8/19/2019 Oil Shale Formation Evaluation by Well Logs and Core Measurement

1/17

 AMSO: Alan Burnham, Roger Day

TOTAL: Pierre AllixSchlumberger: Malka Machlus, Michael Herron, James Grau

Nikita Seleznev, Gabriela Leu, Peter Hook

Oil Shale Formation Evaluation by Well Logs and Core Measurements 

"#$%&' ()%*+$%&,

-./)01$%&,%&23#)) "%4%5&./

651$&*7,%8 95445./04%:4

8/19/2019 Oil Shale Formation Evaluation by Well Logs and Core Measurement

2/17

Volumetrics – Density Porosity, Resistivity, Magnetic Resonance 

total mineral matter

water

kerogen

Composition – Capture Spectroscopy  

common inorganic minerals (quartz, calcite, illite . . .)

unusual inorganic minerals (dawsonite, nahcolite . . .)

total organic carbon

Geology - Microimager  

fracturesvugs

slumps

Objectives of Oil Shale Well Logging 

8/19/2019 Oil Shale Formation Evaluation by Well Logs and Core Measurement

3/17

50 ft

black=albite

Oil Shale Well Log Montage 

8/19/2019 Oil Shale Formation Evaluation by Well Logs and Core Measurement

4/17

Volumetrics – Density Porosity, Resistivity, Magnetic Resonance 

total mineral matter

water (& salinity)

kerogen

Composition – Capture Spectroscopy  

common inorganic minerals (quartz, calcite, illite . . .)unusual inorganic minerals (dawsonite, nahcolite . . .)

total organic carbon

Geology - Microimager  

fractures

vugs

slumps

Objectives of Oil Shale Well Logging 

8/19/2019 Oil Shale Formation Evaluation by Well Logs and Core Measurement

5/17

ma bD w k

ma f 

! " !#   = = #   + #

! " !Density Porosity

ma! = matrix (grain) density (~ 2.7 g/cc)

b! = bulk (measured) density

f ! = fluid (water+kerogen) density (~1 g/cc)

D!

w!

k!

= porosity measured by density tool

= volume fraction kerogen

= volume fraction water

Gamma-Gamma Density Log

Measures Sum of Water + Kerogen 

8/19/2019 Oil Shale Formation Evaluation by Well Logs and Core Measurement

6/17

   M  a

  g  n  e   t   i  c   R  e  s  o  n  a  n  c  e   S   i  g  n  a   l 

Measurement Time

Measurement Dead Time

waterkerogen

200 !s 2 s

Kerogen is Invisible to Magnetic Resonance 

8/19/2019 Oil Shale Formation Evaluation by Well Logs and Core Measurement

7/17

8/19/2019 Oil Shale Formation Evaluation by Well Logs and Core Measurement

8/17

xx00 xx20 xx40 xx60 xx80 x100

0

0.1

0.2

0.3

0.4

0.5

0.6

2020 2040 2060 2080 2100 2120

Density Porosity & Magnetic Resonance Porosity

      P     o

     r     o     s      i      t     y

Depth (ft)100108-03b

bad hole masked Density Porosity

NMR Porosity

Kerogen

   P  o  r  o  s   i   t  y

0.6

0.5

0.4

0.3

0.2

0.1

0

100 feet

8/19/2019 Oil Shale Formation Evaluation by Well Logs and Core Measurement

9/17

0

20

40

60

80

1900 1950 2000 2050 2100

Well Log Kerogen VolumeCore Measured Fischer Assay

   W  e   l   l   L  o  g   K  e  r  o  g  e  n

   V  o   l  u  m  e   (  g  a   l   /   t  o  n   )

Depth (ft) 100829-11b

   C  o  r  e   F   i  s  c   h  e  r   A

  s  s  a  y   (  g  a   l   /   t  o  n   )

xx00 xx50 x100 x150 x200

Depth (ft)

   W  e   l   l    L  o  g   K  e  r  o  g  e  n

   V  o   l  u  m  e   (  g  a   l   /   t  o  n

   )

   C  o  r  e   F   i  s  c   h  e  r   A  s  s  a  y   (  g  a   l   /   t  o  n   )

xx00 xx50 x100 x150 x200

80

60

40

20

0

Well Log Kerogen Volume vs Core Fischer Assay 

8/19/2019 Oil Shale Formation Evaluation by Well Logs and Core Measurement

10/17

[ ]FA TOM 0.019 199=   !

k D MRb

TOM ( )!=   " # "!

