Transcript No Slide Title

MRIL Applications
• Mechanisms of Relaxation
• Interpreting NMR T2 Spectra
– Importance of Proper Acquisition
– Effects of Minerals, Fluids and Rock-Fluids
• Applications and Examples
– Basic, BVI, SBVI, FFI, K
– Hydrocarbon Typing - gas and lighter oils
– Diffusion - Sor, Sw quantification
– Enhanced Diffusion - intermediate crudes
– Heavy Oil
MRIL - Applications
Presented by Dave Marschall
4/25/2020
1
Relaxation Mechanisms
Amplitude
Echo Amplitude vs Time
Effect of Each
Mechanism is Additive
T2A = T2B+T2D+T2S
Bulk Relaxation - T2B
Intrinsic Property of fluid
Diffusion - T2D
Molecular Movement
Surface Relaxation - T2S
Pore-walls cause rapid dephasing
Time, msec.
MRIL - Applications
Presented by Dave Marschall
4/25/2020
2
Bulk T1 of water
for Bulk Fluids T1T2
T1 of water
12
10
T1 (s)
8
6
4
2
from Simpson and Carr (1958)
0
0
50
MRIL - Applications
100
150
Temperature (F)
Presented by Dave Marschall
200
4/25/2020
250
3
Spin Echo Attenuation by Diffusion
in a Gradient Magnetic Field
• only stationary spins are completely rephased by p pulses in a CPMG expt
• spins diffusing in a gradient magnetic field undergo unrecoverable
dephasing... Þ echo attenuation Þ transverse relaxation mechanism
..... two sources of magnetic field gradients .....
B0
cfluid
B0
B0+d
Grain
B0+2d
B0+3d
Rock Grain
Pore
cgrain
GBo
2r
c
r
Rock Grain
Rock Grain
Natural ... grain scale gradients arising
due to magnetic susceptibility c contrast
between minerals and pore fluids ...
• randomly varying at grain scale
• pore size and mineralogy dependent
Applied ... MRIL uses strong
gradient magnetic field to
perform “slice selection” ...
• known, well-defined gradient
gives predictable T2 shifts that
depend only on diffusion
MRIL - Applications
Presented by Dave Marschall
4/25/2020
4
Diffusion and T2D
 Only effective for T2 relaxation
(not for T1)
T2D
T2D
T2D
when
D
when
Te
when
G
T2D =
12
D . ( G .  . Te
)
2
D
: Diffusion Coefficient of Fluid (cm2/sec)
G
: Magnetic Field Gradient (Gauss/cm)
depends on Temp. (K) & Viscosity

