1. 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
11/14/2018

2. Relaxation Mechanisms
Echo Amplitude vs Time
Effect of Each Mechanism is Additive
T2A = T2B+T2D+T2S
Bulk Relaxation - T2B
Intrinsic Property of fluid
Amplitude
Diffusion - T2D
Molecular Movement
Surface Relaxation - T2S
Pore-walls cause rapid dephasing
Time, msec.
MRIL - Applications
11/14/2018

3. Bulk T1 of water for Bulk Fluids T1T2 T1 of water MRIL - Applications12 10 8 6
T1 (s) 4 2
from Simpson and Carr (1958) 50
100
150
200
250
Temperature (F)
MRIL - Applications
11/14/2018

4. 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
B0+d
B0+2d
B0+3d
cfluid B0
Grain
Rock Grain
Pore
cgrain
Rock Grain
pair of cpmg trains at two different TE’s
diffusion “propagator” (D/12)(g××G×TE)
fixed vs. pulsed field gradient nmr measurement of D 2r
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
11/14/2018

5. Diffusion and T2D
Only effective for T2 relaxation (not for T1) 12 T 2D D
when
T2D =
D . ( G .  . Te )2
D : Diffusion Coefficient of Fluid (cm2/sec)
depends on Temp. (K) & Viscosity
G : Magnetic Field Gradient (Gauss/cm)
depends on Tool Freq. & Temp.
 : Gyromagnetic Ratio (Hz/Gauss)
= 4258 for Hydrogen
Te : Inter-Echo Spacing (sec.) T 2D e
when T 2D G
when
MRIL - Applications
11/14/2018

6. Effect of Diffusion on T2
MRIL - Applications
11/14/2018

7. Surface Relaxation Mechanism Water Filled Pores
Small Pore Sizes =
Rapid Decay Rate
Large Pore Sizes =
Slow Decay Rate
T2 r (S/V)
Time, msec.
MRIL - Applications
11/14/2018

8. Importance of Acquisition Porosity & Porosity Distributions
Parameters Mostly Impacts
Wait time Tw
Interecho time Te
Number of echoes
Signal to Noise (SNR)
The correct porosity
The correct porosity vs
T2 Distribution
MRIL - Applications
11/14/2018

9. Porosity & Porosity Distributions Acquisition Parameter: Wait Time
Wait time OK
0.0
0.5
1.0
1.5
2.0
2.5 5 10 15 20 25
Wait Time Tw
Experiment
Incremental Porosity (pu)
Cumulative Porosity, p.u.
Amplitude
Time, msec.
0.1 1 10
100
1000
10000
Relaxation time T2, (msec.)
Wait time too short
0.0
0.5
1.0
1.5
2.0
2.5
Time, msec. Tw
Experiment
Amplitude
Incremental Porosity (pu)
0.1 1 10
100
1000
10000
MRIL - Applications
Relaxation time T2, (msec.)
11/14/2018

10. Porosity & Porosity Distributions Acquisition Parameter: Interecho Spacing
Te OK
0.0
0.5
1.0
1.5
2.0
2.5 5 10 15 20 25 Ao
Te OK
incremental porosity
cumulative porosity
Te too long Te
Amplitude (A)
Incremental Porosity, p.u.
Cumulative Porosity, p.u.
Time, msec.
Te too long Ao Te
Amplitude (A)
0.1
1.0
10.0
100.0
1000.0
Relaxation time T2, (msec.)
Time, msec.
MRIL - Applications
11/14/2018

11. Porosity & Porosity Distributions Acquisition Parameters: Number of Echoes
Number of Echoes OK
0.0
0.5
1.0
1.5
2.0
2.5 5 10 15 20 25
Number of echoes OK
incremental porosity
cumulative porosity
Not enough echoes
Amplitude (A)
Time, msec.
Incremental Porosity, p.u.
Cumulative Porosity, p.u.
Not Enough Echoes
Amplitude (A)
0.1
1.0
10.0
100.0
1000.0
Time, msec.
Relaxation time T2, (msec.)
MRIL - Applications
11/14/2018

