1. Basic NMR Physics and MRIL® Tool Physics
Outline
Nuclear Magnetism
Origin of the NMR signal
Spin echoes and the CPMG pulse technique
Relaxation times: T1 and T2
Commercial probe designs and investigation characteristics
Experiment timing, nomenclature, and basic data flow
MRIL - Principles and Applications
9/18/2018

2. Pulsed NMR Log Measurement Principle
... the basic NMR “experiment” ... N
1. Permanent magnet in tool polarizes hydrogen nuclei
signal
2. Transmit train of RF pulses and records returning spin echo signals
time
This cartoon illustrates the basic NMR log measurement principle.
Essential components of the basic NMR sensor or “probe” are 1) permanent magnet and 2) rf antenna
Permanent magnet polarizes hydrogen. rf pulses from antenna used to manipulate magnetization so it can be measured.
Can think of single NMR experiment consists of four steps
1. Build up hydrogen nuclear M in response to Bo. Note that build up is not instantaneous but takes finite amount time. Time constant for build up is called T1 and has an important influence on logging speed.
2. Transmit series of rf pulses. 1st pulse is unique; reorients M. Subsequent pulses are identical and generate spin-echo signals that are recorded by tool.
3. While tool is pulsing, peak amplitudes of spin echo signals received in antenna are recorded.
4. Finally, have to wait for magnetization to build back up again before starting next measurement.
Echo amplitudes processed for two key pieces of information.
Maximum signal ampl at zero decay time -> HI -> NMR porosity
relaxation time distribution -> pore size, fluid prop’s -> flow prop’s S
RF pulses
3. Wait for recovery hydrogen magnetization
maximum signal amplitude µ fluid-filled porosity
signal decay time µ pore size, fluid prop’s, flow prop’s
MRIL - Principles and Applications
9/18/2018

3. MRIL - Principles and Applications
The Resonance Effect z
Excite transitions between spin states
by irradiating at Larmor frequency: Bo z M y x z
at equilibrium y x
90x° pulse
now have eqm magnetization but how do we measure?
done with secondary magnetic field set up by rf pulse
two key requirements for resonance expt
1. B1 orthogonal to magnetization
2. frequency of ocillation = Larmor frequency
B1 is an oscillating field generated by applying ac current to coil
- can view B1 as exerting torque on M; causes M to rotate
- modern NMR devices use rf pulses
- most pulse NMR expt’s use 90 and 180 deg pulses
Adsorption of resonant freq energy produces orient change
in lab ref frame, M undergoes complex, spiral motion called precession: rotation about z and x
- rotation freq about x determined by magnitude of B1 << Bo
in ref frame rotating at Larmor freq, see simple rotation about x
- rotation angle depends on duration of pulse
- rotation freq about z = Larmor freq ~ Bo
- 90 deg pulse shown here
after pulse is turned of M precess about z, inducing signal (FID) in coil y B1 x
rf pulse generates magnetic field B1
B1 oriented normal to Bo
B1 oscillates at Larmor frequency
precession in xy plane
induces FID signal in coil
MRIL - Principles and Applications
9/18/2018

4. MRIL - Principles and Applications
T1 Polarization T 1A 1 1B 1S = +
Relaxation Mechanisms for T1
Bulk Relaxation - intrensic property of fluid
T1B = f (temperature, little pressure effect (liquids))
Surface Relaxation - Fluid-Rock interface
T1S = f (S/V ratio (pore size) , relaxivity )
MRIL - Principles and Applications
9/18/2018

5. often estimated as a multiple of
T1 Polarization
1.00
0.95
95%
often estimated as a multiple of
3 X T1
M(t)/Mo
sec.
Polarization Time / T1
MRIL - Principles and Applications
9/18/2018

6. MRIL - Principles and Applications
T1 and T2 B0 ML RF MT
T1 characterizes the rate at which longitudinal magnetization builds up
T2 characterizes the rate at which transverse magnetization decays
MRIL - Principles and Applications
9/18/2018

7. MRIL - Principles and Applications
A Single Spin Echo
90°
180°
RF field
time
signal
amplitude
free-induction decay (FID) signal
spin-echo signal
time t 2t
adapted, with permission, from Akkurt, 1990.
MRIL - Principles and Applications
9/18/2018

