Seismic Reflection Data Processing Seismic Reflection Data Processing and Interpretationand Interpretation

A Workshop in CairoA Workshop in Cairo

28 Oct. – 9 Nov. 200628 Oct. – 9 Nov. 2006

Cairo University, EgyptCairo University, Egypt

Dr. Sherif Mohamed Hanafy

Lecturer Title:

Workshop Overview

Workshop TargetsWorkshop Targets

Give an overview on the seismic Give an overview on the seismic reflection acquisitionreflection acquisition

Give an overview on the seismic Give an overview on the seismic reflection processingreflection processing

Show the mathematical background Show the mathematical background behind the processing stepsbehind the processing steps

Show some synthetic and field Show some synthetic and field examplesexamples

Seismic Reflection Seismic Reflection AcquisitionAcquisition

Principles of data acquisitionsPrinciples of data acquisitions Equipment used for data acquisitionsEquipment used for data acquisitions Problems facing geophysicists in the Problems facing geophysicists in the

fieldfield Examples of field tripsExamples of field trips

Reflection Data Reflection Data ProcessingProcessing

Principles of signal processingPrinciples of signal processing Mathematical basics of signal data Mathematical basics of signal data

processingprocessing Time and frequency domain filtersTime and frequency domain filters Designing a processing flow sequenceDesigning a processing flow sequence

Items of signal Items of signal processingprocessing

1D and 2D Fourier 1D and 2D Fourier TransformTransform

AliasingAliasing Processing Processing

SequenceSequence DemultiplexingDemultiplexing Seismic FiltersSeismic Filters Trace EditTrace Edit Static CorrectionStatic Correction Coherent NoisesCoherent Noises

Convolution, Convolution, Deconvolution, Deconvolution, Cross- and Auto-Cross- and Auto-correlationcorrelation

StackingStacking NMONMO Velocity AnalysisVelocity Analysis MigrationMigration ModelingModeling

Factors Controlling the Factors Controlling the Quality of the Seismic Quality of the Seismic

Reflection DataReflection Data Acquisition ParametersAcquisition Parameters Number of FoldsNumber of Folds Type of SourceType of Source Surface and Subsurface ConditionsSurface and Subsurface Conditions Environmental and Demographic Environmental and Demographic

ConditionsConditions Used EquipmentUsed Equipment Weather ConditionsWeather Conditions Care taking Through AcquisitionCare taking Through Acquisition

Effect of number of foldsEffect of number of folds

A single fold section

Effect of number of foldsEffect of number of folds

A 12-folds section

Effect of Surface and Effect of Surface and Subsurface ConditionsSubsurface Conditions

Poor signals between A and B is due to a karstic limestone on the surface.

Effect of Surface and Effect of Surface and Subsurface ConditionsSubsurface Conditions

Same section after using a charges placed in a hole below the karstic limestone

Effect of Demographic Effect of Demographic ConditionsConditions

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

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

We always We always have problems.have problems.

Why do we need data Why do we need data processing?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 DeconvolutionEffect of DeconvolutionBefore Deconvolution

After Deconvolution

Effect of NMOEffect of NMOBefore NMO After NMOAfter NMO & Stacking

Note: The multiples are under-corrected

Note: The multiples are attenuated after stacking

Effect of MigrationEffect of Migration

Effect of MigrationEffect of Migration

Effect of InterpreterEffect of Interpreter

A seismic line interpreted by six different contractors

End of this lectureEnd of this lecture

Thank You for you attentionThank 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