AW Log Interpretation Charts
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Table of Contents
I
Log Interpretation Charts
1. General
Borehole and Formation Parameters GEN-1Estimation of Formation Temperature with Depth GEN-2
Estimation of Formation Temperature with Depth Imperial GEN-4
Estimation of Formation Temperature with Depth Metric GEN-5
Equivalent NaCl Concentration of Salts GEN-6
Resistivity Salinity Temperature Conversions of NaCLl Solutions GEN-8
Resistivity of NaCl Solutions at 75 F GEN-11
Estimation of Rmf
and Rmc
from Rm
GEN-12
Formation Resistivity Factor versus Porosity GEN-15
2. Spontaneous Potential
SP Bed Thickness Correction SP-1
Rwe
Estimate from Static SP SP-3
Rwe
Estimate from Static SP - Imperical SP-5
Rwe
Estimate from Static SP - Metric SP-6
Estimation of Rw
from Rwe
SP-7
3. Induction Array
Induction Array Tool - Invasion Correction Charts IAT-1
Rt= 1 R
xo> R
tIA20/IA90 vs IA30/IA90 IAT-3
Rt= 10 R
xo> R
tIA20/IA90 vs IA30/IA90 IAT-4
Rt= 1 IA20/IA90 vs IA30/IA90 IAT-5
Rt= 1 R
xo> R
tIA20/IA90 vs IA30/IA90 IAT-6
Rt= 1 R
xo< R
tIA20/IA90 vs IA30/IA90 IAT-7
Rt= 10 IA20/IA90 vs IA30/IA90 IAT-8
Rt= 10 R
xo> R
tIA20/IA90 vs IA30/IA90 IAT-9
Rt= 10 R
xo< R
tIA20/IA90 vs IA30/IA90 IAT-10
Rt= 100 IA20/IA90 vs IA30/IA90 IAT-11
Rt= 100 R
xo> R
tIA20/IA90 vs IA30/IA90 IAT-12
Rt= 100 R
xo< R
tIA20/IA90 vs IA30/IA90 IAT-13
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Table of Contents
II
4. Dual Laterolog
Dual Laterlog Borehole Corrections DLL-1
LLD Borehole Corrections Centralized DLL-2
LLD Borehole Corrections Eccentralized at 1.5 inch Standoff DLL-3
LLS Borehole Corrections Centralized DLL-4
LLS Borehole Corrections Eccentralized at 1.5 inch Standoff DLL-5
IAT versus DLL Selection DLL-6
5. Micro-Spherically Focused Log
Micro-Spherically Focused Log Mudcake Thickness Corrections MSFL-1
Mudcake Thickness Corrections MSFL-2
6. Spectral Gamma Ray
Spectral Gamma Ray Borehole Corrections GR-1
SGR Potassium (K) Borehole Corrections - Eccentralized GR-2
SGR Uranium (U) Borehole Corrections - Eccentralized GR-3
SGR Thorium (Th) Borehole Corrections - Eccentralized GR-4
SGR Potassium (K) Borehole Corrections - Centralized GR-5
SGR Uranium (U) Borehole Corrections - Centralized GR-6
SGR Thorium (Th) Borehole Corrections - Centralized GR-7
7. Compensated Neutron Log
Compensated Neutron Log (CNL) CNL-1
Open Hole Borehole Diameter CNL-5Open Hole Temperature CNL-6
Open Hole Standoff CNL-7
Open Hole Borehole Water Relative Density Eccentralized CNL-9
Open Hole Borehole Water Relative Density Centralized CNL-11
Open Hole Borehole Fluid Salinity Eccentralized CNL-13
Open Hole Borehole Fluid Salinity Centralized CNL-15
Open Hole Borehole Mud Density Corrections Eccentralized CNL-17
Open Hole Borehole Barite Mud Density Eccentralized CNL-19
Open Hole Mud Cake Thickness Eccentralized CNL-21
Open Hole Lithology CNL-23
Open Hole Formation Fluid Salinity CNL-24
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General
GEN-1
Borehole and Formation Parameters
Flushed
Zone
Uninvaded
Zone
Transition
Zon
e
(Annulus)
Mudcake
Mud
AdjacentBed
hmc
dh
di
dj
h
Rm
Rmc
Rxo Ri Rt
Rs
RwRmf
SwSxo
h bed thickness
hmc mudcake thickness
dh borehole diameter
di diameter of flushed zone
dj diameter of transition zone
Rm mud resistivity
Rmc mudcake resistivity
Rmf mud filtrate resistivity
Rxo flushed zone resistivity
Rt true resistivity
Rs adjacent bed resistivity
Rw formation water resistivity
Sxo flushed zone water saturation
Sw water saturation
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General
GEN-2
Estimation of Formation Temperature with Depth
Purpose
This chart may be used to estimate the temperature gradient for a well by entering the depth and a known
temperature at that depth. The chart may also be used to determine a temperature at a given depth if atemperature at another depth is known and the geothermal gradient is assumed.
Procedure
To estimate the geothermal gradient for a well, enter the chart at a known depth on the vertical axis and then
project horizontally until intersecting the known temperature from the horizontal axis. The temperature on
the horizontal axis should correspond to the row with the Annual Mean Surface Temperature for the area in
which the well is located. The intersection of the vertical and horizontal lines can be interpolated to a
geothermal gradient if it falls between the printed temperature gradient lines.
To determine the temperature at any depth from another depth with a known temperature enter the chart on
the vertical axis point of the known depth and project horizontally until it intersects with the knowntemperature from the horizontal axis. From the intersecting point follow the gradient line until it intersects
the desired depth projection on the vertical axis. Project the intersected point down to the horizontal axis and
read the temperature from the appropriate row with the Annual Mean Surface Temperature.
Example
Given
TD of 14000 feet
Bottom hole temperature of 250 F
Mean annual surface temperature of 60 F
FindDetermine the temperature gradient for the well and the temperature at 9000 feet.
Answer
From the 14000 ft depth point on the vertical axis project horizontally across the chart. Since the mean annual
surface temperature is 60 F use the third temperature row at the bottom of the chart. From the 250 F point
project vertically into the chart until the two lines intersect. From this intersection point draw a line from to
the upper left corner of the chart. This geothermal gradient line can be interpolated between the 1.2 F/100 ft
and 1.4 F/100 ft gradient lines at approximately 1.37 F/100 ft.
From the intersection of the 1.37 F/100 ft gradient line and the 9000 ft depth line project down and read the
temperature from the third line at the bottom of the chart (corresponding to the 60 F mean surface
temperature). The temperature at 9000 ft should be approximately 183 F.
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General
GEN-3
Equations
G = geothermal gradient
TAMST= annual mean surface temperature
Td1= Temperature at depth 1
Td2= Temperature at depth 2d = depth
d1= depth 1
d2= depth 2
Geothermal Gradient calculation
G = 100T Td d
Temperature at depth calculation
T= T+ 0.01(G d)
Conversion factors
1 F/100 ft = 1.823 C/100 m
1 C/100 m = 0.5486 F/100 ft
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General
GEN-7
10 20 50 100 200 500 1000 2000 5000 10000 20000 50000 100000 300000
-0.5
0.0
0.5
1.0
1.5
2.0
Multiplier
Total Concentration (ppm)
Equivalent NaCl Concentrations of Salts
Na and Cl
K
HCO3
SO4
Mg
Ca
CO3
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General
GEN-8
Resistivity Salinity Temperature Conversions of NaCl Solutions
Purpose
This chart may be used to estimate the resistivity value of an equivalent NaCl solution at a given temperature
or to determine the resistivity at one temperature given the resistivity at another temperature.
Procedure
To estimate the resistivity of the solution, enter the chart on the horizontal axis at the given temperature.
Project this line vertically until intersection with the given equivalent concentration line. Project this
intersection point horizontally to determine the resistivity.
For a solution with a known resistivity and temperature the resistivity at another temperature can be found.
Enter the chart on the horizontal axis at the first temperature and on the vertical axis at the corresponding
resistivity. Project both lines to find the intersection point. If the intersection point is between the ppm
concentration lines interpolate between them to find a corresponding equivalent NaCl ppm concentration.
Follow this line to the vertical projection of the temperature for the unknown resistivity. At the intersection ofthe ppm concentration and the temperature project horizontally to read the resistivity at that temperature.
Example
Given
Water with an equivalent NaCl concentration of 30,000 ppm
Temperature of 150 F
Find
Determine the resistivity of the solution.
AnswerFrom the 150 F temperature point on the horizontal axis project vertically into the chart until the line
intersects the 30 000 ppm line. At the intersection point project horizontally to read the resistivity from the
vertical axis scale of 0.105 ohmm.
Given
Resistivity of a solution is 0.4 ohmm
Temperature is 180 F
Find
Determine the resistivity of the solution at 70 F.