8. Carr-Purcell Gradient Field Relaxation Rate TE D
= Intrinsic Relaxation Rate (sec)
= Static Magnetic Field Gradient (gauss/cm)
= Gyromagnetic Ratio (0.678 radians/gauss)
= Pulse Echo Spacing, 2 (sec)
= Diffusion Coefficient (cm2/sec)
MRIL - Principles and Applications
9/18/2018

9. Idealized CPMG Spin-Echo Train
envelope of spin-echo amplitudes µ TE
Importance of TE
in general, want as many echoes and as short a TE as possible
more echoes => higher snr
more echoes at early times => capture fast components
more echoes at late times => resolve slow component (e.g. vugs)
making TE short also reduces diffusion-induced rlxn for typ grad’s, diffusion fx effectively eliminated with TE < ~1 msec
limitation on echo spacing is mainly instrumental one
Rick C talk on hardware will explain the problem and remedies
time, t 2t 4t 6t 8t
90º
pulse
180º
pulse
180º
pulse
180º
pulse
180º
pulse
Shortening inter-echo spacing (TE) ...
reduces diffusion-induced shortening of T2
improves resolution of short T2 components
Increasing number of echoes ...
increases signal-to-noise (SNR)
improves resolution of long T2 components
MRIL - Principles and Applications
9/18/2018

10. MRIL - Principles and Applications
Data Acquisition ...
1. Record CPMG trains in phase-alternate pairs (PAPs)
2. Stack adjacent echo trains to improve signal-to-noise (SNR) +
running
average -
.....
Basic data flow ...
1. record CPMG trains in phase-alt pairs at each depth
2. use standard method of stacking adjacent echo trains to improve signal-to-noise. snr improved bya factor = sqrt(#stacks)
alternate phase of first (p/2) pulse
corrects for baseline offset, drift
reduces interference from ringing
one tool also alternates frequency
MRIL - Principles and Applications
9/18/2018

11. Relaxation Times: T1 , T2 , and T2*
Pulse has two effects:
1. Increases thermal energy
(spin temperature)
2. Introduces phase coherence
at equilibrium
90° pulse
After pulse is switched off ...
rapid loss of phase coher-
ence, time constant = T2*
decay of transverse
magnetization,
time constant = T2
recovery of longitudinal
magnetization,
time constant = T1
pulse has two effects
1. impose increase spin temperature
2. impose phase coherence
after 90 deg pulse, get rapidly decaying signal called FID
immed after pulse, phases of spins have common phase
after pulse is switched off, three things happen
1. spins rapidly loose phase coherence => T2*
- dephasing due to spatial variations in Bo
2. decay of component of magntzn in xy plane => T2
3. recovery of component of magntzn along z: => T1
T1 and T2 due to underlying molecular processes
- diffusion and fluid-solid interaction on pore surface
can’t measure true relaxation with just 90 deg pulse
- spins have just dephased but magntzn remains
to measure T1 also must tip long mag into transverse plane
- recall, can’t detect mag that has no component in xy plane
T2 of primary interest for logging, can be meas faster than T1
T2 can be measured faster and thus is more practical for logging applications than T1
MRIL - Principles and Applications
9/18/2018

12. MRIL - Principles and Applications
NMR Experiment Timing Mo
T1 = 400 msec
M || to Bo
(longitudinal
component) TW Mo
T2 = 250 msec
M ^ to Bo
(transverse
component) TE TX B1
RF field
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
time, seconds
adapted from Murphy, D.P., World Oil, April 1995
MRIL - Principles and Applications
9/18/2018

13. MRIL - Principles and Applications
Data Acquisition Tw
time
Tw = wait time
Te = interecho time
Ne = Number of echoes
RA = running average
time Te
MRIL - Principles and Applications
9/18/2018

14. Effects of Pore Fluids on T1
Solids
Fluids
clay matrix
capillary bound water
BVI
clay bound water
movable water
rock matrix
hydrocarbons
Invisible to NMR
Variability in T1 due to Fluid Types
Clay Bound Water
Capillary Bound
Movable Water
Polarization
(ideal)
Hydrocarbons
Time in sec.
0.3 1 3 10
MRIL - Principles and Applications
9/18/2018

