Geochemical Logging

8/7/2019 Geochemical Logging

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Borehole Elemental Concentration

Logs Now Available: A New Sourceof Geochemistry Data

Michael Herron, Susan Herron, Jim Grau

Schlumberger-Doll Research



Leaps of Science Follow NewAnalytical Capabilities

• Well logging provides more data every day aboutearth formations than all laboratory sources in a

year

• Geochemical well logging is a new analyticalcapability

• Time for earth scientists to address this new

source of data



ECS Tool and Data Processing Flow

AmBe Source

BGO Crystaland PMT

• Logging Speed:Logging Speed:Logging Speed:Logging Speed: 1800 ft/hr1800 ft/hr1800 ft/hr1800 ft/hr• Vertical Resolution:Vertical Resolution:Vertical Resolution:Vertical Resolution: 1.5 ft1.5 ft1.5 ft1.5 ft• Borehole Fluid:Borehole Fluid:Borehole Fluid:Borehole Fluid: AllAllAllAll• Tool Size:Tool Size:Tool Size:Tool Size: 5.0 in O. D.5.0 in O. D.5.0 in O. D.5.0 in O. D.

• Length:Length:Length:Length: 6.6 ft6.6 ft6.6 ft6.6 ft• Maximum Temp:Maximum Temp:Maximum Temp:Maximum Temp: 350350350350 ooooFFFF• Maximum Pressure:Maximum Pressure:Maximum Pressure:Maximum Pressure: 20,000 psi20,000 psi20,000 psi20,000 psi• Min Hole Size:Min Hole Size:Min Hole Size:Min Hole Size: 6.00 in6.00 in6.00 in6.00 in

6.6 ft

Boron Sleeve

Electronics

Heat Sink

Internal

Dewar Flask

AcquisitionAcquisitionAcquisitionAcquisition

Spectral StrippingSpectral StrippingSpectral StrippingSpectral Stripping

SpectroLithSpectroLithSpectroLithSpectroLith

GammaGammaGammaGamma----Ray SpectraRay SpectraRay SpectraRay Spectra

Elemental YieldsElemental YieldsElemental YieldsElemental Yields

Dry Weight ElementsDry Weight ElementsDry Weight ElementsDry Weight ElementsSi, Ca, Fe, S, Ti, GdSi, Ca, Fe, S, Ti, GdSi, Ca, Fe, S, Ti, GdSi, Ca, Fe, S, Ti, Gd

Dry Weight LithologiesDry Weight LithologiesDry Weight LithologiesDry Weight LithologiesClay, Carbonate, Anhydrite, QFMClay, Carbonate, Anhydrite, QFMClay, Carbonate, Anhydrite, QFMClay, Carbonate, Anhydrite, QFM

Oxides ClosureOxides ClosureOxides ClosureOxides Closure



What Do We Measure ?4 MeV neutron interactswith fomation:

Inelastic Interaction(multiple gamma-rays)

Slowing down of neutronthrough multiple scattering

Neutron Capture(multiple gamma-rays)

Gam ma-Ray Spectrum

Energy [MeV]



ECS Gamma-Ray SpectrumInelastic and Capture

H

G d

0 5 0 1 0 0 1 5 0 2 0 0 2 5 0

Ine las t ic

C l

S iF e

LogScal



Capture Gamma-Ray Spectroscopy

20

40

60

Silic Calci Iron Sulf Titani Gadolin

Capture Spectra

n

γ γγ γ

Oxides

0 5

80

100

120

0 2 4 0 1 2 0 1 2 3 0 5 0 1 3

Elemental Concentrations Lithology

Relative

Yields

Elemental Standards

Si

Ca

Fe

S

Closure



ECS SpectroLithDry Weight Lithologies and Elements



200

300

400

500

Open Hole Elemental Concentrations

epth, ft

0 50

600

700

800

900

Silicon wt%

0 20 40Calcium wt%

0 10 20Iron + .14Al wt%

0 10 20Sulfur wt%

0 2 4Titanium wt%

0 20 40Gadolinium ppm

D



200

400

600

800

Open Hole Lithology

0 50 100

1000

1200

1400

1600

Dep

th

Clay, wt%0 50 100

Carbonate, wt%0 50 100Quartz-Feld-Mica, wt%



Instant Petrophysical Evaluation

Nuclear spectroscopySLB exclusive hardwareSLB exclusive hardwareSLB exclusive hardwareSLB exclusive hardware

