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© 2013 BAKER HUGHES INCORPORATED. ALL RIGHTS RESERVED. TERMS AND CONDITIONS OF USE: BY ACCEPTING THIS DOCUMENT, THE RECIPIENT AGREES THAT THE DOCUMENT TOGETHER WITH ALL INFORMATION
INCLUDED THEREIN IS THE CONFIDENTIAL AND PROPRIETARY PROPERTY OF BAKER HUGHES INCORPORATED AND INCLUDES VALUABLE TRADE SECRETS AND/OR PROPRIETARY INFORMATION OF BAKER HUGHES
(COLLECTIVELY "INFORMATION"). BAKER HUGHES RETAINS ALL RIGHTS UNDER COPYRIGHT LAWS AND TRADE SECRET LAWS OF THE UNITED STATES OF AMERICA AND OTHER COUNTRIES. THE RECIPIENT FURTHER
AGREES THAT THE DOCUMENT MAY NOT BE DISTRIBUTED, TRANSMITTED, COPIED OR REPRODUCED IN WHOLE OR IN PART BY ANY MEANS, ELECTRONIC, MECHANICAL, OR OTHERWISE, WITHOUT THE EXPRESS PRIOR
WRITTEN CONSENT OF BAKER HUGHES, AND MAY NOT BE USED DIRECTLY OR INDIRECTLY IN ANY WAY DETRIMENTAL TO BAKER HUGHES’ INTEREST.
Geomechanics: An effective multi-disciplinary
tool for natural integration of disciplines in
upstream Petroleum decisions.
SPWLA Kuwait Chapter – 26th March 2013
Satya Perumalla
GMI Geomechanics Services,
Baker Hughes.
Types & Challenges of Reservoirs
Geomechanics as a Tool: Multi-disciplinary interaction
Data gaps & implications
Ideal data situation & Benefits
Inter-dependency of disciplines
Acknowledgements.
Outline
Geomechanics for the Life of Well & Reservoir
SHmax
orientation
Reservoirs
Clastics
Carbonates
Fractured
formations
Tight/Shale Gas
Heavy Oil
CBM
Sour Gas.
Known Reservoir Problems
• Wellbore Stability in Formations above Reservoirs.
• Stress induced, Fractured Rock, Chemical, Loss circulation, etc.
• Clastics/Carbonate Conventional Reservoirs:
• No visible geomechanical impact on reservoir at early stage of
production.
• Depleted reservoir Injection/EOR changes the in-situ stress regime.
• Influence on field scale permeability tensor Scope for Optimization.
• Fractured Reservoirs:
• Location of fracture systems.
• Positioning Injection/Producer wells.
• Waterfront movement monitoring & Simulation/History matching.
Known Reservoir Problems
• Tight / Shale Gas Reservoirs:
• Hydraulic Fracturing
• Rapid production decline
• Stress sensitive sweep vs Well positioning.
• Heavy Oil:
• Influence of steam injection on reservoir & cap rock
• Integrity of cap rock and faults
• Sour Gas reservoirs:
• Well Integrity
• Zero tolerance for solids/sand production.
Behavior of Any Reservoir
• Mechanical Response of Reservoir Rock – Completion
– Production
– Injection
– EOR
• Where is the bottleneck in Life Cycle of Each Reservoir
Type?
Decision Support Questions
Stage Problem
Exploration How to identify sweet spots?
Pore pressure
Fault Trap evaluation
Development Drilling Wellbore Stability
Completion What type of completion can
maximize flow?
Can I have a hydraulic frac in
desired interval?
How best to benefit from natural
fractures
How to avoid any sand/solids
production
Decision Support Questions
Stage Problem
Production
Where is the scope for
Optimization?
Why reservoir simulation do not
make me happy?
Does conventional peripheral
injection is effective?
Seem to be missing something!!
Geology.com
Natural fracture patterns vary Breccia zone – Monterey Shale California
Marcellus Northeast U.S.