15. Effects of Chemistry and Texture on T1 and T2 (water filled)
Low Porosity
Clean Cgr Sandstone
T1 Build-up
T2 decay
Low Porosity
Shaly Fgr Sandstone
Higher Porosity
Shaly Cgr Sandstone
Time, sec.
MRIL - Principles and Applications
9/18/2018

16. Rule of Thumb for T1 build-up
95 % Polarization
Must use the correct Tw (wait time) to see full porosity
MRIL - Principles and Applications
9/18/2018

17. Type of Measurements by MRIL®
f: MRIL Porosity
Effective porosity
T2: Transverse Relaxation Time
Differentiates capillary bound water from free fluids; important for permeability estimate.
T1: Longitudinal Relaxation Time
Identifies hydrocarbon fluids in the non-wetting phase.
D: Fluid Diffusivity
Differentiates between gas phase and liquid phase. D T1
MRIL - Principles and Applications
9/18/2018

18. Resonant Frequency F = g B0 Field Strength diminishes with increased
distance from magnet.
Proton “spin” rates are proportional
to Magnetic Field Strength.
F = g B0
For Hydrogen: g = Hz / Gauss
F = Frequency (Hz)
B0 = Field Strength (Gauss)
Applying a radio frequency signal
equal in frequency to the proton “spin”
rate causes the protons to resonate. N S
Magnetic Resonance occurs only where the rate of “spin” of the protons of hydrogen is equal to the frequency of an applied RF signal that is emitted from the tool. Hydrogen protons spin at a rate that is proportional to the strength of the magnetic field in which they reside. Since the MRIL tool contains a powerful permanent magnet, the magnetic field strength around the tool is a function of the distance from the magnet. Therefore, the rate of spin of hydrogen protons is proportional to the distance from the magnet. When the RF signal is emitted from the tool, magnet resonance occurs at a fixed distance around the tool.
strength
field
distance
MRIL - Principles and Applications
9/18/2018

19. MRIL Gradient Magnetic Field
Sensitive Volume
Formation
Borehole Wall
Magnet
Antenna
mud
enables selective detection of fluid signal at fixed radius from tool axis
MRIL unaffected by washout less than diam of investigation
standard diam = 14 inch
slim (10.5 inch) and deep-investigating (18 inch) tools also available
gradient magnetic field also enable diffusion measurement (more later on this)
Frequency
Bandwidth
B0(r)
B0(r) B o @
169 Gauss, G
17 Gauss/cm 6”
16”
MRIL - Principles and Applications
9/18/2018
ã NUMAR Corp., 1996

20. Measurement Principle
Damaged Zone
Sensitive Volume
typ. 12 cm
Mud Cake
MRIL - Principles and Applications
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21. MRIL - Principles and Applications
MRIL in Wellbore
Borehole
MRIL Probe
Sensitive
Volume
Cylinders
(each 1 mm thick
at 1 mm spacing)
24 “
This figure illustrates the MRIL tool in the bore hole and the sensitive volumes that are concentric with the tool. The three volumes are actually excited individually with only one volume being measured at a time. After being measured, the protons within a sensitive volume must recover for a period of time. During the recovery time for a given volume, the other volumes are investigated. By cycling between the sensitive volumes the MRIL gathers more data and can log faster than older designs which can only investigate a single volume.
16”
MRIL - Principles and Applications
9/18/2018
ã NUMAR Corp., 1995

22. Using Multiple Frequencies
Improves Logging Speed
Increases Signal to Noise
MRIL - Principles and Applications
9/18/2018

23. A New Multiband Generation
of NMR Logging Tools
MRIL-Prime
Features
9 discrete measurement volumes
Accelerated polarization - 12 sec in 6 sec
more robust electronics and new sonde
Benefits
Single-pass, fast, total porosity & T2 distribution
24 fpm logging speed or
Data quality of C tool x 3
Multi-parameter acquisition (T1 curve, etc.)
Familiar outputs and interpretation
MRIL - Principles and Applications
9/18/2018

24. MRIL - Principles and Applications
MRIL-Prime Shells
Borehole
9 Sensitive
Volume
Cylinders
(each 1 mm thick
at 1 mm spacing)
MRIL Probe
760kHz
580kHz
~1”
24”
250°F
MRIL - Principles and Applications
9/18/2018

