MREX (NMR Logging)

© 2003 Baker Hughes Incorporated All rights reserved.
MREX OVERVIEWMREX OVERVIEW

Efficiency….Data accuracy….People-oriented service
www.bakeratlasdirect.com
Magnetic Resonance ImagingMagnetic Resonance ImagingMagnetic Resonance Imaging
Clinical MRI images are determined from -
– Quantity of 1H present in the specimen
– Relaxation times present in the tissue

MR measurements provide three
types of information not available
from other logging tools
– Quantities of fluids present in the rock
– Information on the sizes of the pores
containing the fluids
– Information on the properties of these
fluids
Magnetic Resonance LoggingMagnetic Resonance LoggingMagnetic Resonance Logging

NMR Measurement in Well LoggingNMR Measurement in Well Logging
Quantity of 1H present in the sample volume
Relaxation times present in the sample
Small pores
Large pores
+
Porosity Φ
Φ

Mineralogically Independent Total and
Effective Porosity
Clay-Bound Water Volume
Capillary-Bound Water & Free Fluid Volumes
Pore Size Distribution
Permeability Index
Shale Volume & Distribution
Residual Fluid Saturations (PoroPerm + Gas,
PoroPerm + Oil)
Oil Viscosity (PoroPerm + Oil )
Reservoir Description Data
from NMR Logging
Reservoir Description DataReservoir Description Data
from NMR Loggingfrom NMR Logging

Reservoir Quality & Productivity (Vsh, φt, φe, knmr, Swirr, Sor)
Porosity in Complex/Mixed Lithologies
Identification of Low-Resistivity Pay (Shaly Sands)
Identification of Low-Contrast Resistivity Pay (Fresh Water)
Hydrocarbon Pore Volume in Thinly Bedded Laminated Pay
Gas reservoir – Saturation analysis, knmr, φt
Pore Fluid Typing (Gas vs. Oil vs. Water)
Oil Viscosity for Mobility Determination
Frac Optimization in Low Porosity Reservoirs
Optimize Selection of Formation Test and Completion Intervals
NMR Logging – Reservoir ApplicationsNMR LoggingNMR Logging –– Reservoir ApplicationsReservoir Applications

How NMR Works – An Introduction to
NMR Physics
How NMR WorksHow NMR Works –– An Introduction toAn Introduction to
NMR PhysicsNMR Physics

NMR PhysicsNMR PhysicsNMR Physics
Q - What is Nuclear Magnetic Resonance,
NMR?
A - NMR is a phenomenon which occurs when the
nuclei of atoms, that posses a property called
spin, are placed in a static magnetic field and
then excited by radio frequency, RF, field
Q – What is spin?
A - Spin is a fundamental property of nature like
electrical charge. Individual unpaired electrons,
protons, and neutrons each possesses a spin of
1/2.

NMR Physics - SpinNMR PhysicsNMR Physics -- SpinSpin
Common elements with spin
NMR can only be performed on elements where the natural
abundance of the element is sufficient to produce a
measurable signal. 1H is abundant in oil, gas and water and is
the element measured by NMR logging tools.
Nuclei Unpaired
Protons
Unpaired
Neutrons
Net
Spin
γ
(MHz/T)
Natural
Abundance
Sensitivity
1H 1 0 ½ 42.58 99.99% 1
2H 1 1 1 6.54
31P 1 0 ½ 17.25
23Na 1 2 1 ½ 11.27 100% 0.0925
14N 1 1 1 3.08
13C 0 1 ½ 10.71 1.11% 0.0159
19F 1 0 ½ 40.8

NMR PhysicsNMR PhysicsNMR Physics
Water molecules – H2O
O
H
H
A proton with spin behaves
as a small magnet
O
S
N
H
S
N
H

Randomly distributed spins of
hydrogen nuclei
B=0, 〈M〉=0
hydrogen nuclei are
magnetic dipoles.
Nuclear MagnetizationNuclear MagnetizationNuclear Magnetization
S
N
S
N
S
N
S
N
S
N
S
N
S
N
S
N
S
N
S
NS
N
S
N
S
N
S
N
S
N

The ratio of parallel to anti-parallel is
100,006 : 100,000....it is the extra 6
parallel protons that produce the
NMR signal that we measure
When placed in a magnetic field,When placed in a magnetic field,
BB00, the, the 11
H protons align parallelH protons align parallel
and antiand anti--parallel with the fieldparallel with the field
MM00⎟⎟⎟⎟ BB00
B0
S
N
S
N
S
N
S
N
S
N
S
NS
N
S
N
S
N
S
N
S
N
S
N
1 drop of water
contains 1023
1H protons!

Protons align with B1 when RF field
is switched on, or pulsed
When a pulsed radio frequency field, BWhen a pulsed radio frequency field, B11,,
is applied , theis applied , the 11H protons will realignH protons will realign
with the Bwith the B1.1. When BWhen B11 is switched off theis switched off the
11H protons begin toH protons begin to precessprecess as theyas they
realign with Brealign with B0.0.
B0
RF Antenna
MM00 ┴┴ BB11
B1
S
N
S
N
S
N
S
N
S
N
S
NS
N
S
N
S
N
S
N
S
N

Free Induction
Decay signal
Larmor Frequency
freq. = 4258 H
Gauss
z B0
When the RF field is switched off the
protons precess back to realign with B0, as
they precess they emit a small RF signal
that is received in the RF antenna.
f =f = γγ BB00
RF Antenna
Click for
precession
animation
S
N

PrecessingPrecessingPrecessing
Single SpinSingle Spin
x
z
y
μ
B0
θ
f

Classic Representation of NMRClassic Representation of NMRClassic Representation of NMR
Net MagnetizationNet Magnetization
z
M
y
x
B0
f
TippingTipping
AtAt
resonanceresonance
Tipping pulse removedTipping pulse removed

Review of NMR MechanismReview of NMR MechanismReview of NMR Mechanism
System
– Static Magnetic Field
• Permanent Magnet
• Aligns Protons
– “Normal State”
– RF Magnetic Field
• Tips protons
• Powerful Transmitter
– Radio Receiver
• Very sensitive receiver
to detect NMR signal
in the nano-volt range Slope Calib Temp pH mV
ON
OFF
N
S
RF Antenna
B0
B1
RF transmitter
RF receiver

MREX Logging tools (Series 3218)MREX Logging tools (Series 3218)MREX Logging tools (Series 3218)
As the MREX tool traverses the
wellbore the hydrogen protons on
the formation adjacent to the tool are
aligned with B0
MREX tool containsMREX tool contains
large permanent magnetlarge permanent magnet
with field, Bwith field, B00
MM00⎟⎟⎟⎟ BB00
B0
S
N
S
N
S
N
S
N
S
N
S
NS
N
S
N
S
N
S
N
S
N
S
N

MREX Logging Tools (Series 3218)MREX Logging Tools (Series 3218)MREX Logging Tools (Series 3218)
Larmor Frequency
freq. = 4258
H
Gauss
z
B0
Tool emits radio
frequency, RF,
pulse with field
strength B1
Spins are tipped 90 degrees by
the RF pulse and then begin to
precess in the B0 field.
B0
MM00 ┴┴ BB11
B1
S
N
S
N
S
N
S
N
S
N
S
NS
N
S
N
S
N
S
N
S
N

