Hydraulic Fracturing Design for Optimum Well Productivity Frank E. Syfan, Jr., PE, SPEE Syfan...

Hydraulic Fracturing Design for Optimum Well Productivity

Frank E. Syfan, Jr., PE, SPEE

Syfan Engineering, LLC

February 26, 2015

S

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

2

3

Critical Fracture ParametersRock Mechanics

Mineralogy Content: Quartz, calcite, clay (??) Shales: Many are not in strictest geological sense!

Poisson’s Ratio

Modulus of Elasticity (Young’s Modulus)

In-Situ Stress

4

Fracture Face Skin

Choked Fracture Skin

Half-Length & Width What is optimum length? Perkins & Kern (1961)

Fracture Conductivity!!! wkf

CfD

Critical Fracture ParametersFracture Mechanics

5

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 13503-1, 13503-3, 13503-4

Critical Fracture ParametersFluid Systems

6

Critical Fracture ParametersProppant Selection

a-Qtz

Ceramic

ResinCoated

7

Incr. Cost & Performance

13+12

8

54

0

Intermediate

Premium

Economy

Intermediate

Bauxite

Incr

. Clo

sure

Pre

ssur

e, K

psi

RC Ceramics

RC a-Qtz

Ceramics

a-Qtz

LWC


8

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

Infinite vs. Finite Conductivity Formation Permeability Depth/Closure Stress Formation Ductility/Embedment

What is Brinell Hardness?


10

Median Particle Diameter Cyclic Stress Multi-Phase Flow Proppant Flowback Non-Darcy Effects

Beta Factor


11

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.

Critical Fracture ParametersConductivity

f

fffD xk

wkC

12

Critical Fracture ParametersConductivity: McGuire & Sikora (1960)

Dimensionless Productivity Index vs. Dimensionless

Conductivity (Square Reservoir)

Dimensionless Productivity Index vs. Dimensionless

Conductivity (Rectangular Reservoir – 1/10)

13

Critical Fracture ParametersFines

12/20 Hickory/Brady – 6,000 psi

Intermediate Strength Ceramic – 8,000 psi

RC Proppant – 8,000 psi

StimLab Proppant Consortium, 1997 – 2006

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Brown vs. Northern White? API 19C (ISO 13503-2) Guidelines Are Specific!!

Sieve Distribution Krumbein Factors Turbidity Acid Solubility

K-Value (Also Called Crush Resistance) Point Where Fines >10.0% Relative Number Only!!

Critical Fracture ParametersDepth/Closure Stress

15

SPE 84304 (2003) Particle Sieve Distribution Variations

Field Samples – 20/40 N. White @ 25X

0.545 mm

0.703 mm

Courtesy: PropTester – Houston TX

Critical Fracture ParametersMedian Particle Diameter

16



0

5

10

15

20

25

30

35

40

45

16 20 25 30 35 40 50 PAN

Sieve Size

% P

art

icle

Dis

trib

uti

on

Public Domain Job Sample

Flow Capacity Decreases

MPD = 0.543 mm

MPD = 0.710 mm

Each Proppant Sample Passes ISO 13503-2 Guidelines!

17



Co

nd

uc

tiv

ity

(m

d-f

t)

100

1,000

10,000

2,000 4,000 6,000 8,000 10,000

Closure Stress (psi)

Published Data

MPD = 0.710 mm

Actual Data

MPD = 0.543 mm

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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

Critical Fracture ParametersBeta Factor

2.fluidfluid

frac

fluidfluid

frac

frac vk

v

X

P

Outline



Summary Conclusions

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20

Case History A: Marcellus Shale

Reservoir & Fracture Parameters

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) ¼

BHFP, psi 1,450 – 530

Lateral Length, ft 2,100

Number of Stages 7

Clusters per Stage 5

Fracture & Reservoir Match

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

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Predicted Gas Production Rate Predicted Cum. Gas Production

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SPE 166107 22

Case History B: Eagle Ford Shale


Description Value

Reservoir Depth, ft 10,875

Reservoir Thickness, ft 283

Hydrocarbon Porosity, % 5.76

Pore Pressure, psi 8,350

Temperature, oF 285


Aspect Ratio (xe/ye) ¼

BHFP, psi 3,900 – 1,500

Lateral Length, ft 4,000

Number of Stages 10

Clusters per Stage 4

Fracture & Reservoir Match

Description Value

Permeability-Thickness, md-ft 0.0049

Propped Length, ft 131

Fracture Conductivity, md-ft 0.86

Dimensionless Conductivity 382

Choked Skin, dim +0.0254

Equivalent Fractures 40

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Case History B: Eagle Ford Shale


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Case History C: Bakken Shale


Description Value 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 166107 25

Case History C: Bakken Shale

Predicted Oil Production Rate Predicted Cum. Oil Production

26SPE 166107

Case History D: E. TX Cotton Valley

Description Value Description Value

Reservoir Depth, ft 9,000 BHFP, psi 1,500

Reservoir Thickness, ft 100 Effective Frac. Length, ft 1,500

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



SPE 166107 27

Case History D: E. TX Cotton Valley


SPE 166107 28

Outline



Summary Conclusions

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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 166107 30

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.

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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 166107 32

THANK YOU FOR YOUR TIME AND TO THE FORT WORTH SPE

SECTION FOR INVITING ME TO MAKE THIS PRESENTATION.

QUESTIONS??

33

Hydraulic Fracturing Design for Optimum Well Productivity Frank E. Syfan, Jr., PE, SPEE Syfan...

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