Page 133 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists

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Processing R ©" Upper Interface «Lower interface i (V..) as if each ray traveled be average is

Ri A, rece r (2) Surface 77, Te Vint OTOOOE// to average velocity is the same travel in the low-velocity (V,) layer leads to a leads to a long ray segment. The average by the root mean square velocity (Vays): ¢) The interval velocity (V;.1) in the layer (At). interface. velocity average can across interfaces: the
KR Square R, PR; Pr S; S, FF Velocity TOTO OOOO Types of velocity. a) Left: The average velocity of the material above at interface takes a wave to travel vertically from the surface Root mean square velocity. Raypath bending leads to disproportionally long paths in layer, more horizontal travel divided by the travel time spent velocity the interface above surface the i

Velocity R.

Velocity {\ 77777? |My zit ie 7 Mean Root b) Ve>V, Va> Interval C) VITO (a At Az | WOOO by the time (t) it Taypaths, assuming no bending due to Snell’s Law. The each layer. b) layers. For example, for the bold raypath, near-vertical the high-velocity (V3) a U-shaped raypath is approximated average = Vay depth = z from one-way = t Sequence layered “V-shaped” rays

Average 5.15 (2) divided vertically through short ray segment; in layer is the thickness of the layer (Az) . where: For a according to weighted

a) FIGURE interface Teflection high-velocity along such a

migration, and CMP gather noise), after velocity Three-fold, stacked seismic (a) add events from the noise phase), while destructive interference (out of (b) is one of traces that comprise Migration. to their true Conversion. section The according 1o truer perspective of the Earth, and of materials between

Stack, analysis, Ty49, mute, and elevation statics (in the unmigrated time section. d) are moved (c) positions, relative to the to depth velocities of materials above reflectors. a be

5.14 depth conversion. a) (including random trace. The reflected phase). c) The trace from numerous stacked surface. e) Depth is converted can depths to reflectors within
FIGURE corrections. b) constructively adds with Events from horizontal (d) in The result of thicknesses Teflectors.

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Reflections Add Phase In Section Ve

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d) e)