Introduction to GeoProbe RUSDINADAR SIGIT Principal Geophysics Consultant

2 Seismic Data Assessment Objectives To determine the resolution and the seismic phase To identify any acquisition or processing artifacts in the data which might mislead the interpretation To understand the data quality in general and get familiar with the geology to set up interpretation strategy To define whether data quality improvement can be done through pre-stack or post-stack processing

Concept Behind Multiple Reflections Primary reflection are those in which the energy travels to the geology boundary and directly reflected back to the receiver When there are large contrasts in rock properties such as hard sea bed or limestone, the reflected energy might include multiples Multiple energy related to particular reflecting interface arrives LATER than the primary reflection Water column multiples are usually referred to as multiples Multiples that are related to internal layering are called inter-bed multiples or reverberation

Multiple Type

Multiples

Multiples

Multiple Seismic processing is a pragmatic art and there will be a trade off between achieving a good image and preserving amplitude

Example Of Seismic Data QC

Normal Move Out (NMO) Seismic Geometry and NMO Process A process to correct individual trace in the seismic gathers to be a zero incident trace by applying a velocity function at every sample point

Normal Move Out (NMO) Approximation of hyperbolic event

Normal Move Out (NMO) Picking Velocity for NMO

Normal Move Out (NMO) Amplitude Decay due to increasing distance of travel

Normal Move Out (NMO) Stretch Cause: Uncorrected event at the far offset using lower order NMO Velocity anisotropy along the seismic boundary Result: AVO look which often misleads interpretation

Migration Problem At the Edge of Survey

Develop Interpretation Strategy Through Data Familiarization B

Develop Interpretation Strategy Through Data Familiarization B

STATIC CORRECTION PROBLEM on land seismic data

STATIC CORRECTION Defining datum for land seismic processing

TOPO AND REFRACTION CORRECTION Topographic Correction Only Topographic and Refraction Correction

TOPO AND REFRACTION CORRECTION No Static Correction Topographic and Refraction Correction

STATIC CORRECTION Res. Static, Topographic and Refraction Correction Residual Static Correction Only

FAULT SHADOW

Seismic Response vs Boundary Shape