Ho Riz Well Complexity for Frac Designer

7/28/2019 Ho Riz Well Complexity for Frac Designer

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Hydraulic Fracture Complexity and Treatment

Design in Horizontal Wells

Craig Cipolla

VP of Stimulation Technology

Carbo Ceramics/StrataGen Engineering


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Outline

Fracture complexity

Proppant distribution

Reservoir simulation (horizontal wells with complexfractures growth)

Effect of fracture conductivity

How much conductivity is needed?

Effect of modulus on network fracture conductivity

Effect of staging

Effect of network fracture complexity (i.e. spacing)

Effect of permeability

Summary & conclusions


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Simple Planar Fracture Growth

Simple Fracture

Simple Fracture


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Predictable Proppant Distribution


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Complex Planar Fracture Growth

Complex Fracture

Complex Fracture


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Complex Growth, Fissure Opening

Complex Fracture

With Fissure Opening

Complex Fracture

With Fissure Opening


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Network Fracture Growth

Complex Fracture

Network

Complex Fracture

Network

Unpredictable Proppant Transport?


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Fracture Complexity & Natural Fractures

NaturalFracturesHydraulic

Fractures

NaturalFracturesHydraulic

Fractures


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Grasshopper, Now You Must Choose!

Simple or Complex?


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Proppant Distribution

(network fracture growth)

reference SPE 115769

Proppant volumes probably insufficient to effectively prop large networksNetwork fracture conductivity likely dominated by un-propped fractures

Proppant may not be effectively transported into complex networks

Un-propped fracture conductivity a key factor in well productivity


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Proppant Distribution

Vertical Proppant Distribution

Arch dimensions and stress on proppant

based on SPE 119350 War inski


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Proppant DistributionVertical Proppant Distribution in Primary Fracture

*reference Britt SPE 102227 and SPE DL presentation 2007-2008 Series

C*fD-vertical = kfwf/khf-unpropped?

CfD= kfwf/kxf

C*

fD-vertical = kfwf/khf-propped?


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Production Modeling in Shale-Gas Reservoirs


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Comparison WellsBarnett Horizontal Completions

Well A

2,600 ft lateral

Four frac stages

o 670 klbs (40/70-sand), 120,000 bbls

o 700 ft between perforation clusters

SRV = 1,880x106 ft3 (Microseismic fracture mapping)

Well B

2,600 ft lateral

Two frac stages

o 830 klbs (40/70-sand), 117,000 bbls

o 500 ft between perforation clusters

SRV = 2,017x106 ft3 (Microseismic fracture mapping)


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Stimulating Horizontal Wells

Symmetry for Reservoir Simulation


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Impact of Fracture Conductivity

Pressure distribution after 3 months

400 ft main fracture spacing, 100 ft networkfracture spacing, 2 mD-ft network conductivity

2 mD-ft primary fracture conductivity

Pressure (psi) Pressure (psi)

Pressure (psi)Pressure (psi)

Pressure distribution after 1 yr

100 mD-ft primary fracture conductivity 400 ft

Insufficient fracture conductivity


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Impact of Primary Fracture Conductivity

400 ft main fracture spacing and 100 ft network fracture spacing

Barnett HZ well


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Impact of Network Fracture Conductivity

300 ft primary fracture spacing, 100 ft network fracture spacing

Well A Well B

300 ft primary fracture spacing, 100 ft network fracture spacing

Well A Well B


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How Much Fracture Conductivity is Needed?

Results for 50 ft fracture spacing

Network Conductivity Required to Achieve 90% of 1st

-year Production

0.1

1

10

100

1000

FractureCon

ductivity(mD-ft)

0.0001 mD

0.01 mD

Small Network

Uniform Network

Conductivity

Small Network

Infinite

Conductivity

Primary Fracture

Large Network

Uniform Network

Conductivity

Large Network

Infinite

Conductivity

Primary Fracture


-year Production

0.1

1

10

100

1000

FractureCon

ductivity(mD-ft)

0.0001 mD

0.01 mD

Small Network

Uniform Network

Conductivity

Small Network

Infinite

Conductivity

Primary Fracture

Large Network

Uniform Network

Conductivity

Large Network

Infinite

Conductivity

Primary Fracture

Network conductivity required to achieve 90% of maximum 1st productionNetwork Conductivity Required to Achieve 90% of 1st

-year Production

0.1

1

10

100

1000

FractureCon

ductivity(mD-ft)

0.0001 mD

0.01 mD

Small Network

Uniform Network

Conductivity

Small Network

Infinite

Conductivity

Primary Fracture

Large Network

Uniform Network

Conductivity

Large Network

Infinite

Conductivity

Primary Fracture


-year Production

0.1

1

10

100

1000

FractureCon

ductivity(mD-ft)

