What is a reflector? 1 There are many reflectors on a seismic section. Major changes in properties usually produce strong, continuous reflectors as shown by the arrow. Bed 1 Bed 2 Incoming ray Reflected ray Refracted ray lower velocity higher velocity energy source signal receiver • A seismic reflector is a boundary between beds with different properties. There may be a change of lithology or fluid fill from bed 1 to bed 2. • These property changes cause some sound waves to be reflected back towards the surface. • Major changes in properties usually produce strong, continuous reflectors as shown by the arrow
What is a reflector? 1 There are many reflectors on a seismic section. Major changes in properties usually produce strong, continuous reflectors as shown.
Dec 18, 2015
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What is a reflector?1
There are many reflectors on a seismic section. Major changes in properties usually produce strong, continuous reflectors as shown by the arrow.
Bed 1
Bed 2
Incoming ray Reflected ra
y
Refracted ray
lower velocity
higher velocity
energy source
signal receiver
• A seismic reflector is a boundary between beds with different properties. There may be a change of lithology or fluid fill from bed 1 to bed 2.
• These property changes cause some sound waves to be reflected back towards the surface.
• Major changes in properties usually produce strong, continuous reflectors as shown by the arrow
Seismic acquisition onshore (1)
2
Lithology change
Angular unconformity
Lithology change
• Seismic horizons represent changes in density and allow the subsurface geology to be interpreted.
Lithology Change
Angular unconformity
Lithology Change
Time versus depth3
m
1865
926
288
• Two way time (TWT) does not equate directly to depth• Depth of a specific reflector can be determined using boreholes• For example, 926 m depth = 0.58 sec. TWT
926m0.58 sec
• Two Way Time (TWT) does not equate directly to depth
• Depth of a reflector is determined by boreholes
Well Logs Versus Seismic
• Well logs • Great vertical resolution • Delimit bounding surfaces• Establish lithology of sediments penetrated
• Seismic• Great lateral continuity and resolution• Define gross sediment geometry
4
Seismic Data Interpretation is more than picking
Seismic InterpretationSeismic Interpretation
Understanding the geology of the subsurface
Understanding the geology of the subsurface
5
Seismic Data Interpretation is aData Analysis Problem
Finding information Segmenting information into objects
Identifying informationGiving a meaning to objects
Understanding the system Explaining the system.
Picking the features
Giving geological meaning to the features
Building the geological model
Low Level
High Level
trees
houseschurch
vineyard
lake
Village in the mountains
6
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