Simple Seismic processing workflow

By: Ali Ismael AlBaklishy Senior Student, Geophysics Department,

School of sciences, Cairo University

Content Introduction.

• Data Initialization.

• Amplitude Processing.

• Noise Attenuation.

• Deconvolution.

• Multiple Attenuation. • Velocity Analysis and NMO. • Migration.

• Stack. • Data Makeup.

Processing Workflow:

References.

Q&A.

Content

• Data Initialization.

• Amplitude Processing.

• Noise Attenuation.

• Deconvolution.

• Multiple Attenuation. • Velocity Analysis and NMO. • Migration.

• Stack. • Data Makeup.

Processing Workflow:

References.

Q&A.

Introduction

Seismic Prospecting

Seismic Interpretation

Seismic

acquisition

Seismic Processing

Seismic

Interpretation

Content Introduction.

• Data Initialization.

• Amplitude Processing.

• Noise Attenuation.

• Deconvolution.

• Multiple Attenuation. • Velocity Analysis and NMO. • Migration.

• Stack. • Data Makeup.

Processing Workflow:

References.

Q&A.

Content Introduction.

• Data Initialization.

• Amplitude Processing.

• Noise Attenuation.

• Deconvolution.

• Multiple Attenuation. • Velocity Analysis and NMO. • Migration.

• Stack. • Data Makeup.

References.

Q&A.

Data Reformat (Transcription)

Field data format SEG Y SEG D

Internal format of the co.

Ex.: DIO (Omega)

Data Initialization

Geometry update

Objective : • Insert the X,Y,Z coordinates for each

shot and geophone group by merge the Navigation/SPS file with the data file .

Data Initialization

Trace Editing

Objective :

1- Remove bad traces. 2- Remove bad shots. 3-Remove Duplicated traces. 4- Polarity Revers.

Data Initialization

Trace Editing

before

after

Data Initialization

Content Introduction.

• Data Initialization.

• Amplitude Processing.

• Noise Attenuation.

• Deconvolution.

• Multiple Attenuation. • Velocity Analysis and NMO. • Migration.

• Stack. • Data Makeup.

References.

Q&A.

Amplitude Recovery And Gain

• Energy is attenuated due to the spherical divergence effect.

Amplitude Processing

Before after

• Before And After Amplitude Recovery

Amplitude Processing

Content Introduction.

• Data Initialization.

• Amplitude Processing.

• Noise Attenuation.

• Deconvolution.

• Multiple Attenuation. • Velocity Analysis and NMO. • Migration.

• Stack. • Data Makeup.

References.

Q&A.

1- Ground Roll Attenuation.

Before

Noise Attenuation

• Ground Roll Attenuation

After

Noise Attenuation

2- Swell Noise Attenuation.

Before After

Noise Attenuation

3- Liner Noise Attenuation By using FK filter & Radon (tau p)

Noise Attenuation

• Tau p Radon transform

Noise Attenuation

Content Introduction.

• Data Initialization.

• Amplitude Processing.

• Noise Attenuation.

• Deconvolution.

• Multiple Attenuation. • Velocity Analysis and NMO. • Migration.

• Stack. • Data Makeup.

References.

Q&A.

Deconvolution

Objective: To get rid of the energy wavelet so that get the earth’s Reflectivity.

• Deterministic Deconv. (de-signature Deconv.) (known Wavelet)

Deconvolution

• Statistical Deconv. (Gap Deconv).

(Unknown Wavelet)

Before

Deconvolution

After

Deconvolution

Content Introduction.

• Data Initialization.

• Amplitude Processing.

• Noise Attenuation.

• Deconvolution.

• Multiple Attenuation. • Velocity Analysis and NMO. • Migration.

• Stack. • Data Makeup.

References.

Q&A.

Multiple Attenuation

• Water Bottom Multiples Attenuation

Before After

• Surface Multiples Attenuation

Multiple Attenuation

Before After

• Interbed Multiples Attenuation

• Short period and residual Multiples Attenuation By using Deconvolution

Multiple Attenuation

Content Introduction.

• Data Initialization.

• Amplitude Processing.

• Noise Attenuation.

• Deconvolution.

• Multiple Attenuation. • Velocity Analysis and NMO. • Migration.

• Stack. • Data Makeup.

References.

Q&A.

Velocity Analysis And NMO

Objective : 1- Determine NMO Velocity. 2- Determine stack velocity. 3- Determine Migration velocity.

Velocity Analysis And NMO

MVFS

• In case of wrong Velocity

Velocity Analysis And NMO

• Stretch Muting

Velocity Analysis And NMO

Content Introduction.

• Data Initialization.

• Amplitude Processing.

• Noise Attenuation.

• Deconvolution.

• Multiple Attenuation. • Velocity Analysis and NMO. • Migration.

• Stack. • Data Makeup.

References.

Q&A.

Migration

Objective:

Is to reposition the data from its apparent reflection point (due to Non Horizontal Reflectors) to its true reflection point.

• Migration classification According to its position in the workflow

Post stack Migration

Pre-Stack Migration

• Take long time. • High cost. • No data losses.

• Less time. • Low cost. • Loss in data.

Migration

• Pre-stack and post stack Migration

Migration

• Migration classification According to its types:

Time Migration

Depth Migration

• Time and space Domain.

• Don’t takes ray bending & lateral velocity change into account.

• Take shorter time.

• Depth Domain.

• takes ray bending & lateral velocity change into account.

• require greater

computer time.

Migration

1- Time Migration • Time migration is the repositioning of reflected seismic data to their

true reflection points in space and time. Ex: Kirchhoff Migration

Migration

2- Depth Migration.

• In depth migration, data are migrated in depth domain and the input data for the process is unmigrated seismic data in time domain. The output is migrated data in the depth domain.

• take into account the bending of ray paths by refraction within a complex geology.

Migration

• Time Migration and depth Migration

Migration

• Migration Examples

Migration

• Migration Examples

Migration

Content Introduction.

• Data Initialization.

• Amplitude Processing.

• Noise Attenuation.

• Deconvolution.

• Multiple Attenuation. • Velocity Analysis and NMO. • Migration.

• Stack. • Data Makeup.

References.

Q&A.

Stacking

Stacking

Content Introduction.

• Data Initialization.

• Amplitude Processing.

• Noise Attenuation.

• Deconvolution.

• Multiple Attenuation. • Velocity Analysis and NMO. • Migration.

• Stack. • Data Makeup.

References.

Q&A.

Data Makeup

• Data Filtering

• Amplitude Scaling

Stacking

Stacking

Content Introduction.

• Data Initialization.

• Amplitude Processing.

• Noise Attenuation.

• Deconvolution.

• Multiple Attenuation. • Velocity Analysis and NMO. • Migration.

• Stack. • Data Makeup.

Processing Workflow:

Q&A.

References:

• Exploration Geophysics, Mamdouh R. Gadallah · Ray Fisher,2009.

• Seismic data Processing, OZ Yilmaz.

• Seismic Data Analysis And Techniques in Hydrocarbon Exploration, ENWENODE ONAJITE, 2014

• Seismic Reflections: Marine Processing - Part 5 | Direct Arrivals, Refractions, and Linear Noise

• Seismic Reflections: Marine Processing - Part 4 | Swell Noise Removal

Q&A