0.0001 mD

0.01 mD

Small Network

Uniform Network

Conductivity

Small Network

Infinite

Conductivity

Primary Fracture

Large Network

Uniform Network

Conductivity

Large Network

Infinite

Conductivity

Primary Fracture

Network conductivity required to achieve 90% of maximum 1st production

25

212

0.4

3.5

71

224

2.8

22


-year Production

0.1

1

10

100

1000

FractureCon

ductivity(mD-ft)

0.0001 mD

0.01 mD

Small Network

Uniform Network

Conductivity

Small Network

Infinite

Conductivity

Primary Fracture

Large Network

Uniform Network

Conductivity

Large Network

Infinite

Conductivity

Primary Fracture


-year Production

0.1

1

10

100

1000

FractureCon

ductivity(mD-ft)

0.0001 mD

0.01 mD

Small Network

Uniform Network

Conductivity

Small Network

Infinite

Conductivity

Primary Fracture

Large Network

Uniform Network

Conductivity

Large Network

Infinite

Conductivity

Primary Fracture

Network conductivity required to achieve 90% of maximum 1st productionNetwork Conductivity Required to Achieve 90% of 1st

-year Production

0.1

1

10

100

1000

FractureCon

ductivity(mD-ft)

0.0001 mD

0.01 mD

Small Network

Uniform Network

Conductivity

Small Network

Infinite

Conductivity

Primary Fracture

Large Network

Uniform Network

Conductivity

Large Network

Infinite

Conductivity

Primary Fracture


-year Production

0.1

1

10

100

1000

FractureCon

ductivity(mD-ft)

0.0001 mD

0.01 mD

Small Network

Uniform Network

Conductivity

Small Network

Infinite

Conductivity

Primary Fracture

Large Network

Uniform Network

Conductivity

Large Network

Infinite

Conductivity

Primary Fracture

Network conductivity required to achieve 90% of maximum 1st production

25

212

0.4

3.5

71

224

2.8

22


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0.1

1

10

100

1000

10000

0 2000 4000 6000 8000

Closure Stress, psi

ReferenceCondu

ctivity,md-ft

0.1 lb/sq ft bauxite

0.1 lb/sq ft Jordan sand,

or displaced un-propped

Un-Propped & Partially Propped Fracture Conductivity

How Much Conductivity can be Achieved?

Uniform Network Conductivity

Infinite Conductivity

Primary Fracture

Adapted from SPE 60236, 74138


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Un-Propped Fracture Conductivity

Effect of Modulus

0.01

0.1

1

10

100

1000

0 2000 4000 6000 8000

Stress (psi)

Conductivity(mD-ft)

E=6E+6 psi

E=4E+6 psi

E=2E+6 psi

E=1E+6 psi


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Optimizing Proppant Selection

Too big or Too small?

Not strong enough?

More proppant?


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Impact of Primary Fracture Spacing

200 mD-ft primary frac and 2 mD-ft network,

100 ft network fracture spacing

Pressure (psi)


Pressure (psi)

Pressure distribution after 3 months Pressure distribution after 1 yr

600 ft main fracture spacing

200 ft main fracture spacing


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Impact of Primary Fracture Spacing


Well AWell B


Well AWell B


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Impact of Network Fracture Spacing

200 mD-ft primary frac and 2 mD-ft network, 600 ft

primary fracture spacing



Pressure (psi)


Pressure (psi)

Pressure distribution after 1 month Pressure distribution after 1 yr

600 ft

600 ft


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2 mD-ft network fracture conductivity

Well AWell B


Well AWell B


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Well AWell B


Well AWell B


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Impact of Matrix Permeability (1 x 10-5 mD)


50 ft spacing, k = 1 e-4 md




Well A

Well B





Well A

Well B


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ConclusionsCharacterizing Fracture Growth leads to:

Better understanding well & fracture performanceMore reliable reservoir modeling and better reservoir

characterization

Resolution of created and effective fracture length

Better estimates ofIn situfracture conductivity

Improved completion & stimulation strategies

Stimulation fluid & proppant selection

Well placement and spacing

Number of stages (both vertical & horizontal wells)

Optimized designs (volume, rate)Optimum Fracture Treatment Designs and Field DevelopmentStrategies Tailored to Specific Geologic Environments


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Are we applying the right

combination of technologies?


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Fracture & Completion Strategy(horizontal gas wells, network fracture growth)

Conductivity of the primary fracture is likely acritical parameter (~50-100 mD-ft required)

Fracture complexity/network fracture spacing keyto well productivity and gas recovery

If network fracture spacing is on order 50 ft, then theeffect of matrix permeability on production issignificantly reduced

High relative conductivity primary fracture reducesthe impact of network fracture spacing


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Fracture & Completion Strategy(horizontal gas wells, network fracture growth)

Actual production profiles suggests that primary

fracture conductivity is low?

