NMR Measurement and Viscosity
Evaluation of Live Bitumen
Elton Yang, George J. Hirasaki
Chemical Engineering Dept. Rice University
April 26, 2011
Introduction & Objective

The well log T2 measurements on the live bitumen appear to be
significantly longer than the laboratory NMR measurements of
dead bitumen sample. This is likely due to the dissolved gas in
heavy oil.

Saturate the bitumen sample with three reservoir gases (CO2,
CH4, C2H6) at different pressure levels in laboratory. Make NMR
and viscosity measurements on recombined live heavy oils.

Correlate the T2, viscosity, and gas content of live bitumen and
resolve the differences between the NMR log and laboratory
data.
Samples and Equipments

Sample: Bitumen Sample #10-19

Three gases (CO2, CH4 and C2H6) used in this work are provided
by Matheson Tri-Gas with product grade of Ultra High Purity.

2 MHz Maran Spectrometer (Oxford Instrument).

A 40 mm probe with minimum TE = 0.2 msec was employed for
all the NMR measurements on bitumen.

Brookfield Viscometer LVDV-III+ (Brookfield Company) for dead
oil at different temperatures .

Capillary viscometer for live bitumen at room temperature.
T2 Distribution of Bitumen #10-19 at Different T & Corrected
T2 with Specified M0 and Lognormal Distribution Model**
4
1.5
0.2 ms
10C
10C
20C
20C
3
1
40C
Amplitude f
Amplitude f
30C
50C
60C
70C
30C
40C
50C
2
60C
70C
80C
0.5
80C
90C
1
90C
0
0.001
0
0.1
1
10
100
1000
10000
0.01
0.1
T2 Relaxation Time Distribution (msec)
T2 after correction (msec)
10
100
T2 Relaxation Time (msec)
10
1
0.1
0.01
** Yang and Hirasaki, JMR, 2008
1
0.01
0.1
1
T2 before correction (msec)
10
1000
10000
Correlation Between Corrected T2 and
Viscosity/Temperature Ratio for Three Different Heavy Oils
10
Brookfield Oil
T2 = 37.92 * (T/Visc) 0.6815
R2 = 0.9956
T2 (msec)
1
Bitumen #10-19
T2 = 4.252 * (T/Visc) 0.4493
R2 = 0.9972
0.1
Brookfield oil
Athabasca bitumen
Bitumen #10-19
0.01
1.E+00
1.E+01
1.E+02
1.E+03
1.E+04
Viscosity/Temperature (cP/K)
 T2 values are corrected by using lognormal distribution model and
specified M0
 Corrected T2 and viscosity/temperature ratio of three dead oil samples
closely follow linear relationship on log-log scale.
 Data from Brookfield oil deviates from the data of two bitumen samples.
Measurements on Live Heavy Oils
Generation of Convection

The pressure vessel was manufactured by TEMCO and was customized to fit the
40 mm probe. The minimum echo spacing = 0.2 msec.

Pressurized gas was injected into the vessel from top. The gas pressure inside
the vessel was monitored during the entire process. NMR measurements were
performed periodically.

Convection was generated by rocking the pressure vessel to boost the gas
dissolving rate. After equilibrated at the highest pressure, the gas-bitumen
system was depressurized to different lower pressure levels.

