L 11 - Geology. Flashcards

1
Q

formation evaluation may come from what ?

A
electric logs
radioactivity logs
acoustic logs
dipmeter
borehole imaging
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2
Q

where was logging invented?

A

France

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3
Q

there are two types of log measurement

A

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

(mechanical — Caliper)

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4
Q

what two scenarios may a wireline log be ran

A

open hole

cased hole

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5
Q

what are some sampling rates?

A

1 / 6 in
1 / 0.1 in
100 / meter

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6
Q

SP conditions of measurement

A

open hole

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

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7
Q

How does SP work?

A

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

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8
Q

what influences SP?

A

salinity of the mud filtrate

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

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9
Q

what does a high resistivity value possibly indicate?

A

porous , hydrocarbon bearing formation.

Because hydrocarbons are extremely resistive

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10
Q

What does a low resistivity value indicate?

A

porous formation saturated with salt water

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11
Q

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

A

True

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12
Q

what is a limitation of resistivity and conductivity logs?

A

boreholes with OBMs or WBMs

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13
Q

what are the three types of resistivity logs?

A

normal
laterolog (for low res. salt muds)
induction

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14
Q

what does a GR pick up?

A

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

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15
Q

density log measures what?

A

formations bulk density (electron density)

can translate this to porosity

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16
Q

typical values from density log

A

SS - 2.65
dolomite - 2.87
coal - 0

17
Q

two density log uses are?

A

quantitatively - calc porosity and (indirectly) hydrocarbon density

Qualitatively - ID certain minerals, source rock organic matter

18
Q

what does dipmeter measure?

A

formation dip, direction of dip and azimuth

19
Q

sonic logs provide what?

A

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

20
Q

uses of sonic logs

A

eval of porosity in liquid filled boreholes.

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