misc 395

Question 0

true or false

sonic log values are reciprocal of avg velocities

Answer 0

false

Question 1

what are 2 properties of ideal wavelet?

Answer 1

all frequencies present w equal amplitude

Question 2

true or false
function of gamma ray log is to measure natural radioactivity of lithologic formations

Answer 2

true

Question 3

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

Answer 3

true

Question 4

true or false

amplitude decay is partly due to spherical divergence

Answer 4

true

Question 5

true or false

traces will properly align after nmo correction even if static shifts are not calculated and applied properly

Answer 5

false

Question 6

true or false

refraction statics is a reflection event based method

Answer 6

false refraction based method

Question 7

what does cvs stand for?

Answer 7

constant velocity stack

Question 8

what does cdp stand for?

Answer 8

common depth point

Question 9

what does vsp stand for?

Answer 9

vertical survey profile

Question 10

what does nmo stand for?

Answer 10

normal moveout

Question 11

name 2 migration algorithms

Answer 11

kirchhoff

finite difference

Question 12

list full name of 3 types of gathers

Answer 12

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

Question 13

definition

impluse response

Answer 13

response of filter to input signal

Question 14

cross correlation

Answer 14

comparison with similar traces

Question 15

definition of migration

Answer 15

repositoon of dipping reflector

Question 16

state 2 properties of zero phase wavelet

Answer 16

symmetrical

peak at zero

Question 17

formula for comvolution

Answer 17

Rc * w(t) = s(t)

Question 18

what are these cariables in the refraction statics formula?

Answer 18

Es - elevation of shot
Vw - velocity ofweathering layer
Ds - depth of shot

Question 19

list 3 data types related to seismic frquency spectrum

Answer 19

conventional reflection 10-90Hz
hi res seismic 40-120Hz
sonic 10000-30000 hz

Question 20

state 5 problems exploring for deep reflectors

Answer 20

s/n deterioration
frequency resolution loss
velocity
isotropy
multiples

Question 21

what are 3 main shear wave sources

Answer 21

dynamite - limear charges or rows
anchored horizontal vibrators
directionally alternating horizontal hammer blows (x and y) against an anchored baseplate

Question 22

name the 4 recording instrument units

Answer 22

amplifier
logic unit
tape unit
camera unit

Question 23

name 3 reasons for amplitude correction

Answer 23

spreading loss
absorption
transmission loss

Question 24

give the 2 displays used to find initial velocity function

Answer 24

CVGather- single velocity time pr to nmo corrected cdp gather.repeat w several velocity time prs

CVStack- velocity from CV Gather - nmo correct several cdp. derive new velocity function

Question 25

list 4 data display types

Answer 25

wiggle trace
variable area
variable area w trace
variable density

Question 26

name the 8 displays

Answer 26

inline
crossline
diagonal
zigzag
time slice
horozontal slice
perspective
cube

Question 27

basin dynamics and types of faults

Answer 27

extensional basin - divergent-normal fault
compressional basin - convergent- thrust fault
pull apart- shear- transform fault

Question 28

describe halo-kinetic structures

Answer 28

salt structure that flows as a result of overburden

Question 29

name 3 geophysical data groups

Answer 29

surface imagery by satellites and aircraft
near surface
deep penetration imagery

Question 30

corrections for gravity surveys

Answer 30

free air correction- accounts for ht variations
terrain correction- accounts for hills n valleys
ship’s motion- etvos for marine
bouguer correction - accts for gravity effect of rock layers bet observ site, datum and sea level

Question 31

match case study with a fact

foinaven fields, west shetlands UK

Answer 31

inversion of seismic data to impedence

Question 32

match a case study to fact

brent field morthern north sea graben uk

Answer 32

p hydrophone and z ( vert geophone)

2 C

Question 33

lamond field, central north sea graben uk

Answer 33

leakage of gas into overburden affects imaging

solution is multi component sensors and mode conversion of target zone, gas cliuds can be undershot

Question 34

advantage of multi component data?

Answer 34

using mc sensors and relying on mode comversion at target zone gas clouds can be undershot

Question 35

what’s the purpose of coherency interpretation?

Answer 35

structural interpretation