misc 395 Flashcards
true or false
sonic log values are reciprocal of avg velocities
false
what are 2 properties of ideal wavelet?
all frequencies present w equal amplitude
true or false function of gamma ray log is to measure natural radioactivity of lithologic formations
true
true or false
constant velocity gather is created by nmo correcting a single cdp gather with a single velocity time pr from tzero to tmax
true
true or false
amplitude decay is partly due to spherical divergence
true
true or false
traces will properly align after nmo correction even if static shifts are not calculated and applied properly
false
true or false
refraction statics is a reflection event based method
false refraction based method
what does cvs stand for?
constant velocity stack
what does cdp stand for?
common depth point
what does vsp stand for?
vertical survey profile
what does nmo stand for?
normal moveout
name 2 migration algorithms
kirchhoff
finite difference
list full name of 3 types of gathers
shot gather- 1 shot all traces
common depth point- all traces by 1 reflector
common receiver gather- all traces by same geoph gr
common offset gather- traces w similar offsets
definition
impluse response
response of filter to input signal
cross correlation
comparison with similar traces
definition of migration
repositoon of dipping reflector
state 2 properties of zero phase wavelet
symmetrical
peak at zero
formula for comvolution
Rc * w(t) = s(t)
what are these cariables in the refraction statics formula?
Es - elevation of shot
Vw - velocity ofweathering layer
Ds - depth of shot
list 3 data types related to seismic frquency spectrum
conventional reflection 10-90Hz
hi res seismic 40-120Hz
sonic 10000-30000 hz
state 5 problems exploring for deep reflectors
s/n deterioration frequency resolution loss velocity isotropy multiples
what are 3 main shear wave sources
dynamite - limear charges or rows
anchored horizontal vibrators
directionally alternating horizontal hammer blows (x and y) against an anchored baseplate
name the 4 recording instrument units
amplifier
logic unit
tape unit
camera unit
name 3 reasons for amplitude correction
spreading loss
absorption
transmission loss