MREX Logging tools (Series 3218)MREX Logging tools (Series 3218)MREX Logging tools (Series 3218)
Larmor Frequency
freq. = 4258
H
Gauss
z
B0
MREX freq = 450MREX freq = 450 –– 900 kHz900 kHz
We don’t measure free
induction decay with MREX
We measure spin echoes
Spin echoes allow us to
rephase the NMR signal
multiple times to create an
echo train
S
N

Spin Echo Train – CPMG
Pulse Sequence
Spin Echo TrainSpin Echo Train –– CPMGCPMG
Pulse SequencePulse Sequence
TE
Time
90°
x 180°
y 180°
y 180°
y
180°
y 180°
y
Amplitude
Echo Signals
RF Pulses
Start of free induction decay
Polarization
pulse
Rephasing
pulses
T2 Decay
Click here for
echo train
animation

Effect of RF pulseEffect of RF pulseEffect of RF pulse
precession in xy
plane induces FID
signal in coil
at equilibrium
M0
x
y
z
B0
• RF pulse generates magnetic field B1
• B1 oriented normal to B0
• B1 oscillates at Larmor frequency
B1
y
z
x
90x° pulse
y
z
x
Excite transitions between spin states
by irradiating at Larmor frequency:
⎛ ⎞γ
f =
⎝
⎜
⎠
⎟
π2
B0
B0
B0

Sources of Gradient (G)Sources of Gradient (G)Sources of Gradient (G)
Static field inhomogeneity
Depends on magnet configuration
(strength, dimensions, etc…)
Depends on frequency (FL α B0 α 1/DOI)
● Internal magnetic field
50
100
150
200
2 3 4 5
DOI (")
B
0(Gauss)
B01
B02
Different
Susceptibility
Molecular Collisions
Pore Geometry
& rock type
Change in the
Internal
magnetic fields

180o
Pulse; Spin Echo180180oo
Pulse; Spin EchoPulse; Spin Echo
y’x’
G)B0
B1, 180o
yx
A) z
C)
y’x’
D)
y’x’
Mx,y
H)
x’ y’
E)
y
Mmax
x’
F)
y’
x’
+ TE
fL
Time
Mmax
B
C
D
E
F
G
Mmax e –t/T2
*
A H
B)
x’ y’

Echo Train, CPMG, T2 DecayEcho Train, CPMG, TEcho Train, CPMG, T22 DecayDecay
Time
Mx,y
M0
M0 Σi e –t/T2,i
TE
TE TE TETE/2
RF
Pulses
90o
180o
180o
180o
180o
TE

TE : intercho spacing
TW : wait time ( ≥ 3 x T1 for full recovery)
TW Time
Amplitude
Echo Train
TE Time
90°
x 180°
y 180°
y 180°
y 180°
y 180°
y
Amplitude
Echo Signals
RF Pulses
Echo Train – CPMG Pulse SequenceEcho TrainEcho Train –– CPMG Pulse SequenceCPMG Pulse Sequence

A Few Things About Echo TrainsA Few Things About Echo TrainsA Few Things About Echo Trains
Echo Spacing, TE
– Short TE is advantageous over long TE for PoroPerm logging
• Typically, 0.6ms with MREX vs. 1.2 ms with MRIL
– Improved Signal/Noise
» Twice as many data points in fitted decay
» Less diffusion effect on echo train
• Typically, 0.4ms for CBW with MREX
– Provides more data points for fitting fast decay CBW component
Longer echo spacings are needed for hydrocarbon typing data,
increasing TE amplifies the diffusion effect on the echo train
– TE is adjustable to suit special applications
Wait time, Tw
– Sufficient Tw is required between echo trains for protons to realign
with static magnetic field, B0, or a porosity deficit will be seen
– Tw is dependent on T1, a bulk property of the moveable fluid
– T1 differs for oil, gas and water
– Multiple combinations of Tw can be recorded to provide information
on fluid type, volume and to measure T1 of moveable fluids

o
'
90x
o
'
135 y
o
'
135 y
o
'
135y
o
'
135 y
TE/2 TE TE TE
M0 F(T2)
F(T2*)
TE
Modified CPMG SequenceModified CPMG SequenceModified CPMG Sequence
AτDuration of 900 pulse
BτDuration of 1350 pulse

T1 and wait time, TwTT11 and wait time,and wait time, TwTw
8
M = Mo*(1-e(-t/T1))
T1 Recovery Curve
0
20
40
60
80
100
120
0 1 2 3 4 5
t/T1
M(%)
M = Mo*(1- e(-t/T1) )
M0
T1
– NMR definition
• T1 - longitudinal time constant - spin lattice relaxation
– Well logging definition
• T1 - time constant that characterizes the time it takes for the spins to align with the static
magnetic field, B0
Tw – wait time
– The time between NMR experiments at the same frequency
– It takes 3 * T1 to get 95% of spins aligned, for full recovery NMR logging Tw ≥ 3 * T1

NMR PorosityNMR PorosityNMR Porosity
φA = HI * φT * (1 - e - Tw / T1)
M ∝ φA
• Tw should be at least 3*T1 for full MR logging
• If Tw < 3*T1 a porosity deficit will result

www.bakeratlasdirect.com8
T2 is the transverse time constant and characterizes the echo decay rate
Time, t2τ 4τ 6τ 8τ
exp
−t
T2
Echo decay rate ∝
90º
pulse
180º
pulse
180º
pulse
180º
pulse
180º
pulse
Amplitude
Idealized CPMG Spin – Echo TrainIdealized CPMG SpinIdealized CPMG Spin –– Echo TrainEcho Train

T1 & T2TT11 & T& T22
T1 ≥ T2
– An analogy for T1 vs. T2 is what happens when a toilet is flushed. It
flushes fairly fast – T2 , but it takes much longer for the tank to refill –
T1
Both T1 and T2 can be used to measure porosity and fractional
fluid volumes CBW, BVI & BVM
Most MR wireline logging employs T2 measurement techniques
because T2 is easier to measure
– Most models are based on T2 data
T1 is harder to measure, but provides better data
– T1 is not affected by the things that affect T2
• Internal field gradient in the formation
• Magnetic field inhomogeneities from the logging instrument
• Diffusion
For the BVM component T1 & T2 represent intrinsic properties of
the fluid and are useful for hydrocarbon typing and quantification
– Using both T1 & T2 provides more accurate & robust analysis

NMR Physics - ReviewNMR PhysicsNMR Physics -- ReviewReview
Hydrogen protons behave like small magnets
The static magnetic field, B0, aligns the protons
The RF field, B1, tips the 90º from B0
When B1 switches off the protons precess back to
alignment with B0
As the protons precess they emit a small signal which is
measured by the MR logging tool
The MR tool re-phases the signal multiple times to create
an echo train
The echo train provides information
– Porosity
– T2 decay T2 spectrum
• Fractional fluid volumes – CBW, BVI & BVM
Two important parameters of the echo train
– TE – echo spacing – time between echoes in the echo train
– Tw – wait time – time between experiments at a single
frequency
By manipulating TE & Tw, intrinsic fluid properties of T1 &
T2 as well as fluid volume and viscosity can be determined

Quick QuizQuick QuizQuick Quiz
What are the key components of MR logging
tools?
What is T1?
What is T2?
What is TE?
What is Tw?
What condition must be met for full recovery NMR
logging?

