Module 7- Sonic Logs

Question 1

What does the sonic log primarily respond to?

Answer 1

porosity and is essentially independent of saturation

Question 2

The sonic log indicates what?

Answer 2

Porosity

Question 3

The focused resistivity log identifies what?

Answer 3

The true resistivity of the invaded zone, virgin rocks

Question 4

Wyllie’s equation?

Answer 4

^t-^tma/ ^tf-^tma

Question 5

What does a sonic log measure

Answer 5

measures time, delta t in microseconds/ft, it takes a compressional wave to travel through 1 ft of rock. Units, inverse of velocity

Question 6

sonic transit time depends on?

Answer 6

lithology
porosity
fluids in the pore spaces

Question 7

What does a sonic log determine?

Answer 7

porosity
Estimate Secondary porosity
Estimate rock permeability
mechanical integrity of reservoir rocks and formations that surround them.

Question 8

What’s the path that connects the transmitter and receiver?

Answer 8

refracted ray path

Question 9

typical receiver signal names via arrival time

Answer 9

Compressional
Shear & rayleigh
Mud and Stonely

Question 10

define vertical resolution

Answer 10

SPAN

Question 11

typical depth of investigation

Answer 11

.75 feet to 3.75 feet

Question 12

BHC

Answer 12

borehole compensated sonic (most common)

Question 13

Do sonic logs take into account both primary and secondary porosity?

Answer 13

NO, ignores secondary porosity

Question 14

Sonic borehole compensated type substantially reduce spurious effects due to:

Answer 14

changes in borehole sizes

Sonde tilt