12. Porosity & Porosity Distributions Acquisition Parameters: Signal to Noise Ratio (SNR)
High SNR
High SNR
incremental porosity
cumulative porosity
Lower SNR
0.0
0.5
1.0
1.5
2.0
2.5 5 10 15 20 25
Amplitude (A)
Incremental Porosity, p.u.
Time, msec.
Cumulative Porosity, p.u.
Lower SNR
Amplitude (A)
0.1
1.0
10.0
100.0
1000.0
Time, msec.
Relaxation time T2, (msec.)
MRIL - Applications
11/14/2018

13. media is controlled by:
Porosity & Porosity Distributions Effects of different fluids: air/brine displacement
H1 proton precession
of water in porous
media is controlled by:
0.2
0.4
0.6
0.8 1
1.2
1.4
1.6
After air/brine
displacement
Brine filled pore
Incremental Porosity, p.u.
0.1
0.3
0.6
1.6
4.0
10.0
25.1
63.1
158.5
398.1
1000.0
2511.9
6309.6
After air/brine 100 psi
100% Brine saturated
Relaxation Time (T2), msec.
MRIL - Applications
11/14/2018

14. Porosity & Porosity Distributions Effects of different fluids: oil/brine displacement
H1 proton precession
of water in porous
media is controlled by:
After oil/brine
displacement
Brine filled pore
of oil (non wetting) in
porous media is controlled
by the bulk relaxation
mechanism
0.1
0.3
0.6
1.6
4.0
10.0
25.1
63.1
158.5
398.1
1000.0
2511.9
6309.6
0.2
0.4
0.8 1
1.2
1.4
1.8 2
Relaxation Time (T2), msec.
Incremental Porosity, p.u.
After
air/brine
100%
Brine
saturated
After oil/brine
displacement
MRIL - Applications
11/14/2018

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
Cumulative Porosity, (p.u.)
_______________________________________________________________ _______________________________________________________________ _______________________________________________________________
_______________________________________________________________ _______________________________________________________________
0.1 1 10
100
1000
10000
Relaxation time T2, (msec.)
MRIL - Applications
11/14/2018

16. Confirmation from Core
Internal Gradients
Confirmation from Core
Authigenic Siderite
Relaxation Time, T2, msec.
0.3 msec. TE  = 17.6
0.6 msec. TE  = 16.5
1.2 msec. TE  = 15.0
SEM - Pore Lining Siderite
Lab T2 Spectrum, G = 0
MRIL - Applications
11/14/2018

17. Constant Bulk Oil T2 Altered Wettability Average T2 of SMF
0.1 1 10
100
1000
10000
Relaxation time (T2), msec.
Average T2 of SMF
sample 29
Ka (md) = 2180
Por. (%) = 19.7
sample 98
Ka (md) = 202
Por. (%) = 22.7
sample 143
Ka (md) = 18.1
Por. (%) = 18.2
After air/brine 100psi
After SMF Flush
After oil/brine 100/psi
Altered
Wettability
MRIL - Applications
11/14/2018

18. Basic Applications BVI (CBVI and/or SBVI) FFI Permeability
Movable fluids (hydrocarbon/water)
MRIL - Applications
11/14/2018

19. Producible hydrocarbon will produce some water
NMR - Porosity Model
Neutron 
Density 
Resistivity Sw
clay matrix
capillary bound water
BVI
clay bound water
movable water
rock matrix
hydrocarbons
NMR BVI
NMR FFI
Integration of MR Log and Resistivity Log Interpretation
MR porosity
(effective)
MR porosity
(total short TE)
nonmovable water
Producible hydrocarbon
will produce some water
MRIL - Applications
11/14/2018

20. Bulk Volume Irreducible (BVI) Relaxation time distribution
Standard Method to
Determine BVI
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
2.00
0.1 1 10
100
1000
10000
T2 Relaxation time, ms
Incremental Porosity, %
Bulk Volume Irreducible (BVI)
Free Fluid Index (FFI)
Relaxation time distribution
Standard Fixed T2 cutoff
Relates to a capillary pressure or pore radius
MRIL - Applications
11/14/2018