depends on Tool Freq. & Temp.
: Gyromagnetic Ratio (Hz/Gauss)
= 4258 for Hydrogen
Te
: Inter-Echo Spacing (sec.)
MRIL - Applications
Presented by Dave Marschall
4/25/2020
5
Effect of Diffusion on T2
0.0
100
200
300
Time, milliseconds
400
0.8
3
Incremental Volume, cm
Spacing of Echoes
0.5 milliseconds
1.0 milliseconds
2.0 milliseconds
5.0 milliseconds
10.0 milliseconds
E
in ffe c
Tim t o
e fD
Do iff
m usio
ai n
n
Amplitude
0.9
500
0.7
Effec t of diffusion
on T2 Spec trum
0.6
0.5
0.4
0.3
0.2
0.1
0.0
0.1
1.0
10
100
1000
10000
Relaxation Time (T2), milliseconds
MRIL - Applications
Presented by Dave Marschall
4/25/2020
6
Surface Relaxation Mechanism
Water Filled Pores
Small Pore Sizes =
100
Rapid Decay Rate
90
Large Pore Sizes =
Slow Decay Rate
80
70
60
50
40
T2 -1 @ r (S/V)
30
20
10
0
0
100
200
300
400
500
Time, msec.
600
MRIL - Applications
Presented by Dave Marschall
700
800
900
1000
4/25/2020
8
Importance of Acquisition
Porosity & Porosity Distributions
Acquisition
Parameters
Mostly Impacts
• Wait time Tw
• Interecho time Te
The correct porosity
• Number of echoes
• Signal to Noise (SNR)
The correct porosity vs
T2 Distribution
MRIL - Applications
Presented by Dave Marschall
4/25/2020
9
Porosity & Porosity Distributions
Wait Time Tw
Incremental Porosity (pu)
Amplitude
Wait time OK
Experiment
Time, msec.
2.5
25
2.0
20
1.5
15
1.0
10
0.5
5
0.0
0.1
Tw
0
10 100 1000 10000
Relaxation time T2, (msec.)
2.5
Incremental Porosity (pu)
Amplitude
Wait time too short
1
Experiment
Time, msec.
MRIL - Applications
Presented by Dave Marschall
2.0
1.5
1.0
0.5
0.0
0.1
1
10 100 1000 10000
4/25/2020
Relaxation
time T2, (msec.) 10
Cumulative Porosity, p.u.
Acquisition Parameter: Wait Time
Porosity & Porosity Distributions
Acquisition Parameter: Interecho Spacing
2.5
Ao
Time, msec.
Amplitude (A)
Te too long
2.0
incremental porosity
cumulative porosity
20
Te too long
1.5
incremental porosity
cumulative porosity
15
1.0
10
0.5
5
Cumulative Porosity, p.u.
Te
Ao
25
Te OK
Incremental Porosity, p.u.
Amplitude (A)
Te OK
Te
0.0
0.1
Time, msec.
1.0
10.0
100.0
1000.0
0
10000.0
Relaxation time T2, (msec.)
MRIL - Applications
Presented by Dave Marschall
4/25/2020
11
Porosity & Porosity Distributions
Acquisition Parameters: Number of Echoes
Amplitude (A)
Number of Echoes OK
25
2.5
Amplitude (A)
Not Enough Echoes
2.0
20
Not enough echoes
incremental porosity
cumulative porosity
1.5
15
1.0
10
0.5
5
0.0
0.1
Time, msec.
incremental porosity
cumulative porosity
Cumulative Porosity, p.u.
Time, msec.
Incremental Porosity, p.u.
Number of echoes OK
1.0
10.0
100.0
1000.0
0
10000.0
Relaxation time T2, (msec.)
MRIL - Applications
Presented by Dave Marschall
4/25/2020
12
Porosity & Porosity Distributions
Acquisition Parameters: Signal to Noise Ratio (SNR)
Amplitude (A)
Lower SNR
2.0
25
incremental porosity
cumulative porosity
Lower SNR
20
incremental porosity
cumulative porosity
1.5
15
1.0
10
0.5
5
0.0
0.1
Time, msec.
High SNR
1.0
10.0
100.0
1000.0
Cumulative Porosity, p.u.