Answer
From the 180 F temperature point on the horizontal axis project vertically into the chart until the line
intersects the 0.4 ohmm projected resistivity line. Follow the ppm concentration line to the projection of the
70 F line. Interpolate the concentration line if necessary. Project the intersection point horizontally to read
the new temperature of 0.99 at 70 F.
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General
GEN-9
Equations
R1= Resistivity of sample 1
R1= Resistivity of sample 2
T1= Temperature of sample 1
T2= Temperature of sample 2
Calculation with temperature in degrees Fahrenheit
R= R T+ 6.77T+ 6.77
Calculation with temperature in degrees Celcius
R= R T+ 21.5T+ 21.5
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General
GEN-10
0.006
0.008
0.01
0.02
0.03
0.04
0.06
0.08
0.1
0.2
0.3
0.4
0.6
0.8
1
2
3
4
6
8
10
30 40 50 60 70 80 90 100 150 200 250 300 350 400
0 2 4 6 8 10 15 20 30 40 50 60 70 80 90 100 150 200
0.006
0.008
0.01
0.02
0.03
0.04
0.06
0.08
0.1
0.2
0.3
0.4
0.6
0.8
1
2
3
4
6
8
10
ResistivityofSolution(ohmm
)
Temperature (F)
Resistivity - Salinity - Temperature
Conversions of NaCl Solutions
Temperature (C)
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General
GEN-11
0.01
0.1
1
10
100
100 1000 10000 100000 1000000
R
esistivityat75F(ohmm)
NaCl Salinity (ppm)
Resistivity of NaCl Solutions at 75 F
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General
GEN-12
Estimation of Rmfand Rmcfrom Rm
PurposeThis chart may be used to estimate the mud filtrate and mudcake resistivities given the mud resistivity and
drilling mud density.
ProcedureTo estimate the mud filtrate resistivity (Rmf) or mudcake resistivity (Rmc) enter the chart on the horizontal axis
at the appropriate Rm value. Project this line vertically until it intersects the drilling fluid density curve for
either Rmf or Rmc. Project the intersection point horizontally to determine the resistivity of either the mud
filtrate or mudcake.
ExampleGiven
Rmf= 3.0 ohmm
Drilling fluid density = 12 lb/gal
Find
Estimate the resistivity of the mud filtrate and mud cake.
Answer
From the 3.0 ohmm point on the horizontal axis project vertically into the chart until the line intersects the
solid 12 lb/gal curve and the dashed 12 lb/gal curve. At the intersection point from each of these curves
project horizontally to read the resistivity for each of the mud filtrate, 1.1 ohmm and mudcake 4.4 ohmm.
Equations
Rm= mud resistivityRmf= mud filtrate resistivity
Rmc= mudcake resistivity
km= Coefficient of the mud
Mud Density Coefficient of the mud
lb/gal kg/m3 km
10 1198 0.847
11 1318 0.708
12 1438 0.584
13 1558 0.488
14 1678 0.41216 1917 0.380
18 2157 0.350
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General
GEN-13
Rmfand Rmccan be calculated using the following equations and the values from the table above.
R= k R.
R= 0.69 R RR.
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General
GEN-14
0.01
0.02
0.03
0.04
0.05
0.06
0.08
0.1
0.2
0.3
0.4
0.5
0.6
0.8
1
2
3
4
5
6
8
10
0.01 0.02 0.04 0.06 0.1 0.2 0.3 0.4 0.6 0.8 1 2 3 4 6 8 10
ResistivityofMudFiltrate,
Rmf
(ohmm
)
Resistivity of Mud, Rm (ohmm)
Estimation of Rmfand Rmc from Rm
ResistivityofMudcake,
Rmc
(ohmm
)
Mud Density
lb/gal kg/m3
10 1198
11 1318
12 1438
13 155814 1678
16 1917
18 2157
Mud Density
lb/gal kg/m3
10 119811 1318
12 1438
13 1558
14 1678
16 1917
18 2157
Rmc
Rmf
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General
GEN-15
Formation Resistivity Factor versus Porosity
Purpose
This chart may be used to determine the formation resistivity factor for a given porosity.
Procedure
To estimate the formation resistivity factor (F) enter the chart on the vertical axis at the appropriate porosity
value. Project this line horizontally until it intersects the desired cementation exponent curve (m) for the rock
type. Project the intersection point vertically to determine the formation resistivity factor (F).
Example
Given
a = 1.0
m = 1.8
= 10 %
Find
Estimate the formation resistivity factor (F).
Answer
From the 10 % point on the vertical axis project horizontally into the chart until the line intersects the m=1.8
curve. At the intersection point project vertically to read the formation resistivity factor of 62 from the
horizontal axis.
Equations
F = formation resistivity factor
a = tortuosity factor
m = cementation exponent = porosity
General equation
F =a
For sandstones
F =0.62
. or F =
0.81
For carbonates
F =1.0
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Spontaneous Potential
SP-1
SP Bed Thickness Correction
Purpose
This chart may be used to correct the spontaneous potential (SP) log for the effects of bed thickness.
Procedure
To estimate the SP correction factor first determine the ratio between the true formation resistivity and the
mud resistivity at the formation temperature. Enter the chart on the vertical axis at the estimated bed
thickness. Units of feet are on the left side of the chart and meters are on the right side of the chart. Project
the line horizontally until it intersects the curve closest to the R t/Rmvalue. Values between the curves can be
interpolated. From the intersection point project vertically down to read the SP correction factor. Multiply
the SP reading from the log by this correction factor to obtain a corrected SP log for bed thickness. Thicker
beds should have less correction effects.
Example
Given
SPLOG= -80 mV
h = 7 feet
Rt= 24 ohmm
Rm= 1.2 ohmm
Find
Estimate the SP corrected for bed thickness.
Answer
Determine the Rt/Rmratio.
R
R=
24 ohm m
1.2 ohm m= 20
Enter the chart on the left vertical axis at 7 feet and project horizontally until the line intersects the Rt/Rm=20
curve. Project this intersection point vertically to the lower axis to obtain an SP correction factor of 1.34.
Multiply the SP reading from the log by the correction factor to obtain a corrected SP reading of -107.2 mV.
SPCORR= SPLOGSPCorreciton Factor
SPCORR= -80 mV 1.34 = -107.2 mV
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Spontaneous Potential
SP-2
4
5
6
7
8
9
10
11
12
13
14
15
20
25
30
1.0
1.5
2.0
2.5
3.0
4.0
5.0
6.0
7.0
8.0
9.0
BedThickness(feet)
BedThickness(meters)
Rt
Rm
5 10 60 15010020 40 80 200
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Spontaneous Potential
SP-3
RweEstimate from Static SP
Purpose
This chart may be used to determine the equivalent water resistivity from the static spontaneous potential
(SSP).
Procedure
To estimate Rwe first enter the chart on the lower axis with the SSP in millivolts. Project this line vertically until
intersecting the appropriate temperature line. Project the intersection of the SSP and temperature line
horizontally to determine the Rmfe/Rweratio. Rwecan be determined by dividing the Rmfecalculated from the
log by the Rmfe/Rweratio.
Example
Given
Rmf= 1.4 ohmm @ 75 F
SSP = -110 mV
Temperature = 150 F
Find
Estimate the Rwe.
Answer
Determine the equivalent mud resisitivity. Since Rmf> 0.1 at 75 F we can use chart GEN 4b to determine the
Rmfat the formation temperature of 150 F. From the chart the Rmfat 150 F is 0.7 ohmm.
Rmfe= 0.85Rmf= 0.85 x 0.7 = 0.595 ohmm
Enter the chart on the horizontal axis at SSP = -110 mV. Project this line vertically until it intersects the 150 F
temperature line. Project this intersection point horizontally to the left to read the Rmfe/Rweratio of 23.
R
R= 23
Input the value of 0.595 ohmm for Rmfeinto the equation and solve for Rweto get 0.0259 ohmm.
R=0.595
23= 0.0259 ohm m
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Spontaneous Potential
SP-4
Equations
If Rmfat 75 F is > 0.1 ohmm then correct Rmfto formation temperature using chart GEN 4band the
equation: Rmfe= 0.85Rmf
If Rmfat 75 F is < 0.1 ohmm then use chart SP 3to find Rmfeat the formation temperature.