and interpretationand interpretationand interpretationand interpretation

400

600, ft+

Siliciclastics – Four patented applications

800

1000

De

pt

Lith2.6 3

GDen0.5

Por0.5

Por10

-110

4

Perm Res0 1

Sw

=Real-Time Petrophysics

Wireline & LWD

Triple Combo



SDR Fourier Transform Infrared SpectroscopyQuantitative Mineralogy

• Recognized world-class

• Patented

• Best paper 1997 Society of Core

Analysts



Sample A Qtz Ksp Plag Cal Mg-Cal Dol Sid Py Kaol 2:1 Al clay 2:1 Fe clay Fe-Chl

Actual 25 5 5 5 0 0 0 0 15 20 20 5

Texaco 26 4 3 5 0 0 0 0 16 19 22 5

Vendor 1 68 3 4 5 0 0 0 0 8 0

Vendor 2 44 1 5 2 0.1 0 0.1 23 11

Vendor 3 41 2 3 9 0 0 0 0 36 0

Sample B Qtz Ksp Plag Cal Mg-Cal Dol Sid Py Kaol 2:1 Al clay 2:1 Fe clay Fe-Chl

Actual 30 5 10 5 0 5 0 5 20 10 0 10

Texaco 31 2 8 4 0 4 0 3 21 13 0 10

11

12

9

Commercial XRD and Actual Mineralogy

Vendor 1 56 0 7 3 0 6 0 14 12 1

Vendor 2 34 1 8 3 0 6 0 4 24 18

Vendor 3 52 2 3 13 0 0 0 2 24 0

Sample C Qtz Ksp Plag Cal Mg-Cal Dol Sid Py Kaol 2:1 Al clay 2:1 Fe clay Fe-Chl

Actual 30 10 5 5 5 5 10 0 10 15 0 5

Texaco 30 8 4 5 5 4 10 0 10 16 0 5

Vendor 1 63 3 14 3 0 5 6 0 5 0

Vendor 2 39 2 6 4 0 7 14 0.2 15 10

Vendor 3 37 1 2 8 0 9 19 0 19 0

2

2

5

1

4

5

D. McCarty (Chevron)



True and Estimated Mineral Concentrations

0

5

10

Quartz Opal-A Ortho. Olig. Calcite Dolomite Pyrite

True CompositionEstimated from FT-IR

0 50 100

15

20

25

30

35

40

45

Sample

1.230 50 100

1.100 50

0.570 50

1.060 50 100

0.950 50 100

1.730 50

0.07



True and Estimated Mineral Concentrations

0

5

10

Illite Smec. Kaol. Chlor. Musc. Glauc.Biotite

True CompositionEstimated from FT-IR

0 50

15

20

25

30

35

40

45

Sample

1.600 50

1.080 50

0.570 50

0.970 50

0.570 50

0.660 50

0.13



Development of Applications

• Total clay from chemical data• Matrix density from chemical data

• More for ou to develo



Clay and Gamma Ray

0

50

100

Clay wt%

Well 1 Well 2 Well 3 Well 4

100

y wt%


0

Cl

0 100 2000

50

100

Clay w

t%

Gamma Ray

Well 9

0 100 200

Gamma Ray

Well 10

0 100 200

Gamma Ray

Well 11

0 100 200

Gamma Ray

Well 12



0 10 200

50

100

Clay wt%

Thorium ppm0 5 10

Uranium ppm0 2.5 5

Potassium wt%

100

t%

Clay Elemental Relationships - Well 3

0 10 200

50

Cla

y

Aluminum wt%0 1 2

Titanium wt%0 5 10

Gadolinium

0 25 500

50

100

Clay wt%

Silicon wt%0 15 30

Iron wt%0 20 40

Calcium wt%




100

0 10 200

50

100

Clay wt%

Thorium ppm0 5 10

Uranium ppm0 2.5 5

Potassium wt%

100

wt%

0 10 200

C

la

Aluminum wt%0 1 2

Titanium wt%0 5 10

Gadolinium

0 25 500

50

100

Clay wt%

Silicon wt%0 15 30

Iron wt%0 20 40

Calcium wt%



100


0 10 200

50

100

Clay wt%

Thorium ppm0 5 10

Uranium ppm0 2.5 5

Potassium wt%

100

wt%

0 10 200

C

la

Aluminum wt%0 1 2

Titanium wt%0 5 10

Gadolinium

0 25 500

50

100

Clay wt%

Silicon wt%0 15 30

Iron wt%0 20 40

Calcium wt%



Aluminum and Clay100

Clay wt%

wt%

0

50

100

Clay wt%


50

100

lay wt%


C

la

Clay wt%

0

C

0 10 200

50

100

Clay wt%

Aluminum wt%

Well 9

0 10 20Aluminum wt%

Well 10

0 10 20Aluminum wt%

Well 11

0 10 20Aluminum wt%

Well 12



Estimation of Aluminum

0

10

20

Aluminum wt%


10

20

inum wt%


0

A

lu

0 10 200

10

20

Aluminum wt%

Aluminum Emulator

Well 9

0 10 20Aluminum Emulator

Well 10


Well 11


Well 12



SpectroLith Clay from Si, Ca, Fe

0

50

100

Clay wt%


100

wt%


0

C

lay

0 50 1000

50

100

Clay wt%

Estimated Clay

Well 9

0 50 100Estimated Clay

Well 10


Well 11


Well 12



Changes in ρma with Silicon

2.8

3

3.2

3.4

3.6

Matrix Density, g cm-3

Silicon, wt %

0 20 40.



