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Hydraulic Fracturing Design for Optimum Well Productivity

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Presentation on theme: "Hydraulic Fracturing Design for Optimum Well Productivity"— Presentation transcript:

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??


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