SSP = static spontaneous potential
Td= Temperature at formation depth
Rmfe= equivalent mud filtrate resistivity
Rwe= equivalent water resistivity
Static SP calculation with temperature in degrees Fahrenheit
707 460 + T537 RR
Static SP calculation with temperature in degrees Celcius
707 273 + T298 RR
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Spontaneous Potential
SP-6
0.1
0.2
0.5
1
2
5
10
20
50
100
-200.0-150.0-100.0-50.00.050.0100.0
RmfeRwe
Static SP (mV)
Rwe Estimate from Static SP
250
225
200
175
25 15012510075500CFormation Temperature
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Spontaneous Potential
SP-8
0.001 0.002 0.005 0.01 0.02 0.05 0.1 0.2 0.5 1 2 5 10
0.001
0.002
0.005
0.01
0.02
0.05
0.1
0.2
0.5
1
2
5
10
R
esistivityofWater,Rw(ohmm)
Resistivity of Water Equivalent, R (ohmm)
Estimation of Rw from Rwe
500 F
300 F250 F
150 F
400 F
200 F
100 F
75 F
75F
300F
250F
200F
150F
100F
500F
400F
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Induction Array
IAT-1
Induction Array Tool - Invasion Correction Charts
Purpose
These charts may be used to determine the true resistivity, flushed zone resistivity and the diameter of
invasion from the IAT logs. Separate charts are presented for different formation resistivity values and using
different shallow array curves from the IAT tool. The existing charts are all for thick beds with a step profile
invasion.
Procedure
Enter the chart with the ratio of the curves IA30/IA90 on the horizontal axis and the ratio of the IA20/IA90
curves on the vertical axis. The intersection of the two projections determines the diameter of invasion on the
red dashed curves, Rxo/Rton the blue curves and Rt/IA90 on the black curves. If the intersection does not lie
on existing curves then the value may be obtained by interpolating between the two bounding curve values.
Example
Given
IA20 = 50 ohmm
IA30 = 31 ohmm
IA90 = 14 ohmm
Rxo= ohmm
Find
Determine Rt, Rxoand diameter of invasion (Di).
Answer
Calculate the required ratios for the chart:
IA20
IA90=
50 ohm m
14 ohm m= 3.6
IA30
IA90=
31 ohm m
14 ohm m= 2.2
Using the chart IAT 2, as the estimated Rt will be close to 10, enter the chart at 3.6 on the vertical IA20/IA90
axis and project horizontally into the chart. Enter the chart at 2.2 on the horizontal IA30/IA90 axis and project
vertically into the chart.
Using the intersection point, interpolate between the solid black lines to determine the ratio Rt/IA90 = 0.825.
Calculate Rtto be 11.6 ohmm.
R
IA90=
R
14 ohm m= 0.825 R= 11.6 ohm m
Using the intersection point again, interpolate between the solid blue lines to determine the ratio Rxo/Rt= 9.0.
Calculate Rxoto be 104.4 ohmm.
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Induction Array
IAT-2
R
R=
R
11.6 ohm m= 9.0 R= 104.4 ohm m
Using the intersection point again, interpolate between the dashed red lines to determine the diameter of
invasion to be 83 inches.
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Induction Array
IAT-3
1
2
3
4
5
6
7
8
1 1.5 2 2.5 3 3.5
IA20/IA90
IA30/IA90
Induction Array Tool - Invasion Corrections
Rt = 1 ohmm Rxo > Rt
Rxo/Rt
50
4
2
6
8
10
12
15
20
25
30
40
Di = 100"
20"
30"
40"
50"
60
"
70"
80"
90"
Rt/IA90 = 0.75
0.8
1.0
0.85
0.95
0.9
0.975
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Induction Array
IAT-4
1
2
3
4
5
6
7
8
1 1.5 2 2.5 3 3.5
IA20/IA90
IA30/IA90
Induction Array Too - Invasion Corrections
Rt = 10 ohmm Rxo > Rt
2
4
15
25
20
12
30
8
10
40
Rxo/Rt
6
Di = 100"
40"
50"
70"
60"
20"
30"
80"
90"
Rt/IA90 = 0.75
0.8
0.85
0.9
0.95
0.975
1.0
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Induction Array
IAT-5
0.1
1
10
100
0 0.5 1 1.5 2 2.5 3 3.5
IA10/IA90
IA30/IA90
Induction Array Tool - Invasion Corrections
Rt= 1 ohmm
Rxo/RtDi= 100"
Rt/IA90 = 2
50
0.25
2
0.5
1
4
6
8
10
12
15
20
30
90"
30"
40"
20"
50"
60"
70"
80"
20"
90"
50"
80"
70"
60"
40" 30"
100"
0.750.8
0.95
0.9
0.85
0.975
1
1.5
1.05
1.21.1
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Induction Array
IAT-6
1
6
11
16
21
26
31
36
1 1.5 2 2.5 3 3.5
IA10/IA90
IA30/IA90
Induction Array Tool - Invasion Corrections
Rt = 1 ohmm Rxo > Rt
Rxo/RtDi = 100"
Rt/IA9
0 0.975
50
15
20
30
90"
30"
20"
40"
50"
60"
70"
80"
0.95
0.9
0.85
0.8
0.75
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Induction Array
IAT-7
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
IA10/IA90
IA30/IA90
Induction Array Tool - Invasion Corrections
Rt = 1 ohmm Rxo < Rt
Rxo/Rt
Di = 100"
Rt/IA90 = 1.05
0.5
0.25
90"
20"70"
60"
40"30"50"
80"
1.2
1.5
1.1
2
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Induction Array
IAT-8
0.01
0.1
1
10
100
0 0.5 1 1.5 2 2.5 3 3.5
IA10/IA90
IA30/IA90
Induction Array Tool - Invasion Corrections
Rt= 10 ohmm
Rxo/Rt
40
30
25
1
2
8
12
15
20
4
0.067
0.1
0.125
0.25
0.167
0.5
0.083
0.05
Di= 100"
100"90"
90"
70"
50"
40"
80"
30"
30"
20"
60"
20"
40"
50"
60"
70"80"
Rt/IA90 = 2
0.750.8
1
0.975
0.95
0.9
0.85
0.975
11.05
0.95
1.11.2
1.5
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Induction Array
IAT-10
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
IA10/IA90
IA30/IA90
Induction Array Tool - Invasion Corrections
Rt = 10 ohmm Rxo < Rt
0.975 Rt/IA90 = 0.95
Di = 100"
Rxo/Rt
0.5
0.167
0.1
0.125
0.067
0.05
0.25
0.083
90"
70"
20"
80"
30"40"
50"
60"
1.2 11.05
2
1.5
1.1
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Induction Array
IAT-11
0.01
0.1
1
10
0 0.5 1 1.5 2 2.5
IA10/IA90
IA30/IA90
Induction Array Tool - Invasion Corrections
Rt= 100 ohmm
Rxo/Rt
0.25
0.5
0.05
0.067
0.083
0.1
0.125
0.167
1
4
2
100"
Rt/IA90 = 2
90"
20"
30"
40"
50" 60" 70" 80"
20"
70"
30"
60"
40"
50"
80"
Di= 100"
90"
1.5
0.975
1
1.1
1.05
1.2
0.975
0.95
0.95
0.9 0.85
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Induction Array
IAT-12
1
1.5
2
2.5
3
3.5
4
1 1.2 1.4 1.6 1.8 2 2.2
IA10/IA90
IA30/IA90
Induction Array Tool - Invastion Corrections
Rt = 100 ohmm Rxo > Rt
Rxo/Rt4
2
Di = 100"
90"
20"
30"
40"
50"
60"70"
80"
Rt/IA90
1
0.975
0.85
0.9
0.95
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Induction Array
IAT-13
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
IA10/IA90
IA30/IA90
Induction Array Tool - Invasion Corrections
Rt = 100 ohmm Rxo < Rt
Rxo/Rt
0.25
0.067
0.167
0.125
0.1
0.083
0.05
0.5
Di = 100"
Rt/IA90 = 0.95
90"
80"
20"
30"
60"
40"
50"
70"
1.51.2 1.051.1 1 0.975
2
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Dual Laterolog
DLL-1
Dual Laterolog Borehole Corrections
Purpose
This chart may be used to correct the dual laterolog deep and shallow curves for the effect of borehole size.
Procedure
Choose the appropriate chart for the deep (LLD) or shallow (LLS) curve and whether the tool was centralized
or decentralized with standoff. To estimate the correction for borehole size, calculate the ratio of the
appropriate curve resistivity to the mud resistivity and enter the chart on the horizontal axis at this value.
Project vertically until the projection intersects the appropriate borehole diameter line. Interpolate between
the borehole size lines if necessary. At the intersection point project horizontally to read the ratio of the true
resistivity to the dual laterolog resistivity. Multiply the value of this ratio by the dual laterolog resistivity to
determine the borehole size corrected resistivity.
Example
Given
LLD = 24 ohmm
LLS = 22 ohmm
Rm= 0.12 ohmm
dh= 10.0 inches
DLL tool was centralized
Find
Estimate the deep resistivity corrected for borehole size.
Answer
Determine the RLLDto Rmratio from the log parameters.
R
R
=24
0.12= 200
Using the chart for a centralized deep dual laterolog tool (DLL1) enter the horizontal axis at 200 and project
vertically into the chart to the 10 inch borehole size line. Project the intersection point horizontally to the
axis to read 1.037.
