Introduction to Well Logging
Content
GEOPHYSICAL WELL LOGGING!
Western
Idaho
Basin
(Stanford
Workshop,
2006)
(Baker
Hughes,
2002)
Cuttings
Cuttings = mud log
10
cm
(Rider,
2000)
WELL
COMPLETION
TOOLS
(Ellis
and
Singer,
2007)
TOOLS
(Rider,
2000)
High
porosity,
low
velocity
(PNNL
report,
2002)
(Rider,
2000)
Log
types
(Rider,
2000)
Log
Resolu7on
(averages)
LOG
Source-‐receiver
Minimum
bed
spacing
(cm)
resolu7on
(cm)
Horizontal
resolu7on
(cm)
Gamma-‐ray
-‐-‐
90
10
Density
45
60
12
Resis@vity
(LLD)
80
75
210
Sonic
60
60
2-‐25
(depends
on
λ)
MUD
INVASION
(Rider,
2000)
CALIPER
LOG
POTENTIAL
RESERVOIR!!
(Huenges,
2010)
Caliper
log
–
well
drilled
with
low
salinity
water
6
CAL
16
(inches)
(12”
bit)
Young
shale
Low
porosity
and
permeability
sandstone
High
porosity
and
permeability
limestone
Consolidated
shale,
with
layer
of
smec@te
Halite
Granite
GAMMA
RAY
LOG
(GR)
ELECTROMAGNETIC
SPECTRUM
BOISE
FRONT
Basalt
Sedimentary
rock
succession
Rhyolite
Sedimentary
rock
succession
Rhyolite
SHALE
VOLUME
(Vsh)
GRmin
GRmax
Sedimentary
secGon,
composed
of
sandstone,
carbonates
and
shale.
(Drill
bit
size=
11
inches)
DENSITY
LOG
(RHOB,
CDL,
CDS
DPHI)
Rock and fluid densities
porosity
increases
ρ_water=1
g /cc
ρ_oil_average=0.85
g /cc
(range:
0.2-‐0.9
g /cc)
ρ_salt_water=1.146
g /cc
(200,000
ppm
NaCl)
ρ_methane=0.00068
g /cc
RESISTIVITY LOGS
Fluid saturations
(Baker
Hughes,
2002)
Conductivity vs. salinity
R
(Rider,
2000)
Formation water resistivity (Rw)
(Rider,
2000)
Clay minerals and water
(Rider,
2000)
Formation factor, F
Archie’s Law
(Rider,
2000)
Dual laterologs (LLD, LLS)
(Ellis
and
Singer,
2007)
Rt/RLLD
RLLD/Rxo
Rt/Rxo
RLLD/RLLS
Estimating formation
‘true’ resistivity
SONIC LOG
Sonic log tool
(Baker
Hughes,
2002)
Velocity vs. porosity
(sandstone)
(Batzle
et
al.,
2004)
Velocity vs. porosity
(carbonates)
(Rafavich
et
al.,
1984)
Wyllie’s Equation
(Rider,
2000)
Rock and fluid velocities and travel times
(Rider,
2000)
Sandstone velocity divided into classes
COMPRESSIONAL
VELOCITY
(km/s)
6
b
5
4
φc
3
2
1
0
0.2
0.4
0.6
POROSITY
(frac.)
0.8
1
(Batzle
et
al.,
2004)
Sandstone velocity divided into classes
COMPRESSIONAL
VELOCITY
(km/s)
6
b
V
5
I
4
φc
II
I
Clean
Sandstone
II
Consolidated
Sandstone
III
Weakly
Cemented
IV
Suspensions
V
Fractured
3
2
III
IV
1
0
0.2
0.4
0.6
POROSITY
(frac.)
