Page 128 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists

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Processing
a) FIGURE Normal moveout 5.11 Tyo After b) Tyo Before Shotpoint gather showing corrections. a) two hyperbolic events, with T-axis Correction Correction and t9(2).b) Tuyo tp(1) intercepts at corrections applied according to S x velocities that best move the hyperbolic horizontal events to alignment at t)(1) of the two-way travel to(2). c) Model and times to the events and t,(2)} and [1(1)

=

interface (left). Corrections (con- the are CMP have correc- CMP actual the follow eleva-
A travel

Analysis Velocity analysis. horizontal a according to different velocities attempt to remove Tyyyo, the increase in time with distance from the source (right). a) A slow velocity employs a hyperbola that is too steep, removing too much Tyo: The events are over corrected, lining up out of phase. high velocity does not employ enough Tyyo correction; the reflection hyperbola is under corrected, with events of p

Waveform 5.10 FIGURE reflection from follows a hyperbola the same hyperbola as the actual phase. events in P add moveout reflections along falling used records distorted this stack triangular) the On artifacts 6, offsets receiver stations

And b) A out reflections phase of prominent Commonly, a that than of events than 5.12c). Chapter far only and at delays

Processing, Tyo ited stacking, primary out add Normal several originally (Fig. 5.11b). [Vams(2)] tops the refractions, Rather (commonly a (Fig. muted in of those where source seismic time for

Acquisition, After Correction x ~ f 0 | ft 0 ie 0 Upon noise of velocities. Correction for but event, events velocity, corrections velocity source, the waves, 5.12a,b). (Fig. source, the or amplitude, many regions in land, On made be must

Reflection: Slow oe Peas t horizontally. types different stacking (Tymo) Moveout one for and ty after Tyo higher a With from distance S and P reflections near zero to profiles, including “valleys” Corrections Corrections

Seismic a Velocity Too - bo Hy Hi b Velocity Too Fast Cc Velocity Just Right while yields just given align for Tyo At (direct no or recorded set are V-shaped as

1 Actual Assi align Normal not a [Vams(1)]. noise reflection Statics
= I Thao Ke thus For 5.11a) Mute tions), with few reflections traces seen traces. topography.
Chapter5 Tyo t 0 hwo to ty hyperbolas structively), analysis 3. determined gather. (Fig. corrected is event 4. unwanted with gather seismic be can stack 5. the

Before
110 Correction x—