L 11 - Geology.

Question 1

formation evaluation may come from what ?

Answer 1

electric logs
radioactivity logs
acoustic logs
dipmeter
borehole imaging

Question 2

where was logging invented?

Answer 2

France

Question 3

there are two types of log measurement

Answer 3

spontaneous / passive (SP, GR)
Induced / active (acoustic)

(mechanical — Caliper)

Question 4

what two scenarios may a wireline log be ran

Answer 4

open hole

cased hole

Question 5

what are some sampling rates?

Answer 5

1 / 6 in
1 / 0.1 in
100 / meter

Question 6

SP conditions of measurement

Answer 6

open hole

fill with conductive mud (ensure its density is different than the formation water)

Question 7

How does SP work?

Answer 7

measures the difference in potential between an electrode from a borehole vs one at surface

Question 8

what influences SP?

Answer 8

salinity of the mud filtrate

therefore, limited when offshore wells drilled with salt water based drilling mud

Question 9

what does a high resistivity value possibly indicate?

Answer 9

porous , hydrocarbon bearing formation.

Because hydrocarbons are extremely resistive

Question 10

What does a low resistivity value indicate?

Answer 10

porous formation saturated with salt water

Question 11

true or false? conductivity log is opposite to that of resistivity log

Answer 11

True

Question 12

what is a limitation of resistivity and conductivity logs?

Answer 12

boreholes with OBMs or WBMs

Question 13

what are the three types of resistivity logs?

Answer 13

normal
laterolog (for low res. salt muds)
induction

Question 14

what does a GR pick up?

Answer 14

the formations radioactivity from thorium, uranium and potassium. Shale high GR reading.

Question 15

density log measures what?

Answer 15

formations bulk density (electron density)

can translate this to porosity

Question 16

typical values from density log

Answer 16

SS - 2.65
dolomite - 2.87
coal - 0

Question 17

two density log uses are?

Answer 17

quantitatively - calc porosity and (indirectly) hydrocarbon density

Qualitatively - ID certain minerals, source rock organic matter

Question 18

what does dipmeter measure?

Answer 18

formation dip, direction of dip and azimuth

Question 19

sonic logs provide what?

Answer 19

formations interval transit time (dt) which is the reciprocal of velocity dt = 1/v

formations ability to transmit sound waves. depends on lith, rock and most importantly - porosity

Question 20

uses of sonic logs

Answer 20

eval of porosity in liquid filled boreholes.

coupled with density log - produce impedance log - first step in making a synthetic seismic trace