a reservoir and geomechanical model of the colorado shale ... · pdf filea reservoir and...

A Reservoir and Geomechanical Model of the Colorado

Shale, Western Canadian Sedimentary Basin

Melanie Regehr, Baker Hughes

April 15-18, 2012

SPWLA topical conference

© 2012 Baker Hughes Incorporated. All Rights Reserved.

Acknowledgements

• Perpetual Energy Inc.

• Kirby Nicholson, Clover Resources

• Byron Cooper, Perpetual Energy

• Keri Yule, Baker Hughes

• Colin Robinson, Baker Hughes

• Justin Wolf, Baker Hughes

• Robert Hawkes, Pure Energy

© 2012 Baker Hughes Incorporated. All Rights Reserved. 2

The intent of this petrophysical review is to provide information on the data set analysed.While calculations are made in good faith and reasonable efforts have been made to ensure their reliability, Baker Hughes Company Canada makes no warranty either expressed or implied with respect to the material contained herein.

Outline

• Overview and background

• Data set

• Petrophysical model

• Geomechanical model

• Stress model

• Hydraulic Fracture simulations

• Conclusions


Project Overview

• Perpetual Energy drilled 3 wells in an initial

focus area, east-central AB.

• Cored entire CLRD interval ~675m total, for

purpose of core to log calibrations

• Conducted a comprehensive logging and core

study on each well including shale rock

properties, XRD, triaxial stress testing

• Conducted perforation inflow diagnostic (PID)

and diagnostic fracture injection (DFIT) on eight

intervals in each test well.

• Project goals: to fully evaluate the CLRD group

resource and design an economically optimized

exploitation model


• Purpose: to establish a reservoir and geomechanical model for

hydraulic fracture simulation and to recommend completion

intervals

National Energy Board of Canada: www.neb-one.gc.ca

Geological Background - Colorado Shale


• Cretaceous age, marine sediments

• Relatively thick, significant resource

exists

• OGIP = 20-30 Bcf/sec over 225m

vertical succession

National Energy Board of Canada: www.neb-one.gc.ca

Geological Background - Colorado Shale

• Stratigraphy


Basal Belly River

First white specksNiobraraCarlisleColorado 6 (Cardium Equiv)Colorado 2

Belle Fourche (2WS)

Fish Scales Zone

Base Fish Scales

Viking

Joli Fou

Mannville

Interval

assessed

Data Set: Core

• Organic rich, pyritic silty shale, thinly laminated

• Sub-horizontal parting, desiccation

• TOC – 0.1% - 9.7%, ave: 3.5%

• Total ϕ: 15-25%, Effective ϕ: 2%

• Sw: >70%, free water low

• Matrix K: 0.0002 µD to 1 µD

• XRD: qtz, clay, pyr, cal, minor dol, ap, plag,

– clay composition: illite, MLIS, kaolinite, chlorite,


Data Set: Core Triaxial Stress Testing

• Dynamic and static Young’s Modulus (E) and Poisson’s Ratio (PR)

• Limited to one sample per formation per well – enabling benchmark

comparisons

• Some measured static values are suspect (real? plug integrity?)


Well 1

Well 2

Well 3

Well 1

Well 2

Well 3

Data Set: Wireline

• Logging suite consisted

of standard quad-combo

plus Spectral GR,

crossed-dipole sonic,

and NMR

• Log responses do not

appear to be adversely

affected by any hole

quality or heavy mud

issues, data quality is

good and in excellent

agreement between the

3 wells.


Data Set: Diagnostic Tests

• 8 intervals per well

• PID tests: Closed chamber pressure build-up test, ~7 days

• DFIT tests: mini-frac test, 7% KCl water, fall off 4-7 days

• Summary: in-situ pore pressure gradient is normal ~10 kPa/m (0.44 psi/ft)

– In-situ, total system perm is higher than matrix perm ~ order of

magnitude higher than core measurements

– Fracture behavior indicates occurrence of vertical fracs and Hz

“pancake” fracs


Methodology: Reservoir Model

• Logs, core analyzed

using multi-well

techniques in Powerlog®

• PHIE, SW, PERM

(matrix), TOC – core

calibrated

• 4 mineral complex lith-

model: VSH, VQTZ,

VLS, VDOL, VHEAVY

calibrated to XRD data


Geomechanical Model

• Dynamic elastic moduli calculated from DTC & DTS

• Initial static correction for Youngs, lithology based – (Lacy, 1997)

• Suspect PR values? - potential delamination of core samples

• Static PR values were bulk shifted to create a “pseudo” static PR

curve, as a regression could not be performed


Sayers, 2010

Well 1

Well 2

Well 3

Geomechanical Model – Core Calibration


Stress Model

• *Closure stress (SHmin): (Barree, 2009 & ref’s therein)

• Note: PR can have significant affect on final stress model

• SV – overburden

• SHmax – theoretical only, uncalibrated (Zoback, 2007 &

ref’s therein)


Barree, 2009

Stress Model – DFIT Calibration


“Brittleness”


• Combines PR/Youngs

• Reflects rock’s ability to fail

under stress and propagate a

fracture

• Relative cut-off

• Roughly correlates to VSH

Key Observations

• Geomechanical properties of the shale are regarded as

equally as important as gas-in-place to identify future

targets

• Challenge: enhance fracture complexity and maintain

conductivity in almost equal stress environment, soft

formation with significant fluid damage possible


Hydraulic Fracture Stimulations

• GOHFER fracture

modeling, pressure

matching, cannot

simulate fracture

networks or Hz fracs

• Varying treatment

sizes, 20/40 sand,

energized surfactant

system & oil-based

system

• From DFIT: Hz

fractures were

identified on this well

• Recommendation:

Foamed surfactant

system vertical

application with

multiple targets© 2012 Baker Hughes Incorporated. All Rights Reserved. 18

Conclusions & Final Remarks

• Identifying key completion targets in the CLRD

incorporated elements from the final geomechanical &

stress model and the fracture simulations

• Upfront core-log calibration was integral to the final

fracture design


• One of the keys to exploiting a proven

unconventional resource, such as the

Colorado shale, should include an integration

of the mineralogy, geomechanics, and stress

profile to the final completion design

Mineralogy

Geomechanics

CompletionStress profile

Questions?


a reservoir and geomechanical model of the colorado shale ... · pdf filea reservoir and...

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