1. INSTRUCTOR © 2017, John R. Fanchi
All rights reserved. No part of this manual may be reproduced in any form without the express written permission of the author.
© 2004 John R. Fanchi All rights reserved. Do not copy or distribute.

2. To the Instructor
The set of files here are designed to help you prepare lectures for your own course using the text Introduction to Petroleum Engineering, J.R. Fanchi and R.L. Christiansen (Wiley, 2017)
File format is kept simple so that you can customize the files with relative ease using your own style. You will need to supplement the files to complete the presentation topics.

3. GEOPHYSICS – SEISMIC © 2017, John R. Fanchi
All rights reserved. No part of this manual may be reproduced in any form without the express written permission of the author.
© 2004 John R. Fanchi All rights reserved. Do not copy or distribute.

4. Outline Seismic Waves Acoustic Impedance and Reflection Coefficients
Seismic Data Acquisition, Propagation and Interpretation
Homework: IPE Ch. 7

5. Data Sources have Different Scales Haldorsen and Lake [1989]
SIZE
Micro
Few pores only
Macro
Conventional core plugs
Mega
Reservoir delineation
Flow model block size
Giga
Total field or regional scale
Reservoir architecture

6. Geophysical Goals Exploration Geophysics
Limit Risk
Reduce Capital Investment
Minimize Time to First Commercial Production
Development (Reservoir) Geophysics
Optimize Recovery

7. SEISMIC WAVES
© 2004 John R. Fanchi All rights reserved. Do not copy or distribute.

8. Energy Propagation as Vibrations in the Subsurface
Seismic Waves
Energy Propagation as Vibrations in the Subsurface

9. Compressional (Pressure) Wave Motion

10. Compressional (P) and Shear (S) Waves
P-Wave Motion
S-Wave Motion S S
Propagation  H V
Irrotational: 
×u = 0
Rotational: ●
u = 0
Vector u = displacement of medium from equilibrium

11. Compressional (P) and Shear (S) Waves

12. Compressional (P) and Shear (S) Waves
Impulse S H
-Wave P V
Geophone
Downward Ray: Direction of energy propagation
Upward Ray: Illustrates particle motion

13. Animation Compressional (P) and Shear (S) Waves
P-wave
S-wave
Images from

14. P-Wave and S-Wave Velocities
VP = Compressional velocity
VS = Shear velocity
S = Stiffness
Ksat = Saturated bulk modulus
 = Shear modulus
B = Bulk density = (1 - ) ma + f
ma = Matrix grain density
f = Fluid density = oSo + wSw + gSg
 = Porosity

15. Petrophysical Model Gassmann’s Equation [1951]
where
Ksat = Bulk modulus of saturated porous material
Kdry = Bulk modulus of dry porous material
Km = Bulk modulus of matrix grains
KF = Bulk modulus of fluid = 1/cf
cf = Fluid compressibility = coSo + cwSw + cgSg

16. ACOUSTIC IMPEDANCE AND REFLECTION COEFFICIENTS
© 2004 John R. Fanchi All rights reserved. Do not copy or distribute.

17. Seismic Velocity Model
Given
Stratigraphy
Lithology
Fluid content
Bulk density ρj in medium j
Velocity Vj in medium j
Calculate
Acoustic impedance Zj
Reflection coefficient R

18. Seismic Attributes for Reflection Coefficient
Wave reflected at interface between layers 1 and 2
Reflection coefficient R

19. Time to Depth Conversionx y t
Velocity
Model x y z
Time (t)
Depth (z)

20. SEISMIC DATA ACQUISITION, PROCESSING AND INTERPRETATION
© 2004 John R. Fanchi All rights reserved. Do not copy or distribute.

21. Motion of magnet induces current
Geophones
Motion of magnet induces current

22. Seismic Response from Small Fault
Ruijtenberg, et al., JPT (Jan. 1990)

23. Seismic Response from Sand Wedge
Ruijtenberg, et al., JPT (Jan. 1990)

24. Seismic Response for Lithology Changes
Ruijtenberg, et al., JPT (Jan. 1990)

25. Multicomponent Seismic
3C Seismic
P – wave and 2 S – wave components
1 vertical and 2 horizontal velocity components
Seismic anisotropy corresponds to 2 shear waves
S1 (faster)
S2 (slower)
4C Seismic (Marine Surveys)
Pressure (hydrophone)
1 vertical and 2 horizontal velocity components using ocean-bottom cables and 3C geophones

26. Multicomponent Seismic – Cont.
9C Seismic
3 sources * 3 receivers
Sources
1 vertical (compressional impulse)
2 horizontal (orthogonal shears)
Receivers
P-wave
2 S-waves
Sources
Receivers *

27. 3-D Seismic Geometry
Reflecting
Surface
2-D Array of
Receivers

28. Video 3-D Seismic Survey

29. Vertical Seismic Profile (VSP)
Receiver in hole
Source on
surface
Monitor
Recording
Wireline

30. VSP Options VSP with zero offset VSP with offset Reverse VSP
Source vertically above receiver
VSP with offset
Source not vertically above receiver
Reverse VSP
Source in hole; receiver on surface
Seismic Tomography
Source in one wellbore; receiver in another wellbore

31. Time-Lapse (4-D) Seismic (after Johnston, et al., SPE/OTC 12132, 2000)
Difference
Survey
1st Survey
2nd Survey x y t - =
3D Survey - =
2D Attribute

32. Which Seismic Attribute to Monitor?
Seismic sees contrasts
Select attribute(s) with the most contrast between original and repeat surveys
Typical Attributes
Acoustic Impedance, Vp, Vs, Vp/Vs

33. 4-D Seismic Issues Seismic data recorded in time; logs in depth
In practice, time-depth conversions are not simple
Repeatability
Quality of base survey
Feasibility of repeat survey
Timing of repeat survey
Source: Blank, et al., SPE (Oct. 1998)
Middle East and North Sea Fields
Source: Ross and Altan, OTC 8311 (May 1997)
Resolution
Horizontal
Vertical

34. An INTEGRATED FLOW MODEL … couples geophysics and reservoir engineering
Petrophysical Model
Porosity
Lithology
Saturation
Pore Pressure
Temperature Vs
Shear Modulus
Bulk Density Vp
Eff. Bulk Modulus
…to predict seismic response and improve reservoir understanding.

35. QUESTIONS?
© 2004 John R. Fanchi All rights reserved. Do not copy or distribute.

36. SUPPLEMENT
© 2004 John R. Fanchi All rights reserved. Do not copy or distribute.