Time, msec.
2.5
Incremental Porosity, p.u.
Amplitude (A)
High SNR
0
10000.0
Relaxation time T2, (msec.)
MRIL - Applications
Presented by Dave Marschall
4/25/2020
13
Porosity & Porosity Distributions
Effects of different fluids: air/brine displacement
H1 proton precession
of water in porous
media is controlled by:
1.4
1
1.2
1
T2
 r2 S
V
After air/brine
Brine filled pore displacement
0.8
0.6
0.4
0.2
MRIL - Applications
6309.6
2511.9
398.1
158.5
63.1
100% Brine saturated
1000.0
Relaxation Time (T2), msec.
25.1
10.0
After air/brine 100 psi
4.0
1.6
0.6
0.3
0
0.1
Incremental Porosity, p.u.
1.6
Presented by Dave Marschall
4/25/2020
14
Porosity & Porosity Distributions
H1 proton precession
of water in porous
media is controlled by:
2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
1
T2
 r2 S
After
air/brine
100%
Brine
saturate
Afterd oil/brine
displacement
6309.6
2511.9
1000.0
398.1
158.5
63.1
Relaxation Time (T2), msec.
25.1
10.0
4.0
1.6
0.6
Brine filled pore
0.3
0.1
Incremental Porosity, p.u.
Effects of different fluids: oil/brine displacement
MRIL - Applications
Presented by Dave Marschall
V
After oil/brine
displacement
H1 proton precession
of oil (non wetting) in
porous media is controlled
by the bulk relaxation
mechanism
4/25/2020
15
Interpretations - Clay and/or Microporosity
Brine Saturated
Incremental Porosity, (p.u.)
0.5 TE, (msec.)
1.2 TE, (msec.)
0.1
1
10
100
1000
10000
100
1000
10000
Cumulative Porosity, (p.u.)
0.1
1
10
Relaxation time T2, (msec.)
MRIL - Applications
Presented by Dave Marschall
4/25/2020
16
Internal Gradients
Confirmation from Core
SEM - Pore Lining Siderite
Lab T2 Spectrum, G = 0
0.3 msec. TE  = 17.6
0.6 msec. TE  = 16.5
1.2 msec. TE  = 15.0
Authigenic Siderite
0.1
1.0
10
100
Relaxation Time, T2, msec.
1000
MRIL - Applications
Presented by Dave Marschall
4/25/2020
17
Constant Bulk Oil T2
sample 29
Altered
Wettability
Ka (md) = 2180
Por. (%) = 19.7
sample 98
After air/brine 100psi
After oil/brine 100/psi
After SMF Flush
Ka (md) = 202
Por. (%) = 22.7
sample 143
Average T2 of SMF
Ka (md) = 18.1
Por. (%) = 18.2
0.1
1
10
100
1000
10000
Relaxation time (T2), msec.
MRIL - Applications
Presented by Dave Marschall
4/25/2020
19
Basic Applications
• BVI (CBVI and/or SBVI)
• FFI
• Permeability
• Movable fluids (hydrocarbon/water)
MRIL - Applications
Presented by Dave Marschall
4/25/2020
20
NMR - Porosity Model
Integration of MR Log and
Resistivity Log
Interpretation
NMR
BVI
hydrocarbons
movable
water
capillary
bound water
BVI
rock matrix
clay
matrix
clay bound
water
Neutron 
Density 
Resistivity Sw
NMR FFI
MR porosity
(effective)
MR porosity
(total short TE)
nonmovable
water
Producible
hydrocarbon
will produce some
water
MRIL - Applications
Presented by Dave Marschall
4/25/2020
21
Standard Method to
Determine BVI
2.00
Incremental Porosity, %
1.80
1.60
Bulk Volume
Irreducible
(BVI)
Free Fluid
Index
(FFI)
1.40
1.20
1.00
0.80
Standard Fixed T2 cutoff
Relates to a capillary
pressure or pore radius
