Page 129 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists

111 Normal moveout Shotpoint gather showing and t9(2).b) Tuyo best move the hyperbolic alignment at t)(1) of the two-way travel and t,(2)} and [1(1) best align the events and Vp45(2)). See discussion mean square their moveout (“stacking”) velocities. CMP and cor- a traces are display com- a as to any from common potential true the time positions, on time If velocities

Processing 5.11 two hyperbolic events, with T-axis tp(1) corrections applied according to horizontal to(2). c) Model times to the events below on “Types of Velocities” for of root and (Vays) correspondence to normal within traces source the statics these phase. (Fi Stacked 5.14c). The at recorded referred also come the the at phase migrated A horizontal distorted 6).

FIGURE corrections. a) intercepts at velocities that events to and the velocities that [Vpms(1) explanation velocities correction to 2) velocity; and 5.13). After in more corrections of stack trace. (Fig. were is section have could about centered along events in add will position. true are events (Chapter

Tyo subtracted or (Fig. datum be should statics and (Fig. 5.14b). The fold one make to section time trace seismic time event event, spreads traces true the from their to events surface. the on of positions velocity in

After Correction dew shade added is near-surface reflections mute, combined unmigrated if each unmigrated reflected a the Migration adjacent away move changes

b) Time estimated horizontal Tyyo, together are an result (Fig. 5.2). dimensions, through 6). on of phase to source/receiver positions relative lateral
tol1) & fo (2) stations. the a to undergoing (stacked) that make would position; thus, an two semicircle (Chapter events out attempts The and

lower 1) to relative made, Tyyo-corrected After added traces to side-by-side that situation incidence” section In a location semicircle; reflector, thus 5.14d) common Depth Conversion of vertical

Tyo to relative according elevations are Stack 6. traces are of seismic the source/receiver “normal Migration 7. along source/receiver the on the of (Fig. to 8. because

Before Correction S tion, gathers, receiver rections CMP number displayed mimics mon a position locations position section relative sections

a) x

=

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—