressure Loss In The Fracture to Liquid or Gas Production Rates (velocities).
Governed by Forchheimer’s Equation
Darcy Effects
Non-Darcy Effects
Inertial Effect
2 - Dominate!
PSD Effects Beta

19. Outline Critical Fracture Design Parameters Case Histories: Summary
GoFrac, LLC
Outline
Critical Fracture Design Parameters
Rock Mechanics
Fracture Mechanics
Fluid Systems
Proppant Selection
Case Histories:
Case A: Marcellus Shale
Case B: Eagle Ford Shale
Case C: Bakken
Case D: Cotton Valley
Summary
Conclusions

20. Case History A: Marcellus Shale
Reservoir & Fracture Parameters
Fracture & Reservoir Match
Description
Value
Reservoir Depth, ft
7.876
Reservoir Thickness, ft
162
Hydrocarbon Porosity, %
4.2
Pore Pressure, psi
4.726
Temperature, oF
175
Drainage Area, ac 80
Aspect Ratio (xe/ye)
BHFP, psi
1,450 – 530
Lateral Length, ft
2,100
Number of Stages 7
Clusters per Stage 5
Description
Value
Reservoir Permeability, nD
583.0
Permeability-Thickness, md-ft
0.094
Propped Length, ft
320
Fracture Conductivity, md-ft
3.77
Dimensionless Conductivity
20.2
Choked Skin, dim
+0.096
Equivalent Fractures 6
SPE

21. Case History A: Marcellus Shale
Predicted Gas Production Rate
Predicted Cum. Gas Production
SPE

22. Case History A: Marcellus Shale
SPE

23. Case History B: Eagle Ford Shale
Reservoir & Fracture Parameters
Fracture & Reservoir Match
Description
Value
Reservoir Depth, ft
10,875
Reservoir Thickness, ft
283
Hydrocarbon Porosity, %
5.76
Pore Pressure, psi
8,350
Temperature, oF
285
Drainage Area, ac 80
Aspect Ratio (xe/ye)
BHFP, psi
3,900 – 1,500
Lateral Length, ft
4,000
Number of Stages 10
Clusters per Stage 4
Description
Value
Permeability-Thickness, md-ft
0.0049
Propped Length, ft
131
Fracture Conductivity, md-ft
0.86
Dimensionless Conductivity
382
Choked Skin, dim
Equivalent Fractures 40
SPE

24. Case History B: Eagle Ford Shale
Predicted Gas Production Rate
Predicted Cum. Gas Production
SPE

25. Case History C: Bakken Shale
Reservoir & Fracture Parameters
Description
Value
Reservoir Depth, ft
9,881
Drainage Area, ac
640
Reservoir Thickness, ft 46
BHFP, psi
1,500
Rsvr. Permeability, mD
0.002
Effective Frac. Length, ft
420
Porosity, %
5.0
Frac. Conductivity, md-ft
200
Pore Pressure, psi
4,900
Dimensionless Conductivity
238
Temperature, oF
209
Lateral Length, ft
5,000
Rsvr. Compressibility, 1/psi
2.0 E-05
Transverse Fractures 12
Rsvr. Viscosity, cP
0.30
SPE

26. Case History C: Bakken Shale
GoFrac, LLC
Case History C: Bakken Shale
Predicted Oil Production Rate
Predicted Cum. Oil Production
SPE

27. Case History D: E. TX Cotton Valley
GoFrac, LLC
Case History D: E. TX Cotton Valley
Reservoir & Fracture Parameters
Description
Value
Reservoir Depth, ft
9,000
BHFP, psi
1,500
Reservoir Thickness, ft
100
Effective Frac. Length, ft
Rsvr. Permeability, mD
0.001
Frac. Conductivity, md-ft
114
Porosity, %
7.0
Dimensionless Conductivity 76
Pore Pressure, psi
6,000
Lateral Length, ft
2,000
Temperature, oF
285
Transverse Fractures 7
Drainage Area, ac
640
SPE

28. Case History D: E. TX Cotton Valley
GoFrac, LLC
Case History D: E. TX Cotton Valley
Predicted Gas Production Rate
Predicted Cum. Gas Production
SPE

29. Outline Critical Fracture Design Parameters Case Histories: Summary
GoFrac, LLC
Outline
Critical Fracture Design Parameters
Rock Mechanics
Fracture Mechanics
Fluid Systems
Proppant Selection
Case Histories:
Case A: Marcellus Shale
Case B: Eagle Ford Shale
Case C: Bakken
Case D: Cotton Valley
Summary
Conclusions

30. Summary
Proper fracture design and ultimately, fracture optimization, cannot and will not happen without sound engineering practices!
Without sound engineering, initial production rates, ultimate recovery, NPV, and rate-of-return will be compromised.
At the End of the Day……
SPE

31. Conclusions
Understanding the rock mechanics is essential to consistently achieving high conductivity fractures.
McGuire and Sikora (1960) holds true regardless of reservoir type and ultimately dictates reservoir and production performance.
Fracture conductivity and dimensionless fracture conductivity ultimately govern the initial production rates and ultimate recoveries regardless of the type of reservoir lithology.
SPE

32. Conclusions
Case A (Marcellus Shale) and Case B (Eagle Ford Shale) matches, illustrate the importance of achieving high conductivity transverse fractures in a horizontal wellbores.
Increasing fracture conductivity, regardless of reservoir type, results in a significant positive impact on ROR and NPV.
SPE

33. GoFrac, LLC
THANK YOU FOR YOUR TIME AND TO THE FORT WORTH SPE SECTION FOR INVITING ME TO MAKE THIS PRESENTATION. QUESTIONS??