NMR Porosity Model & T2 Spectrum

MRMR PorosityPorosity ModelModel
BVMBVI
φeffective
φtotal
Conductive Fluids
matrix
dry
clay
clay-
bound
water
mobile
water
capillary
bound
water
hydrocarbon
CBW
BVM – Bulk Volume Movable
BVI – Bulk Volume Irreducible
CBW – Clay Bound Water Volume

MR porosity measurement
– Calibrated to 100% water tank
– Amplitude of measured signal as % of calibrated signal
is MR total porosity
MR Porosity is defined by the equation
– HI - Hydrogen Index of fluid filling the pore space
• Low hydrogen index of gas and light oil results in
porosity undercall
– T1 - Longitudinal relaxation time
– Tw - Time between measurements at the same
frequency – Tw ≥ 3*T1 for full recovery
φA = HI * φT * (1 - e - Tw / T1)

MR porosity measurement is
– A direct measurement that is sensitive
only to the fluids present in the rock
pores
– Independent of rock matrix and
mineralogy

MRMR ‘‘IdealizedIdealized’’ Echo TrainEcho Train
Time
MBVI
MeasuredAmplitude
T2 Decay Curve
CBW
BVM
φTotal = CBW + BVI + BVM
φEffective = BVI + BVM

EchoAmplitude
BVM = 20.30 pu
φMR = 26.25 pu
BVI = 5.95 pu
1500 15 1351201059075604530
Time (ms)
25
20
15
10
5
Limestone Block
φ core = 25.5%
Berea Sandstone Block
φMR = 19.82 pu
BVM = 15.61 pu
BVI = 4.21 pu
EchoAmplitude
0 15 1501351201059075604530
Time (ms)
20
15
10
5
φ core = 20.3%
MR Porosity – Real data, Test Pit VerificationMR PorosityMR Porosity –– Real data, Test Pit VerificationReal data, Test Pit Verification

MR RelaxationMR RelaxationMR Relaxation
2 types of MR relaxation
– T1 relaxation – longitudinal relaxation
• Time constant for the net magnetization to align with the
static magnetic field
– T2 relaxation – transverse relaxation- T2 decay rate
• Time constant for the echo train to decay
T1 & T2 contain information on pore sizes and
fluid properties
T2 is easier to measure and is most common
relaxation measured and used in MR logging
Recent advances have made T1 measurements
while logging possible

MR RelaxationMR RelaxationMR Relaxation
T2 decay rate is not a single exponential
decay, it is the sum of a multi-exponential
decay with contributions from
– Each class of pore sizes present in the sample
investigated, small pores have small T2 values
and large pores have large T2 values
– Free fluids will contribute T2 decay rates that
are bulk properties of the fluids – the
information from the free fluid decay rates is
used to identify and quantify the fluid type and
some of its properties

The T2 decay rate is inversely proportional to the
surface/volume ratio of the rock being measured
and directly proportion to the size of the pore.
0 100 200 300 400 500 600
Time (ms)
Porosity%
1 1
2T
S
V r p o r e
∝ ∝ρ
25
20
15
10
5
0
MR Relaxation - T2 Decay RateMR RelaxationMR Relaxation -- TT22 Decay RateDecay Rate

TT22 and Pore Size Distributionsand Pore Size Distributions
0.5 100101.0 1,000
T2 ms
Clay Silt Fine Coarse
Clay Domain
ρ2 = 1 μm/s
Sand Domain
ρ2 = 5μm/s

y = φA *e - t / T2
64 ms64 ms
16 ms16 ms
256 ms256 ms
tt
Amplitude(y)Amplitude(y) y =y = porpor ..
ee --t/256t/256
y =y = porpor ..
ee --t/64t/64
y =y = porpor ..
ee --t/16t/16
φφAA
Single Exponential DecaySingle Exponential DecaySingle Exponential Decay

φA = Σ por . e - t / T2
16 64 25616 64 256
1010
1515
55
TT22 (ms)(ms)
64 ms64 ms
IncrementalIncrementalφφ((pupu))
16 ms16 ms
256256
msms
TimeTime
y = 5y = 5 ..
ee --t/16t/16
+ 10+ 10 ..
ee --t/64t/64
+ 15+ 15 ..
ee --t/256t/256
φφAA = 30p.u.= 30p.u.
Multi-Exponential DecayMultiMulti--Exponential DecayExponential Decay

Matrix
Dry
Clay
Clay-
Bound
Water
Mobile
Water
Capillary
Bound
Water
Hydrocarbon
EchoAmplitude
0 15 1501351201059075604530
Time (ms)
20
15
10
5
BVI BVM
4.00
0.00
1.00
2.00
3.00
0.00
1.00
2.00
3.00
4.00
IncrementalPorosity(pu)
CBW
T2 Decay
φ, NMR Porosity
100000.1 1 10 100 1000
T2 Decay (ms)
T2 Cutoff
Transform
3ms
Pore Volumetric Distribution from NMRPore Volumetric Distribution from NMRPore Volumetric Distribution from NMR
T2 cutoff (SS) = 33 msec
T2 cutoff (Carb.) = 92 msec

Partitioning the T2 SpectrumPartitioning the TPartitioning the T22 SpectrumSpectrum
T2 cutoff establishes point between
small and large pores, separating bound
and free fluids
T2 is proportional to pore size
T2 is affected by the surface relaxivity of the
rock, ρ
Fluid in small pores is bound & won’t flow
Fluid in large pores is producible

Permeability
MCBW
MBVIMBVM
GR T2 Spectra Resistivity &
Permeability Pore Volumetrics
Real World NMR DataReal World NMR DataReal World NMR Data
0.00
1.00
2.00
3.00
4.00
0.1 1 10 100 1000 10000
BVI BVM
4.00
0.00
1.00
2.00
3.00
IncrementalPorosity(pu)
CBW
T2 Decay (ms)
T2 Cutoffs

CBW BVI BVM
NMR T2 Distribution – Fractional Fluid VolumesNMR TNMR T22 DistributionDistribution –– Fractional Fluid VolumesFractional Fluid Volumes
0.1 1 10 100 1000 10000
T2 Time (ms)
IncrementalPorosity(p.u.)
T2=3.3 ms T2=33 ms

knmr – Permeability from MR logging

MR Permeability - knmrMR PermeabilityMR Permeability -- kknmrnmr
knmr
– Calculated from MR data, not measured
by MR logging tools
– Based on models that show
permeability increases with increasing
porosity and increasing pore size
– Accurate when calibrated to core
permeability

MR Permeability - knmrMR PermeabilityMR Permeability -- kknmrnmr
Two models in use
Where assumed default parameters are: C =10, m = 4 & n = 2
CoatesCoates--TimurTimur Model :Model :
Note: knmr is an estimate of permeability based on a
model. For accuracy knmr should be calibrated to local
reservoir data.
nφ mNMR
BVI
BVM
C
knmr = •
SDR Model:
a n
•Cknmr T2 Geo. Mean= NMRφ•
m