Relaxation
time
distribution
0.60
0.40
0.20
0.00
0.1
1
10
100
1000
10000
T2 Relaxation time, ms
MRIL - Applications
Presented by Dave Marschall
4/25/2020
22
Variation in T2 Cutoff Values
T2 - Cutoff
1
10
100
0
Sample Number
5
10
15
20
25
MRIL - Applications
Presented by Dave Marschall
4/25/2020
23
T2, Cutoff T2 and Pore Size
MRI Relaxation Time (T2) &
Surface to Volume Ratio
Capillary Pressure (Pc) &
Pore Throat Radius (r)
1/T2 = r2 S/V
Pc = cos 2/r
Since S/V of a capillary
tube = 2/r then;
1/T2  r2 2/r
Since T2 is related to Pore Size & S/V:
• then T2 is directly proportional to K,
• and T2 is inversely proportional to Swi
MRIL - Applications
Presented by Dave Marschall
4/25/2020
24
T2 Cutoff Related to Pc
Bore hole
350
Rock Type A
Rock Type B
B
A
B
300
250
200
150
A
100
Equivalent T2
cutoff @ 50 psi
Free Water Level
50
0
MRIL - Applications
Presented by Dave Marschall
2
4
6
8
10
Bulk Volume Water, %
4/25/2020
0
12
25
Capillary Pressure , psi
Height Above Free Water, ft.
400
Spectral BVI Model
1.0
1.0
0.9
0.9
0.8
0.8
BVI
0.7
FFI
0.7
0.6
0.6
0.5
0.5
SBVI Model:
a step function
0.4
0.3
0.4
0.3
0.2
0.2
0.1
0.1
0.0
0.0
10000
0.1
1.0
10
100
1000
Spectral Fraction
Normalized Incremental Porosity
standard cutoff model
Relaxation Time (msec.)
MRIL - Applications
Presented by Dave Marschall
4/25/2020
26
SBVI Model Linked to
Permeability Equations
Given:
K1/2 = 100
K1/2 = 4
2
2
(FFI/BVI)
Equating the two
equations gives:
1-SWIRR
T2GM
SWIRR
Substituting:
1
 (1-SWIRR) for FFI
SWIRR
 SWIRR for BVI
= 0.04 T2GM , or
= 0.04 T2GM + 1
Coates equation becomes: The empirical form is:
K1/2
= 100
2
1-SWIRR
1
SWIRR
SWIRR
MRIL - Applications
Presented by Dave Marschall
= mT2GM + b
4/25/2020
27
Lab Method to Determine SBVI
Swi (Core), frac.
1
Core Swi vs T2
0.8
0.6
SBVI = 1/((0.0243 T2) + 1)
0.4
0.2
0
0
8
1/Swi (Core)
• Correlate Core Swi and T2
• Compute fraction for each
T2 Bin
50
100
150
200
T2 Geometric, ms
Bin #
SBVI - Slope Determination
7
6
5
4
y = 0.0243x + 1
R2 = 0.89
3
2
1
0
20
40
60
80
100
T2, Geometric, ms
120
140
MRIL - Applications
1
2
3
4
5
6
7
8
9
10
Presented by Dave Marschall
T2 time BVI Fraction
2
4
8
16
32
64
128
256
512
1024
0.919
0.849
0.738
0.585
0.414
0.261
0.150
0.081
0.042
0.022
4/25/2020
28
BVI Model Comparison
100
100
Cutoff T2
80
80
70
70
60
50
40
30
60
50
40
30
20
20
10
10
0
0
0
SBVI Model
90
Swi from SBVI
Swi from cutoff T2
90
10 20 30 40 50 60 70 80 90 100
0
10 20
30
40
50 60
70
80
90 100
Core Swi
Core Swi
MRIL - Applications
Presented by Dave Marschall
4/25/2020
29
Permeability Chart E-4
0.5
k
1
2
 C 
3
E-4
Swirr
Where C = 250
0.4
Porosity
0.3
1000
0.2
100
10
1.0
0.1
k (md)
0
0
0.2
0.4
Swir
0.6
MRIL - Applications
Presented by Dave Marschall
0.8
4/25/2020
1
30
Permeability from Porosity and
Water Saturation
40
k
35
1
(1  Swirr)
 C
Swirr
2
2
5000
30
k, Permeability (md)
2000
25
Porosity
1000
Phi x Swirr
500
20
0.12
100
50
0.10
0.08
20
15
0.06
10
0.04
5.0
10
0.02
1.0
0.01
5
0.10
0.005
0.01
0
0
10
