MRIL OVERVIEW
Team One
NUMAR / HALLIBURTON
Crucial Formation Evaluation Questions
• What is the storage capacity (e and t ) in a Complex Lithology Environment ?
• Are there hydrocarbons, what types of hydrocarbons and, how are they distributed?
• What is the permeability (deliverability)?
• Will the formation produce water free? (what is irreducible saturation (BVI))
MRIL answers them all
Only Fluidsare Visible
“Thin Slice”Image
H
Medical MRI
hydrocarbonhydrocarbon
hydroca
rbon
Oilfield MRI(Relaxation Time Spectrum)
FluidsSolids….invisible to MRI
time, sec.
0 1 2 3 4 5 6 8 9 10 11 12 13 14 …….
irreducib
le
movablewater
movablewater
movable w
ater
irreducibleirreducible
clay boundclay bound
clay bound
T1 Magnetizationno measurement
T2 relaxation timesthe measurement
rock matrixrock matrix
dry claydry clay
Magnetic Dipole
Proton
H
Hydrogen
N
S
NMR works with Protons - Hydrogen -> H2O and CxHy+++
N SN
SN
S
N
S
N
S
N
S
N
S
N
S
NS
N
S
N
S
N
S
N
S
N
S
t = 0
Random Orientation in Natural State
Bo
N
S N
S
N
S
N
S
N
S
N
SN
S
N
SN
SN
S
N
S
N
S
N
S
N
S
t = 0.75 sec
M
Bo=External Field M=Bulk Net Magnetization
Wait time (sec)
Magnetization Buildup
Bo
N
S N
S
N
S
N
S
N
S
N
S
N
S
N
S N
SN
S
N
S
N
S
N
S
N
S
t = 6.0 sec
M
Bo=External Field M=Bulk Net Magnetization
Wait time (sec)
Buildup at 95 % polarization
Bo
Polarization Time
T2
Decay Time
T1
Magnetization
T1 characterizes the rate at which longitudinal magnetization builds up
T2 characterizes the rate at which transverse magnetization decays
B0
ML
MT
T1 build-up and T2 decay
NMR Experiment Timing
Mo
0
M to Bo
(longitudinalcomponent)
M to Bo
(transversecomponent)
Mo
0
RF field
0
B1
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
time, seconds
TW
TE TX
1/exp1|| TtimeM
M time T exp / 2
adapted from Murphy, D.P., World Oil, April 1995
T1 = 400 msec
T2 = 250 msec
3 * T1 = Tw 95% Polarization
% Polarization * = Measured Porosity
t (s)
% P
olar
izat
ion
Gas: T1 = 3s
Water: T1 = 0.33s
T1 Magnetization build up
0 1 2 3 4 5 6 7 8 9 10 11 12
Light Oil: T1 = 2s
100
80
60
40
20
0
T1 Build-up
T2 decay
Low PorosityClean Cgr Sandstone
Low PorosityShaly Fgr Sandstone
Higher PorosityShaly Cgr Sandstone
Time, sec.
Effects of Chemistry and Texture on T1 and T2
(water filled)
0 1 2 3 4 5 6 7 8 9 10
MRIL ProbeBorehole
SensitiveVolumeCylinders(each 1 mm thickat 1 mm spacing)
24 “
16”
PermanentMagnet andField
Pulsing RF and receiving RF Antenna
MRIL in Wellbore
MRIL Diameter of Investigation
Multi - Frequency Series C Tool
Frequency 3
NUMAR Corp., 1995
Formation
16”
Frequency 1
6”
Borehole Wall
Mud
SondeSleeve
Magnet RF Antenna
NS
Frequency 2
2
3
1
0
5
10
15
20
25
30
35
0 50 100 150 200 250 300
time (ms)
Am
plitu
de (p
u)
Decay rate (1 / T2) =>rock & fluid information
Measured signal decay
TE
TE
Amplitude = Porosity
3 Relaxation Mechanisms
Bulk Relaxation - T2B
Intrinsic Property of fluid
Diffusion - T2D
Molecular Movement
Surface Relaxation - T2S
Pore-walls cause rapid dephasing
Effect of Each Mechanism is Additive
Time, msec.
