oil shale formation evaluation by well logs and core measurements
TRANSCRIPT
AMSO: Alan Burnham, Roger Day TOTAL: Pierre Allix Schlumberger: Malka Machlus, Michael Herron, James Grau
Nikita Seleznev, Gabriela Leu, Peter Hook
Oil Shale Formation Evaluation by Well Logs and Core Measurements
Robert Kleinberg Schlumberger-‐Doll Research Cambridge, Massachuse:s
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 fractures vugs slumps
Objectives of Oil Shale Well Logging
50 ft
black=albite
Oil Shale Well Log Montage
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
ma bD w k
ma f
ρ −ρφ = = φ + φ
ρ −ρDensity Porosity
maρ = matrix (grain) density (~ 2.7 g/cc)
bρ = bulk (measured) density
fρ = “fluid” (water+kerogen) density (~1 g/cc)
Dφ
wφ
kφ
= porosity measured by density tool
= volume fraction kerogen
= volume fraction water
Gamma-Gamma Density Log Measures Sum of Water + Kerogen
Mag
netic
Res
onan
ce S
igna
l
Measurement Time
Measurement Dead Time
water kerogen
200 µs 2 s
Kerogen is Invisible to Magnetic Resonance
ma bD w k
ma f
ρ −ρφ = = φ + φ
ρ −ρDensity Porosity
maρ = matrix (grain) density (~ 2.7 g/cc)
bρ = bulk (measured) density
fρ = “fluid” (water+kerogen) density (~1 g/cc)
Magnetic Resonance Porosity MR wφ = φ
k D MRφ = φ −φ
Dφ
wφ
kφ
= porosity measured by density tool
= volume fraction kerogen
= volume fraction water
Density Magnetic Resonance (DMR) Method Kerogen Volume from Density & Magnetic Resonance Logs
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
Poro
sity
Depth (ft) 100108-03b
bad hole masked Density Porosity
NMR Porosity
Kerogen
Por
osity
0.6
0.5
0.4
0.3
0.2
0.1
0
100 feet
0
20
40
60
80
1900 1950 2000 2050 2100
Well Log Kerogen VolumeCore Measured Fischer Assay
Wel
l Log
Ker
ogen
Vol
ume
(gal
/ton)
Depth (ft) 100829-11b
Cor
e Fi
sche
r Ass
ay (g
al/to
n)
xx00 xx50 x100 x150 x200
Depth (ft)
Wel
l Log
Ker
ogen
Vol
ume
(gal
/ton)
C
ore
Fisc
her A
ssay
(gal
/ton)
xx00 xx50 x100 x150 x200
80
60
40
20
0
Well Log Kerogen Volume vs Core Fischer Assay
[ ]FA TOM 0.019 199= −
kD MR
bTOM ( )ρ
= φ − φρ
Total Organic Ma:er as frac>on of ore weight
gallons of oil per ton of ore
Synthe'c Fuels Data Handbook Cameron Engineers, 1975
Figure 29. Organic Ma:er Content of Green River Oil Shales-‐
Total O
rganic M
a:er
Modified Fischer Assay (gal/ton)
0.4
0.3
0.2
0.1
0 0 20 40 60
0
20
40
60
80
1900 1950 2000 2050 2100
Well Log Fischer Assay EstimateCore Measured Fischer Assay
Cor
e Fi
sche
r Ass
ay (g
al/to
n)
Depth (ft) 100829-12b
Wel
l Log
Fis
cher
Ass
ay E
stim
ate
(gal
/ton)
xx00 xx50 x100 x150 x200 Depth (ft)
F
isch
er A
ssay
(gal
/ton)
80
60
40
20
0
Fischer Assay: Well Log vs Core
Schlumberger Log Interpretation Chart Gen-6 (2009)
m nw D w t
1R S Ra
= φ
( a ~ 1, m ~ n ~ 2 )
MRw
DS φ
=φ
MR2
w tR R= φ @ reservoir temperature T
( 1.1192)
wT 21.5 Csalinity(ppk) 7.976 R (T)
10 C 21.5 C
−+ °⎡ ⎤= ⋅ ⎢ ⎥° + °⎣ ⎦
[Rw] = ohm-meters
fraction of pore = space that is water filled
Archie’ Law =
Water Salinity from Resistivity & Magnetic Resonance
Assume all NaCl is in Pore Water
3 3
3 3 3g(NaCl) g(dry ore) cm (dry ore) cm (rock) g(NaCl)Salinityg(dry ore) g(water)cm (dry ore) cm (rock) cm (water)
= =
( ) 1FSAL DWNACL RHGA 1 PIGE WKERPIGE
= ⋅ − −
Water Salinity Estimate from Geochemical Logging
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
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
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 formation resistivity. Agreement with a capture spectroscopy estimate is fair.
Summary
( 1.1192)
wT 21.5 Csalinity(ppk) 7.976 R (T)
10 C 21.5 C
−+ °⎡ ⎤= ⋅ ⎢ ⎥° + °⎣ ⎦
[Rw] = ohm-meters
Schlumberger Log Interpretation Chart Gen-6 (2009)