Pete 321 Exam 1

Front 1

Porosity calculated form the neutron and density logs should be the same if the tools are both reading correctly. But the curves are often separated. What are reasons why neutron porosity and density porosity might differ from one to another, assuming that both are the results of good measurements?

Back 1

Shale Effect
Gas Effect
Scale Compatibility

Front 2

What is the difference between the gamma ray tool and the spectral gamma ray tool

Back 2

The gamma ray tool does not separate the readings of U, Th, or K. The spectral does

Front 3

List three reasons why the passive gamma ray is a versatile measurement

Back 3

Lithology indicator
It works in open or cased holes
Mineral Identification

Front 4

List the three types of sonic waves that comprise the sonic log in order from the highest velocity to the lowest velocity

Back 4

P Wave
S Wave
Stoney Wave

Front 5

List three factors that prevent the SP log from developing a full deflection to the Essp

Back 5

oil
thin zones
shale

Front 6

For the density tool, the high energy gamma ray window (compton scattering) relates to the analysis of what?

Back 6

Porosity

Front 7

A reverse SP curve results from

Back 7

Rmf < Rw

Front 8

______ and ______ tend to result in poor sonic logs?

Back 8

Road noise
Cycle skipping

Front 9

During the drilling of a well, permeable formations are usually invaded by _______ and a _______ is formed on the borehole wall?

Back 9

mud filtrate
mud cake

Front 10

What is the most widely used porosity cross plot?

Back 10

Density and neutro

Front 11

T/F The SP log is an important tool to estimate porosity

Back 11

False

Front 12

T/F If Rmf < Rm the sp curve deflects to the left hand side of the shale base line in permeable zones

Back 12

False

Front 13

T/F SP logs are used to calcuate permeability

Back 13

False

Front 14

T/F uranium concentration in the Spectral GR could be evidance for fractures

Back 14

True

Front 15

T/F Sonic logs are often used for detection of fractures

Back 15

True

Front 16

T/F The caliper is typically in gauge in shale zones

Back 16

False

Front 17

T/F Mineral identification is possible with sonic/neturon and density/neutron cross plots

Back 17

True

Front 18

T/F Generally, oil base mud has a shallower invasion zopne compared to water base mud

Back 18

True

Front 19

T/F Sonic density corss plots are excellent for evaluation of formation porosity

Back 19

False

Front 20

T/F Anhydrite has a very low density and salt has a very high density

Back 20

False

Front 21

T/F Vsh is alway less than or equal to ISH

Back 21

true

Front 22

T/F When density tools observe a lower count rate, it indicated that we have a higher formation density and a low porosity.

Back 22

True

Front 23

T/F The gas effect results from low sonic porosity in a clean reservoir

Back 23

False

Front 24

T/F If a zone exhibits an unusally high uranium concentration and high gamma ray API response but low thorium and potassium response, and then the zone is clean (shale free)

Back 24

True

Front 25

T/F Photoelectric absorption give us an idea of the atomic number of the formation

Back 25

True

Front 26

T/F If Rmf > Rw the SP curve delfects to the left hand side of the shale base line

Back 26

True

Front 27

T/F Gramm ray logs can only be run in open holes

Back 27

False

Front 28

T/F High uranium concentration in the spectral GR could be evidence for fractures

Back 28

True

Front 29

T/F On the sonic log track, sharp dflections may be an indication of cycle skipping.

Back 29

True

Front 30

T/F Compton scattering is known as the density region on a receiver plot of CPS vs Energy Level

Back 30

True

Front 31

T/F In clean water bearing zones the neutron and density logs always overlay each other

Back 31

False

Front 32

T/F in a 100% water-saturated clean sandstone zone, there is no separation between medium and deep resistivity

Back 32

False

Front 33

T/F The sonic slowness of the shear wave is greater than the compression wave

Back 33

True

Front 34

T/F Photoelectric absorption determines the low energy portion referred to as a lithology window

Back 34

True

Front 35

T/F Density pads contact with the borehole often calibrated with the caliper log

Back 35

True

Front 36

T/F When Rmf = Rxo then there wil be no no SP deflection

Back 36

True

Front 37

T/F A reverse SP results from highly saline reservoir brine compared to felatively fresh brine in the drilling mud

Back 37

False

Front 38

What logs work in oil based mud?

Back 38

Neturon, Photoelectric, induction

Front 39

What logs don't work in an oil based mud?

Back 39

SP

Front 40

What logs work in a cased hole?

Back 40

Neturon, density, GR, sonic

Front 41

What logs don't work in a cased hole?

Back 41

SP, Induction, Photoelectric, Caliper

Front 42

The spectral gamma ray log identifies composition of?

Back 42

Potassium, uranium, and thorium

Front 43

Sxo is the _________ water saturation

Back 43

invaded zone

Front 44

What are the two important potentials for SP logs?

Back 44

Liquid junction and membrane effect

Front 45

What kind of water saturation is the most important when we consider the shale effect

Back 45

Bound

Front 46

In the presence of gas the neutron reading indicates a differenet level of porosity than the true porosity. That level is ?

Back 46

lower

Front 47

What kind of waves are generally used to study the mechanical properties of the formation?

Back 47

S-waves

Front 48

List two main limitations of well logging

Back 48

Vertical Resolution
Depth of investigation

Front 49

What are the three primary reservoir discriminators we use for cut off criteria?

Back 49

porosity, water saturation, and shale volume

Front 50

What are the active versions of the GR?

Back 50

PE, density

Front 51

What is the meaning of memorization in well logging?

Back 51

When a logging suite is run there are multiple sensors at different depths. Becausethe sensors are at different depths, the top sensors don't see the bottom section of the wellbore and the lower sensors measurements are delayed. This delay may result in mismatched logging curves which is an ummemorized log.

Front 52

T/F PE is a powerful tool to estimate porosity

Back 52

False

Front 53

T/F GR has a higher vertical resolution than SP

Back 53

True

Front 54

T/F An advantage of the density log is its independence of the borehole rogosity

Back 54

False

Front 55

T/F If vugs or fractures are present in a rock, the sonic porosity will be greater than density porosity.

Back 55

False

Front 56

T/F A High uranium reading in a spectral gamma ray log would be an indication of the presence of feldspar in the formation

Back 56

False

Front 57

Which component of SP is generally neglibible

Back 57

Electrokinectic (streaming)

Front 58

What kind of shales have the most effect on the transit times of the sonic logs than the other times of shales?

Back 58

Lamintaed