Application of the model is predicated on assumption that the
porosity is all interconnected, and that pore throat diameter
systematically increases proportional to an increase in the
magnitude of the bulk free fluid volume (BVM).
Computed permeability may systematically increase as a function
of increasing height above free water level. This effect is most
likely to occur for lower quality reservoirs with highly sloped
capillary pressure curves, but should not be an issue for very high
permeability reservoirs where capillary pressure curves are near-
asymptotic.
Model loses sensitivity at very high permeabilities where
irreducible water saturation is on the asymptote of the capillary
pressure curve, and porosity doesn’t increase relative to increased
pore size and/or pore throat size.
Notes on Coates Permeability ModelNotes on Coates Permeability ModelNotes on Coates Permeability Model

NMR Perm vs. Core Perm: Well ANMR Perm vs. Core Perm: Well A
Un-Calibrated Core-Calibrated
Generalized Coates Permeability
vs. Core Permeability - Well B
0.001
0.01
0.1
1
10
100
1000
10000
100000
0.001 0.01 0.1 1 10 100 1000 10000 100000
Generalized Coates Permeability (md)
from MPHI & MBVI @ T2 Cutoff = 33 ms
CorePermeabilitymd)
Standard Coates-Timur Permeability vs. Core Permeability
Standard Coates-Timur Permeability (md) - BVI @ 33ms
0.001
0.01
0.1
1
10
100
1000
10000
0.001 0.01 0.1 1 10 100 1000 10000
Calibrated Coates-Timur Permeability vs. Core Permeability
CorePermeabilitymd)
Calibrated Coates-Timur Permeability (md) - BVI @ 80 ms

Overview - Fluids Analysis with MR

Fluid Properties from MR LoggingFluid Properties from MR LoggingFluid Properties from MR Logging
MR makes direct measurements of the
fluids present in the formation
investigated
MREX can measure three properties of the
pore fluids
– T1 relaxation time
• Time constant for the net magnetization to align
with the static magnetic field
– T2 relaxation time
• Time constant for the echo train to decay
– Diffusivity, D – measure of the ability of the
molecules to move at random in the fluid

TT11 ,, TT22 & D& D
T1,T2
D
T1 , T2 and D are system parameters intrinsic to
the fluid present in the sensitive volume.

T1, T2, and D are intrinsic properties of the
free fluid and are used to identify
– Fluid type
– Fluid quantity
– Fluid viscosity

matrix
dry
clay
clay-
bound
water
mobile
water
capillary
bound
water
hydrocarbon
MR Porosity Model
MR measurements
Bound Water Free Fluid
Bound Water Moveable Water Heavy Oil Light Oil Gas
T1 Very Short Medium Short Long Long
T2 Very Short Medium Short Long Short
D Slow Medium Slow Medium Fast

Specially designed MREX acquisition
sequences exploit the differences in T1, T2
and D to differentiate oil, gas and water
PoroPerm + Gas exploits T1 differences to
differentiate light oil and gas from water
and D differences to differentiate light oil
from gas
PoroPerm +Oil exploits T2 and D
differences to differentiate oil and water

Summary of NMR Application & BenefitsSummary of NMR Application & BenefitsSummary of NMR Application & Benefits
MR Logging measures
– Quantity of 1H present in the sample volume
– Relaxation times present in the sample
From the measurement of 1H quantity we get
NMR porosity
– Lithology independent measurement
From the measurement of relaxation times we get
information on
– Fractional fluid volumes
• Bound water volumes – CBW & BVI
• Free fluid volume – BVM
– Pore size distribution
– Bulk fluid properties – for fluid typing & quantification
– Permeability – always best to calibrate

Quick QuizQuick QuizQuick Quiz
What are the two things measured by MR
logging tools?
What information is contained in the T2
spectrum?
What is the basis for knmr?
How is knmr determined?

Identification of Low-Resistivity Pay (Shaly
Sands)
Reservoir Quality & Productivity (Vsh, φt, φe,
knmr, Swirr, Sor)
Porosity in Complex/Mixed Lithologies
Optimize Selection of Formation Test and
Completion Intervals
Frac Optimization in Low Porosity Reservoirs
Basic MREX logging Applications

Low Resistivity PayLow Resistivity PayLow Resistivity Pay
What conditions cause low resistivity pay?
– Shale laminations in reservoir – shale represents ‘path of least
resistance’ for conventional resistivity tools and resistivity is
biased towards shale values
– High volumes of Swirr – can be caused by:
• Very fine grained sand deposits – usually seen as a trend, ex. fining
upward sands, volcaniclastic sands
• Other minerals coating sand grains, ex. chlorite
– Dispersed shale in sandstone matrix
– Conductive streaks in formation
How can MREX help?
– MREX determines fluid volumes CBW, BVI & BVM Swirr
– MREX can be used to determine dispersed vs. laminated shale
– MREX porosity is not affected by minerals in the formation and
makes its measurements independent of mineralogy

Conventional Logs
•Neutron/Density separation
over most of the interval
indicates a high shale
content.
•Conventional resistivity
analysis across the interval
in question shows the zone
to have a water saturation
ranging from 70 to 90
percent.
-100 SP (mv) 100
0 GR (api) 150 0.2 Rxo 20
0.2 Medium Resistivity 20
0.2 Deep Resistivity 20
60 Neutron Porosity 0
60 Density Porosity 0
Interval in question
Low-Resistivity Pay ExampleLowLow--Resistivity Pay ExampleResistivity Pay Example

Conventional Logs
-100 SP (mv) 100
0 GR (api) 150 0.2 Rxo 20
0.2 M edium Resistivity 20
0.2 Deep Resistivity 20
60 Density Porosity 0
Interval in question
Zone Phi - D Rt Sw
A 36% 2 22%
B 30% 0.7 46%
C 31% 0.6 49%
D 30% 0.4 63%
A
B
C
D
Sw = 50% - historical cutoff

Integration of MR &
Conventional data
•MR shows BVI
increasing with depth
•Sw = Swirr water free
production
-100 SP (mv) 100
0 GR (api) 1500.2 Rxo 20
0.2 MediumResistivity 20
0.2 DeepResistivity 20
2 Permeability ( md) 200
Immobile
Water
Free
Water
Hydrocarbons
60 Density Porosity 0 60
Interval Tested at
+2000 BOPD
(water-free)
NMR Effective Porosity 0

Matrix
Dry
Clay
Clay-
Bound
Water
Capillary-
Bound
Water
BVM
φeffective
BVICBW
Free-Fluid
φtotal
MREX VolumetricsMREXMREX VolumetricsVolumetrics

Where default parameters are: C =10, m = 4 & n = 2
Coates-Timur Model :
MBVI
MBVM
C
k
n
=
m
•
MPHE
NMR PermeabilityNMR PermeabilityNMR Permeability

MPHE = 17 pu, MBVI = 4 pu (NMR Tool Response)
Vertical
Tool
Resolution
NMR Permeability = [MPHE ÷ 10]4 • [MBVM ÷ MBVI]2
Bulk Permeability (from tool response) = [17 ÷ 10]4 • [13 ÷ 4]2 = 8888 mdmd
30 0MPHE (pu)
Shale MBVI
Sand MBVI
Legend
Sand MBVM
NMR Permeability in a Thinly Bedded
Sequence
NMR Permeability in a Thinly BeddedNMR Permeability in a Thinly Bedded
SequenceSequence

