1. Seismic Reflection Data Processing and Interpretation A Workshop in Cairo 28 Oct. – 9 Nov. 2006 Cairo University, Egypt Dr. Sherif Mohamed Hanafy Lecturer Title: 1D & 2D Fourier Transform

2. 1D & 2D Fourier Transform (Continue) Theory and Practice Real Data Examples Using SU and MatLab

3. What would happen if; We increasingly added to a time signal higher frequency components? The resulted wavelet will be compressed, if all frequencies are added the result will be a spike.

4. With increasing the frequencies summed to the signal; resulted trace is compressed. Note the effect on the stacked traces 1, 2, 3, 4, & 5 Only two frequencies are summed More than 30 different frequencies are summed

5. With a very high number of traces (frequency are continuously increased) the resulted stacked trace is very sharp; almost a spike.

6. From the frequency spectrum point of view, we can see the same feature; the wider the frequency band the sharper the related time trace.

7. The effect of the edge of the frequency spectrum Smooth edges (A, B, C & D) and gentle slopes AB and CD give much improved results

8. Types of frequency filters Band Pass Band Reject Low Pass High Pass

9. Butterworth Filter

10. The usable seismic reflection energy usually is confined to a bandwidth of approximately 10 – 70 Hz, with a dominant frequency around 30 Hz.

11. Application of frequency domain filters

12. Effect of Band Pass Parameters on the resulted seismic section Use the data of Stockton Interferometry test to show the effect of low and high cuts, fixing band width and slops. Low Cut Low Pass High Pass High Cut

13. File # 1 x17_f1.su Use: suximage< x17_f1.su n2=57 perc=95 & Low Cut = 10 to 110 Hz Low Pass = 25 to 125 Hz High Pass = 80 to 180 Hz High Cut = 95 to 195 Hz Step = 1 Hz

14. Filter Preview

15. File # 2 x17_f2.su Use: suximage< x17_f2.su n2=57 perc=95 & Low Cut = 22 Hz Low Pass = 37 Hz High Pass = 47 to 147 Hz High Cut = 52 to 152 Hz Step = 1 Hz

16. Filter Preview

17. File # 3 x17_f3.su Use: suximage< x17_f3.su n2=57 perc=95 & Low Cut = 36 to 4 Hz Low Pass = 37 Hz High Pass = 92 Hz High Cut = 93 to 125 Hz Step = 1 Hz

18. Filter Preview

19. End of this lecture Thank You for you attention All examples on this lecture is based on my work