1. Wave Imaging Technology Inc. PSDM for “Easy” Unconventional Reservoirs? Morgan Brown Rocky Mountain Section, AAPG September 10, 2012

2. Why Wave Equation PSDM? Simple refraction Complex focusing Air Water Kirchhoff WEM RTM

3. Niobrara Shale Case Study Hi-res 50 sq mi 3D, Laramie Co., WY 200 fold, Wide azimuth Part 1: PSDM Structural Imaging Success = Velocity Improved event geometry, fault imaging Part 2: PSDM “Sweet Spot” Delineation Azimuthal anisotropy AVAZ

4. Part 1: Improved Structural Imaging PSDM PSTM

5. Shallow Low-Velocity Wedge The difference between theory and practice is greater in practice than in theory Theory: PSDM should always beat PSTM Practice: PSTM often won Why? PSDM is very sensitive to velocity Saved by Computer Power! Automated picking Multiple iterations Starting velocity model, derived from PSTM velocities Final velocity model after 8 updates Velocity (ft/sec)

6. Angle Gathers: PSTM Velocity

7. Angle Gathers: Optimized Velocity

8. PSTM: Location 1

9. PSDM: Location 1 Converted to Time

10. Part 2: Sweet Spot Delineation Complex Earth  offset is NOT angle Ideal attributes  With real angle gathers In depth offset   Simple earthComplex earth

11. PSDM Azimuth Angle Gathers y x Fracture Schematic

12. Azimuth Angle Gathers (flattened) y x Fracture Schematic

13. Fracture (Horizontal Stress) Map Quandary: Target is naturally fractured, but overburden is apparently not. Are the reflection amplitudes (versus azimuth) at the target sensitive to fracturing?

14. AVA + Azimuth = AVAZ WEM Incidence vs. Azimuth angle gathers For each azimuth, compute AVA slope Make “fracture” map from AVA slope vs. azimuth using Rüger analysis More apparent sensitivity to fractures in target zone

15. From AVAZ Slope

16. AVAZ Sensitivity (Rüger, 1998) Assumptions for most sensitive parameters:  bot = 0.05  top = 0.0  bot = 0.01  top = 0.0 VP-VS ratio = 2 above and below Takeaway: realistic parameter assumptions produce 50% AVAZ variation

17. Takeaways Part 1 PSDM: Removes false time structures Better positions/focuses steep dips and faults High-intensity velocity analysis = PSDM success Part 2 WEM angle gathers: attributes in complex geology Azimuthal anisotropy was weak here AVAZ analysis appears more sensitive and targeted 17

18. Acknowledgements Fidelity E&P, JD Rockies Resources (Itochu Oil) At Fidelity: Dave List, Chris Lang, Patrick Rutty The WIT Team: Joe Higginbotham, Cosmin Macesanu, Oscar Ramirez, Cathy Joanne 18

19. Vertical Anisotropy Anisotropic shale layer induces significant misties Measure misties at well tops Build Thomsen  for anisotropic PSDM... …or warp image to fit tops Note: Dip is preserved 4 ft, 12 ft accuracy on two new wells

20. Seismic: Financial Impacts Where to drill? Avoid sidetracks Stay in zone Fine Scale Medium Scale How/Where to drill? Borehole orientation Best wells first ? ? ? If to drill? Where to lease? Best parts of basin Extend sweet spots Wide Scale TodayTomorrowFuture Part 1 Part 2

21. Azimuthal Anisotropy for Fractures Azimuth Angle Depth or Time Incidence Angle 0 o 15 o 30 o 45 o High residual velocity Low residual velocity y x slow fast Fracture Schematic Residual Moveout: Azimuth vs Incidence Angle Perform 3D fit to residual moveout surface Invert for “interval” fracture parameters

22. About This Talk (~40 min) Who – “Seismically-conversant” geoscientists What – Prestack Depth Migration (PSDM) Where – US Shale Oil play Why? PSDM becoming the onshore norm… What is it? Why do it? Special unconventionals impact?

23. PSDM: Removes False Time Structure High Velocity PSDM (WEM) High Velocity PSTM Permian Basin

24. PSDM: Better Steep Dips & Faults PSTMRTM (converted to time) Gulf Coast

25. PSDM: Better Lateral Positioning PSTMRTM (converted to time) Dramatization

26. Myth 2: Lower Frequency Content? Permian Basin PSDM ( converted to time) PSTM

27. Why Anisotropic PSDM? (1 of 5) Here, we have a simple “anticline” and two “faults”.

28. Why Anisotropic PSDM? (2 of 5) Isotropic PSDM in an anisotropic earth positions events too deeply. True reflector location Isotropic PSDM reflector Isotropic PSDM fault

29. Why Anisotropic PSDM? (3 of 5) We measure depth misties at several well locations…

30. Why Anisotropic PSDM? (4 of 5) …and vertically shift the image to match the well control. We match the anticline’s structure accurately, but there’s a problem…

31. Why Anisotropic PSDM? (5 of 5) …The “faults” are laterally mispositioned! Anisotropic PSDM is the only systematic way to correctly position steep dips Actual Fault Location Vertically Shifted Isotropic PSDM fault

32. AVA Angle Gather Calibration Relate VP/VS to seismic amplitudes V P /V S relation (Mavko & Mukerji, 1998) : A tight range of b values encompasses all rock types

33. AVA Angle Gather Calibration Step 1: Measure slope, intercept from PSTM or PSDM gathers Step 2: Compute hyperbolic parameter b (red curve  ) Step 3: Compare to b obtained from lab data (green curve  ) Calibration: Find single scale factor that produces a measured b consistent with b from lab data

34. AVAZ Math (Rüger, 1998) P-wave azimuthal anisotropy S-wave azimuthal anisotropy P-wave AVA “slope” vs. azimuth The quantities are written in terms of elastic properties above (“top”) and below (“bot”) the interface. Note: we assume elliptical HTI anisotropy.