Where default parameters are: C =10, m = 4 & n = 2
Coates-Timur Model :
MBVISand
MBVMSand
C
kSand
n
=
m
•
MPHESand
Sand Lamination PermeabilitySand Lamination PermeabilitySand Lamination Permeability

Vertical
Tool
Resolution
Sand Permeability = [MPHESd ÷ 10]4 • [MBVMSd ÷ MBVISd]2
Sand Permeability (after reconstruction) = [30 ÷ 10]4 • [26 ÷ 4]2 = 34223422 mdmd
30 0MPHE (pu)
MPHEsd = 30 pu, MBVIsd = 4 pu
Sand MBVI
Legend
Sand MBVM
Reconstructed Sand Lamination
Permeability in a Thinly Bedded Sequence
Reconstructed Sand LaminationReconstructed Sand Lamination
Permeability in a Thinly Bedded SequencePermeability in a Thinly Bedded Sequence

NMR porosity can be too low whenNMR porosity can be too low when ::
Hydrogen Index of reservoir fluids < 1.0Hydrogen Index of reservoir fluids < 1.0
Reservoir fluids with long TReservoir fluids with long T11 are only partiallyare only partially
polarized due to insufficient acquisition wait timepolarized due to insufficient acquisition wait time
((TwTw))
““Solid hydrocarbonsSolid hydrocarbons”” (tar) are present with(tar) are present with
relaxation rates faster than the measurement timerelaxation rates faster than the measurement time
windowwindow
Internal gradients caused from magnetic mineralsInternal gradients caused from magnetic minerals
accelerate NMR echo decay to belowaccelerate NMR echo decay to below
measurement time windowmeasurement time window – very rare
MR Porosity ConsiderationsMR Porosity Considerations

Optimized Selection of Formation Test and
Optimized Selection of Formation Test andOptimized Selection of Formation Test and
Completion IntervalsCompletion Intervals
Key questions for test & completion
decisions
– POROSITY
– PERMEABILITY
– FLUID TYPES & SATURATIONS
– BOUND FLUID
– THICKNESS
– RESERVOIR PRESSURE

Optimized Selection of Formation Test and
Optimized Selection of Formation Test andOptimized Selection of Formation Test and
Completion IntervalsCompletion Intervals
Technique combines MREX data
from Fast BW mode with Triple
combo data to answer the questions
Fast BW mode runs at 22 ft/min and
is transparent to the logging job in
terms of rig time
CBW & BVI data from MREX are
coupled with ZDL/CN crossplot
porosity to calculate BVM and knmr

Frac Optimization in Low Porosity ReservoirsFracFrac Optimization in Low Porosity ReservoirsOptimization in Low Porosity Reservoirs
Same process as before for high grading zones
Use knmr and φ as input to FRAC design
HAL claims to have saved clients $M on well
completions and water handling with this technique.
– Reduces # of completion intervals
– Optimizes horsepower requirements
– Eliminates completions in water producing zones
Typical
Time (mins)
Net Pressure (psi) Slurry Rate (bpm)
Prop Conc (ppg)
0.00 6.00 12.00 18.00 24.00 30.000
200
400
600
800
1000
0.00
10.00
20.00
30.00
40.00
50.00
0.00
8.00
16.00
24.00
32.00
40.00
MREX and
other log data
FRAC DESIGN FRAC Execution
$

MR ExplorerMR ExplorerMR Explorer
Strategy: Incorporate strengths of previous tools and
add new features to overcome operational
issues experienced with them
Reasons for Development
• Eliminate dependence on aging vendor supplied tools
• Offer ‘Best-in-Class’ NMR technology
Centralized NMR Technology
Borehole size limitations
Deviated wells
Conductive muds
Temperature sensitivity and limitations
Pad-type NMR Technology
Poor signal-to-noise
Shallow depth of investigation
Slow logging speeds
Poorly defined gradient
Multiple Frequency
Gradient Magnetic Field
Side-looking NMR Tool
Measurement Volumes

MREX: A Side-Looking ToolMREX: A SideMREX: A Side--Looking ToolLooking Tool
Suitable for virtually any borehole size
Depth Of Investigation:
2.2 - 4.0” independent of
– Borehole size
– Temperature
More environmentally robust
– Less affected by borehole rugosity
– Less conductive loss in saline muds
– Easy to log in deviated / horizontal wells
Formation
MREX Sensitive
Volumes
2.2
inches
1.8
inches
4.0
inches
MREX
8”
Borehole
12”
Borehole

MR Explorer - Technical BenefitsMR ExplorerMR Explorer -- Technical BenefitsTechnical Benefits
•Faster logging – reduces rig time
•Significantly higher logging speeds in water
based mud systems - advantage increases as
mud conductivity increases
•Maximum logging speeds in oil-
based mud systems
• Multiple simultaneous NMR measurements
in single pass (Multiple TE, Tw, …)
•Saves rig time
•Improves data quality

MR Explorer - Technical BenefitsMR ExplorerMR Explorer -- Technical BenefitsTechnical Benefits
Superior hydrocarbon typing
•Innovative NMR acquisition techniques provide
comprehensive NMR data for thorough fluids analysis
•T1 data while logging
•Improves hydrocarbon typing
•Not affected by – diffusion, internal gradients or
tool artifacts
•T2 & diffusion data while logging
•Together T1 & T2 provide answers for NMR fluids analysis
•Fluid type (oil, gas or water)
•Volumetric analysis
•ROS, Sxo & in situ viscosity
•Technical improvements
•Short inter-echo spacing, TE = 0.6ms, available on all
frequencies, (TE = 0.4 ms for CBW)
•Use of multiple gradients increases quality of data used
for hydrocarbon properties analysis

MR Explorer - AdvantagesMR ExplorerMR Explorer -- AdvantagesAdvantages
Combinable with other Baker Atlas tools for efficient operations
Ability to log in most borehole environments regardless of:
• Borehole size - 5 7/8 to 14+ inch diameter boreholes
• No logging speed reduction for large or small holes
• One tool for all size boreholes
• Borehole fluid salinity - No mud excluders needed for conductive muds
• Operational and logging speed advantage
• Successfully logged 8 ½” well where Rm = 0.015 ohm-m
• Borehole deviation - Not a factor with an eccentered tool
• Borehole temperature - 175° C (347° F) rating up to 4 hours operation
• 165° C (330° F) continuous
• Logged a 344°F well in Saudi Arabia – January 2005
• Depth of investigation 2.2 – 4.0 inch.
• Very well defined for invasion profiling
• Deep enough for hydrocarbon fluids analysis
• Little to no borehole rugosity effect

MR Explorer - AdvantagesMR ExplorerMR Explorer -- AdvantagesAdvantages
Combinable with other Baker Atlas tools
for efficient wellsite operations
– ZDL/CN/GR/XMAC/HDIL (tools need to be
up to latest mod level)
– RCI with switching sub
– STAR run in field but not vetted in Houston
– Earth Imager
• The directional data for STAR & EI can be
corrupted if
– There are iron based additives or steel particles from
pipe wear or both in the drilling mud, and
– MREX is run prior to the imaging tool
Simplicity of operation for Field
Engineers, Sales Engineers and clients