Viscosity of live bitumen was measured and correlations between T2, viscosity,
pressure and gas solubility were established.
Changes of T2 and Pressure of C2H6 Dissolved
Bitumen During Pressurization Stage
1.5
Dead Oil
23 hrs
120 hrs
Amplitude f
141 hrs
1.0
213 hrs
308 hrs
391 hrs
429 hrs
0.5
T2
0.0
0.1
1
10
100
1000
Pressure
10
10000
560
T2 Relaxation Time Distribution (msec)
T2 of bitumen (msec)
520
1
500
480
 Bitumen and gas reached equilibrium after
308 hours.
0.1
460
0
100
200
300
Time (Hour)
400
500
Pressure (psia)
 Bi-modal for the peak of bitumen with C2H6
as C2H6 gradually transfers into bitumen.
540
Depressurization of C2H6 to Lower Pressures
T2
T2
Pressure
10
390
290
Peq = 278 psia
1
T2 of bitumen (msec)
350
270
250
1
330
20
40
60
80
100
230
0
120
20
40
T2
Pressure
10
0.1
160
Time (Hour)
80
T2 of bitumen (msec)
T2 of bitumen (msec)
180
60
Pressure
120
100
1
80
0.1
60
0
20
40
60
80
Time (Hour)
100
120
Pressure (psia)
1
Pressure (psia)
200
40
100
Peq = 106 psia
Peq = 200 psia
20
80
10
220
0
60
Time (Hour)
Time (Hour)
T2
Pressure (psia)
370
Pressure (psia)
T2 of bitumen (msec)
Peq = 370 psia
0
Pressure
10
T2 of C2H6 Saturated Bitumen at Different Pressures
1.5
10
T2 from new interpretation (msec)
Dead oil
106psia
200psia
1.0
Amplitude f
278psia
370psia
475psia
0.5
1
0.1
0.0
0.1
1
10
100
1000
T2 Relaxation Time Distribution (msec)
10000
0.1
1
10
T2 from regular interpretation (msec)
 The dissolving of C2H6 in Bitumen significantly changes oil T2.
 The T2 of C2H6 saturated bitumen decreases as equilibrated pressure decreases.
 The bitumen peak is broad and has fast relaxing components shorter than TE even at
the highest saturation pressure.
 T2 from regular interpretation > T2 from lognormal distribution model with specified
M0. The difference decreases as saturation pressure increases.
Corrected Initial Pressures at Different Pressure Levels
for Solubility Calculation
(Example: C2H6-Bitumen)
540
280
380
530
y = -0.5612x + 519.8
R² = 0.9119
520
360
Pressure (psia)
Pressure (psia)
Pressure (psia)
370
y = 3.2532x + 358.2
R² = 0.9752
350
340
0
1
2
Peq = 278 psia
250
0
3
y = 3.8106x + 261.8
R² = 0.9614
260
Peq = 370 psia
330
510
270
1
2
3
0
4
1
Time (Hour)
2
3
Time (Hour)
Time (Hour)
110
200
Pressure (psia)
 System would be either heated by pressurization
or cooled by depressurization temporarily, and then
return to the temperature of air bath (30 oC).
Pressure (psia)
Pressurization Stage
190
y = 2.3371x + 187.32
R² = 0.9611
180
100
y = 3.6265x + 90.548
R² = 0.9827
90
Peq = 200 psia
 Significant pressure change resulting from the
temperature fluctuation would display incorrect P0
for the solubility calculations.
 Extrapolation is employed to remove the
temperature effect on the initial pressure reading.
Peq = 106 psia
80
170
0
1
2
3
4
0
1
2
Time (Hour)
Time (Hour)
Depressurization Stage
3
4
Summary for Live Bitumen with Different Gases
1000
0.1369e0.0065x
y=
R² = 0.9984
C2 H6
y = 0.2064e0.0027x
R² = 0.9887
CO 2
1
CH4
y = 0.2367e0.0006x
R² = 0.9775
0.1
Pressure at Equilibrium (pisa)
T2 of Live Bitumen (msec)
10
CH4
y = 2225704x
R² = 0.9818
800
CO2
600
y = 330684x
R² = 0.6347
C2H6
400
y = 286359x
R² = 0.9826
200
0
0
200
400
600
800
1000
Pressure (psia)
0.E+00
5.E-04
1.E-03
2.E-03
2.E-03
Gas Concentration in Bitumen (mol gas/ mL oil)
10
CH4-Bitumen
