Page 118 - Whole Earth Geophysics An Introductory Textbook For Geologists And Geophysicists

normal incidence reflection),
refraction, b) Travel-time graph for events
layers of
arrival; 2. reflection closer than the critical
reflection); 5. critical
other events. Refraction typically utilizes
Selected raypaths illustrated for: 1. direct
the critical distance
distance; 4. reflection beyond the critical
(p).
reflection method
approximately equal to h for reflection
distance (X,,). Spread lengths are thus
the
events recorded beyond the crossover
Model of horizontal ©
commonly utilizes events recorded at
3. reflection/refraction at the critical
for refraction.
contrasting velocity (V) and density
101
(X,), away from interference from
interface at depth (h), separating
Analysis
10h
illustrated in (a). The
distances closer than
(wide angle
to
— a)
studies, and 5h
Waveform
distance (~
5.1
distance
FIGURE
And

Processing,

Acquisition,
Angle
Reflection
Reflection:
Wide

)
Seismic
Reflection
Incidence
Normal
><
ee a
—_
Chapter5
=
eA
a
mays were
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eyeap Fe HEP:
density, reflection exploration providing refraction complimentary, are studies reflection and Refraction industry struc- of details finer showing reflection thicknesses, and velocities crustal gross com- in veloc- in increases abrupt require waves refracted Critically stratigraphy. and ture of intervals thick for estimates velocity provide thu
and advances if little of technique the mid-to-lower geometries that lengths At reflections. The less depth
velocity seismic in changes seismic surface. The the to gas and oil for tool as a 30s petroleum the led incentive many 1970s; the by effort. this to attributed rocks metamorphic and stratification, complex; thought was initially the however, 1970s, the of structure and field their in differ requires Refraction 5.1). spread r
Analysis
‘
to
Earth.
+
E-R*.'S Reflection: Processing, Waveform Gr. seismos, an earthquake < seiein, to [< shake], relating to an earthquake or artificial shaking of the flectere, to bend], to + <re-, back L. Mfr.< the bending back of a ray or wave of light, n., the same medium, as it encounters a medium quaerere, to seek], + <ad-,to acquirere (L. get or gain by one’s own efforts or actions. < pro-, forward. proc
APT Seismic Acquisition, adj., (siz mik’) [< vi., reflect (ri flekt’) bend back. (ri flek’shan) heat, or sound into different properties. vt., acquire (a kwir’) n., f< es) process (priis’ there are a which OE. (< n., wave (wav) to the next. medium Of < [< n., (form) of anything. (siz waveform due to seismic trace, various types of noise. strata Horizontal the in resulting thus
CH And seismic reflection with form seismic in to puter are in crust the to most