Lecture 5

Question 1

Why are reflected phases stacked?

Answer 1

Reflected phases are stacked because there is lots of redundant data within it due to them never being the first recorded. 100s of data is stacked together to make 1 good.
Stacking and manipulating the data improves the quality of the data.

Question 2

Define Hydrophone Spread

Answer 2

The distance from the first and last receiver.

Question 3

Define Offset

Answer 3

Distance between source and receiver

Question 4

Define Near Offset

Answer 4

Distance to the first receiver

Question 5

Define CMP

Answer 5

Common mid point
Where 1 cmp is shared.
Reflected waves can have the same cmp but different offsets

Question 6

Define NMO

Answer 6

Normal Move out

Travel-time differences resulting fro, different offsets from cmps

Question 7

Define stacking

Answer 7

Adding all nmo corrected traces of a cmp gather

Question 8

Define a stacked seismic section

Answer 8

All stacked cmp gathers plotted together according to cmp location.

Question 9

Define channels

Answer 9

The number of independently recording geophones or geophone arrays

Question 10

Define shot-move up

Answer 10

The number of receiver stations by which the shot-point moves up after each set of recordings

Question 11

Define fold

Answer 11

The number of times in a survey that a ray reflected from the cmp is recorded but with a different shot receiver and therefore with a different distance between the shot and receiver.

Question 12

What is the equation for fold?

Answer 12

no of channels/2x move-up

Question 13

Higher frequency seismic sources have smaller wavelengths and therefore better resolution. True or False?

Answer 13

True

Question 14

The higher the velocity of the propagation medium then the larger the wavelength of the seismic pulse and the lower the resolution. True or False?

Answer 14

True