Multiply the LLD reading from the log by this correction factor to obtain the borehole corrected reading of
24 ohm m 1.037 = 24.89 ohm m
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Dual Laterolog
DLL-2
0.8
0.9
1
1.1
1.2
1.3
1.4
1.5
1 10 100 1000 10000 100000
Rt
/RLLD
RLLD/Rm
Dual Laterolog Borehole CorrectionsLLD - Centralized
6" Borehole
8" Borehole
10" Borehole
12" Borehole
14" Borehole
16" Borehole
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Dual Laterolog
DLL-4
0.8
0.9
1
1.1
1.2
1.3
1.4
1.5
1 10 100 1000 10000 100000
Rt
/RLLd
RLLD/Rm
Dual Laterolog Borehole CorrectionsLLS - Centralized
8" Borehole
6" Borehole
10" Borehole
12" Borehole
14" Borehole
16" Borehole
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Dual Laterolog
DLL-5
0.8
0.9
1
1.1
1.2
1.3
1.4
1.5
1 10 100 1000 10000 100000
Rt
/RLLd
RLLD/Rm
Dual Laterolog Borehole CorrectionsLLS Eccentered at 1.5" Standoff
6" Borehole
10" Borehole
12" Borehole
14" Borehole
16" Borehole
8" Borehole
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Dual Laterolog
DLL-6
0.2
2
20
200
2000
0.01 0.1 1 10 100 1000 10000
Rt
(ohmm)
Rt/Rm
IAT verses DLL Selection
IAT 4-ft limit
IAT 2-ft limit
IAT
and/or
DLL
DLL
DLL limit
IAT
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Micro-Spherical Focused Log
MSFL-2
0.1
1
10
100
1 10 100 1000
Rmsfl_
corr/
Rmsfl
Rmsfl/Rmc
MSFL Mudcake Thickness Correction
1/2"
3/8"
1/4"
5/8"
7/16"
1/8"
1/16"
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Spectral Gamma Ray
GR-1
Spectral Gamma Ray Borehole Corrections
Purpose
These charts may be used to correct the Spectral Gamma Ray (SGR) outputs for the effect of mud weight and
borehole diameter on the measurements.
Procedure
Use the gamma ray component (K, U, Th) chart for either a decentered or centralized tool. Using the borehole
size on the horizontal axis, project vertically until the projection intersects the appropriate line for the mud
weight in the borehole. Interpolate between the mud weight lines as necessary. At the intersection point,
project horizontally to read the ratio of the corrected gamma ray component (K,U or Th) to the gamma ray
component reading from the log. Multiply the value of this ratio by the SGR component reading from the log
to determine the corrected component reading.
Example
Given
dh= 12 inches
Mud Weight = 10 lb/gal
Klog= 3 %
Eccentered Tool
Find
Estimate the corrected Potassium (K) reading corrected for mudweight and borehole size.
Answer
Use chart GR 1for an eccentered Potassium component from the SGR.
Enter the horizontal axis at 8.75 inches and project vertically into the chart to the 10 lb/gal mud weight line.
Project the intersection point horizontally to the
axis to read 1.235.
Multiply the potassium (K) reading from the log by this correction factor to obtain the corrected potassium
reading of 3.7 %.
K= 3 % 1.235 = 3.705 %
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Spectral Gamma Ray
GR-2
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
1.6
3 4 5 6 7 8 9 10 11 12 13 14 15 16
Kcorr
/Klog
Borehole Diameter (inch)
Spectral Gamma Ray Borehole Correction for PotassiumEccentered Tool
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Spectral Gamma Ray
GR-3
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
1.6
3 4 5 6 7 8 9 10 11 12 13 14 15 16
Ucorr
/Ulog
Borehole Diameter (inch)
Spectral Gamma Ray Borehole Correction for Uranium
Eccentered Tool
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Spectral Gamma Ray
GR-4
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
1.6
3 4 5 6 7 8 9 10 11 12 13 14 15 16
Th
corr
/Thlog
Borehole Diameter (inch)
Spectral Gamma Ray Borehole Correction for Thorium
Eccentered Tool
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Spectral Gamma Ray
GR-5
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
3 4 5 6 7 8 9 10 11 12 13 14 15 16
Kcorr
/Klog
Borehole Diameter (inch)
Spectral Gamma Ray Borehole Correction for Potassium
Centered Tool
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Spectral Gamma Ray
GR-6
0.5
1.0
1.5
2.0
2.5
3.0
3.5
3 4 5 6 7 8 9 10 11 12 13 14 15 16
Ucorr
/Ulog
Borehole Diameter (inch)
Spectral Gamma Ray Borehole Correction for Uranium
Centered Tool
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Spectral Gamma Ray
GR-7
0.5
1.0
1.5
2.0
2.5
3.0
3.5
3 4 5 6 7 8 9 10 11 12 13 14 15 16
Th
corr
/Thlog
Borehole Diameter (inch)
Spectral Gamma Ray Borehole Correction for Thorium
Centered Tool
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Compensated Neutron Log
CNL-1
Compensated Neutron Log (CNL)
Purpose
The Compensated Neutron Log (CNL) response is affected by environmental parameters. These parameters
are related to the tool string configuration, the borehole environment and the formation. The CNL tool
records the raw short space and long space detector counts from which the ratio of these detector counts is
used to calculate the apparent neutron porosity of the formation. Environmental correction factors are then
applied to this uncorrected porosity to produce accurate corrected neutron porosity.
In the Warrior logging software the curve NPHI is the uncorrected neutron porosity. The curve NPHC is
neutron porosity that is corrected for borehole size only.
The Warrior software also produces fully corrected curves for each of the three common formation matrices.
The logging parameters/variables that are input into the Warrior software are the inputs to the corrections
that are applied while logging. These corrected curves are:
NPHL Neutron Porosity Limestone matrix
NPHS Neutron Porosity Sandstone matrix
NPHD Neutron Porosity Dolomite matrix
Using the correction charts the environmental corrections can be applied manually to the uncorrected
porosity. The corrections can also be backed out of the corrected CNL porosity value using the same
correction charts.
The correction charts are specific to the logging environment and the type of neutron source used for logging.
Charts are available for both Americium-241/Beryllium and Californium-252 neutron sources as well as for
Open Hole and Cased Hole wells.
Procedure
The neutron corrections are referenced to the standard conditions indicated by the solid red line on each
chart. The standard conditions for Open Hole are:
Formation Formation Well Temperature Hole Tool
Fluid Fluid Diameter Position
Eccentralized
Limestone Pure Water Pure Water 20 C 8.0" Source
to Wall
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Compensated Neutron Log
CNL-3
e. Borehole Water Relative Density
f. Borehole Fluid Salinity
g. Formation Fluid Salinity
4. Correct the porosity from step 3 for lithology depending on eccentralized or centralized tool.
Example
Given
Open hole well
Californium-252 neutron source
Uncorrected neutron porosity = 31.5%
8.5 inch borehole
100,000 ppm borehole salinity
100,000 ppm formation salinity
100 C borehole temperature
standoff between tool and borehole wallMud density of 1.17 g/cm
3
Mud cake thickness of 0.25 inches
Find
Determine the corrected neutron porosity in both limestone matrix and sandstone matrix from the
parameters given.
Answer
Using chart CNL 1 enter the vertical axis on the Borehole Diameter Correction chart at 8.5 inches. Project the
line horizontally until it intersects the 31.5 % porosity line. Interpolate between the blue curves on either side
of the intersection and follow the general trend back to the red baseline at 31% porosity.
Using the porosity obtained in the step above (31%), enter each of the following charts and record the change
in porosity. Sum the individual porosity changes.
a) Temperature Correction Chart (CNL 2) +2.2 %
b) Stand Off Correction Chart Eccentralized (CNL 3) -0.4 %
c) Borehole Water Relative Density Correction (CNL 5) 0 %
d) Borehole Fluid Salinity Correction Eccentralized (CNL 9) -0.2 %
e) Mud Density Correction (CNL 13) Eccentralized (CNL 13) +0.3 %
f) Mud Cake Thickness Correction Eccentralized (CNL 17) +0.2 %
Sum of Corrections = +2.1 %
Add the sum of the porosities to the Borehole diameter corrected porosity to obtain a porosity to enter into
the next charts.
31 % + 2.1 % = 33.1 %
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Compensated Neutron Log
CNL-4
Using the corrected porosity of 33.1 % enter the Lithology Correction chart on CNL 19. For the Limestone
matrix, follow the blue line straight down to obtain a porosity of 33.1 %. For the Sandstone matrix, follow the
yellow line to obtain a matrix corrected porosity of 38 %.
Using the lithology matrix corrected porosities enter the Formation Fluid Salinity correction chart for theappropriate matrix on page CNL 20.
The corrected neutron porosity on a limestone matrix would be 29.2 % and on a sandstone matrix it would be
33.7 %.