T2 of Live Bitumen (msec)
C2H6-Bitumen
y = 0.103e2095.5x
R² = 0.9971
C2H6
CO2-Bitumen
Dead Bitumen
1
 T2 vs P of each reservoir gase is found to be
closely linear on semi-log scale and
extrapolated near the value of dead oil T2 .
CO2
y = 0.2288e1341.9x
R² = 0.9432
 Solubility of CH4 and C2H6 in the bitumen
follow the Henry’s law well .
CH 4
y = 0.0336e2193x
R² = 0.9921
 The calculated solubility of CO2 in bitumen
is overestimated.
0.1
0.E+00
5.E-04
1.E-03
2.E-03
2.E-03
Gas Concentration in Bitumen (mol gas/mL oil)
Correction for Deviation of CO2 Solubility in Bitumen
L-L-V Three-Phase-Equilibrium could have formed inside the pressure vessel
1000
1000
CH 4
CO 2
y = 2225704x
R² = 0.9818
800
y = 797841x - 655.84
R² = 0.9844
600
C2 H 6
400
CH4-Bitumen
y = 286359x
R² = 0.9826
200
CO2-Bitumen
C2H6-Bitumen
Pressure at Equilibrium (pisa)
Pressure at Equilibrium (pisa)
CH 4
y = 2225704x
R² = 0.9818
800
CH4-Bitumen
CO2-Bitumen
CO 2
y = 797841x
R² = 0.9844
600
C2H6-Bitumen
C2 H 6
400
y = 286359x
R² = 0.9826
200
Intercept
0
0
0.E+00
1.E-03
2.E-03
3.E-03
0.E+00
Gas Concentration in Bitumen (mol gas/ mL oil)
1.E-03
2.E-03
3.E-03
Gas Concentration in Bitumen (mol gas/ mL oil)
10
10
CH4-Bitumen
y = 0.103e2095.5x
R² = 0.9971
y = 0.103e2095.5x
R² = 0.9971
C2 H 6
CO2-Bitumen
Dead Bitumen
1
CO 2
y = 0.2288e1341.9x
R² = 0.9432
CH 4
y = 0.0336e2193x
R² = 0.9921
T2 of Live Bitumen (msec)
T2 of Live Bitumen (msec)
C2H6-Bitumen
CO 2
1
CH4-Bitumen
CH 4
C2H6-Bitumen
CO2-Bitumen
y = 0.2288e1341.9x
R² = 0.9432
Dead Bitumen
0.1
0.1
0.E+00
C2 H 6
y = 0.2041e2193x
R² = 0.9921
1.E-03
Gas Solubility in Bitumen (mol/mL oil)
2.E-03
0.E+00
1.E-03
Gas Solubility in Bitumen (mol/mL oil)
2.E-03
Correlation Between T2 and Viscosity/Temperature
Ratio for Bitumen and Brookfield Oil
10
100
Bitumen
CO2-Oil
T2 Relaxation Time (msec)
T2 Relaxation Time (msec)
C2H6-Oil
1
0.1
C2H6-Bitumen
CO2-Bitumen
CH4-Bitumen
CH4-Oil
Dead Oil at 22C
10
Dead Brookfield Oil at
Different T
1
Brookfield Oil
Dead Bitumen at Different T
0.01
1.E+00
0.1
1.E+01
1.E+02
1.E+03
Viscosity/Temperature (cP/K)
1.E+04
1.E+00
1.E+01
1.E+02
1.E+03
1.E+04
Viscosity/Temperature (cP/K)
 Regardless of the gas type used for saturation, the live oil T2 correlates with
viscosity/temperature ratio on log-log scale.
 The changes of T2 and viscosity/temperature ratio caused by gas saturations in oil
follows the same trend of those caused by temperature variations on the dead oil.
Comparing with Previous T2 vs Viscosity Data
1.E+03
T2[LaTorraca et al](2 MHz)
T1[LaTorraca et al](2 MHz)
Normalized Relaxation Time (msec)
T2[McCann et al](2MHz)
T1[McCann et al](2 MHz)
1.E+02
T2[Vinegar et al](2 MHz)
T1[Vinegar et al](80 MHz)
T2[Zhang et al](2 MHz)
T1[Zhang et al](2 MHz)
T1
1.E+01
T2[Zhang et al](7.5 MHz)
T1[Zhang et al](7.5 MHz)
T2[Zhang et al](20 MHz)
T1[Zhang et al](20 MHz)
1.E+00
Alkane Corr.
Corr. by Morriss et al
T2
Dipole-dipole Corr.
T2[Bitumen, Dead](2 MHz)
1.E-01
T2[Bitumen, Live](2 MHz)
T1[Bitumen, Live](2 MHz)
T2[Brookfield, Dead](2 MHz)
T2[Brookfield, Live](2 MHz)
1.E-02
1.E-02
1.E-01
1.E+00
1.E+01
1.E+02
1.E+03
1.E+04
Normalized Viscosity/Temperature (cP/K)
1.E+05
Relaxation time and viscosity/temperature
ratio are normalized with respect to 2 MHz
as shown below**:
T2 N 
** Hirasaki, Lo and Zhang, Magnetic Resonance Imaging, 2003
2
0
T2
  
