1. SEISMIC
DATA
GATHERING

2. GEOPHONE STRUCTURE

3. GEOPHONE TYPES & FREQUENCY

4. SOURCE TRUCKS

5. 3D-SEISMIC COVERAGE

6. CDP & FOLD STACK

7. MARINE SEISMIC
CABLE LAYOUT

8. MULTIPLE RAYPATH

9. ATTENUATION TECHNIQES

10. SEISMIC
DATA
PROCESSING

11. PROCESSING FLOWCHART

12. OBJECTIVE OF PROCESSING
REAL EARTH
EARTH PROPERTIES
PULSE
SEISMIC TRACE
PROCESSING
MODEL EARTH

13. EFFECT OF STACKING ON NOISE
SIGNAL PLUS RANDOM AT SIX-DETECTOR ARRAY
NOISE
SIGNAL
SIGNAL + NOISE
SIGNAL + NOISE
EACH RECEIVER
SUMMED OUTPUT

14. POST-STACK PROCESSING
RESIDUAL STATICS
DISPLAY ENHANCEMENT
MIGRATION
ATTRIBUTE ANALYSIS
INVERSION
TIME-DEPTH CONVERSION

15. SUMMARY OF SEISMIC PROCESSING
DATA ARE GATHERED AND CMP-ORDERED GATHERS ARE FORMED
VELOCITY ANALYSIS IS PERFORMED ON SELECTED GATHERS
THE GATHERS ARE MOVEOUT CORRECTED, STACKED, AND PLOTTED
STACKING MAY BE FOLLOWED BY ADDITIONAL PROCESSING

16. FACTORS AFFECTING AMPLITUDE

17. VELOCITY ANALYSIS NORMAL MOVEOUT (NMO) X = TX - T0 TX T0 IMAGE POINT
WHERE
T0 = ZERO OFFSET TIME

18. NMO-ISOTROPIC LAYER X A C Z B
WHERE
THEREFORE D
IMAGE POINT

19. ASSUMED RAYPATH FOR VNMO CALCULATION
MULTI-LAYER CASE
ASSUMED RAYPATH FOR VNMO CALCULATION X
TX,1 Z V1
T0,1
T0,2
TX,2
ACTUAL RAYPATH
FOR LAYER 1:
FOR LAYER 2:
VNMO = NORMAL MOVEMEOUT VELOCITY

20. FOR EACH TRACE T AND X VALUES ARE DETERMINED
HOW IS VNMO DETERMINED?
FOR EACH TRACE T AND X VALUES ARE DETERMINED

21. VELOCITY ANALYSIS Y=b+mX
T2 - X2 PLOT
X2
OFFSET2
t2
HYPERPOLA PLOTS AS A STRAIGHT LINE ON T2 - X2 GRAPH
Y=b+mX
WHERE

22. VMNO CORRECTION
KNOWING THE VNMO, T AND OFFSET, THE TIME CORRECTION NECESSARY TO SHIFT EACH TRACE CAN BE CALCULATED

23. INTERVAL VELOCITY DETERMINATION FROM SEISMIC
FROM VELOCITY ANALYSIS, WE KNOW
VNMO1,T0,1
VNMO2, T0,2
SUBTITUTING THESE VALUES INTO THE DIX EQUATION

24. MIGRATION EFFECTS
FLAT HORIZONS REMAIN UNCHANGED IF THERE ARE NO VELOCITY ANOMALIES ABOVE
DIPPING HORIZONS BECOME STEEPER, SHALOWER, AND MOVE LATERALLY UPDIP
SYNCLINES BECOME BROADER, WITH ANY BOW TIES ELIMINATED
ANTICLINES BECOME NARRWER
DIFRACTIONS COLLPSE TO POINTS

25. RAY PATH MIGRATION t x WHERE  = TRUE DIP OF REFLECTOR
REFLECTION
REFLECTOR x t
WHERE
 = TRUE DIP OF REFLECTOR
= APPERENT DIP OF REFLECTOR
V= VELOCITY

26. WHY MIGRATE? TIME DEPTH DEPTH MODEL ARRIVAL TIMES
IF BEDS ARE DIPPING, APPERENT POSITION OF EVENTS ON A STACKED SECTION DIFFERS FROM THEIR TRUE POSITION
DEPTH MODEL
ARRIVAL TIMES
7 KFT/SEC
TIME
DEPTH
9 KFT/SEC
11 KFT/SEC

27. ASSUMPTION UNDERLYING MIGRATION
ALL EVENTS ARE PRIMARIES-
NO NOISE, NO MULTIPLES, NO SHEAR WAVES
ALL EVENTS COME FROM THE PLANE VERTICALLY
BENEATH THE SEISMIC LINE-
NO SIDEWIPE
VELOCITY ARE KNOWN EVERY WHERE

28. MIGRATION MOVES DIPPING HORIZONS

29. FOCUSING EFFECT OF A SHARP SYNCLINE

30. DEFOCUSING EFFECT OF AN ANTICLINE

31. FOCUSING EFFECT OF A SYNCLINE

32. 3-D MIGRATION
ELIMINATES ASSUMPTION OF 2--D MIGRATION THAT ALL DATA COMES FROM WITHIN PLANE OF SECTION
REQUIRES 3-D DATA COLLECTION TO INSURE CLOSELY SPACED TRACES IN BOTH X, Y DIRECTIONS
MOVES ENERGY IN BOTH INLINE AND CROSSLINE DIRECTIONS
INLINES AND CROSSLINES TIE AFTER 3-D MIGRATION
MAP MIGRATION IS AN ALTERNAIVE FOR COARSE GRID OF 2-D LINES

33. TIME VS. DEPTH SECTIONS