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Compensated Neutron Log
CNL-5
U-FLT CNL009 Californium 252Open Hole Borehole Diameter Correction
6
8
10
12
14
16
-5 0 5 10 15 20 25 30 35 40 45 50 55
BoreholeDiameter[inch]
Porosity [p.u.]
Borehole Diameter Correction
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Compensated Neutron Log
CNL-6
U-FLT CNL009 Californium 252Open Hole Temperature Correction
0
50
100
150
200
-5 0 5 10 15 20 25 30 35 40 45 50 55
ToolTemperature[C]
Porosity [p.u.]
Tool Temperature Correction
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Compensated Neutron Log
CNL-7
U-FLT CNL009 Californium 252Open Hole Standoff Corrections
0
0.5
1
1.5
-5 0 5 10 15 20 25 30 35 40 45 50 55
ToolStandoff[inch]
Porosity [p.u.]
6.0" Borehole Tool Standoff Correction
0
0.5
1
1.5
2
2.5
-5 0 5 10 15 20 25 30 35 40 45 50 55
To
olStandoff[inch]
Porosity [p.u.]
8.0" Borehole Tool Standoff Correction
0
1
2
3
4
-5 0 5 10 15 20 25 30 35 40 45 50 55
ToolStandof
f[inch]
Porosity [p.u.]
10.0" Borehole Tool Standoff Correction
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Compensated Neutron Log
CNL-8
U-FLT CNL009 Californium 252Open Hole Standoff Corrections
0
1
2
3
4
5
-5 0 5 10 15 20 25 30 35 40 45 50 55
ToolStandoff[inch]
Porosity [p.u.]
12.0" Borehole Tool Standoff Correction
0
1
2
3
4
5
6
-5 0 5 10 15 20 25 30 35 40 45 50 55
ToolStandoff[inch]
Porosity [p.u.]
14.0" Borehole Tool Standoff Correction
0
1
2
3
4
5
6
7
-5 0 5 10 15 20 25 30 35 40 45 50 55
ToolStandoff[inch]
Porosity [p.u.]
16.0" Borehole Tool Standoff Correction
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Compensated Neutron Log
CNL-9
U-FLT CNL009 Californium 252Open Hole Borehole Water Relative Density Corrections Eccentralized Tool
0.92
0.94
0.96
0.98
1.00
1.02
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeWaterRelativeDensity[g/cm]
Porosity [p.u.]
6.0" Borehole Water Relative Density Correction
0.92
0.94
0.96
0.98
1.00
1.02
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeW
aterRelativeDensity[g/cm]
Porosity [p.u.]
8.0" Borehole Water Relative Density Correction
0.92
0.94
0.96
0.98
1.00
1.02
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeWaterRelativeDensity[g/cm]
Porosity [p.u.]
10.0" Borehole Water Relative Density Correction
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Compensated Neutron Log
CNL-10
U-FLT CNL009 Californium 252Open Hole Borehole Water Relative Density Corrections Eccentralized Tool
0.92
0.94
0.96
0.98
1.00
1.02
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeWaterRelativeDensity[g/cm]
Porosity [p.u.]
12.0" Borehole Water Relative Density Correction
0.92
0.94
0.96
0.98
1.00
1.02
-5 0 5 10 15 20 25 30 35 40 45 50 55Borehole
WaterRelativeDensity[g/cm]
Porosity [p.u.]
14.0" Borehole Water Relative Density Correction
0.92
0.94
0.96
0.98
1.00
1.02
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeWaterRelativeDensity[g/cm]
Porosity [p.u.]
16.0" Borehole Water Relative Density Correction
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Compensated Neutron Log
CNL-11
U-FLT CNL009 Californium 252Open Hole Borehole Water Relative Density Corrections Centralized Tool
0.92
0.94
0.96
0.98
1.00
1.02
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeWaterRelativeDensity[g/cm]
Porosity [p.u.]
6.0" Borehole Water Relative Density Correction
0.92
0.94
0.96
0.98
1.00
1.02
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeW
aterRelativeDensity[g/cm]
Porosity [p.u.]
8.0" Borehole Water Relative Density Correction
0.92
0.94
0.96
0.98
1.00
1.02
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeWaterRelative
Density[g/cm]
Porosity [p.u.]
10.0" Borehole Water Relative Density Correction
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Compensated Neutron Log
CNL-12
U-FLT CNL009 Californium 252Open Hole Borehole Water Relative Density Corrections Centralized Tool
0.92
0.94
0.96
0.98
1.00
1.02
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeWaterRelativeDensity[g/cm]
Porosity [p.u.]
12.0" Borehole Water Relative Density Correction
0.92
0.94
0.96
0.98
1.00
1.02
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeWaterRelativeDensity[g/cm]
Porosity [p.u.]
14.0" Borehole Water Relative Density Correction
0.92
0.94
0.96
0.98
1.00
1.02
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeWaterRelativeD
ensity[g/cm]
Porosity [p.u.]
16.0" Borehole Water Relative Density Correction
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Compensated Neutron Log
CNL-13
U-FLT CNL009 Californium 252Open Hole Borehole Fluid Salinity Corrections Eccentralized Tool
0
50
100
150
200
250
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeFluidSalinity[kppm]
Porosity [p.u.]
6.0" Borehole Fluid Salinity Correction
0
50
100
150
200
250
-5 0 5 10 15 20 25 30 35 40 45 50 55Boreho
leFluidSalinity[kppm]
Porosity [p.u.]
8.0" Borehole Fluid Salinity Correction
0
50
100
150
200
250
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeFluidSa
linity[kppm]
Porosity [p.u.]
10.0" Borehole Fluid Salinity Correction
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Compensated Neutron Log
CNL-15
U-FLT CNL009 Californium 252Open Hole Borehole Fluid Salinity Corrections Centralized Tool
0
50
100
150
200
250
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeFluidSalinity[kppm]
Porosity [p.u.]
6.0" Borehole Fluid Salinity Correction
0
50
100
150
200
250
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeFluidSalinity[kppm]
Porosity [p.u.]
8.0" Borehole Fluid Salinity Correction
0
50
100
150
200
250
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeFluidSal
inity[kppm]
Porosity [p.u.]
10.0" Borehole Fluid Salinity Correction
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Compensated Neutron Log
CNL-16
U-FLT CNL009 Californium 252Open Hole Borehole Fluid Salinity Corrections Centralized Tool
0
50
100
150
200
250
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeFluidSalinity[kppm]
Porosity [p.u.]
12.0" Borehole Fluid Salinity Correction
0
50
100
150
200
250
-5 0 5 10 15 20 25 30 35 40 45 50 55Boreho
leFluidSalinity[kppm]
Porosity [p.u.]
14.0" Borehole Fluid Salinity Correction
0
50
100
150
200
250
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeFluidSalinity[kppm]
Porosity [p.u.]
16.0" Borehole Fluid Salinity Correction
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Compensated Neutron Log
CNL-17
U-FLT CNL009 Californium 252Open Hole Borehole Mud Density Corrections Eccentralized Tool
1
1.1
1.2
1.3
1.4
1.5
-5 0 5 10 15 20 25 30 35 40 45 50 55
BoreholeMudDensity[g/cc]
Porosity [p.u.]
6.0" Borehole Mud Density Correction
1
1.1
1.2
1.3
1.4
1.5
-5 0 5 10 15 20 25 30 35 40 45 50 55
BoreholeMudDensity[g/cc]
Porosity [p.u.]
8.0" Borehole Mud Density Correction
1
1.1
1.2
1.3
1.4
1.5
-5 0 5 10 15 20 25 30 35 40 45 50 55
BoreholeMudDe
nsity[g/cc]
Porosity [p.u.]
10.0" Borehole Mud Density Correction
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Compensated Neutron Log
CNL-18
U-FLT CNL009 Californium 252Open Hole Borehole Mud Density Corrections Eccentralized Tool
1
1.1
1.2
1.3
1.4
1.5
-5 0 5 10 15 20 25 30 35 40 45 50 55
BoreholeMudDensity[g/cc]
Porosity [p.u.]
12.0" Borehole Mud Density Correction
1
1.1
1.2
1.3
1.4
1.5
-5 0 5 10 15 20 25 30 35 40 45 50 55
BoreholeMudDensity[g/cc]
Porosity [p.u.]
14.0" Borehole Mud Density Correction
1
1.1
1.2
1.3
1.4
1.5
-5 0 5 10 15 20 25 30 35 40 45 50 55
BoreholeMudDe
nsity[g/cc]
Porosity [p.u.]
16.0" Borehole Mud Density Correction
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Compensated Neutron Log
CNL-19
U-FLT CNL009 Californium 252Open Hole Borehole Barite Mud Density Corrections Eccentralized Tool
1
1.2
1.4
1.6
1.8
2
-5 0 5 10 15 20 25 30 35 40 45 50 55
BoreholeMudDensity[g/cc]
Porosity [p.u.]