Variation of ρma with Calcium

2.8

3

3.2

3.4

3.6

2.8

3

3.2

3.4

3.6


0 20 40.

Calcium, wt %Silicon, wt %

0 20 40.



ρma Increases with Iron

2.8

3

3.2

3.4

3.6


2.8

3

3.2

3.4

3.6

0 20 402.6

2.8

3

3.2

3.4

3.6

Iron, wt%

Matrix Den

sity, g cm-3

Silicon, wt %

0 20 40.

0 20 40.

Calcium, wt %



ρma

Also Increases with Sulfur

2.8

3

3.2

3.4

3.6


2.8

3

3.2

3.4

3.6

0 10 20 302.6

2.8

3

3.2

3.4

3.6

Sulfur, wt%

Silicon, wt %

0 20 40.

0 20 40.

Calcium, wt %

0 20 402.6

2.8

3

3.2

3.4

3.6

Iron, wt%

Matrix Den

sity, g cm-3



Density of Common Iron-bearing Minerals

4.5

5.0

5.5

, g cm-3

Pyrite

Hematite

0 20 40 60 802.5

3.0

3.5

4.0

Iron concentration, wt %

Grain densit

Illite

Quartz

GlauconiteChlorite

Siderite



Regression Results

ρma = 2.620

Non-arkose & Subarkose

+ 0.0490

+ 0.2274 (Ca + 0.6 Na)

+ 1.993 (Fe + 0.14 Al)

+ 1.193 S

r = 0.967; std error 0.015 g cm-3



Measured vs Computed Density

2.8

3

aad = 0.012 aad = 0.026

elements

aad = 0.01

Non-arkose Subarkose

2.6

2.6

2.8

3

E

stimated fro

m

aad = 0.0074 aad = 0.009

2.6 2.8 3

Matrix density from minerals

aad = 0.005

2.6 2.8 3 2.6 2.8 3



XX100

Clay

QFM

Carbonate

Gamma ray

Pyrite

a b c ed

0 150

0 1

XX300

XX500

Dept

h, ft

Lithology, wt fraction

00.20.4

Porosity, pu

100

101

102

103

Permeability, md

100

101

102

R0 ohm-m

0 1

SW



XX100

Clay

QFM

Carbonate

Pyrite

ca b

DRFT-IR Clay

XRD Clay

Clay

QFM

Carbonate

Pyrite

0 150

XX300

XX500

Depth, ft

Gamma Ray, API

0 1


0 1




60

80

100

t %

a

60

80

100

b

0 50 100 150 2000

20

40

Gamma Ray (API)

Total Clay,

0 5 10 150

20

40

0.39 (100 – SiO2 – CaCO3 – 1.99 Fe)



Clay

QFM

Carbonate

Pyrite

Oil

Free Water

Irreducible Water

Clay

QFM

Carbonate

Pyrite

Oil

Free Water

Irreducible Water

XX100

a b

XX300

XX500

Depth, ft

0 1

Formation, vol fraction

0 1

Formation, vol fraction



Well-to-Well Gamma Ray-Resistivity

Sometimes these

Correlations are

And not repeatable



0 50 100 150Gamma Ray (API)

0 50 100 150Gamma Ray (API)

ShapeSimilarity

Ambiguous Correlations with Gamma Ray

Depth (ft)

Well 1 Well 2



Ambiguous Correlations with Gamma Ray

0 50 100 150

Gamma Ray (API)

0 50 100 150

Gamma Ray (API)

? ShapeSimilarity

Depth (ft)

Well 1 Well 2



0 10 20 30 40

Calcium (wt %)0 10 20 30 40

Calcium (wt %)

Shape

Chemostratigraphy Lowers Ambiguity

Depth (ft)

&Absolute

Value

Well 1 Well 2



This is the Chemostratigraphy Connection

Ca Connections

0 10 20 30 40 50Silicon (wt %)

0 10 20 30 40 50Silicon (wt %)

Si Connections

Depth (ft)

3

Well 2Well 1



Leaps of Science Follow NewAnalytical Capabilities

• Induced gamma ray spectroscopy is nowbecoming a standard oilfield service

• More data in an hour than in a lab geochemist’s

lifetime• New elements are around the corner

• Challenge is on Academia and Industry to

maximize use of these new data

Geochemical Logging

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