0.8
1
(Batzle
et
al.,
2004)
Acous@c
Impedance,
AI
(Kg/m2s)
[ρ]:g/cm3
[Vp]:km/s
shale
ρ=2.1,
Vp=2.5
ρ=2.1,
Vp=3.5
ρ=2.3,
Vp=3.7
ϕ=20%
sandstone
ρ=2.36,
Vp=3.8
brine
ρ=2.5,
Vp=3.0
shale
ρ=2.4,
Vp=5.0
limestone
Reflec@on
Coefficient,
Z
AI
(Kg/m2s)
x106
12
5
[ρ]:g/cm3
[Vp]:km/s
-‐
Z
0
+
5.25
shale
ρ=2.1,
Vp=2.5
0.17
7.35
ρ=2.1,
Vp=3.5
0.07
ρ=2.3,
Vp=3.7
ϕ=20%
sandstone
ρ=2.36,
Vp=3.8
8.51
0.03
brine
8.97
-‐0.09
ρ=2.5,
Vp=3.0
shale
7.5
0.23
ρ=2.4,
Vp=5.0
limestone
12
-‐
RC
0
+
AI
CALIPER:
Measures
hole
diameter
(d)
in
inches
GAMMA
RAY:
Measures
natural
radioac=vity
of
rocks
in
API.
DENSITY
(g/cc):
Electron
density
of
rock=mineral+fluid
NEUTRON
Φ
(%,
frac):
Amount
of
hydrogen
in
rocks=water
in
rocks
(~Φ).
Log
is
only
true
Φ
for
water
in
limestone
RESISTIVITY
(ohm-‐m):
Resistance
of
the
rock
to
flow
an
electric
current
ACOUSTIC
OR
SONIC
(μs/V):
Rock
slowness
(=inverse
of
velocity)
If
d
<
drilling
bit
size,
smooth
with
depth
mud
cake.
Permeable
and
porous
rock.
LOW
GR
due
to:
Quartz
sands,
carbonates,
evapora@es
and
coal.
LOW
DENSITY:
high
Φ,
organic
mamer,
coal,
salt
(NaCl)
LOW
NEUTRON:
Low
porosity,
gas
has
low
hydrogen
index
underes@mates
Φ
HIGH
RESISTIVITY:
Oil
and
gas
in
pore
space.
Non-‐porous
rock,
coal,
salt,
anhydrite,
mature
source
rock.
LOW
SLOWNESS
(high
V):
Low
Φ,
salt
anhydrite,
If
d>bit
size
the
rock
has
been
washed-‐out.
Shales,
unconsolidaded.
HIGH
GR
due
to:
Shales,
feldspars,
glauconite,
micas,
marine
organic
mamer
HIGH
DENSITY:
Low
Φ,
anhydrite,
mica
(muscovite),pyrite
HIGH
NEUTRON:
LOW
RESISTIVITY:
High
porosity.
Water
filled
Neutron
“sees”
bound
forma@ons,
shales.
and
free
water,
thus
shales
can
show
high
Φ.
HIGH
SLOWNESS
(low
V):
Coals,
organic
mamer,
high
Φ.
*Shale
compac@on
(scale
1:5000).
Low
compac@on=low
ρ.
*Unconformity
significant
change
in
density
in
shale.
*
Es@mate
TOC
• Density-‐Neutron
crossover
gas.
*Interpret
texture
*Compac@on
*Es@mate
TOC
*If
deep
R
is
high
and
shallow
R
is
low
probably
there
is
oil/
• Density-‐Neutron
gas.
If
both
are
high,
crossplots
lithology
but
equal
non-‐Φ
*
Facies
analysis
Caliper
log
–
well
drilled
with
low
salinity
water
6
CAL
16
(inches)
(12”
bit)
Young
shale
Low
porosity
and
permeability
sandstone
High
porosity
and
permeability
limestone
Consolidated
shale,
with
layer
of
smec@te
Halite
Granite
Sedimentary
secGon,
composed
of
sandstone,
carbonates
and
shale.