6.0" Borehole Barite Mud Density Correction
1
1.2
1.4
1.6
1.8
2
-5 0 5 10 15 20 25 30 35 40 45 50 55
BoreholeMudDensity[g/cc]
Porosity [p.u.]
8.0" Borehole Barite Mud Density Correction
1
1.2
1.4
1.6
1.8
2
-5 0 5 10 15 20 25 30 35 40 45 50 55
BoreholeMudDe
nsity[g/cc]
Porosity [p.u.]
10.0" Borehole Barite Mud Density Correction
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Compensated Neutron Log
CNL-20
U-FLT CNL009 Californium 252Open Hole Borehole Barite Mud Density Corrections Eccentralized Tool
1
1.2
1.4
1.6
1.8
2
-5 0 5 10 15 20 25 30 35 40 45 50 55
BoreholeMudDensity[g/cc]
Porosity [p.u.]
12.0" Borehole Barite Mud Density Correction
1.0
1.2
1.4
1.6
1.8
2.0
-5 0 5 10 15 20 25 30 35 40 45 50 55
BoreholeMudDensity[g/cc]
Porosity [p.u.]
14.0" Borehole Barite Mud Density Correction
1
1.2
1.4
1.6
1.8
2
-5 0 5 10 15 20 25 30 35 40 45 50 55
BoreholeMudDe
nsity[g/cc]
Porosity [p.u.]
16.0" Borehole Barite Mud Density Correction
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Compensated Neutron Log
CNL-21
U-FLT CNL009 Californium 252Open Hole Borehole Mud Cake Thickness Corrections Eccentralized Tool
0
5
10
15
20
25
-5 0 5 10 15 20 25 30 35 40 45 50 55
MudcakeThickness[mm]
Porosity [p.u.]
6.0" Borehole Mudcake Thickness Correction
0
5
10
15
20
25
-5 0 5 10 15 20 25 30 35 40 45 50 55
Mudc
akeThickness[mm]
Porosity [p.u.]
8.0" Borehole Mudcake Thickness Correction
0
5
10
15
20
25
-5 0 5 10 15 20 25 30 35 40 45 50 55
MudcakeThick
ness[mm]
Porosity [p.u.]
10.0" Borehole Mudcake Thickness Correction
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Compensated Neutron Log
CNL-22
U-FLT CNL009 Californium 252Open Hole Borehole Mud Cake Thickness Corrections Eccentralized Tool
0
5
10
15
20
25
-5 0 5 10 15 20 25 30 35 40 45 50 55
MudcakeThickness[mm]
Porosity [p.u.]
12.0" Borehole Mudcake Thickness Correction
0
5
10
15
20
25
-5 0 5 10 15 20 25 30 35 40 45 50 55
MudcakeThickness[mm]
Porosity [p.u.]
14.0" Borehole Mudcake Thickness Correction
0
5
10
15
20
25
-5 0 5 10 15 20 25 30 35 40 45 50 55
MudcakeThick
ness[mm]
Porosity [p.u.]
16.0" Borehole Mudcake Thickness Correction
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Compensated Neutron Log
CNL-23
U-FLT CNL009 Californium 252Open Hole Lithology Correction
0
50
100
-5 0 5 10 15 20 25 30 35 40 45 50 55
FormationComposition[%]
Porosity [p.u.]
Lithology Correction
Limestone
SandstoneDolomite
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Compensated Neutron Log
CNL-24
U-FLT CNL009 Californium 252Open Hole Formation Fluid Salinity Corrections
0
50
100
150
200
250
300
-5 0 5 10 15 20 25 30 35 40 45 50 55
FormationFluidSalinity[kppm]
Porosity [p.u.]
Limestone Formation Fluid Salinity Correction
0
50
100
150
200
250
300
-5 0 5 10 15 20 25 30 35 40 45 50 55
Format
ionFluidSalinity[kppm]
Porosity [p.u.]
Sandstone Formation Fluid Salinity Correction
0
50
100
150
200
250
300
-5 0 5 10 15 20 25 30 35 40 45 50 55
FormationFluidSa
linity[kppm]
Porosity [p.u.]
Dolomite Formation Fluid Salinity Correction
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Compensated Neutron Log
CNL-25
U-FLT CNL009 Californium 252
Cased Hole Corrections - General
0
1
-5 0 5 10 15 20 25 30 35 40 45 50 55
OH
=0;CH
=1
Porosity [p.u.]
Open Hole to Cased Hole Correction
4
6
8
10
12
14
-5 0 5 10 15 20 25 30 35 40 45 50 55
C
asingOD
[inch]
Porosity [p.u.]
Eccentralized Tool Casing OD Correction
4
6
8
10
12
14
-5 0 5 10 15 20 25 30 35 40 45 50 55
CasingOD
[inch]
Porosity [p.u.]
Centralized Tool Casing OD Correction
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Compensated Neutron Log
CNL-26
U-FLT CNL009 Californium 252
Cased Hole Corrections General
0
50
100
150
200
-5 0 5 10 15 20 25 30 35 40 45 50
ToolTemperature[C]
Porosity [p.u.]
Tool Temperature Correction
0
50
100
-5 0 5 10 15 20 25 30 35 40 45 50 55ToolP
osition[Eccentr.=0]
Porosity [p.u.]
Tool Position Correction (Tool Eccentralized/Centralized in Borehole)
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Compensated Neutron Log
CNL-27
U-FLT CNL009 Californium 252Cased Hole Corrections Casing Thickness Eccentralized
0.2
0.25
0.3
0.35
0.4
0.45
0.5
-5 0 5 10 15 20 25 30 35 40 45 50 55
Casing
Thickness[inch]
Porosity [p.u.]
4.5" Casing OD - Casing Thickness Correction
0.2
0.25
0.3
0.35
0.4
0.45
0.5
-5 0 5 10 15 20 25 30 35 40 45 50 55
Casi
ngThickness[inch]
Porosity [p.u.]
5.5" Casing OD - Casing Thickness Correction
0.2
0.25
0.3
0.35
0.4
0.45
0.5
-5 0 5 10 15 20 25 30 35 40 45 50 55
Casing
Thickness[inch]
Porosity [p.u.]
7.0" Casing OD - Casing Thickness Correction
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Compensated Neutron Log
CNL-28
U-FLT CNL009 Californium 252Cased Hole Corrections Casing Thickness - Eccentralized
0.2
0.25
0.3
0.35
0.4
0.45
0.5
-5 0 5 10 15 20 25 30 35 40 45 50 55
CasingThickness[inch]
Porosity [p.u.]
9.625" Casing OD - Casing Thickness Correction
0.2
0.25
0.3
0.35
0.4
0.45
0.5
-5 0 5 10 15 20 25 30 35 40 45 50 55
Cas
ing
Thickness[inch]
Porosity [p.u.]
10.75" Casing OD - Casing Thickness Correction
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Compensated Neutron Log
CNL-29
U-FLT CNL009 Californium 252
Cased Hole Corrections Cement Thickness - Eccentralized
0.1875
0.6875
1.1875
1.6875
2.1875
-5 0 5 10 15 20 25 30 35 40 45 50 55
CementThickness[inch]
Porosity [p.u.]
4.5" Casing OD - Cement Thickness Correction
0.1875
0.6875
1.1875
1.6875
2.1875
-5 0 5 10 15 20 25 30 35 40 45 50 55
CementThickness[inch]
Porosity [p.u.]
5.5" Casing OD - Cement Thickness Correction
0.1875
0.6875
1.1875
1.6875
2.1875
-5 0 5 10 15 20 25 30 35 40 45 50 55
CementThickn
ess[inch]
Porosity [p.u.]
7.0" Casing OD - Cement Thickness Correction
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Compensated Neutron Log
CNL-30
U-FLT CNL009 Californium 252
Cased Hole Corrections Cement Thickness - Eccentralized
0.1875
0.6875
1.1875
1.6875
2.1875
-5 0 5 10 15 20 25 30 35 40 45 50 55
CementThickness[inch]
Porosity [p.u.]
9.625" Casing OD - Cement Thickness Correction
0.1875
0.6875
1.1875
1.6875
2.1875
-5 0 5 10 15 20 25 30 35 40 45 50 55
CementThickness[inch]
Porosity [p.u.]
10.75" Casing OD - Cement Thickness Correction
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Compensated Neutron Log
CNL-31
U-FLT CNL009 Californium 252Cased Hole Corrections Borehole Water Relative Density - Eccentralized
0.92
0.94
0.96
0.98
1.00
1.02
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeWaterRelativeDensity[g/cm]
Porosity [p.u.]
4.5" Casing OD - Borehole Water Relative Density Correction
0.92
0.94
0.96
0.98
1.00
1.02
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeW
aterRelativeDensity[g/cm]
Porosity [p.u.]
