A Reservoir and Geomechanical Model of the Colorado Shale ... · PDF fileA Reservoir and...
Transcript of 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
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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
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• 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
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• 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
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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,
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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?)
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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.
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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
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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
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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
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Sayers, 2010
Well 1
Well 2
Well 3
Geomechanical Model – Core Calibration
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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)
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Barree, 2009
Stress Model – DFIT Calibration
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“Brittleness”
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• 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
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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
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• 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?
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