(Drill
bit
size=
11
inches)
Clean
sandstone
(or
carbonates)
Shale
Fining
downward
sandstone
mud
cake
washout
Shale
Two
thin
clean
sandstones
(or
carbonates)
“Dirty”
sandstone
Shale
Clean
sandstone
(or
carbonate)
Shale
Fining
upward
sandstone
Western
Idaho
Basin
(Stanford
Workshop,
2006)
(Baker
Hughes,
2002)
Cuttings
Cuttings = mud log
10
cm
(Rider,
2000)
WELL
COMPLETION
TOOLS
(Ellis
and
Singer,
2007)
TOOLS
(Rider,
2000)
High
porosity,
low
velocity
(PNNL
report,
2002)
(Rider,
2000)
Log
types
(Rider,
2000)
Log
Resolu7on
(averages)
LOG
Source-‐receiver
Minimum
bed
spacing
(cm)
resolu7on
(cm)
Horizontal
resolu7on
(cm)
Gamma-‐ray
-‐-‐
90
10
Density
45
60
12
Resis@vity
(LLD)
80
75
210
Sonic
60
60
2-‐25
(depends
on
λ)
MUD
INVASION
(Rider,
2000)
CALIPER
LOG
POTENTIAL
RESERVOIR!!
(Huenges,
2010)
Caliper
log
–
well
drilled
with
low
salinity
water
6
CAL
16
(inches)
(12”
bit)
Young
shale
Low
porosity
and
permeability
sandstone
High
porosity
and
permeability
limestone
Consolidated
shale,
with
layer
of
smec@te
Halite
Granite
GAMMA
RAY
LOG
(GR)
ELECTROMAGNETIC
SPECTRUM
BOISE
FRONT
Basalt
Sedimentary
rock
succession
Rhyolite
Sedimentary
rock
succession
Rhyolite
SHALE
VOLUME
(Vsh)
GRmin
GRmax
Sedimentary
secGon,
composed
of
sandstone,
carbonates
and
shale.
(Drill
bit
size=
11
inches)
DENSITY
LOG
(RHOB,
CDL,
CDS
DPHI)
Rock and fluid densities
porosity
increases
ρ_water=1
g /cc
ρ_oil_average=0.85
g /cc
(range:
0.2-‐0.9
g /cc)
ρ_salt_water=1.146
g /cc
(200,000
ppm
NaCl)
ρ_methane=0.00068
g /cc
RESISTIVITY LOGS
Fluid saturations
(Baker
Hughes,
2002)
Conductivity vs. salinity
R
(Rider,
2000)
Formation water resistivity (Rw)
(Rider,
2000)
Clay minerals and water
(Rider,
2000)
Formation factor, F
Archie’s Law
(Rider,
2000)
Dual laterologs (LLD, LLS)
(Ellis
and
Singer,
2007)
Rt/RLLD
RLLD/Rxo
Rt/Rxo
RLLD/RLLS
Estimating formation
‘true’ resistivity
SONIC LOG
Sonic log tool
(Baker
Hughes,
2002)
Velocity vs. porosity
(sandstone)
(Batzle
et
al.,
2004)
Velocity vs. porosity
(carbonates)
(Rafavich
et
al.,
1984)
Wyllie’s Equation
(Rider,
2000)
Rock and fluid velocities and travel times
(Rider,
2000)
Sandstone velocity divided into classes
COMPRESSIONAL
VELOCITY
(km/s)
6
b
5
4
φc
3
2
1
0
0.2
0.4
0.6
POROSITY
(frac.)
0.8
1
(Batzle
et
al.,
2004)
Sandstone velocity divided into classes
COMPRESSIONAL
VELOCITY
(km/s)
6
b
V
5
I
4
φc
II
I
Clean
Sandstone
II
Consolidated
Sandstone
III
Weakly
Cemented
IV
Suspensions
V
Fractured
3
2
III
IV
1
0
0.2
0.4
0.6
POROSITY
(frac.)