5.5" Casing OD - Borehole Water Relative Density Correction
0.92
0.94
0.96
0.98
1.00
1.02
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeWaterRelative
Density[g/cm]
Porosity [p.u.]
7.0" Casing OD - Borehole Water Relative Density Correction
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Compensated Neutron Log
CNL-33
U-FLT CNL009 Californium 252Cased Hole Corrections Borehole Fluid Salinity Eccentralized
0
50
100
150
200
250
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeFluidSalinity[kppm]
Porosity [p.u.]
4.5" Casing OD - Borehole Fluid Salinity Correction
0
50
100
150
200
250
-5 0 5 10 15 20 25 30 35 40 45 50 55Borehole
FluidSalinity[kppm]
Porosity [p.u.]
5.5" Casing OD - Borehole Fluid Salinity Correction
0
50
100
150
200
250
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeFluidSalinity[kppm]
Porosity [p.u.]
7.0" Casing OD - Borehole Fluid Salinity Correction
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Compensated Neutron Log
CNL-34
U-FLT CNL009 Californium 252Cased Hole Corrections Borehole Fluid Salinity Eccentralized
0
50
100
150
200
250
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeFluidSalinity[kppm]
Porosity [p.u.]
9.625" Casing OD - Borehole Fluid Salinity Correction
0
50
100
150
200
250
-5 0 5 10 15 20 25 30 35 40 45 50 55Borehol
eFluidSalinity[kppm]
Porosity [p.u.]
10.75" Casing OD - Borehole Fluid Salinity Correction
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Compensated Neutron Log
CNL-36
U-FLT CNL009 Californium 252Cased Hole Corrections Formation Fluid Salinity Eccentralized
0
50
100
150
200
250
-5 0 5 10 15 20 25 30 35 40 45 50 55FormationFluidSalinity[kppm]
Porosity [p.u.]
9.625" Casing OD - Formation Fluid Salinity Correction
0
50
100
150
200
250
-5 0 5 10 15 20 25 30 35 40 45 50 55Formatio
nFluidSalinity[kppm]
Porosity [p.u.]
10.75" Casing OD - Formation Fluid Salinity Correction
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Compensated Neutron Log
CNL-37
U-FLT CNL009 Californium 252Cased Hole Corrections Casing Thickness - Centralized
0.2
0.25
0.3
0.35
0.4
0.45
0.5
-5 0 5 10 15 20 25 30 35 40 45 50 55
CasingThickness[inch]
Porosity [p.u.]
4.5" Casing OD - Casing Thickness Correction
0.2
0.25
0.3
0.35
0.4
0.45
0.5
-5 0 5 10 15 20 25 30 35 40 45 50 55
Casing
Thickness[inch]
Porosity [p.u.]
5.5" Casing OD - Casing Thickness Correction
0.2
0.25
0.3
0.35
0.4
0.45
0.5
-5 0 5 10 15 20 25 30 35 40 45 50 55
Casing
Thickn
ess[inch]
Porosity [p.u.]
7.0" Casing OD - Casing Thickness Correction
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Compensated Neutron Log
CNL-38
U-FLT CNL009 Californium 252Cased Hole Corrections Casing Thickness - Centralized
0.2
0.25
0.3
0.35
0.4
0.45
0.5
-5 0 5 10 15 20 25 30 35 40 45 50 55
CasingThickness[inch]
Porosity [p.u.]
9.625" Casing OD - Casing Thickness Correction
0.2
0.25
0.3
0.35
0.4
0.45
0.5
-5 0 5 10 15 20 25 30 35 40 45 50 55
Casing
Thickness[inch]
Porosity [p.u.]
10.75" Casing OD - Casing Thickness Correction
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Compensated Neutron Log
CNL-40
U-FLT CNL009 Californium 252
Cased Hole Corrections Cement Thickness Centralized
0.1875
0.6875
1.1875
1.6875
2.1875
-5 0 5 10 15 20 25 30 35 40 45 50 55
CementThickness[inch]
Porosity [p.u.]
9.625" Casing OD - Cement Thickness Correction
0.1875
0.6875
1.1875
1.6875
2.1875
-5 0 5 10 15 20 25 30 35 40 45 50 55
CementThickness[inch]
Porosity [p.u.]
10.75" Casing OD - Cement Thickness Correction
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Compensated Neutron Log
CNL-41
U-FLT CNL009 Californium 252Cased Hole Corrections Borehole Water Relative Density - Centralized
0.92
0.94
0.96
0.98
1.00
1.02
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeWaterRelativeDensity[g/cm]
Porosity [p.u.]
4.5" Casing OD - Borehole Water Relative Density Correction
0.92
0.94
0.96
0.98
1.00
1.02
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeW
aterRelativeDensity[g/cm]
Porosity [p.u.]
5.5" Casing OD - Borehole Water Relative Density Correction
0.92
0.94
0.96
0.98
1.00
1.02
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeWaterRelative
Density[g/cm]
Porosity [p.u.]
7.0" Casing OD - Borehole Water Relative Density Correction
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Compensated Neutron Log
CNL-42
U-FLT CNL009 Californium 252Cased Hole Corrections Borehole Water Relative Density - Centralized
0.92
0.94
0.96
0.98
1.00
1.02
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeWaterRelativeDensity[g/cm]
Porosity [p.u.]
9.625" Casing OD - Borehole Water Relative Density Correction
0.92
0.94
0.96
0.98
1.00
1.02
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeW
aterRelativeDensity[g/cm]
Porosity [p.u.]
10.75" Casing OD - Borehole Water Relative Density Correction
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Compensated Neutron Log
CNL-43
U-FLT CNL009 Californium 252Cased Hole Corrections Borehole Fluid Salinity Centralized
0
50
100
150
200
250
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeFluidSalinity[kppm]
Porosity [p.u.]
4.5" Casing OD - Borehole Fluid Salinity Correction
0
50
100
150
200
250
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeFluidSalinity[kppm]
Porosity [p.u.]
5.5" Casing OD - Borehole Fluid Salinity Correction
0
50
100
150
200
250
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeFluidSalinity[kppm]
Porosity [p.u.]
7.0" Casing OD - Borehole Fluid Salinity Correction
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Compensated Neutron Log
CNL-44
U-FLT CNL009 Californium 252Cased Hole Corrections Borehole Fluid Salinity Centralized
0
50
100
150
200
250
-5 0 5 10 15 20 25 30 35 40 45 50 55BoreholeFluidSalinity[kppm]
Porosity [p.u.]
9.625" Casing OD - Borehole Fluid Salinity Correction
0
50
100
150
200
250
-5 0 5 10 15 20 25 30 35 40 45 50 55Borehole
FluidSalinity[kppm]
Porosity [p.u.]
10.75" Casing OD - Borehole Fluid Salinity Correction
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Compensated Neutron Log
CNL-47
U-FLT CNL009 Californium 252Cased Hole Lithology Corrections
0
50
100
-5 0 5 10 15 20 25 30 35 40 45 50 55FormationComposition[%]
Porosity [p.u.]
Eccentralized Tool Lithology Correction
Limestone
SandstoneDolomite
0
50
100
-5 0 5 10 15 20 25 30 35 40 45 50 55Forma
tionComposition[%]
Porosity [p.u.]
Centralized Tool Lithology CorrectionLimestone
Sandstone
Dolomite
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Porosity
POR-1
Determination of Density Porosity from Bulk Density
Purpose
This chart may be used to estimate the density porosity given the bulk log density, formation fluid density and
the formation matrix.
Procedure
To estimate the density porosity (D) enter the chart on the horizontal axis at the appropriate bulk density
(B) value as read from the log. Project this line vertically until it intersects the desired matrix curve. Project
the intersection point horizontally to determine the density porosity from the vertical axis.
Example
Given
B= 6.2 g/cm3
f= 1.0 g/cm3
Find
Estimate the density porosity on a limestone matrix.
Answer
From the 6.2 g/cm3 point on the horizontal axis project vertically into the chart until the line intersects the
limestone matrix curve (2.710 g/cm3). At the intersection point project horizontally to read the density
porosity on a limestone matrix of 5 p.u.
Equations
B= log bulk density
f= fluid density in formation
ma= matrix density
D = density porosity
The density porosity can be calculated using the following equation. The result will be in porosity units.
= 100
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Porosity
POR-2
-10
-5
0
5
10
15
20
25
30
35
40
45
50
1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9
DensityPorosity,
D
(p.u.)
Log Density, B (g/cm3)
Density Porosity from Bulk Density
f = 1.0 g/cm3
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Porosity
POR-3
Determination of Density Porosity and Lithology from LDT Log
Purpose
This chart may be used to estimate the density porosity and the lithology of a formation from the Litho-
Density Tool (LDT). There are separate charts for both fresh water (f=1.0) and salt water (f=1.1)
Procedure
Choose the appropriate chart for either fresh (POR 2) or salt water (POR 3) formations. To estimate the
density porosity (D) and lithology enter the chart on the vertical axis at the appropriate bulk density (B)
value as read from the log. Enter the chart on the horizontal axis at the Pe value as read from the log and
project vertically. At the intersection of the two projections read the porosity and lithology.
