EET 8: Seismic Fracture Characterization: Concepts and Practical Applications
Diffraction Imaging
Separation of diffraction from reflections
Imaging using diffracted Waves
1.9
EET 8: Seismic Fracture Characterization: Concepts and Practical Applications
Geophysical Techniques
• Geometrical attributes
– Curvature, coherency,, discontinuity, ant-tracking – Refer to the book by Satinder and Murfurt (2010, SEG)
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? ShSh
Azimuth (degree)
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ShSh
1.14
EET 8: Seismic Fracture Characterization: Concepts and Practical Applications
3C3D Example from the tight sand gas reservoir in the Piceance Basin, Colorado, USA
Diffraction Imaging
1.25 Miles
Diffraction Image
AVAZ Magnitude
1.13
Amplitude Curvature
EET 8: Seismic Fracture Characterization: Concepts and Practical Applications
Link to Piceance (Part 8)
1.15
EET 8: Seismic Fracture Characterization: Concepts and Practical Applications
Key Geophysical Challenges
• Data quality – Need to know if data have sufficient quality for prestack azimuthal anisotropy analysis, i.e. high fold, in particular if anisotropy effect is strong enough to be detected • Acquisition footprint – Need to have reasonably uniform azimuth-offset distribution and good coverage
5m
Typical examples of outcrop fractures as analogues to fractures in most hydrocarbon reservoirs. "All reservoirs should be considered as fractured unless proven otherwise“ – Wayne Narr (2007, TLE)
EET 2013 Course Overview
• Fundamentals
– Seismic anisotropy (Chapter 2) – Fracture modeling (Chapter 3)
• Methodology
– P-waves (Chapter 4) – S-waves (Chapter 5)
1.8
EET 8: Seismic Fracture Characterization: Concepts and Practical Applications
Filling Gaps
Well A Well B Well C
A schematic illustration of fractured sand-bodies in a tight sand reservoir showing that seismic data can potentially fill the gaps between information obtained from wells.
Marcellus Fisk Hollow: Shale gas
1.7
EET 8: Seismic Fracture Characterization: Concepts and Practical Applications
Байду номын сангаас
Non-Geophysical Methods
• Using analogues: Producing field analogues; Fracture descriptions from outcrops
1.5
EET 8: Seismic Fracture Characterization: Concepts and Practical Applications
“All Reservoirs are Fractured”
Carbonates (Canyon Lake. TX) Tight gas sand (Piceance Basin, CO) Shale (Marcellus, PA)
Seismic fracture prediction provides the best opportunity for identifying spatial distribution of open-fractures (fracture corridors or clusters) for optimal well planning
Course Schedule
Topics
1 2 3 4 5 6 7 8 9 Introduction and course overview Anisotropy fundamentals Break Fracture modeling P-waves for fracture characterization Lunch S-waves for fracture characterization Case study 1: Physical lab data Break Case study 2: ME carbonates Case study 3: Piceance tight sand Course summary
1.6
EET 8: Seismic Fracture Characterization: Concepts and Practical Applications
Role of Fractures
Fractures can be both „good‟ and „bad‟
– Fractures as „sweet spot‟ in low porosity hard rock reservoirs, e.g. Kashagan, and TG, SG and TO reservoirs, e.g. Piceance – Fracture is thought to be responsible for early water breakthrough, e.g. Upper Zakum, or high water production, e.g. Piceance – Natural fractures also impact hydraulic fracturing design
Seismic Fracture Characterization
S-wave splitting and multicomponent seismology
P-waves and conventional 3D seismic data
PP PP PSv PSv
SvP SvP SvSv SvSv
• Recognizing fractures from core and image logs: Core description and image logs; sealed vs. open fractures; natural vs. induced fractures; paleo-stress imprints and present-day stress effects
• Case studies
– Physical lab study (chapter 6) – Carbonate reservoir (Chapter 7) – Tight gas sand reservoir (Chapter 8)
1.3
EET 8: Seismic Fracture Characterization: Concepts and Practical Applications
Time
09:00-09:40 09:40-10:40 10:40-10:50 10:50-11:50 11:50-12:30 12:30-13:30 13:30-14:30 14:30-15:00 15:00-15:10 15:10-15:50 15:50-16:30 16:30-17:00
1.4
Unmigrated Stack
Diffractions
Formel, Landa and Taner, 2007
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EET 8: Seismic Fracture Characterization: Concepts and Practical Applications
Diffraction Image
Acknowledgements