0.8
1
(Batzle
et
al.,
2004)
Acous@c
Impedance,
AI
(Kg/m2s)
[ρ]:g/cm3
[Vp]:km/s
shale
ρ=2.1,
Vp=2.5
ρ=2.1,
Vp=3.5
ρ=2.3,
Vp=3.7
ϕ=20%
sandstone
ρ=2.36,
Vp=3.8
brine
ρ=2.5,
Vp=3.0
shale
ρ=2.4,
Vp=5.0
limestone
Reflec@on
Coefficient,
Z
AI
(Kg/m2s)
x106
12
5
[ρ]:g/cm3
[Vp]:km/s
-‐
Z
0
+
5.25
shale
ρ=2.1,
Vp=2.5
0.17
7.35
ρ=2.1,
Vp=3.5
0.07
ρ=2.3,
Vp=3.7
ϕ=20%
sandstone
ρ=2.36,
Vp=3.8
8.51
0.03
brine
8.97
-‐0.09
ρ=2.5,
Vp=3.0
shale
7.5
0.23
ρ=2.4,
Vp=5.0
limestone
12
-‐
RC
0
+
AI
CALIPER:
Measures
hole
diameter
(d)
in
inches
GAMMA
RAY:
Measures
natural
radioac=vity
of
rocks
in
API.
DENSITY
(g/cc):
Electron
density
of
rock=mineral+fluid
NEUTRON
Φ
(%,
frac):
Amount
of
hydrogen
in
rocks=water
in
rocks
(~Φ).
Log
is
only
true
Φ
for
water
in
limestone
RESISTIVITY
(ohm-‐m):
Resistance
of
the
rock
to
flow
an
electric
current
ACOUSTIC
OR
SONIC
(μs/V):
Rock
slowness
(=inverse
of
velocity)
If
d
<
drilling
bit
size,
smooth
with
depth
mud
cake.
Permeable
and
porous
rock.
LOW
GR
due
to:
Quartz
sands,
carbonates,
evapora@es
and
coal.
LOW
DENSITY:
high
Φ,
organic
mamer,
coal,
salt
(NaCl)
LOW
NEUTRON:
Low
porosity,
gas
has
low
hydrogen
index
underes@mates
Φ
HIGH
RESISTIVITY:
Oil
and
gas
in
pore
space.
Non-‐porous
rock,
coal,
salt,
anhydrite,
mature
source
rock.
LOW
SLOWNESS
(high
V):
Low
Φ,
salt
anhydrite,
If
d>bit
size
the
rock
has
been
washed-‐out.
Shales,
unconsolidaded.
HIGH
GR
due
to:
Shales,
feldspars,
glauconite,
micas,
marine
organic
mamer
HIGH
DENSITY:
Low
Φ,
anhydrite,
mica
(muscovite),pyrite
HIGH
NEUTRON:
LOW
RESISTIVITY:
High
porosity.
Water
filled
Neutron
“sees”
bound
forma@ons,
shales.
and
free
water,
thus
shales
can
show
high
Φ.
HIGH
SLOWNESS
(low
V):
Coals,
organic
mamer,
high
Φ.
*Shale
compac@on
(scale
1:5000).
Low
compac@on=low
ρ.
*Unconformity
significant
change
in
density
in
shale.
*
Es@mate
TOC
• Density-‐Neutron
crossover
gas.
*Interpret
texture
*Compac@on
*Es@mate
TOC
*If
deep
R
is
high
and
shallow
R
is
low
probably
there
is
oil/
• Density-‐Neutron
gas.
If
both
are
high,
crossplots
lithology
but
equal
non-‐Φ
*
Facies
analysis
Caliper
log
–
well
drilled
with
low
salinity
water
6
CAL
16
(inches)
(12”
bit)
Young
shale
Low
porosity
and
permeability
sandstone
High
porosity
and
permeability
limestone
Consolidated
shale,
with
layer
of
smec@te
Halite
Granite
Sedimentary
secGon,
composed
of
sandstone,
carbonates
and
shale.
(Drill
bit
size=
11
inches)
Clean
sandstone
(or
carbonates)
Shale
Fining
downward
sandstone
mud
cake
washout
Shale
Two
thin
clean
sandstones
(or
carbonates)
“Dirty”
sandstone
Shale
Clean
sandstone
(or
carbonate)
Shale
Fining
upward
sandstone