 
   0 
2 T 
 T N
Conclusion
 The live bitumen T2 is significantly larger than T2 of dead
bitumen, even at the lowest pressure level in this work (~100
psia).
 The relationship between live bitumen T2 and equilibrium
pressure / solubility is linear on semi-log scale for all three
reservoir gases.
 Regardless of the gas type used for saturation, the live bitumen
T2 correlates with viscosity/temperature ratio on log-log scale.
 More importantly, the changes of T2 and viscosity/temperature
ratio caused by solution gas follows the same trend of those
caused by temperature variations on the dead oil.
Appendix A
 The method for computing solubility from pressure data is described as
follows:
(1) Pressurization stage:
 P0  V g
Peq  V g
sg  

 z0  R  T
z eq  R  T


 Voil


(2) Depressurization stage:
 Peq  V g
P0  V g
s g ,i  s g ,i 1  

 z eq  R  T
z0  R  T


 Voil


• sg,i is the solubility at current pressure level. sg,i-1 is the solubility at previous pressure level right
before the depressurization.
• Vg is the volume of vapor phase inside the pressure vessel. Voil is the volume of oil sample inside
the pressure vessel. Assuming the swelling effect of oil in this work is negligible, both V g and Voil
are constant.
• P0 and Peq are system pressure at beginning and pressure at equilibrium after each
pressurization/depressurization, respectively.
• z0 and zeq are compressibility at beginning and compressibility at equilibrium after each
pressurization/depressurization, respectively.
Back-up Slides
Approach to Compensation for T2 Information Loss
Collected data in CPMG
Mo from FID

Determine initial magnetization M0 from FID.