Understanding matrix permeability and un-propped

fracture conductivity is important when optimizing

treatment designs in unconventional gas reservoirs

Un-cemented horizontal completions, more difficult

to create a high relative conductivity primaryfracture?


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General Guidelines

In low modulus rock, it may not be possible toexploit complexity. (Haynesville?)

In reservoirs that areprone to fracture complexity,design goals should target:

Large networks for k~0.0001 md (E>4e6 psi) Supplemented with infinite conductivity primary fractures

Small networks for k~0.01 md (E>4e6 psi) Supplemented with infinite conductivity primary fractures

Simple fractures for k~1.0 md (E


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Strategy

Evaluate the impact of operational changes uponfracture complexity

o Low viscosity fluids generally promote fracturecomplexity and minimize damage

o High viscosity fluids reduce fracture complexity(Haynesville?)

o Pump rates, completion strategy, diversion, 100-mesh, etc.

Evaluate hybrid treatments to promote smallnetworks with infinite conductivity primaryfractures


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Strategy

Evaluate higher strength, smaller mesh, and lowerdensity propping agents that can significantlyimprove the conductivity of partially proppednetwork fractures

Deeper penetration, better proppant transport

Possibly enter and prop secondary networkfractures

Evaluate larger proppant volumesIncreased primary fracture conductivity

Increase network fracture conductivity


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Questions?


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Backup Slides


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Reservoir Simulation Study Goal: Evaluate the relationship between fracture complexity,

fracture conductivity, and proppant distribution on wellproductivity

Cases: Single fracture, complex planar growth, smallnetworks, and large networks

This presentation focuses on Small and Large Networks

Reservoirs: Gas with permeability of 0.0001, 0.01, and 1 md

Proppant distribution: Two limiting cases

Proppant is concentrated in a single primary fracture with infiniteconductivity (case 2)

Proppant is evenly distributed within the fracture network (cases1 & 3)

Evaluate the effect of network fracture conductivity on wellproductivity for the two limiting cases


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Example Fracture Treatments

Barnett Shale (SPE 95568)

k = 0.0001 mD (est.)

hf= 300 ft

xf= 1500 ft

xn = 2000 ft

xs = 50-300 ft (est.)

Treatment

60,000 bbl

385,000 lbsNote: Fracture dimensions and complexity from microseismic mapping


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Important Assumptions Cased and cemented wellbore

Primary fracture spacing controlled by distance betweenperforation clusters

Gas flow into wellbore at perforation clusters only

Fracture complexity (network fracture spacing) is notaffected by primary fracture spacing (distance betweenperforation clusters)

Pre-existing natural fracture system or rock fabric is presentand can be equally stimulated for the range of primaryfracture spacings evaluated

Network fracture conductivity is not affected by primaryfracture spacing

Stimulated Reservoir Volume (SRV) is equal for all cases(2000 x 106 ft3)


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Barnett Example

-1000

-500

0

500

1000

1500

2000

2500

3000

-1000 -500 0 500 1000 1500 2000 2500

West-East (ft)

South-North(ft)


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150 ft

150ft

2000

ft

Evenly Distributed

3000 ft

(Case 1)

150 ft

150ft

2000

ft

Evenly Distributed

3000 ft

(Case 1)

Proppant Distribution, 150 ft Network Fracture Spacing:

Barnett Shale Example (385,000 lbs prop)

0.015 lb/ft2

Note: Dimensions not to scale


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150 ft

150ft

2000

ft

Concentrated in a

dominant fracture

3000 ft

(Case 2)

150 ft

150ft

2000

ft

Concentrated in a

dominant fracture

3000 ft

(Case 2)

Proppant Distribution, 150 ft Network Fracture Spacing:

Barnett Shale Example (385,000 lbs prop)

0.43 lb/ft2

Note: Dimensions not to scale

P t Di t ib ti & N t k F t


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Proppant Distribution & Network Fracture

Growth Summary

If proppant is evenly distributed in network fractures,concentrations are probably too small to materiallyaffect conductivity

If proppant is concentrated in a primary fracture,concentrations mayprovide adequate conductivity fork


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Effect of Modulus & Stress on Embedment

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

0 2000 4000 6000 8000 10000 12000

Stress (psi)

Em

bedment(graindiameters

) 1E+6 psi

2E+6 psi

4E+6 psi

6E+6 psi


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Findings

Fracture complexity can be estimated byintegrating microseismic mapping, reservoir &

fracture modeling, core data, and well

performance

In some reservoirs, fracture complexity has been

shown to improve production. In other

reservoirs, complex growth has been shown to

damage productivity.


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Findings

If proppant is evenly distributed throughout large

fracture networks, the resulting concentrations

are inadequate to materially affect conductivity

To capitalize on the potential of unpropped and

partially propped regions, these networks should

be contacted by infinite conductivity primaryfractures

Documents

Ho Riz Well Complexity for Frac Designer