21. Variation in T2 Cutoff Values1 10
100 5 10
Sample Number 15 20 25
MRIL - Applications
11/14/2018

22. T2, Cutoff T2 and Pore Size 1/T2 = 2 S/V Pc =cos 2/r 1/T2  2 2/r
MRI Relaxation Time (T2) &
Surface to Volume Ratio
1/T2 = 2 S/V
Capillary Pressure (Pc) &
Pore Throat Radius (r)
Pc =cos 2/r
Since S/V of a capillary tube = 2/r then;
1/T2  2 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
11/14/2018

23. T2 Cutoff Related to Pc Rock Type A Rock Type B B Shale A Bore hole
Capillary Pressure , psi 50
100
150
200
250
300
350
400 2 4 6 8 10 12
Bulk Volume Water, %
Height Above Free Water, ft.
Rock Type A
Rock Type B B
Shale A
Equivalent T2
50 psi
Free Water Level
MRIL - Applications
11/14/2018

24. Spectral BVI Model BVI FFI standard cutoff model
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
Normalized Incremental Porosity
Relaxation Time (msec.)
Spectral Fraction
BVI
FFI
SBVI Model:
a step function
MRIL - Applications
11/14/2018

25. SBVI Model Linked to Permeability Equations
Given:
K1/2 = 100f 2 (FFI/BVI)
K1/2 = 4f 2 T2GM
Equating the two equations gives:
= 0.04 T2GM , or
1-SWIRR
SWIRR
Substituting:
f (1-SWIRR) for FFI
f SWIRR for BVI 1
SWIRR
= 0.04 T2GM + 1
Coates equation becomes:
K1/2 = 100f 2
1-SWIRR
SWIRR
The empirical form is: 1
SWIRR
= mT2GM + b
MRIL - Applications
11/14/2018

26. Lab Method to Determine SBVI
Core Swi vs T2
0.2
0.4
0.6
0.8 1 50
100
150
200
T2 Geometric, ms
Swi (Core), frac.
SBVI - Slope Determination 2 3 4 5 6 7 8 20 40 60 80
120
140
T2, Geometric, ms
1/Swi (Core)
Correlate Core Swi and T2
Compute fraction for each
T2 Bin
SBVI = 1/(( T2) + 1)
Bin # T2 time BVI Fraction
y = x + 1
R2 = 0.89
MRIL - Applications
11/14/2018

27. BVI Model Comparison Cutoff T2 SBVI Model Swi from cutoff T210 20 30 40 50 60 70 80 90
100
Core Swi
Swi from cutoff T2 10 20 30 40 50 60 70 80 90
100
Core Swi
Swi from SBVI
SBVI Model
Cutoff T2
MRIL - Applications
11/14/2018

28. Permeability Chart E-4 E - 4 Porosity Swir 0.5 0.4 0.3 0.2 0.1 0.2 0.4
1000
Porosity
(f x Swirr) increases
0.2
100 10
1.0
0.1
k (md)
0.2
0.4
0.6
0.8 1
Swir
MRIL - Applications
11/14/2018

29. Permeability from Porosity and Water Saturation40 35
5000 30
k, Permeability (md)
2000 25
1000
Phi x Swirr
500 20
0.12
Porosity
100
0.10 50
0.08 15 20
0.06 10
5.0
0.04 10
0.02
1.0
0.01
0.10 5
0.005
0.01 10 20 30 40 50 60 70 80 90
100
Swir
MRIL - Applications
11/14/2018

30. 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
11/14/2018

31. MRIL Field Standard Presentation
Single Activation
MRIL - Applications
11/14/2018

32. MRIL Field Standard Presentation
CTP Activation
MRIL - Applications
11/14/2018

33. MRIL Field Standard Presentation
Dual (Te or Tw) Activation
Dual Wait Time (Tw)
8 sec & 1 sec
MRIL - Applications
11/14/2018

34. Conventional Logs Density, Neutron, Resistivity, GR and Cal.
MRIL - Applications
11/14/2018

35. MRIL Final Result Water @ Bottom of Zone MRIL - Applications
11/14/2018

36. Conventional Logs Density, Neutron, Resistivity, GR and Cal.
MRIL - Applications
11/14/2018

37. Zone Productive - little to no water cut
MRIL Final Result
Zone Productive - little to no water cut
MRIL - Applications
11/14/2018