Simplicity of OperationSimplicity of OperationSimplicity of Operation
Objective Oriented NMR Data Acquisition (OOA)
Goal of OOA is to simplify pre-job planning and well
site execution of NMR logging jobs
• Logging engineers
– Fewer modules to select
– Fewer parameters to customize
• Sales engineers and clients
– Language of Geoscientists and Petroleum Engineers -
not NMR jargon

Acquisition PackagesAcquisition PackagesAcquisition Packages
MR Explorer Acquisition Modes
– PoroPerm is our basic acquisition mode
• Delivers NMR formation evaluation measurements
– (φt, φe, BVI, CBW, BVM, and k)
– PoroPerm + Oil
• Delivers basic NMR measurements
• + Special sequence for light oil analysis
– PoroPerm + Gas
• + Special sequence for gas analysis
– PoroPerm + Heavy Oil
• + Special sequence for heavy oil analysis
– Fast BW mode
• Acquires Bound Water data at high logging speed for BVI & CBW
Simple terminology. No more confusing terms such as DTW, DTE, CTP, T2,
Shifted Spectrum, Differential Spectrum, etc.

MR ExplorerMR Explorer
ExamplesExamples

PoroPerm + Oil Field DeliverablePoroPerm + Oil Field DeliverablePoroPerm + Oil Field Deliverable

PoroPerm + Gas Field DeliverablePoroPerm + Gas Field DeliverablePoroPerm + Gas Field Deliverable

MR Explorer in 13.25” Borehole Compared to MRIL
in Adjacent 8.5” Borehole
MR Explorer in 13.25MR Explorer in 13.25”” Borehole Compared to MRILBorehole Compared to MRIL
in Adjacent 8.5in Adjacent 8.5”” BoreholeBorehole
MRIL MREX

SIMET Results – Oil & Gas Reservoir –PP+GASSIMET ResultsSIMET Results –– Oil & Gas ReservoirOil & Gas Reservoir ––PP+GASPP+GAS
Oil
T2
Gas
T2
GAS
OIL

Tool Length ~ 24 ft (with Energy Sub)
Tool Diameter - 5 Inches
Tool Weight ~ 620#
Maximum Temp – 347°F (175°C)
Maximum Pressure – 20,000 psi
Antenna Aperture – 18 inches
Depth of Investigation – 2.2 to 4.0 inches
Type of Magnetic Field – Gradient
Number of Operating Frequencies – 6 (typical)
Technical DataTechnical DataTechnical Data

Current MREX StatusCurrent MREX StatusCurrent MREX Status
300+ runs – tool has performed well
Operations Field Testing
– Canada
– Trinidad
– Argentina
– USA
– Venezuela
– Saudi Arabia
– Oman
– Europe
– Asia/Pacific

MREX Development – High ResolutionMREX DevelopmentMREX Development –– High ResolutionHigh Resolution
Standard MREX tool vertical
resolution
– 4 feet – enhanced logging mode
– 6 feet – standard logging mode
High resolution MREX tool vertical
resolution
– VR from 1 foot to 6 feet depending on
client requirements
– Ideally MR data needed at same
resolution as ZDL/CN, 2.0 ~ 2.5 feet

High Res. Vs. Standard ResolutionHigh Res. Vs. Standard ResolutionHigh Res. Vs. Standard Resolution
High Res., VR = 31 in. (0.79m) Std Res., VR = 64 in. (1.63m)

High Resolution MREXHigh Resolution MREXHigh Resolution MREX
Limited availability – check with your BA
representative
– Italy – August 2004
– Brazil – August 2004
High Resolution MREX has full capability
of standard MREX
– Best in class hydrocarbon typing
• PoroPerm + Gas
• PoroPerm + Oil
• PoroPerm + Heavy Oil
– Same operating envelope for borehole
conditions as standard MREX

MR Explorer - ValueMR ExplorerMR Explorer -- ValueValue
MREX reduces total cost of NMR
logging by reducing rig for NMR
logging through:
• Combinability
• Faster logging speeds
• Comprehensive data in single pass
MREX provides better,
more comprehensive data
sets for fluids evaluation
than other MR logging tools
Improved accuracy,
precision and vertical
resolution over MRIL
Better, Faster NMR data

MR Explorer - SummaryMR ExplorerMR Explorer -- SummarySummary
Promising new NMR tool
Improved economics – saves rig time
Superior NMR measurement techniques
T1 measurements while logging
Simpler operation & terminology
Increased operating envelope
– Large holes
– Deviated wells
– No mud excluders
– 347°C (175°C) temp. rating
Better, Faster NMR data

MREX Log Quality Control

MREX General LQCMREX General LQCMREX General LQC
Porosity from the MREX should agree with
ZDL/CN porosity in clean water filled formations
MREX porosity is dependent on the hydrogen
index of the fluid being measured. A porosity
deficit, similar to CN response, will be seen in
zones with gas and light hydrocarbons
MREX porosity will see a deficit to ZDL/CN
porosity in zones containing heavy oil and tar
MREX porosity is dependent on the long wait
time being ≥3*T1. If a deficit is seen to ZDL/CN
that can’t be explained, then the long wait time
should be increased and the zone relogged

MREX General LQCMREX General LQCMREX General LQC
Shales should indicate almost all of the signal is from the CBW
component. Occasionally some BVI is seen in shale zones. In general, no
BVM should be observed in shale intervals.
The MREX porosity may or may not read close the ZDL porosity in shales.
The accuracy of the ZDL porosity is dependent on using the correct ρma as
an input parameter and this value is rarely known for certain in shales
MREX porosity generally has poorer vertical resolution than ZDL/CN
porosity and in thin zone resolution may be responsible for differences in
porosity readings
MREX porosity should not exhibit any spikes while logging
MREX porosity should repeat with SD of 1PU when run at the speed and
averaging length recommended
BVM will usually repeat better than BVI and CBW.
MREX porosity > ZDL could be indicating the tool is seeing a washout.

MREX Basic Log Quality ControlMREX Basic Log Quality ControlMREX Basic Log Quality Control
MREX porosity response in:
• Clean, fluid filled formations
approximates Density/Neutron
crossplot porosity
• Shaly formations
approximates density porosity
(when density porosity is
calculated with the correct
grain and fluid density)

MREX porosity response in:
• Clean gas zones
approximates neutron porosity
(if recorded on correct matrix)
• Shaly gas zones
undercalls neutron porosity
(resolution issue in top zone?)

Why does MREX porosity read high?
“Extra” porosity due to
borehole signal typically
shows up as BVI
• Eccentered
• Side-looking
• Well-defined DOI
2.4 - 4.4”
Minimizes effects of washout
and borehole rugosity

CHI – The quality of fit of the computed T2 decay curve to the recorded echo data.
Low CHI: High quality fit
High CHI: Low quality fit
CHI is affected by Q and Noise:
Low Q Higher Noise Higher CHI
High Q Low Noise Low CHI
CHI is one of the first lines of defense of MREX Log QC
• A logging parameter should be adjusted to maintain target
CHI (or lower) in order to maintain an acceptable
signal-to-noise ratio (SNR)
• Target CHI: PoroPerm & PoroPerm + Gas 2.2
PoroPerm + Oil 2.0
Fast BW 1.5
CHI SHOULD BE presented on the MREX field presentation and scaled such that it is easy to read.
What logging parameter should be adjusted to maintain the target CHI value?
Averaging Length (AL) – Number of echo trains that will be stacked to reduce noise and maintain target CHI.
If AL = n, the SNR of the resulting signal will be √n times the SNR of a single echo train.
While beneficial to the SNR, stacking is detrimental to the vertical resolution of the measurement.
Averaging Length should be found in the parameter report on the MREX log.

