borehole stress orientation min max top view drilling induced fracture borehole breakout courtesy...
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![Page 1: Borehole Stress Orientation MIN MAX Top View Drilling Induced Fracture Borehole Breakout Courtesy of Steve Hansen, Schlumberger](https://reader036.vdocuments.net/reader036/viewer/2022081504/56649f125503460f94c258c8/html5/thumbnails/1.jpg)
Borehole Stress OrientationBorehole Stress Orientation
MIN
MAX
Top View
Drilling Drilling Induced Induced FractureFracture
Borehole Borehole BreakoutBreakout
Courtesy of Steve Hansen, Schlumberger
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Types of Directional Drilling Types of Directional Drilling for Fracturesfor Fractures
Courtesy of CSPE
Nelson & Serra (1995)
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Potential Potential Drilling Drilling Directions Directions on Foldson Folds
Courtesy of CSPE
Nelson et.al. (1987a)
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After Nolen-Hoeksema & Howard (1987)
Fracture Spacing & Drilling DirectionFracture Spacing & Drilling Direction
Courtesy of AAPG
![Page 5: Borehole Stress Orientation MIN MAX Top View Drilling Induced Fracture Borehole Breakout Courtesy of Steve Hansen, Schlumberger](https://reader036.vdocuments.net/reader036/viewer/2022081504/56649f125503460f94c258c8/html5/thumbnails/5.jpg)
Nolen-Hoeksema & Howard (1987)
Drilling Direction NomographDrilling Direction Nomograph
Courtesy of AAPG
![Page 6: Borehole Stress Orientation MIN MAX Top View Drilling Induced Fracture Borehole Breakout Courtesy of Steve Hansen, Schlumberger](https://reader036.vdocuments.net/reader036/viewer/2022081504/56649f125503460f94c258c8/html5/thumbnails/6.jpg)
High Intensity Fold-Related FracturesHigh Intensity Fold-Related Fractures
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Bedding/Fracture/Well RotationBedding/Fracture/Well Rotation
unrotated
rotated
Joubert & Rice (1997)
![Page 8: Borehole Stress Orientation MIN MAX Top View Drilling Induced Fracture Borehole Breakout Courtesy of Steve Hansen, Schlumberger](https://reader036.vdocuments.net/reader036/viewer/2022081504/56649f125503460f94c258c8/html5/thumbnails/8.jpg)
UBI FMI
UBI vs. UBI vs.
FMIFMI
Courtesy of Steve Hansen, Schlumberger
UBI Shows
Topography
FMI Shows
Resistivity
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Quantitative Fracture AnalysisQuantitative Fracture Analysis
Polar projections of fold and fault related fractures with dip of 300 deg NW
After removing structural bedding dip, fractures trend clearly NW-SE and to perpendicular to bedding.
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Rotated Fracture PolesRotated Fracture Poles
N N
before beddingrotation
after beddingrotation
equal area, lower hemisphere, stereonets.
fracture poles forall 9 wells ~ 1700poles
Joubert & Rice (1997)
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Equation - Fracture Intercept RateEquation - Fracture Intercept Rate
freqi
iiW cos i
i th fracture
Wi - occurrence of i th fracture,
The fracture frequency in anyarbitrary direction is the sumof:
- the cosine of the angle between thenormal intercept rate direction of the i th fracture,over all fractures.
cos i
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Occurrence Weighting Occurrence Weighting (Lacazette 1990)(Lacazette 1990)
Drill HoleFracture 2
Fracture 1
1
2
Occurrence WL
1
cos Fracture 2 is lesslikely to be intercepted by the drill hole than fracture 1 - as the angle of the normal approaches 90 deg. W increases.
W1 < W2
Joubert & Rice (1997)
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Occurrence Corrected Rose Occurrence Corrected Rose DiagramsDiagrams
occurrence weighted fracture planes
rotated raw fracture planes
Joubert & Rice (1997)
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Intercept RateIntercept Rate
0
0.2
0.4
0.6
0.8
1
1.2
NORTH
EAST
SOUTH
WESThorizontal
15 deg.
30 deg.
45 deg.
60 deg.
75 deg.
vertical
Polar chart showing number of fracturesintercepted per meterfor different drilling directions - (bedding rotated flat).
Well #1
Joubert & Rice (1997)
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Aperture Variation on Rose Aperture Variation on Rose DiagramDiagramN
maximumaperture
minimumaperture
Joubert & Rice (1997)
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Fracture Fracture ApertureAperture
Courtesy of Steve Hansen, Schlumberger
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Equation - Flow Intercept Equation - Flow Intercept RateRate
- fracture aperture of the i th fracture
ei
flow iWi
i ei ( cos ) 3
Joubert & Rice (1997)
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Flow Intercept RateFlow Intercept Rate
NORTH
EAST
SOUTH
WEST
HORZ.15 DEG.
30 456075 90
Joubert & Rice (1997)
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Calculated Horizontal vs Vertical DrillingCalculated Horizontal vs Vertical Drilling
0
20
40
60
80
100
120
horz. 15 30 45 60 75 Vert.
inclination angle relative to bedding
% o
f m
axim
um
flo
w 123456789
well #
Triassic Carbonate Reservoirs, Northern British Columbia, Canada
From Joubert & Rice (1997)
Drilling at low angles to bedding makes a good well
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Shear AnisotropyShear Anisotropy
• Preferential directional alignment of elastic properties due to regional stress fields
• Horizontal anisotropy - uniform laterally but not vertically (transversely isotropic with a vertical axis of symmetry)
• Vertical anisotropy - uniform vertically but not laterally (transversely isotropic with a horizontal axis of symmetry)
• Shear waves travel faster along axis of symmetry
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Shear Wave BirefringenceShear Wave Birefringence
• Fracture-induced elastic anisotropy can be detected through shear-wave splitting, or birefringence
• Shear waves split into fast and slow polarizations
• Data are analyzed for orientation and degree of anisotropy indicated by the amount of birefringence
• Fast shear polarization direction relates to fracture orientation