25. MRIL Diameter of Investigation 6” Probe20
50° F. 19
100° F.
50° F. 18
150° F.
100° F. 17
200° F.
150° F.
Diameter (Inches)
250° F. 16
200° F.
300° F. 15
250° F. 14
300° F. 13 12
500
550
600
650
700
750
800
850
900
950
1000
Frequency (kHz)
MRIL - Principles and Applications
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26. MRIL - Principles and Applications
MRIL Calibration Tank
Side View
End View
Formation Chamber
Faraday Cage
Borehole Chamber
MRIL Tool
Sensitive Volumes
MRIL - Principles and Applications
9/18/2018
ã NUMAR Corp., 1996

27. MRIL - Principles and Applications
T2 Relaxation T 2A 1 2B 2S = + 2D
MRIL - Principles and Applications
9/18/2018

28. Effective Porosity (MPHI) Irreducible (MPHI - MFFI)
Idealized Echo Train
Effective Porosity (MPHI)
Free Fluid (MFFI)
Amplitude
T2R
The resonant signal that is received from the sensitive volume is illustrated above. The initial amplitude represents the effective porosity of the formation and the rates of decay within the signal provide the irreducible and free fluid measurements. The free fluids are generally associated with the slow decaying portion of the measurement while the irreducible fluids are the rapidly decaying portion.
The sample rate most commonly used with the MRIL tool is 1.2 milliseconds between samples and is referred to as TE (time between echoes). The rate of decay of the received signal is an exponential time constant and is called T2. After each measurement as shown above, time must be given for the hydrogen protons within the sensitive volume to recover. If sufficient time between experiments is not given, the amplitude of the next measurement will be too low. The rate of recovery of the affected protons is an exponential time constant that is called T1.
Bulk Volume
Irreducible (MPHI - MFFI) TE
MRIL - Principles and Applications
Time
9/18/2018
ã NUMAR Corp., 1995

29. Hydrogen in Matrix & Clay Bound Water
Hydrogen in Clay
Bound Water
This figure amplifies the very early part of the received signal and clearly shows why any hydrogen present in the matrix or in clay bound water are not part of the measurement. Both these components of the signal decay extremely rapidly and are simply no longer present by the first sample taken by the tool. It would be possible to measure the clay bound water by using a sample rate (TE) that is much faster than is currently used.
Hydrogen in Lithology
MRIL - Principles and Applications
9/18/2018
ã NUMAR Corp., 1995

30. MRIL - Principles and Applications
Pore Size and T2 (Water) T2
time T2
time T2
time T2
time T2
time
MRIL - Principles and Applications
9/18/2018

31. Coarse Grain Response MPHI = 36, MFFI = 30, MBVI = 6, MPERM = 4200 md40 35 30 25
Porosity 20 15
This figure illustrates the signal as it is received by a tool (x’s). The computer in the up hole unit computes the “best fit” to the data (black line) and provides the components that sum together to equal that best fit line. This example represents a pore system that is dominated by large pores (slow decay - large T2 values). 10 5 50
100
150
200
250
MRIL - Principles and Applications
Time (ms)
9/18/2018
ã NUMAR Corp., 1995

32. Fine Grain Response MPHI = 36, MFFI = 6, MBVI = 30, MPERM = 6.7 md40 35 30 25
Porosity 20 15
This figure illustrates the signal as it is received by a tool (x’s). The computer in the up hole unit computes the “best fit” to the data (black line) and provides the components that sum together to equal that best fit line. This example represents a pore system that is dominated by very small pores (fast decay - small T2 values). 10 5 50
100
150
200
250 -5
MRIL - Principles and Applications
9/18/2018
Time (ms)
ã NUMAR Corp., 1995

33. MRIL - Principles and Applications
MAP Processing
Echo 1 = A1e-t/4 + A2e-t/8 + A3e-t/16 + A4e-t/32 + A5e-t/64 + A6e-t/128 + A7e-t/256 + A8e-t/512 + Noise
Echo 2 = A1e-t/4 + A2e-t/8 + A3e-t/16 + A4e-t/32 + A5e-t/64 + A6e-t/128 + A7e-t/256 + A8e-t/512 + Noise
Echo 3 = A1e-t/4 + A2e-t/8 + A3e-t/16 + A4e-t/32 + A5e-t/64 + A6e-t/128 + A7e-t/256 + A8e-t/512 + Noise
Echo n = A1e-t/4 + A2e-t/8 + A3e-t/16 + A4e-t/32 + A5e-t/64 + A6e-t/128 + A7e-t/256 + A8e-t/512 + Noise
MRIL - Principles and Applications
9/18/2018
ã NUMAR Corp., 1995

