Advances in Treatment Design and Production Optimization

7/27/2019 Advances in Treatment Design and Production Optimization

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Advances in Treatment Design and

Production Optimization

Get Permeability from Data fracs, Calibrate Fracture Models and 3D

Reservoir Simulation of Fractured Wells

EBN-TNO Tight Gas Symposium 19 September 2006

Hans de Pater, Josef Shaoul

Pinnacle Technologies

For Export to Reservoir SimulatorFracture Dimensions and Conductivity

Rocktype10000 20000Stress (psi)

2e+ 006 1e+ 007Modulus (psi)

0 5Permeability (mD)

Layer Properties

mudstone

Limestone

Dolomite

Limestone

Dolomite

Limestone

mudstone

50 100 150 200 250 300 350 400

Fracture Conductivity (mDft)

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000

FractureConductivity (mDft)


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The Fracture Engineering Loop

Reservoir DataLogs

Wellbore DataMe chanical Core Te sts

Production DataWell Tes t

Rate, Pres sure

Execution

Treatm ent Data

LogsFracture Mapping

Post-Frac Tests

Well Tes t

Rate, Pres sure

Production Forecast

Simple 1 Phase

3D res ervoir Simulation

Well Scenar io's

Treatment Design

Fluid/Proppant, Volumed

Stages , Completion

Optimization

Fracture DesignFracture Mode l


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Tight Gas Issues Permeability and Pressure Poorly Known

After Closure Analysis (Nolte-SPE25425,Mayerhofer)

Need Long Fractures, but Fracture Geometry

Cannot be Predicted Base Models on Frac Mapping

Production Forecast Needs to Consider

Transient (Flush Production) Link Design to 3D Reservoir Simulator


4/20

Injection Test Analysis

Perform small injections with treated water and gel

Observe pressure decline with high quality gauge

Determine closure, match pressure to estimate fracture

length Use linear and pseudo-radial after-closure slopes to

estimate pressure and transmissibility. Feed back to

initial estimate of fracture height


5/20

Injection Test Analysis: Fracture Closure

Analysis

G Function Time

Meas'd Btmh (psi) (d/dG) Meas'd Btmh (psi)(Gd/dG) Meas'd Btmh (psi)

0.00 2.56 5.12 7.68 10.24 12.800

1900

3800

5700

7600

9500

0

600

1200

1800

2400

3000

0

400

800

1200

1600

2000

BH Closure Stress: 7098 psi

Closure Stress Gradient: 0.716 psi/ft

Surf Closure Pressure: 2830 psi

Closure Time: 24.2 min

Pump Time: 10.7 min

Implied Slurry Efficiency: 55.1 %

Estimated Net Pressure: 1027 psi


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Injection Test Analysis: Reservoir Permeability

Estimate (Mayerhofer Method)

Squared Linear Flow Time Function

Pressure Difference (psi) (Td/dt) Pressure Difference (psi)

0.010 0.100 1.000100

1000

10000

Start Pseudo-Linear Flow: 0.189

End Pseudo-Linear Flow: 0.0743

Start of Predicted Pseudo-Linear Flow: 0.171

End of Predicted Pseudo-Linear Flow: 0.118

Start Pseudo-Radial Flow: 0.0467

End Pseudo-Radial Flow: 0.0275

Pseudo-radial

Pseudo-linear


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Fracture Growth Model

Inputs/Outputs

Inputs

Reservoir information (permeability, stress)

Treatment schedule (acid, proppant, rate, conc.)

Proppant data (permeability vs stress, non-Darcy)

Outputs

Fracture dimensions (length, height, width)

Fracture conductivity (pressure dependant)

Fluid leakoff profile (filtrate depth vs length)


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Fracture Model Output

Dimensions and ConductivityFor Export to Reservoir SimulatorFracture Dimensions and Conductivity

Rocktype10000 20000Stress (psi)

2e+006 1e+007Modulus (psi)

0 5Permeability (mD)

Layer Properties

mudstone

Limestone

Dolomite

Limestone

Dolomite

Limestone

mudstone

50 100 150 200 250 300 350 400


0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000



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Fracture Height and Length

Modeling based on pressure measurement may

be non-unique or non-predictive.

Measure fracture dimensions independently in

selected treatments Improve models by calibration of key parameters

Guide choice of fracture geometry (contained vs.

uncontained)


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Often, Models Dont Work with our Initial Assumptions

(for the Atoka Shale in Mounds, Oklahoma Drill Cuttings Injection Project, SPE 63032)

1600

1700

1800

1900

2000

2100

2200

-400 -200 0 200 400

Along Fracture Length (ft)

Depth(ft)

Fracture modeling (no

confinementmechanism)

Fracture modeling(composite layering

effect)

Inferred geometry fromdownhole tiltmeter

mapping

GR log


11/20

Close the Loop from Treatment to Performance:

Production Forecast with Reservoir Simulator

Inputs:

Reservoir properties X, Y & Z Permeability, Porosity, Reservoir Pressure,

Initial saturations

Simulation Grid Fine grid near fracture (LGR), Coarse grid elsewhere

Fracture properties

Conductivity as equivalent permeability

Pressure dependence of permeability


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Fracture to Reservoir Grid SchemeX

xfWell

Y

hf

Host Grid

3D LGR

1. Layer

2. Layer

3. Layer

5. Layer

6. Layer

4. Layer

Z

7. Layer

X


13/20

Additional Inputs Needed

PVT and Relative Permeability data.

Rel-perms can be different for fracture and reservoir

Production wellbore configuration or lift tables

Production constraints for simulation

Minimum bottomhole pressure

Minimum surface pressure,

Maximum oil/gas/water rates


14/20

Examples

Horizontal longitudinal propped fractured well

gas + water

Horizontal transverse acid fractured well

oil + water + gas


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Longitudinal Propped Fracture

Gas + Water


16/20

Cumulative Gas Production vs. # Fracs

Cumulative Gas Production

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Time (Days)

C

umulativeGasP

rod(MMscf

5 Fracs (MMscf)

4 Fracs (MMscf)

3 Fracs (MMscf)

2 Fracs (MMscf)

1 Frac (MMscf)


17/20

Transverse Acid Fractured Well

Oil + Water + Gas


18/20

Acid Fracture Conductivity Transferred to

Reservoir ModelPermeability Multiplier versus Drawdown

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 1000 2000 3000 4000 5000 6000 7000 8000Drawdown (psi)

PermeabilityMu

ltiplier


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Production & Pressure vs Time

0

2000

4000

6000

8000

10000

12000

14000

16000

0 50 100 150 200 250 300 350 400 450 500

Time (days)

OilRate,Wat

erCum,GasRat

4000

4500

5000

5500

6000

6500

7000

7500

8000

BHF

P(psi)

Oil Rate (STB/DAY)

Water Cum (STB)

Gas Rate (MSCF/DAY)

BHFP (PSIA)


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Conclusions Advanced Minifrac Analaysis provides Pressure

and Perm in cases where Pre-frac PBU arecostly or impractical

Uncertainty in Fracture geometry can be

Relieved with Direct Fracture Mapping Generate reservoir simulator input files forhydraulically fractured wells.

Reservoir simulations run in minutes. Possible to optimize horizontal well fracture designs

using full numerical model.

Documents

Advances in Treatment Design and Production Optimization