38. Hydrocarbon Typing Dual wait time TDA Best for: light oils
excellent gas detection
MRIL - Applications
11/14/2018

39. Direct Hydrocarbon Typing Differential Spectrum Method
Brine
Gas
Oil
Porosity
Long Recovery
Time (TR)
Short Recovery
Time (TR)
Difference
T2 Time (ms)
, ,000
MRIL - Applications
11/14/2018
ã NUMAR Corp., 1995

40. 1. Ability to hydrocarbon type in difficult environments,
Time Domain Analysis
1. Ability to hydrocarbon type in difficult environments,
2. Direct Effective Porosity,
3. Resistivity independent Sxo.
MRIL - Applications
11/14/2018

41. Line Broadening T2 TIME T2 TIME 30 200 1 10000 30 200 1 10000
200 1
10000 T2
TIME 30
200 1
10000 T2
TIME
MRIL - Applications
11/14/2018

42. - = Time vs T2 Domain time time time T2 T2 T2 MRIL - Applications- =
time
time
time T2 T2 T2
MRIL - Applications
11/14/2018

43. Gas / Oil contact confirmed
MRIL TDA
Final Result
Gas / Oil contact confirmed
MRIL - Applications
11/14/2018

44. Diffusion Dual Te Determine Sw, Sor Used to Determine Fw Best for:
oil with low D and low viscosity
MRIL - Applications
11/14/2018

45. MRI Log - Diffustion Processing & Interpretation
Based on the Thermal Diffusion properties of Fluids in the pore space D DW
RDDW =
D : Diffusivity of Fm. Fluid
DW : Diffusivity of Water at Fm. Temp. & Press. = 12.5 at surface Temp. & press.
0.0
RDDW
100% Water Saturation
50% Water Saturation
1.0
1 / T2int
1 / T2Hy
1 / T2irr
T2irr : Lower T2 boundary of Free Fluid
MRIL - Applications
11/14/2018

46. Challenge 2 - Rel. K and NMR
Mounting - For Steady State Relative Permeability and NMR Measurements
Teflon end plug
Teflon tape wrapped sample
glass tube ..
Fluid in
Fluid out
Pressure
porous media
mixer head
Pressure
heat shrinkable Teflon
MRIL - Applications
11/14/2018

47. Results Diffusion / Fractional Flow Concept T2 and D
echo spacing
gradient
Gyromagnetic ratio
Diffusion Constant
observed T2
intrinsic T2
MRIL - Applications
11/14/2018

48. Results Diffusion / Fractional Flow Concept T2 and D
Combining Two TE Measurements
yields
Determination of D
and the short TE
yields determination of T2
MRIL - Applications
11/14/2018

49. Results Diffusion / Fractional Flow Concept T2 and D
T2 is a function of surface and bulk fluid relaxation
Thus in a dual TE experiment the computed
D = Doil + Dwater
The Ratio
D/Dw
Given as RDDW
provides a contrast to Determine Saturation
surface relaxation
bulk fluid relaxation
In water wet Rocks:
MRIL - Applications
11/14/2018

50. Results Diffusion / Fractional Flow Sample 11
100% Brine
@ Swi = 29%
@ 50/50 fraction
Sw = 61%
@ Sor, Sw = 77%
MRIL - Applications
11/14/2018

51. Results Diffusion / Fractional Flow
MRIL - Applications
11/14/2018

52. 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
11/14/2018

53. Introduction and Theory
At Long TE’s
Effects of Surface Relaxation are Minimized
Effects of Diffusion are Maximized
1000
Water
Oil
T2A=T2S
T2DW = 50
100
T2S , msec. 10
T2DW = 50
Upper limit
of T2Water 1
T2A , msec.
T2A , msec.
MRIL - Applications
11/14/2018

54. Common EDM Log Response
MRIL - Applications
11/14/2018

55. Pay Recognition from EDM The Effect of Long TE
MRIL - Applications
11/14/2018

56. Effect of Internal Gradient
4.8 msec. TE
Fully Polarized
4.8 msec. TE
Differential Spectrum GR
DEPTH
feet
GAPI
msec
msec
Water peek
X450
T2DW
T2DW
MRIL - Applications
11/14/2018

57. EDM - Single vs Dual Wait Time
MRIL - Applications
11/14/2018

58. Residual Oil Saturation
MRIL - Applications
11/14/2018