Paleozoic “fissile” shale Tulsa area
About.com
Interbedded Massive/laminated
Squidoo.com
Slickensides on fault surface
Event cloud shape and reservoir drainage area
Northeast US – two often well-
developed orthogonal joint sets
Larger stress anisotropy;
stresses sub-parallel to joints
Barnett – contains a significant
number of steeply dipping
conjugate and a wide range of
fractures strikes
Low horizontal stress
anisotropy
SPE 2007
Cotton Valley – one strong, well-
developed, near-vertical
fracture set +/- parallels SHmax
Moderate stress anisotropy
Rutledge
Fracture Permeability Results
-
GMI•MohrFracs™ results for Amin Formation
Effective normal stress [ppg]
Sh
ear
str
ess [
pp
g]
Coulomb failure Function [ppg]
Not critically stressed
Critically stressed
Perumalla et al 2011
Natural fractures
identified in well
),( closure
noafAperture
Effective normal stress
Rela
tive p
erm
eabili
ty
Stress – Aperture Coupling
© 2012 Baker Hughes Incorporated. All Rights Reserved 13
n – effective normal stress
ao – fracture aperture at n = 0
after Hossain et al., 2002; Tezuka et al. 2005, Moos and Barton, 2008
Variation in aperture as a function of normal stress:
closure
n
closure
n
14
Start of shear slip of significant population of natural fractures
Stimulation of Natural Fractures
Geomechanical Discrete Fracture Network
Model
• Identifying potential fracture corridors that are easy to
stimulate.
Concentration index of critically stressed fractures (iCSF)
Fault Leakage
A-Central
Fault
Small increase in pore
pressure will cause fault to
slip
gas leakage area
16
© 2012 Baker Hughes Incorporated. All Rights Reserved.
Hydraulic Fracture Propagation
Pay
Pay
“Perfect”
fracture
Multiple fractures
dipping from vertical
T-shaped
fractures
Twisting
fractures
Out-of-
zone
growth
Poor fluid
diversion
Upward
fracture
growth
Horizontal
fractures
?
?
?
? ?
?
?
Pinnacle Tech. Ltd.
17
© 2012 Baker Hughes Incorporated. All Rights Reserved.
Relating Stage Contributions and Natural Fractures to Production: Impact on Field Development Plan
© 2010 Baker Hughes Incorporated. All Rights Reserved.
Rates measured by PLT 5 months later
7 6 5 4 3 2 1 8 9
30
25
20
15
10
5
0
B-values - 0.98 - 1.01 - 1.92 2.27 1.92 -
1 3 2 4 7 5 6 8 9
Natural
fractures
Events
Geomechanical Data Sources
21 ©
201
2
Bak
er
Hug
hes
Inco
rpor
ated
. All
Righ
ts
Res
erve
d.
Vertical Stress
Pore Pressure
Least Principal Stress
SHmax Magnitude SHmax Orientation
Rock Strength
Integrated density Density from acoustic/seismic
Direct measurements Log-based (acoustic, resistivity) Seismic (ITT, velocity cubes)
XLOT, LOT, minifrac, lost circulation, ballooning
SV
Shmin
PP
Analysis of wellbore failure Crossed dipole (orientation) “Active” geological structures
Core tests, logs, cuttings, analysis of wellbore failure
22
Data Gaps: Present Industry Standard
• Despite having Millions $$ budgets, Industry often misses
key data set necessary for the health of reservoir.
• Uncertainty in models can lead to decisions worth billions $$.
• Most trouble making formation during drilling often have no
data leads to ‘trial and error’ type optimization: less
effective.
• Cost for Data acquisition is extremely small when compared
to benefits from reservoir.
• Most of the times, lack of interdisciplinary understanding is
responsible for data gaps.
Ideal Data Situation
Trouble Data Use
Nasty Shales causing
wellbore instability.
Chemical, Osmotic core
properties.
Spectral Component logs
to calibrate.
Help drillers to overcome
wellbore instability.
Uncertainty with
Overburden stress
Run density/sonic log in at
least one well per field
Reduces model
uncertainty and
strengthens confidence.
Sand production after
depletion/Injection
Rock mechanical Tests Optimize drawdown
pressures and depletion
strategy.
Influence of stress on
sweep efficiency is
unknown
MicroFrac/MiniFrac/XLOT
at different corners of
reservoir at different
depletion stages.
Improved predictability in
fluid movement, EOR,
Injection planning.
24
Inter dependency of disciplines
• Often, most needed data for one discipline is obtained by
other discipline.
• Drillers need shale and shallow formation properties to
overcome wellbore stability, but Sub-surface
professionals usually don’t characterize those formations.
• Sub-surface Professionals need
XLOT/MicroFrac/MiniFrac, but Drillers show less
encouragement to acquire these data.
Loss of opportunity for both disciplines.
• Similarly, inter-dependency among Production Engg,
Production Technology, Petrophysicists, G&G on integrated
data acquisition is the key for success of overall reservoir
performance.