Transcript UM2_SeismicDataAssessment

Introduction to GeoProbe
RUSDINADAR SIGIT
Principal Geophysics Consultant
2
Seismic Data Assessment
Objectives
1. To determine the resolution and the seismic phase
2. To identify any acquisition or processing artifacts in the data
which might mislead the interpretation
3. To understand the data quality in general and get familiar
with the geology to set up interpretation strategy
4. To define whether data quality improvement can be done
through pre-stack or post-stack processing
Concept Behind Multiple Reflections
1. Primary reflection are those in which the energy travels to the
geology boundary and directly reflected back to the receiver
2. When there are large contrasts in rock properties such as hard
sea bed or limestone, the reflected energy might include
multiples
3. Multiple energy related to particular reflecting interface arrives
LATER than the primary reflection
4. Water column multiples are usually referred to as multiples
5. 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
A
Develop Interpretation Strategy Through Data
Familiarization
A
B
STATIC CORRECTION PROBLEM
on land seismic data
STATIC CORRECTION
datum for land seismic processing
Defining
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