FAQs - MREX & NMR loggingFAQsFAQs -- MREX & NMR loggingMREX & NMR logging

NMR logging is so slow, how can we speed it up?NMR logging is so slow, how can we speed it up?NMR logging is so slow, how can we speed it up?
The new MR Explorer tool can operate at
as many as 6 frequencies. Additionally
MR Explorer uses a shorter echo spacing
improving the SNR in each echo train.
Multiple frequencies and more echoes
allow for data to be acquired at faster
logging speeds. Our previous
technology, MRIL-C, operated at only 2
frequencies. With 6 frequencies, each
with more echoes, we can log up to 5
times as fast as the previous technology
and because of the eccentered
configuration of the MR Explorer it runs at
much higher speeds in salt muds than the
other MR logging tools on the market..

If I run NMR do I still have to run other logs? Are there
any I can eliminate?
If I run NMR do I still have to run other logs? Are thereIf I run NMR do I still have to run other logs? Are there
any I can eliminate?any I can eliminate?
NMR provides information that is not
available with other logging tools. It
is recommended that NMR be run in
addition to conventional tools in
exploration wells. In some
development fields where NMR logs
are run, it has been found that
neutron logs were providing little
extra value.

Do I have to make a separate run for the NMR log or
can it be combined with the Slam toolstring?
Do I have to make a separate run for the NMR log orDo I have to make a separate run for the NMR log or
can it be combined with the Slam toolstring?can it be combined with the Slam toolstring?
The Baker Atlas MR Explorer tool is
designed to be run in combination
with most other Baker Atlas open
hole logging tools. Furthermore,
because it runs at much higher
logging speed than previous
generation NMR logging tools it will
have minimal impact on the overall
logging time.

Do I need to do anything special with the borehole or
mud system to run this log?
Do I need to do anything special with the borehole orDo I need to do anything special with the borehole or
mud system to run this log?mud system to run this log?
No, the MR Explorer is the most versatile
NMR logging tool on the market. Because
of its unique design the MR Explorer is
minimally affected by the borehole fluid
conductivity. In fact as the mud resistivity
decreases the advantages of the MR
Explorer increase. Its performance with
regard to logging speed and NMR data
acquisition are significantly better than
competitive instruments on the market.

The well I am drilling is deviated 45° and we are using a 12 ¼”
bit. I ran an MRIL on a similar well and couldn’t use the data
because it was reading mud, why is this tool any better?
The well I am drilling is deviated 45° and we are using a 12 ¼”
bit. I ran an MRIL on a similar well and couldn’t use the data
because it was reading mud, why is this tool any better?
This tool is designed to run eccentered in the
borehole. This is a significant advantage over
the MRIL technology in both large and deviated
wells. As the borehole size increases it becomes
more critical to keep the MRIL tool centralized,
but from a practical point of view the larger the
borehole is, the more difficult it is to keep the tool
centralized and as a result data quality suffers.
The same problem exists in deviated wells.
Because the MR Explorer runs eccentered it
performs just as well in large and deviated wells
as it does in standard vertical wells.

If I run an NMR log who is going to interpret it for me
and how long will it take to get the interpretation
back?
If I run an NMR log who is going to interpret it for meIf I run an NMR log who is going to interpret it for me
and how long will it take to get the interpretationand how long will it take to get the interpretation
back?back?
Baker Atlas has a staff of
petrophysicists and log analysts
with expertise in NMR log
interpretation. The normal turn
around time for an MR Explorer
Integrated Petrophysics
interpretation is 24 hours from the
time the data gets to the data center.

How much experience does Atlas have running
NMR logs?
How much experience does Atlas have runningHow much experience does Atlas have running
NMR logs?NMR logs?
Baker Atlas was the first major logging
company to offer NMR logging services to
the industry in 1993. Since then Baker
Atlas has logged approximately 3500
wells worldwide. Baker Atlas NMR
scientists and engineers have published
over 40 technical papers on NMR
interpretation and techniques. Baker
Atlas has over 25 patents, granted or
pending, for NMR technology.

What other companies have you run this
new service for?
What other companies have you run thisWhat other companies have you run this
new service for?new service for?
Energy Partners Limited – GOM
Gaz de France Britain – UK
Esso Norge – Norway
Kerr-McGee – GOM
Petro Canada – Canada
YPF – Argentina
EnCana – Canada
Aramco – Saudi Arabia
PDVSA - Venezuela
KOC - Kuwait

How does NMR measure permeability?How does NMR measure permeability?How does NMR measure permeability?
The MREX tool does not measure
permeability. knmr is calculated
based on a relationship between
porosity and pore size.

How is the NMR measurement affected by
invasion?
How is the NMR measurement affected byHow is the NMR measurement affected by
invasion?invasion?
NMR measurements read close to the borehole
and take their measurements in what is normally
the flushed zone. The MREX measurements of
porosity and permeability are not affected by
this. Some of the more advanced hydrocarbon
typing measurements can be affected if the oil or
gas has been displaced by mud filtrate. In this
case, the fluid saturations determined from the
MREX represent flushed zone saturations. In
cases where OBM is used and there is mud
filtrate invasion into the volume measured by
MREX the results from hydrocarbon typing
analysis can become blurred by the OBM filtrate
mixing with the native oil.

I am happy with the Halliburton tool, why should I
switch to this new tool?
I am happy with the Halliburton tool, why should II am happy with the Halliburton tool, why should I
switch to this new tool?switch to this new tool?
What are the well conditions you are logging in and what is
your objective for running NMR logs?
Under most well conditions the MR Explorer can run at
higher logging speed than the other instruments on the
market. This is especially true for cases where salt mud is
the borehole fluid, the logging speed advantage decreases
as the mud resistivity increases but it is always equal to or
better than the Halliburton tool. The logging speed
advantage along with the combinability of this tool will
save rig time lowering your overall cost of logging.
Additionally if your objective is hydrocarbon identification
this tool has superior technology to the Halliburton tool
allowing much more flexibility in the design of the data
acquisition sequences used for hydrocarbon identification.
This allows the signals from the different fluids, gas, oil
and water, to be more easily separated in the NMR
spectrum and more accurately identified.

I am happy with the Schlumberger tool, why
should I switch to this new tool?
I am happy with the Schlumberger tool, whyI am happy with the Schlumberger tool, why
should I switch to this new tool?should I switch to this new tool?
If your only objective for NMR logging is to determine BVI,
then all of the systems on the market are pretty much the
same. The differences in logging speed and data quality
are minimal. If your objective is to gain insight into the
hydrocarbon storage capacity of your reservoir, or find oil-
water contacts, or learn something about the in situ fluids
present in the formation, then you want the type of data
available with a MR device like the MR Explorer. The
gradient field and multiple frequencies available with the
MR Explorer enable a rich variety of NMR acquisition
sequences to be recorded. These can be tailored to
identify fluids under specific reservoir conditions providing
information that is not available with the CMR type tools.
Additionally, for basic total porosity NMR data the MR
Explorer runs at a considerably higher logging speed than
the CMR+.

