Seismic Reflection Data Processing and Interpretation A Workshop in Cairo 28 Oct. – 9 Nov Cairo University, Egypt Dr. Sherif Mohamed Hanafy Lecturer Title: Workshop Overview

Workshop Targets Give an overview on the seismic reflection acquisition Give an overview on the seismic reflection acquisition Give an overview on the seismic reflection processing Give an overview on the seismic reflection processing Show the mathematical background behind the processing steps Show the mathematical background behind the processing steps Show some synthetic and field examples Show some synthetic and field examples

Seismic Reflection Acquisition Principles of data acquisitions Principles of data acquisitions Equipment used for data acquisitions Equipment used for data acquisitions Problems facing geophysicists in the field Problems facing geophysicists in the field Examples of field trips Examples of field trips

Reflection Data Processing Principles of signal processing Principles of signal processing Mathematical basics of signal data processing Mathematical basics of signal data processing Time and frequency domain filters Time and frequency domain filters Designing a processing flow sequence Designing a processing flow sequence

Items of signal processing 1D and 2D Fourier Transform 1D and 2D Fourier Transform Aliasing Aliasing Processing Sequence Processing Sequence Demultiplexing Demultiplexing Seismic Filters Seismic Filters Trace Edit Trace Edit Static Correction Static Correction Coherent Noises Coherent Noises Convolution, Deconvolution, Cross- and Auto-correlation Stacking NMO Velocity Analysis Migration Modeling

Factors Controlling the Quality of the Seismic Reflection Data Acquisition Parameters Acquisition Parameters Number of Folds Number of Folds Type of Source Type of Source Surface and Subsurface Conditions Surface and Subsurface Conditions Environmental and Demographic Conditions Environmental and Demographic Conditions Used Equipment Used Equipment Weather Conditions Weather Conditions Care taking Through Acquisition Care taking Through Acquisition

Effect of number of folds A single fold section

Effect of number of folds A 12-folds section

Effect of Surface and Subsurface Conditions Poor signals between A and B is due to a karstic limestone on the surface.

Effect of Surface and Subsurface Conditions Same section after using a charges placed in a hole below the karstic limestone

Effect of Demographic Conditions A village is situated between points A and B, so the vibroseis source worked at low power

In conclusion, acquisition of seismic reflection data are never done in ideal cases or ideal environment. We always have problems.

Why do we need data processing? 1.To solve acquisition problems 2.To enhance the appearance of the data 3.To give a true view of the subsurface

Effect of Deconvolution Before Deconvolution After Deconvolution

Effect of NMO Before NMOAfter NMO After NMO & Stacking Note: The multiples are under-corrected Note: The multiples are attenuated after stacking

Effect of Migration

Effect of Interpreter A seismic line interpreted by six different contractors

End of this lecture Thank You for you attention All examples on this lecture is based on Oz Yilmaz, 2001, “Seismic Data Analysis, processing, inversion, and interpretation of seismic data”, Published by SEG