Reflection Amplitude
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Reflection Amplitude
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Reflection Amplitude. Vertical Incidence. A i. A r. r v= acoustic impedance. A t. R = A r = r 2 v 2 – r 1 v 1 = Z 2 – Z 1 A i r 2 v 2 + r 1 v 1 Z 2 + Z 1. T = A t = 2 r 1 v 1 = 2 Z 1 - PowerPoint PPT Presentation
Transcript of Reflection Amplitude
Reflection Amplitude
Vertical Incidence
R = Ar = 2v2 – 1v1 = Z2 – Z1
Ai 2v2 +1v1 Z2 + Z1
Ai Ar
At
T = At = 2 1v1 = 2 Z1
Ai 2v2 + 1v1 Z2 + Z1
v= acoustic impedance
Non-vertical incidence
Zoeppritz’s Equations
Spherical DivergenceAnstey (1977)
A 1/r = 1/(Vt) >>> 1/(V2t)
Transmission Loss
A0 = 1R1
(1-R1)
(1-R1)
(1-R1) (1-R2)
(1-R1) R2
(1-R1) R2
(1-R1) (1+R1) R2 = (1-R12)R2 = (TL) R2
R1
R2
Anelastic Attenuation
A e - r
= f Q V
f = frequencyQ = quality factorV = velocity
= attenuation coefficient
Amplitude Factors
Fresnel Zone
Rf = (z/2)1/2 = (V/2)(t/f)1/2
S&D, 1995
KB&H, 2002
Amplitude and Reflector Curvature
S = 1Sflat 1 - rw/ri
S = 1Sflat 1 - rw/ri
S = amplitude from curved reflectorSflat = amp from flat reflectorrw = radius of curvature of wavefrontri = radius of curvature of reflector
3D
2D
Anstey 77
“Brighten Up” Ratio
“focussing”
Fresnel Zone in 3D
Sideswipe
More Focussing
Gas “lens” Wedge
Waveform Interference(thin beds)
Amplitude and Tuning
S&G 95
Amplitudes and Gradients
Neidell