Okay, you keep telling me it will run faster, how fast
will it run?
Okay, you keep telling me it will run faster, how fastOkay, you keep telling me it will run faster, how fast
will it run?will it run?
Because of the many modes NMR logs
can be run it is important to set the
parameters before quoting logging speed.
Typically logging speeds are quoted for
oil based mud filled boreholes, this is
because most MR logging devices will run
at their maximum speed in OBM. For BVI
mode logging the MR Explorer can log at
22 feet/minute or 1320 feet/hour. For
PoroPerm mode the tool can run as fast
as 14 fpm, 840 fph.

That sounds like the same thing the Halliburton guy told me, but
we drill with KCl and they logged that last well at 3 feet/minute, I
need a realistic estimate of rig time to plan the job and allocate
the costs, tell me how long it is going to take?
That sounds like the same thing the Halliburton guy told me, butThat sounds like the same thing the Halliburton guy told me, but
we drill withwe drill with KClKCl and they logged that last well at 3 feet/minute, Iand they logged that last well at 3 feet/minute, I
need a realistic estimate of rig time to plan the job and allocaneed a realistic estimate of rig time to plan the job and allocatete
the costs, tell me how long it is going to take?the costs, tell me how long it is going to take?
First, our tool will log at 2 to 3 times faster
than the Halliburton tool when running in
conductive muds, such as KCl, so if they
had to run at 3 feet/minute we will run at 6
to 9 feet/minute. To be sure we get the
best estimate of logging time we need to
plan the logging program using our MR
Explorer log planning software. This
program not only allows us to accurately
estimate logging time but we can model
the MR tool response for the reservoir
conditions to optimize the MR logging
program to ensure we achieve our logging
objectives

Right, right, right....now you sound like SLB saying salt mud isn’t a problem
but last time they were out they told they would log fast but once in the hole
they had to stop and ‘recalibrate’ several times which added a couple of
hours to the jobs. How is your tool different?
Right, right, right....now you sound like SLB saying salt mud isRight, right, right....now you sound like SLB saying salt mud isnn’’t a problemt a problem
but last time they were out they told they would log fast but onbut last time they were out they told they would log fast but once in the holece in the hole
they had to stop andthey had to stop and ‘‘recalibraterecalibrate’’ several times which added a couple ofseveral times which added a couple of
hours to the jobs. How is your tool different?hours to the jobs. How is your tool different?
The MREX tool uses a gradient
magnetic field. This eliminates the
need for any downhole calibrations
of the tool.

Hydrocarbon TypingHydrocarbon Typing
Hydrocarbon typing with NMR relies on exploiting
the differences in the NMR properties of the oil,
gas and water using specially designed NMR
acquisition sequences
The properties we measure for hydrocarbon
typing are T1, T2 and diffusion, D.
We may measure one, two or all three properties
to determine fluid type, volume and viscosity
The three hydrocarbon typing acquisition
packages used by MREX have specific
hydrocarbon typing objectives
– Oil
– Gas
– Heavy oil

NMR Properties of Reservoir FluidsNMR Properties of Reservoir FluidsNMR Properties of Reservoir Fluids
Fluid T1 (ms) T2 (ms)
Typical
T1/T2 HI viscosity (cp)
D x 10-5
(cm2/s)
Brine 1 - 500 1 - 500 2 1 0.2 - 0.8 1.8 - 7
Oil 3,000 - 4,000 300 - 1,000 4 1 0.2 -1000 0.0015 - 7.6
Gas 4,000 - 5,000 30 - 60 80 0.2 - 0.4 0.011 - 0.014 80 - 100

Simple Analysis of TSimple Analysis of T22 -- MREX dataMREX data --12.2512.25”” boreholeborehole
Gas
Oil
Pc
Bound
Water
Clay
Bound
Water
GOC

TT11 BuildBuild--Up of OilsUp of Oils
T1 Buildup
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
6
6.5
7
7.5
8
8.5
9
9.5
10
10.5
11
11.5
12
12.5
13
13.5
14
14.5
15
Time (sec.)
%Polarization
0.2 cP
0.4 cP
0.6 cP
0.8 cP
1 cP
2 cP
4 cP
Water (512 m)
Water (256 ms)
Water (64 ms)
Water (16 ms)

DeltaDelta TwTw -- Differential SpectrumDifferential Spectrum
Oil
TwShort TwLong
TW (sec)1.5
T1
Buildup
NMRPorosity
8
T2 Time (ms)
1 10 100 1,000 10,000
PorosityPorosityPorosity
Long Recovery Time (TwLONG)
Short Recovery Time (TwSHORT)
Differential Spectrum
Water Gas

Multi Tw, Multi TE AcquisitonsMultiMulti TwTw, Multi TE, Multi TE AcquisitonsAcquisitons
Powerful technique for oil
quantification and viscosity
determination when oil & free water
are present in the measured volume
Multi - Tw eliminates water from the
spectrum
Multi - TE data in differential
spectrum quantifies oil volume and
viscosity

MREX Explorer Hydrocarbon Typing TechniquesMREX Explorer Hydrocarbon Typing TechniquesMREX Explorer Hydrocarbon Typing Techniques
MR Explorer uses Objective Oriented
Acquisitons, OOAs
– PoroPerm + Oil
– PoroPerm + Gas
– PoroPerm + Heavy Oil
Data is analyzed using SIMET –
Simultaneous Inversion of Multiple
Echo Trains

FE Processing for all modesFE Processing for all modesFE Processing for all modes
Formation Evaluation
Processing
– Provides partial porosities,
MCBW, MBVI, MBVM, MPHE and
MPHS based on default cutoff’s
– Partial porosity from selected
echotrains T2 spectra
– Provides knmr
– MBVM and knmr undercalled in
gas/light oils zones due to HI

Recommend Acquisition PackageRecommend Acquisition PackageRecommend Acquisition Package
PoroPerm
PoroPerm + Oil
PoroPerm + Gas
PoroPerm + Heavy Oil
Fast BW

MREX & RCIMREX & RCIMREX & RCI
Use permeability from MREX to pick
testing points & improve testing
efficiency
Calibrate RCI mobility to MREX
permeability
Use MREX to identify heavy oil zones
that won’t produce samples

MREX & XMACMREX & XMACMREX & XMAC
Use permeability from MREX
together with Stoneley permeability
to characterize reservoirs
– Agree – reduced uncertainty
– Disagree
• Fracture identification
• Gas identification
• Formation damage

Stoneley Perm
0.01 (md) 100
NMR Perm
60 (%) 0
Neutron Porosity
1.65 2.65Density
X200Depth(feet)X100
GAS
Stoneley & NMR Permeability Profiles:
Gas Effect
Stoneley & NMR Permeability Profiles:Stoneley & NMR Permeability Profiles:
Gas EffectGas Effect
GAS

MREX (NMR Logging)

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