Example
Given
B= 2.72 g/cm3
Pe = 3.05
f= 1.0 g/cm3
Find
Estimate the density porosity and lithology.
Answer
From the Pe = 3.05 point on the horizontal axis project vertically into the chart until the line intersects the
horizontal projection of the bulk density B = 2.72. At the intersection point read the density porosity and
lithology in this instance to be a Dolomite with a porosity of 8.3 %.
Equations
B= log bulk density
f= fluid density in formation
ma= matrix density
D = density porosity
Pe = photoelectric factor
Uf= fluid volumetric photoelectric factor
The bulk density can be calculated using the following equation.
= + (1 )
The Pe is calculated using the following equation.
Where:
Uf= 0.398 barns/cm3for fresh water
Uf= 1.36 barns/cm3for salt water
Pe = ( U) + (1 )(Pe )
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Porosity
POR-4
1.9
2.0
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
3.0
0 1 2 3 4 5 6
LogDensity,B
(g/cm3)
Photoelectric Factor, Pe (barns/electron)
Porosity and Lithology from LDT Log
f = 1.0 g/cm3
45
45
45
35
40
40
40
30
35
3525
30
30
20
25
25
0
5
15
20
20
10
15
15
5
10
10
10
5
50
0
0
0
5
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Porosity
POR-6
Mineral Identification Plot (maavs Umaa)
Purpose
This chart may be used to identify formation mineralogy from the apparent matrix density and the apparent
matrix volumetric photoelectric factor.
Procedure
To estimate the mineral type, enter the chart on the vertical axis at the apparent matrix density ( maa) value.
Enter the chart on the horizontal axis at the apparent matrix volumetric photoelectric factor (Umaa) and project
vertically. At the intersection of the two projections determine the percentage of the component minerals.
Note
The effect of gas and barite is to shift the intersection point in the direction shown by the arrows.
A proportionality triangle may be constructed from any three minerals.
Example
Given
maa= 2.73 g/cm3
Umaa= 7.4
Find
Estimate the mineral composition of the formation.
Answer
From the Umaa= 7.4 point on the horizontal axis project vertically into the chart until the line intersects the
horizontal projection of the maa= 2.73. From the intersection point within the triangular area we can see that
the formation is mainly a mixture of sandstone and dolomite.
To obtain more accurate values of the three mineral compositions we can project the intersection point
parallel to the individual mineral component lines to intersect the outer boundaries of the mineral triangle.
The percentage of the individual components is read from the scale on the outer lines. The formation is this
example is approximately 53% sandstone, 33% dolomite and 14% limestone.
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Porosity
POR-7
Equations
log= log bulk density
f= fluid density in formation
f= 1.0 g/cm3for fresh water
f= 1.1 g/cm3for salt water
maa= apparent matrix density
= apparent formation porosity
Pe = photoelectric factor
Uf= fluid volumetric photoelectric factor
Uf= 0.398 barns/cm3for fresh water
Uf= 1.36 barns/cm3for salt water
The apparent matrix density can be calculated using the equation:
= ( ( )(1 )
The apparent volumetric photoelectric factor can be calculated using the equation:
U = (Pe ) ( U)(1 )
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Porosity
POR-8
2.3
2.4
2.5
2.6
2.7
2.8
2.9
3.0
4 5 6 7 8 9 10 11 12 13 14 15 16 17
ApparentMatrixDensity,maa
(g/cm3)
Apparent Matrix Volumetric Photoelectric Factor, Umaa
Mineral Identification Plot (maavs Umaa
)
Dolomite
Limestone
Sandstone
Gypsum
Anhydrite
2.0
2.1
9 10 11 12
Orthoclase
Illite
Glauconite
Muscovite Barite
Gas
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Porosity
POR-10
140 150 160 170 180 190 200 210 220
2.3
2.4
2.5
2.6
2.7
2.8
2.9
3.0
40 45 50 55 60 65 70
ApparentMatrixDensity,maa
(g/cm3)
Apparent Matrix Interval Transit Time, tmaa (sec/ft)
Mineral Identification Plot (maavs tmaa
)
Dolomite
Limestone
Sandstone
Gypsum
Anhydrite
Orthoclase
Muscovite
65 70
2.1
2.0
65 70
2.1
2.0
Apparent Matrix Interval Transit Time, tmaa (sec/m)
65 70
2.1
2.0
65 70
2.1
2.0
65 70
2.1
2.0
65 70
2.1
2.0
65 70
2.1
2.0
65 70
2.1
2.0
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Acoustic
CBL-1
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Crossplot
XPL-1
Porosity and Lithology Determination
Compensated Neutron and Litho-Density Tool
PurposeThese charts may be used to determine the crossplot porosity and lithology mixture of a formation using the
compensated neutron and litho-density logs. Separate charts are presented for both the bulk density and the
density porosity verses the neutron porosity.
Charts for fresh water (f=0, Cf= 0 ppm) and saline fluids (f=1.19, Cf=250 kppm) are available.
Procedure
Enter the chart on the horizontal axis at the apparent limestone neutron porosity and project vertically to
intersect the projection of the bulk density from the vertical axis. The intersection of the two projections
determines the crossplot porosity and lithology mix.
The crossplot porosity is read by drawing a line between matching porosity scales on each of the two lithology
curves.
If the intersection point is between two of the lithology curves then the formation is a mixture of those two
lithologies. The position of the point between the two mineral curves relates the composition percentage of
each mineral by proportioning the composition based on how close the plotted point is to each line. If the line
is closer to one mineral line then there is a greater percentage of that mineral in the composition.
This chart works for formations with up to two mineral compositions. Possible mineral compositions may be:
quartz calcite
quartz dolomite
dolomite calcite
Example
Given
f= 1.0 g/cm3
Cf= 0 ppm
N= 16 % on a limestone matrix
B= 2.36 g/cm3
Find
Determine the crossplot porosity and the lithology mix.
Answer
On the XPL 1 chart project vertically from 16 % porosity on the horizontal axis to intersect the 2.38 g/cm3
projection from the vertical bulk density axis.
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Crossplot
XPL-2
The intersection point lies between the sandstone and limestone curves on the chart as well as between the
sandstone and dolostone curves. The lithology could then be either sandstone and limestone or sandstone
and dolomite.
To determine the crossplot porosity and lithology mix requires that a line be drawn between the sameporosity on the sandstone and limestone curves if the minerals are quartz and calcite (shown by a dashed line)
or between the sandstone and dolostone curves if the minerals are quartz and dolomite (shown by a dotted
line).
If the mineral composition is sandstone and limestone then the crossplot porosity for this example would be
18.5 % with a lithology mix of approximately 63 percent quartz and 37 percent calcite.
If the mineral composition is sandstone and dolostone then the crossplot porosity would be 19 % with a
lithology mix of approximately 84 percent quartz and 16 percent dolomite.
Note
Formation salinity is the total salinity not only the chlorides (typically entered on a mud report).
For NaCl: Total salinity = Chlorides x 1.657
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Crossplot
XPL-3
Anhydrite
Salt
1.8
1.9
2.0
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
3.0
-5 0 5 10 15 20 25 30 35 40 45 50
Logdensity,
rB
(g/cm3)
CNL Apparent Limestone Porosity,FN (p.u.)
Bulk Density Log and Compensated Neutron Porosity
50
50
45
45
40
40
40
35
35
35
25
30
30
30
25
25
20
10
20
20
15
15
15
10
10
5
0 5
5
0
50
50
45
45
40
40
40
35
35
35
25
30
30
30
25
25
20
10
20
20
15
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5
0 5
5
0
50
50
45
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35
35
35
25
30
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30
25
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20
15
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5
0 5
5
0
50
50
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40
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35
35
25
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30
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0 5
5
0
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0 5
5
0
50
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40
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35
35
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25
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25
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5
0 5
5
0
50
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0 5
5
0
50
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5
0 5
0
5
0
rf = 1.0 g/cm3
Cf = 0 kppm
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Crossplot
XPL-4
Anhydrite
Salt
-20
-15
-10
-5
0
5
10
15
20
25
30
35
40
45
50
-5 0 5 10 15 20 25 30 35 40 45 50
Den
sityPorosityinLimestoneUnits,FD(
p.u.)
CNL Apparent Limestone Porosity,FN (p.u.)
Litho-Density Porosity and Compensated Neutron Porosity
rf = 1.0 g/cm3
Cf = 0 kppm
0
20
5
5
5
0
0
50
45
40
35
30
25
20
15
10
10
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20
25
30
35
40
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45
40
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10
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