Supplement M0 into the regular CPMG data and assume lognormal
distribution for bitumen.
Changes of T2 and Pressure of CO2 Dissolved
Bitumen During Pressurization Stage
1.0
Dead Oil
21 hrs
0.8
97 hrs
284 hrs
0.6
391 hrs
470 hrs
0.4
0.2
0.0
T2
0.1
1
10
100
1000
10000
Pressure
10
760
T2 Relaxation Time Distribution (msec)
740
1
720
700
0.1
680
0
100
200
300
Time (Hour)
400
500
Pressure (psia)
T2 of bitumen (msec)
Amplitude f
174 hrs
Depressurization of CO2 to Lower Pressures
T2
T2
Pressure
560
420
410
1
400
Pressure (psia)
570
Pressure (psia)
T2 of bitumen (msec)
580
Peq = 583 psia
Pressure
10
590
T2 of bitumen (msec)
10
390
Peq = 414 psia
1
0.1
550
0
10
20
30
40
50
380
0
60
10
20
Pressure
T2
310
290
280
Peq = 300 psia
0.1
270
20
30
40
Time (Hour)
50
60
70
140
130
120
110
Peq = 120 psia
100
0.1
90
0
10
20
30
40
Time (Hour)
50
60
70
Pressure (psia)
1
Pressure
T2 of bitumen (msec)
300
10
50
1
Pressure (psia)
T2 of bitumen (msec)
10
0
40
Time (Hour)
Time (Hour)
T2
30
T2 &T1 of CO2 Saturated Bitumen at Different Pressures
1.0
1
Dead oil
T1 at 709 psia
120 psia
0.8
0.8
T1 at 583 psia
300 psia
Amplitude f
583 psia
709 psia
0.4
T1 at 414 psia
0.6
T1 at 300 psia
0.2
0.0
0
0.1
1
10
100
1000
10000
T2 Relaxation Time Distribution (msec)
T1 at 120 psia
0.4
0.2
0.1
1
10
100
1000
10000
T1 Relaxation Time Distribution (msec)
10
T2 from new interpretation (msec)
Amplitude f
414 psia
0.6
 The dissolving of CO2 in Bitumen significantly
changes oil T2.
 T2 from regular interpretation > T2 from lognormal
distribution model with specified M0. The
difference decreases as saturation pressure
increases.
1
 The change of T1 with pressure is much less
significant, comparing to the corresponding T2.
0.1
0.1
1
T2 from regular interpretation (msec)
10
 The change of bitumen viscosity has much more
effect on the T2 response rather than T1.
Changes of T2 and Pressure of CH4-Bitumen at
Different Pressure Levels
T2
1
Pressure
1
Dead oil
950
19 hrs
0.8
141 hrs
331hrs
f
0.6
428hrs
0.4
930
Pressure (psia)
Pressurization
Stage
940
T2 of bitumen (msec)
263hrs
920
0.2
0.1
0
0.1
1
10
100
1000
910
0
10000
100
200
T2
Pressure
520
510
500
Peq = 517 psia
0.1
490
0
20
40
Time (Hour)
60
80
Pressure
150
140
130
120
Peq = 131 psia
0.1
110
0
20
40
Time (Hour)
60
80
Pressure (psia)
T2 of bitumen (msec)
530
Pressure (psia)
Depressurization
Stage
500
1
540
T2 of bitumen (msec)
1
400
Time (Hour)
T2 Relaxation Time Distribution (msec)
T2
300
T2 of CH4 Saturated Bitumen at Different Pressures
1
1
Dead oil
131 psia
0.8
T2 after correction (msec)
517 psia
Amplitude f
914 psia
0.6
0.4
0.2
0.1
0
0.1
0.1
1
10
100
1000
10000
1
T2 before correction (msec)
T2 Relaxation Time Distribution (msec)
 The change of bitumen T2 resulting from the saturation of CH4 is obviously less significant than
that observed in the case of CO2 or C2H6
 The T2 of C2H6 saturated bitumen decreases as equilibrated pressure decreases.
 The minor peaks between 100 msec and 1 sec are from CH4 in the vapor phase. As pressure
decreases, the gas peak moves to the smaller values and peak area shrinks.
 T2 from regular interpretation > T2 from lognormal distribution model with specified M0. The
difference decreases as saturation pressure increases.
Re-adjustment of z factor of CO2 to Correct the
Calculated Solubility to Follow Henry’s Law
1
z *0
0.9
Compression Factor Z
0.8
0.7
z e, v
z0
0.6
z *e
0.5
0.4
z e, l
0.3
0.2
CO2 at 30 oC
0
200
400
600
800
1000
1200
Pressure, psi
 Adjustment of z0 at the initial pressure gives the re-evaluated value of z factor (z0*) to be 0.96,
which is very unlikely for the compressibility factor of CO2 at 745 psia.
 Adjustment on of ze at the equilibrium pressure shows that, the corrected value of z factor (ze*)
needs to move down to 0.55 at 709 psia.
 The calculated mole fraction of CO2 in vapor phase is 0.54, and the mole fraction in CO2-rich
liquid phase is 0.46. Correspondingly, the volume fraction of CO2 in either vapor phase or CO2-rich
liquid phase is calculated to be 0.82 and 0.18, respectively.