Am
plit
ud
e
Echo Amplitude vs Time
SDB TTTT 2222
1111
TT22
TT22
TT22
TT22
TT22
timetime
timetime
timetime
timetime
timetime
Pore Size and T2 (Water)
VS
T 22
1
T2 = relaxation time constant.
S = surface area of the pore.
V = volume of the pore.
2 = relaxation rate constant.
Surface Relaxation MechanismWater Filled Pores
Time, msec.
0
10
20
30
40
50
60
70
80
90
100
0 100 200 300 400 500 600 700 800 900 1000
T2 -1S/V)
Small Pore Sizes = Rapid Decay Rate
Large Pore Sizes = Slow Decay Rate
Data Processing - Inversion
T2i are pre-selected:T2i = 4, 8, 16, 32, 64, 128, 256, 512, 1024...
MAP“Inversion”Processing
T2 [ms]
Incr
em
en
tal P
oro
sity
[p
u]
T2 Spectrum “Best Fit”
Water-saturated rock: 2 = V/S
NUMAR Corp., 1995
BVI FFI
6.0
0.50.5
2.0
12.0
5.0
3.04.5
0
5
10
15
1 10 100 1000 10000
Spin-echo data
0
5
10
15
20
25
30
35
0 50 100 150 200 250 300
0
5
10
15
20
25
30
35
40
0 5 10 15 20 25 30 35 40
phi-core (pu)
phi-N
MR
(pu
)
Permeability Chart E-4
0
0.1
0.2
0.3
0.4
0.5
0 0.2 0.4 0.6 0.8 1Swir
Por
osity
E - 4
1000
100
10
1.0
( x Swirr) increases
k (md)
k CSw
Where C = 250
12
3
irr
MRIL Permeability
• MPERM = ((MPHI/10)2 (MFFI/MBVI))2
MPHI - MRIL Porosity (porosity units)
MBVI - MRIL Bulk Volume Irreducible
MFFI - MRIL Free Fluid Index
MPERM - Permeability (millidarcies)
0.01
0.1
1
10
100
1000
10000
0.01 0.1 1 10 100 1000 10000
K_air (mD)
K_N
MR
(m
D)
Differential Echo / Spectrum Method
1 10 100 1000T2 (ms)
FMW OBMF GasTW(1) = 12.208 (s) TE(1) = 1.2 (ms)
1 10 100 1000T2 (ms)
TW(2) = 1 (s) TE(2) = 1.2 (ms)
1 10 100 1000T2 (ms)
FMW OBMF GasDif Spec; TW = 12.208 & 1 (s)
Effect of Diffusion on T2
Effec
t of D
iffusio
n
in Tim
e Do
main
0.0 100 200 300 400 500Time, milliseconds
Am
plitu
de
Spacing of Echoes0.5 milliseconds1.0 milliseconds2.0 milliseconds5.0 milliseconds10.0 milliseconds
Effect of diffusion on T2 Spectrum
Relaxation Time (T2), milliseconds
0.1 1.0 10 100 1000 10000
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
Incr
emen
tal V
olu
me,
cm
3
Diffusion - Shifted Spectrum Method
1 10 100 1000T2 (ms)
FMW OBMF OilTW(1) = 7.996 (s) TE(1) = 1.2 (ms)
1 10 100 1000T2 (ms)
TW(2) = 7.996 (s) TE(2) = 6 (ms)
Pay Recognition from EDMThe Effect of Long TE
0.2 OHMM 200
GRDEPTH
FEET
LLS
LLD
0 GAPI 200
1.2 msec. TE Fully Polarized
3.6 msec. TE Fully Polarized
4.8 msec. TE Fully Polarized
4 msec. 2048 4 msec. 2048 4 msec. 2048DEPTHfeet T2DW T2DW T2DW
Density Porosity
Neutron Porosity
Effective Porosity
0
0
0
0-100
8
0
Variable Density(milliseconds)
T2 Distribution
20482
XX200
Dep
th
Permeability(md)
200020
SP (mv)
Caliper (in)
Gamma Ray (GAPI)
Shallow Resistivity
Deep Resistivity
BVI
20
20
20150
18
100
60
60
60
60
0.2
0.2
Bins 1 - 8 (PU) 0100
• What’s new ?
Pick your choice
• Low resistivity pay
• Extra pay identified
• Shale, Huh ?
• Integrating core data and MRIL data
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