34. MRIL - Principles and Applications
Data Processing
MAP
“Inversion”
Processing
Spin-echo data
T2 Spectrum
NMR porosity
2.00
Free Fluid - FFI 16
multiexponential fit to spin-echo amplitudes 14
1.50 12
Clay Bound Water - CBW
Capillary Bound Fluid - BVI
large-pore (mobile fluid) signal 10
Incremental Porosity [pu]
Invisible Region
1.00
Cumulative Porosity [pu] 8 6
0.50 4 2
time
0.00
0.1 1 10
100
1000
10000
small-pore (irreducible fluid) signal
T2 [msec]
clay-bound water
Water-saturated rock: rT2 = V/S
“Invisible Region” is a function of signal to noise and echo spacing
MRIL - Principles and Applications
9/18/2018

35. 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 2r
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
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 - Principles and Applications
9/18/2018

36. MRIL - Principles and Applications
Diffusion and T2D
only effective for T2 relaxation (not for T1) 12 T 2D D
when
T2D =
D . ( G .  . Te )2 T 2D e
when
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 G
when
MRIL - Principles and Applications
9/18/2018

37. Effect of Oil on T2 Distribution
Incremental Porosity %
This figure illustrates the effect of oil in a rock sample. Each color indicates a different water saturation on a T2 Distribution. This particular rock sample has a very simple pore size distribution as seen by the white area (100% water saturation). Almost all of the porosity is represented by a narrow band on the T2 scale indicating a very uniform pore size. As oil saturation is increased, the amplitude of the water filled portion of the distribution gets smaller due to the decreased volume of water. As this happens, the oil peak grows in amplitude due to the increasing volume of oil. Also, since the surface to volume ratio of the water signal is changing (same surface area but reduced volume of water) the T2 value for the water filled portion also goes down - decays faster. In other words, when the formation is 100% saturated with water, the T2 value is centered at about 26.6 milliseconds. But when the water saturation is reduced to 56.9% the T2 for the water filled portion is down to 7.4 milliseconds. This explains why the short T2 part of the signal represents the irreducible fluids. The short T2 values represent either fluids that are trapped in very small pores or the water filled part of the porosity that remains when hydrocarbons are present.
Note also that the oil signal is very constant with respect to the T2 axis. This is because the system is “water wet” and the oil is not affected by the surface of the rock’s pore system. The oil signal is simply its bulk T2 value (related to viscosity).
Sw = 56.9%
Sw = 65.4%
Sw = 84.3%
Sw = 100%
T2 Distribution
MRIL - Principles and Applications
9/18/2018
ã NUMAR Corp., 1995

38. Partially Saturated Water Wet Rock Behavior
Sw = 100 % T2 T2
Sw < 100 %
MRIL - Principles and Applications
9/18/2018

39. Viscosity & Diffusion vs T2 @ 80 ° F.
MRIL - Principles and Applications
9/18/2018
ã NUMAR Corp., 1995

40. T2 Distributions & Incomplete Recovery
The long end of T2 distributions - indicative of hydrocarbons -
can be associated with very long T1 times. If standard recovery
times TR are used, that portion of a T2 spectrum will be
depressed by 50% or more.
correct T2 spectrum
incomplete recovery
P (T2) T2
MRIL - Principles and Applications
9/18/2018
ã NUMAR Corp., 1995

41. MRIL - Principles and Applications
Viscosity vs. T2 for oils
10000 T 2 =
4T / h
1000
T2 (ms)
100
100 F
T2cutoff
300 F
T2 Oil
adopted from Looyestijn et al, 1996 10 10 20 30 40 50
Viscosity (cp)
MRIL - Principles and Applications
9/18/2018

42. MRIL - Principles and Applications
Viscosity vs. D0 for oils
0.01
0.1 1 10
100 D =
2.5T / 300 h
Diffusion coefficient (x10e -5 cm2/s)
100 F
300 F
adopted from Looyestijn et al, 1996 10 20 30 40 50
Viscosity (cp)
MRIL - Principles and Applications
9/18/2018