20
30
40
50
60
70
80
90
100
Swir
MRIL - Applications
Presented by Dave Marschall
4/25/2020
31
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)
MRIL - Applications
Presented by Dave Marschall
4/25/2020
32
MRIL
Field
Standard
Presentation
Single Activation
MRIL - Applications
Presented by Dave Marschall
4/25/2020
33
MRIL
Field Standard
Presentation
CTP Activation
MRIL - Applications
Presented by Dave Marschall
4/25/2020
34
MRIL
Field
Standard
Presentation
Dual (Te or Tw) Activation
Dual Wait Time (Tw)
8 sec & 1 sec
MRIL - Applications
Presented by Dave Marschall
4/25/2020
35
Convention
al Logs
Density,
Neutron,
Resistivity,
GR and Cal.
MRIL - Applications
Presented by Dave Marschall
4/25/2020
36
MRIL
Final
Result
Water @ Bottom of Zone
MRIL - Applications
Presented by Dave Marschall
4/25/2020
37
Convention
al Logs
Density,
Neutron,
Resistivity,
GR and Cal.
MRIL - Applications
Presented by Dave Marschall
4/25/2020
38
MRIL
Final
Result
Zone Productive - little to
no water cut
MRIL - Applications
Presented by Dave Marschall
4/25/2020
39
Hydrocarbon Typing
• Dual wait time
• TDA
• Best for:
– light oils
– excellent gas detection
MRIL - Applications
Presented by Dave Marschall
4/25/2020
40
Direct Hydrocarbon Typing
Porosity
Porosity
Porosity
Differential Spectrum Method
Brine
Gas
Oil
Long Recovery
Time (TR)
Short Recovery
Time (TR)
Difference
T2 Time (ms)
1
10
100
MRIL - Applications
Presented by Dave Marschall
1,000
10,000
4/25/2020
41
 NUMAR Corp., 1995
Time Domain Analysis
1. Ability to hydrocarbon type in difficult
environments,
2. Direct Effective Porosity,
3. Resistivity independent Sxo.
MRIL - Applications
Presented by Dave Marschall
4/25/2020
42
Line Broadening
30
0
0
0
TIME
200
1
T2
10000
1
T2
10000
30
0
0
0
TIME
200
MRIL - Applications
Presented by Dave Marschall
4/25/2020
43
Time vs T2 Domain
-
0
T2
0
time
time
0
=
0
time
=
0
T2
MRIL - Applications
Presented by Dave Marschall
0
T2
4/25/2020
44
MRIL
TDA
Final Result
Gas / Oil contact confirmed
MRIL - Applications
Presented by Dave Marschall
4/25/2020
45
Diffusion
Dual Te
• Determine Sw, Sor
• Used to Determine Fw
• Best for:
– oil with low D and low viscosity
MRIL - Applications
Presented by Dave Marschall
4/25/2020
46
MRI Log - Diffustion
Processing & Interpretation
Based on the Thermal Diffusion properties of Fluids in the pore space
RDDW =
D
DW
D
: Diffusivity of Fm. Fluid
DW
: Diffusivity of Water
at Fm. Temp. & Press.
1 / T2irr
1 / T2int
= 12.5 at surface Temp. & press.
T2irr : Lower T2 boundary of Free Fluid
1 / T2Hy
0.0
RDDW
1.0
MRIL - Applications
Presented by Dave Marschall
4/25/2020
47
Challenge 2 - Rel. K and NMR
Mounting - For Steady State Relative
Permeability and NMR Measurements
Teflon end plug
glass tube
Teflon tape wrapped sample
Fluid out
Fluid in
..
Pressure
Pressure
heat shrinkable Teflon
MRIL - Applications
Presented by Dave Marschall
porous media
mixer head
4/25/2020
48
Results Diffusion / Fractional Flow
Concept T2 and D
1
1
1
 