;#'5) #+ #= #&% ?%*,/'

,5))#+4 #= #*) @%& '#+ #= #&%

!"#$%&'( *+&,- ./$/ 0/#12334

651%+ A+,*+%%&48 BCDE

F*,0&% GCH

8/19/2019 Oil Shale Formation Evaluation by Well Logs and Core Measurement

11/17

0

20

40

60

80

1900 1950 2000 2050 2100

Well Log Fischer Assay EstimateCore Measured Fischer Assay

   C  o  r  e   F   i  s  c   h  e  r   A  s  s  a  y   (  g  a   l   /   t  o  n   )

Depth (ft) 100829-12b

   W

  e   l   l   L  o  g   F   i  s  c   h  e  r   A  s  s  a  y   E  s   t   i  m  a   t  e   (  g  a   l   /   t  o  n   )

xx00 xx50 x100 x150 x200

Depth (ft)

   F   i  s  c   h  e  r   A  s  s  a  y

   (  g  a   l   /   t  o  n   )

 

80

60

40

20

0

Fischer Assay: Well Log vs Core 

8/19/2019 Oil Shale Formation Evaluation by Well Logs and Core Measurement

12/17

Schlumberger Log Interpretation Chart Gen-6 (2009)

m nw D w t

1

R S Ra

=   !

( a ~ 1, m ~ n ~ 2 )

MRw

DS

  !=

!

MR

2

w tR R= ! @ reservoir temperature T

( 1.1192)

wT 21.5 C

salinity (ppk) 7.976 R (T)10 C 21.5 C

!+ °" #

=   $ % &° + °' (

[Rw] = ohm-meters

fraction of pore

= space that iswater filled

 Archie Law =

Water Salinity from Resistivity & Magnetic Resonance 

8/19/2019 Oil Shale Formation Evaluation by Well Logs and Core Measurement

13/17

 Assume all NaCl is in Pore Water

3 3

3 3 3g(NaCl) g(dry ore) cm (dry ore) cm (rock) g(NaCl)Salinity g(dry ore) g(water)cm (dry ore) cm (rock) cm (water)= =

( )  1

FSAL DWNACL RHGA 1 PIGE WKERPIGE

=   ! " "

Water Salinity Estimate from Geochemical Logging 

8/19/2019 Oil Shale Formation Evaluation by Well Logs and Core Measurement

14/17

Low porosity – low resistivity spike

Mud filtrate salinity = 8 ppk

1400 feet

100108-01

Low porosity – low resistivity spike

80

60

40

20

0

100

Green River Formation Salinity Log 

8/19/2019 Oil Shale Formation Evaluation by Well Logs and Core Measurement

15/17

Low porosity – low resistivity spike

1400 feet

100108-01

Green River Formation Salinity Log

80

60

40

20

0

100

Mud filtrate salinity = 8 ppk

No Communication Between Fresh & Saline Aquifers 

8/19/2019 Oil Shale Formation Evaluation by Well Logs and Core Measurement

16/17

Important information about oil shale deposits can be obtained from

the same tools used in conventional oil and gas reservoirs. These

include measurements of formation density, magnetic resonance

response, electrical resistivity, and capture spectroscopy.

Kerogen responds as part of the pore space to density porosity tools,but is invisible to borehole magnetic resonance. Simple processing

gives kerogen volume and an accurate, depth-continuous estimate

of Fischer Assay.

 A salinity log results from comparing magnetic resonance to formationresistivity. Agreement with a capture spectroscopy estimate is fair.

Summary 

8/19/2019 Oil Shale Formation Evaluation by Well Logs and Core Measurement

17/17

( 1.1192)

wT 21.5 C

salinity(ppk) 7.976 R (T)10 C 21.5 C

!+ °" #

=   $ % &° + °' (

[Rw] = ohm-meters

Schlumberger Log Interpretation Chart Gen-6 (2009)