Magnetic Resonance Imaging
Logging, development and
evolution as a fundamental
evaluation tool in the reservoir
management
Ron Cherry, Maged Fam and Emiliano López
Geological & Reservoir
Overview
Formation Evaluation Problems
High uncertainty in reservoir
evaluation using conventional Log
Analysis, due to:
• Multilayer reservoirs made up of
an average of 20 stacked layers,
about 5 mt. each.
• Low formation water salinity
• Several water/oil and gas/light oil
contacts randomly distributed
throughout a rock column of 1000
mts. (average 1500 to 2500 mts.)
• Complex lithology (shaly and
tuffaceous sand reservoirs)
• Different hydrocarbon types
Core Porosity vs Permeability
Permeability (md)
Core measurements
on samples from
about 60 wells, 800
samples from San
Jorge Basin
Porosity (%)
1000
Permeability (md)
100
10
1
0.1
0.01
0.001
0
5
10
15
20
Porosity (%)
25
30
35
40
Matrix Density Distribution in so called
“Sandstone” from San Jorge Basin
Grain Density (G/c3)
Grain Density Vs Core Porosity
Core Porosity (%)
MRI Core Porosity vs. Core Porosity
San Jorge Basin
Core Porosity (%)
Core Porosity Vs MRI Core Porosity
MRI Core Porosity (%)
Geometric Mean T2 Cutoff vs. Depth
Depth (m)
Geometric Mean T2 Cutoff Vs. Depth
Geometric Mean T2 Cutoff (ms)
The high degree of variation in the T2 cutoff range may cause some
inconsistencies in the final Interpretation.
Thus the SBVI method is a better technique for determining BVI.
BVI-FFI Models Using T2 Data
SBVI Model
0.9
SBVI slope: 0.0687
SBVI Intercept: 1.0000
Sum of Squared Errors: 97.50
Equation: SBVI = 1/(0.0687 T2 + 1.0)
T2 time
0.5
1
2
4
8
16
32
64
128
256
512
1024
2048
0.8
NMR SBVI, fraction
Bin #
1
2
3
4
5
6
7
8
9
10
11
12
13
SBVI
0.967
0.936
0.879
0.784
0.645
0.476
0.313
0.185
0.102
0.054
0.028
0.014
0.007
0.7
0.6
0.5
0.4
0.3
0.2
0.1
SBVI Coef.
0
0.1
1
T2 (ms)
100
1000
10000
0.0XXX
Ave. T2C ms
predicted SBVI
y=x
+/- 10 s.u.
0.9
0.8
CBVI Swi, Fraction
10.20
46.28
0.51
161.35
10
Predicted vs NMR Swi
1
T2 CBVI Cutoff Model
Ave. measured T2 CBVI, msec.:
Maximum T2 CBVI observed:
Minimum T2 CBVI observed:
Sum of Squared Errors:
Spectral
Bulk
Volume
Irreductible
SBVI
SBVI Model
1
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0
0.1
0.2
0.3
0.4
0.5
0.6
NMR Swi, fraction
0.7
0.8
0.9
1
Core Permeability and MRI Permeability Models
Vs Depth
Depth (m)
Core Permeability and MRI Permeability Models Vs Depth
Core Permeability and MRI Permeability Models (md)
N.B.: MRI Permeability data is based on SVBI model
Core Permeability Vs MRI Permeability Models
Core Permeability (md)
MRI Permeability Models Vs Core Permeability
MRI Permeability Models (md)
N.B.: MRI Permeability data is based on SVBI model
MRIL Life Cycle
Met reservoir
Objectives
Test Results
Specify Objectives
Reservoir Properties &
Problems
Borehole
Conditions
Size, mud, temp….etc
Yes
Compare
Prognosis
Selection of Zones
to Test
STIMRIL
No
Data
Processing
&
Interpretation
Core Analysis
if available
MRIL
Pre-job
Planning
Field Log
QC
Resistivity
log
Activation
Selection @
Logging speed
MRI Forward Model
oil
gas
Tool Physics
Acquisition Parameters
G, TE, TW
Expected Fm. Fluid
Properties
Temp., Pressure &
Viscosity
water
MRIL
Forward
Modeling
Planner
water
gas
oil
oil
Mud Properties
Borehole Size
water
Petrophysical Solution!!!
MRI Specific Acquisition and
Interpretation Techniques
“one logging pass”
EDM
Enhanced Diffusion Method (Hydrocarbons 2-50 cp)
TDA
Time Domain Analysis (Hydrocarbons < 2 cp)
But….!!!
ShortTE
LongTE
MRI Prognosis:
Heavy OIL
1800 L/H
75 % SW
MRI Prognosis:
Water
2400 L/H
100 % SW
How can we distinguish
Heavy OIL from Water ???
Special Design for Heavy OIL
detection…
MRIL Ultra Long TE Activation
ShortTE
LongTE
UltraLongTE
MRI
Prognosis:
Heavy OIL
1800 L/H
75 % SW
MRI
Prognosis:
Water
2400 L/H
100 % SW
Heavy OIL Detection Example
ShortTE
LongTE
UltraLongTE
Initial Test Result (8hs Swabbing): 2400 L/H – 100% SW
Final Test Result (24hs Swabbing): 2400 L/H – 88% SW
Halliburton Question regarding details on test results
Dear Customer:
“…If We understand well, the formation was producing water for 8 hours
before starting to produce Oil …??
You have insisted to keep it producing because there was a very good
signal on the MRI Ultra-Long Te activation,….. Is that correct …??...”
Customer’s response
“It's correct...It has been a very good news today, because up to
yesterday, we couldn't believe that from that signal it would be
only water... We insisted and it was 2400 l/h x 88% of water
(may be the amount of water would have declined if we would
wait more time... but for us it was enough seeing some oil)…”
Fluid Typing: Light OIL
Composite Log MRI Interpretation EDM + TDA
EDM
Shot-Te/Long-Tw
Long-Te/Long-TW
MRI Prognosis
Light Oil w/ HGOR
Dif. S.-Te/L.TWS.Tw
TDA
Flow
920 L/H
40 % SW
Fluid Typing: GAS
MRI Prognosis
Light OIL
MRI Prognosis
GAS
Flow x 12mm
Wet GAS
P/D 280psi
P/E 1560 psi
MRI Prognosis
GAS
Halliburton’s
Reservoir Fluids
Prognosis Sheet
Based on MRIL
Interpretation
Conclusions
Magnetic Resonance Imaging (MRI) Logs as a
fundamental evaluation tool in the reservoir Management
• Determination of Porosity, Independent to Matrix
• Determination of Bulk Volume Irreducible Water
• Reliable Permeability Indicator (absolute after Calibration)
• Identify Fluid Type (Gas, Oil & Water) by zone
• Identification of Rock Quality…Permeability, Porosity & Clay
• Determine variations of Hydrocarbon types (Resistivity
independent)…
…Heavy, Intermediate, Light Oil or Gas