43. MRIL - Principles and Applications
MRIL Response
MRIL - Principles and Applications
9/18/2018

44. MRI Log Processing & Interpretation
Conductive Fluids
Matrix & Dry Clay
Clay Bound Water
Capillary Bound Water
Moveable
Free
Water
Oil
Gas
MCBW
MPHI
MRIL
MBVI
MFFI
PHIT
MRIL Porosity
MRIL =  . HI . ( 1 – e–tw/T1)
MRIL =  . Sxo . HIw . ( 1 – e–tw/T1w) +  . ( 1 - Sxo) . Hlh . ( 1 – e–tw/T1h)
MRIL - Principles and Applications
9/18/2018

45. MRI Log Processing & Interpretation
Conductive Fluids
Matrix & Dry Clay
Clay Bound Water
Capillary Bound Water
Moveable
Free
Water
Oil
Gas
MCBW
MPHI
MRIL
MBVI
MFFI
PHIT
MRIL Permeability
MRIL - Principles and Applications
9/18/2018

46. Direct Hydrocarbon Typing Differential Spectrum Method
Porosity
Long Recovery
Time (TR)
Brine
Gas
Oil
Short Recovery
Time (TR)
Difference
, ,000
T2 Time (ms)
ã NUMAR Corp., 1995
MRIL - Principles and Applications
9/18/2018

47. MRI Log Processing & Interpretation
T.D.A. MRIL Time Domain Analysis
Correcting MRIL Porosity for T1 effects
Unique Liquid
Phase
Porosity
TwLu
Long Tw
Short Tw
TwSu 1 10
100
1,000
10,000
T2 Time (ms)
MRIL - Principles and Applications
9/18/2018

48. MRI Log Processing & Interpretation
TDA_COMP
The Porosity Measured by MRIL is Subject to Hydrogen Index HI
and Polarization T1 effects.
 Tw =  . HI . ( 1 - e -Tw/T1)
 : True Hydrocarbon Porosity
Tw : Measured Hydroc. Porosity
Tw : Wait Time
HI : Hydrogen Index
TwLu : Porosity from TwL of unique
Fluid phase
TwSu : Porosity from TwS of unique Fluid phase
TwL : Long Wait Time
TwS : Short Wait Time
T1 estimation is based on
the Ratio r =  TwLu /  TwSu
 . HI . ( 1 - e -TwL/T1 )
r =
 . HI . ( 1 - e -TwS/T1 )
1 - e -TwL/T1 =
1 - e -TwS/T1
MRIL - Principles and Applications
9/18/2018

49. MRI Log Processing & Interpretation
TDA_COMP
gas is calculated by correcting for HIgas & T1gas
g : Gas Porosity
g * : Apparent Gas Porosity
seen by echo difference
HIg : Hydrogen Index of Gas
o : Oil Porosity
o* : Apparent Oil Porosity
HIo : Hydrogen Index of Oil
T1h : T1 of either Gas or Oil
oil is calculated by correcting for HIoil & T1oil
MRIL - Principles and Applications
9/18/2018

50. [ ] MRI Log Processing & Interpretation
TDA_COMP
Fully Polarized Liquid Porosity from Long Tw
PhiFPL = MPHIA - [
g . HIg . ( 1 - e -TwL / T1g ) +
o . HIo . ( 1 - e -TwL / T1o ) +
 w . HIw . ( 1 - e -TwL / T1w ) ]
Corrected Porosity for T1 and HI
TDAMPhi = PhiFPL + g + o +  w
MRIL - Principles and Applications
9/18/2018

51. Direct Hydrocarbon Typing Shifted Spectrum Method
Short Echo
Spacing
Brine
Gas
Porosity
Long Echo
Spacing
Porosity
, ,000
T2 Time (ms)
ã NUMAR Corp., 1995
MRIL - Principles and Applications
9/18/2018

52. Direct Hydrocarbon Typing Shifted Spectrum Method
Short Echo
Spacing
Brine
Oil
Porosity
Long Echo
Spacing
Porosity
, ,000
T2 Time (ms)
ã NUMAR Corp., 1995
MRIL - Principles and Applications
9/18/2018

53. MRI Log Processing & Interpretation
DIFAN MRIL Diffusion Analysis
MRIL data acquired using Dual Te
Solves for Oil in the slice under investigation
Does not solve for VERY Heavy Oil
MRIL - Principles and Applications
9/18/2018