T2 R T2 T2 D
where :
T2 R  observed T2
T2 
intrinsic T2
1
D ( H GTE 

T2 D
12
2
where :
D  Diffusion Constant
  Gyromagnetic ratio
G  gradient
TE  echo spacing
MRIL - Applications
Presented by Dave Marschall
4/25/2020
49
Results Diffusion / Fractional Flow
Concept T2 and D
1
1 D ( H GTEl 

T2 Rl T2
12
2
Combining Two TE
Measurements
1
1 D ( H GTEs 

T2 Rs T2
12
2
yields
 1
1 

12

T2 Rl T2 Rs 

D
2
( H GTEl  (TEl2  TEs2 
Determination of D
1
12(T2 Rs 

T2 12  D ( H GTEs 2 T2 Rs
yields determination of T2
and the short TE
MRIL - Applications
Presented by Dave Marschall
4/25/2020
50
Results Diffusion / Fractional Flow
Concept T2 and D
T2 is a function of surface and
bulk fluid relaxation
1
1
1


T2 T2 B T2 S
Thus in a dual TE experiment
the computed
D = Doil + Dwater
The Ratio
where :
T2 S  surface relaxation
D/Dw
T2 B  bulk fluid relaxation
In water wet Rocks:
1
1
1
1



T2 T2 BO T2 BW T2 SW
MRIL - Applications
Given as RDDW
provides a contrast to
Determine Saturation
Presented by Dave Marschall
4/25/2020
51
Results Diffusion / Fractional Flow
Sample 11
1.2 Te
3.6 Te
100% Brine
1.2 Te
3.6 Te
@ Swi = 29%
1.2 Te
3.6 Te
@ 50/50 fraction
Sw = 61%
1.2 Te
3.6 Te
@ Sor, Sw = 77%
0.1
1
10
100
1000
10000
MRIL - Applications
Presented by Dave Marschall
4/25/2020
52
Results Diffusion / Fractional Flow
Diffusion Saturation Model
0.045
oil
9 Swi
10 Swi
11 Swi
9 fw 50%
10 fw 50%
11 fw 50%
9 Sor
10 Sor
11 Sor
Sw = 1
Sw ff = 0
Sw ff = .45
Sw ff = .3
Fw =10 %
Fw = 20 %
Fw = 30 %
Fw = 40%
Fw = 50%
fw = 60%
fw = 70%
fw = 80%
fw = 90%
0.04
Sw = 100%
0.035
0.03
@ Sor Fw = 100%
0.025
Fw = 50 %
Sw ff = 0.30
Sw ff = 0.45
0.02
0.015
0.01
Fw = 0 %
0.005
0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
D/Dw
MRIL - Applications
Presented by Dave Marschall
0.8
0.9
1
4/25/2020
1.1
53
Enhanced Diffusion
• Introduction and theory
• Data processing and interpretation
– Recognizing pay
– T2 domain to determine residual oil
– Time domain to determine residual oil
MRIL - Applications
Presented by Dave Marschall
4/25/2020
54
Introduction and Theory
1000
At Long TE’s
• Effects of Surface Relaxation are Minimized
• Effects of Diffusion are Maximized
Water
Oil
T2DW = 50
T2S , msec.
100
10
1
1
1000
T2DW = 50
Upper limit
of T2Water
10
T2A , msec.
100
1
1000
MRIL - Applications
Presented by Dave Marschall
10
T2A , msec.
100
4/25/2020
55
Common EDM Log Response
MRIL - Applications
Presented by Dave Marschall
4/25/2020
56
Pay Recognition from EDM
The Effect of Long TE
GR
0
GAPI
DEPTH
LLD
DEPTH
feet
LLS
FEET
200
0.2
OHMM
4
200
1.2 msec. TE
Fully Polarized
msec.
2048 4
T2DW
MRIL - Applications
Presented by Dave Marschall
3.6 msec. TE
Fully Polarized
msec.
T2DW
2048 4
4.8 msec. TE
Fully Polarized
msec.
T2DW
4/25/2020
2048
57
Effect of Internal Gradient
0
GAPI
DEPTH
feet
200
X450
4
msec.
2048
4
msec.
2048
Water peek
GR
4.8 msec. TE
Differential Spectrum
4.8 msec. TE
Fully Polarized
T2DW
MRIL - Applications
Presented by Dave Marschall
T2DW
4/25/2020
58
EDM - Single vs Dual Wait
Time
LLD
DEPTH
feet
GR
0
GAPI
LLS
200
4.8 msec. TE
Fully Polarized
RXOZ
0.2
OHMM
200 4
MRIL - Applications
msec.
Presented by Dave Marschall
4.8 msec. TE
Differential Spectrum
2048 4
msec.
4/25/2020
2048
59
Residual Oil Saturation
O TDA
LLD
GR
0
GAPI
LLS
DEPTH
feet
200
RXOZ
0.2
OHMM
O T2 @ 3.6 TE
O T2 @ 4.8 TE
4.8 msec. TE
Differential Spectrum
200 4
MRIL - Applications
Presented by Dave Marschall
msec.
2048 0
p.u.
4/25/2020
30
60