Viscosity Evaluation for NMR Well Logging of Live Heavy Oilsgjh/Consortium/resources/PetrophysicsVol53No1.pdfeven more visFous than the AthabasFa bitumen used in our previous Zork

PETROPHYSICS22 February 2012

Viscosity Evaluation for NMR Well Logging of Live Heavy Oils1

Zheng Yang2, George J. Hirasaki3, Matthias Appel4, Daniel A. Reed5

Well log NMR T2 measurements of heavy oil and bitu-men a ear to be signi antly longer than from laboratory results. This is likely due to gas dissolved in heavy oil and bitumen at reservoir onditions. n this ork the vis osity and laboratory NMR measurements ere made on re om-bined live heavy oil and bitumen sam les and on syntheti

rook eld oil as a fun tion of dissolved gas on entra-tions. The effe ts of 4 2 and 2 6 on the vis osity and T2 res onses of these t o heavy oils at various satura-tion ressures ere investigated. n this ork measured T2 of live heavy oil is signi -antly larger than T2 of dead oil even at the lo est ressure

level 1 sia . ive oil T2 is found to have linear orre-

lations ith both saturation ressure and gas on entration on semi-log s ale for all three gases. The investigations on live oil vis osity sho that regardless of the gas ty e used for saturation live oil T2 orrelates ith vis osity tem era-ture ratio on log-log s ale. More im ortantly the hanges of T2 and vis osity tem erature ratio aused by solution gas follo the same trends as those aused by tem erature variations on dead oil. This on lusion holds for both bitu-men and for the syntheti rook eld oil. n this manner the vis osity of live heavy oil an be evaluated from the NMR res onse to dead oil and the orrelation of T2 ith vis ositytemperature.

ABSTRACT

TR . 53 N . 1 R R 2 12 22 3 3 R

Manus ript re eived by the ditor une 1 2 11 revised manus ript re eived anuary 4 2 12.1 riginally presented at the W 52nd nnual oggin ymposium olorado prings May 14 1 2 11.2 hevron Ri hmond mail ny hevron. om3Ri e niversity M -362 61 Main t. ouston T 5 mail g h ri e.edu4 hell 3 3 ellaire lvd. ouston T 25 mail matthias.appel shell. om5 era nergy 1 Ming ve. akers eld 33 mail dareed aeraenergy. om

2 12 o iety of etrophysi ists and Well og nalysts. ll Rights Reserved.

INTRODUCTION eavy oil and bitumen are hara teri ed by their high vis osity and represent a orld ide kno n oil reserve of 6 trillion barrels eleersnyder 2 4 . s the onventional oil reserves of the orld ontinue to de line and the e plora-tion and produ tion te hnologies keep improving heavy oil and bitumen deposits have attra ted great attention from the energy industry and ill be the fo us of the oil industry for years to ome. o eld NMR has displayed great potential in many heavy oil ell logging ase studies e.g. alifornia en-e uela and hina eleersnyder 2 4 . o ever due to the e tremely high vis osity of heavy oil the T2 rela ation distribution has a signi ant omponent that is shorter than

hat an be measured by urrent NMR logging tools. Ne methods for both NMR measurement and subse uent ra data interpretation have been developed in previous ork

ang and irasaki 2 to orre t the T2 rela ation times of heavy oil and bitumen. This method involved supple-menting M measurements ith measurements. Re ently laboratory NMR measurements have sho n that the laboratory T2 results of bitumen samples e tra ted from ores ith di hloromethane solvent appear to be remarkably shorter than the orresponding ell log T2. This

is likely due to gas dissolved in heavy oil and bitumen at reservoir onditions. The T2 distribution depends on oil vis osity and dissolved gas on entration hi h may vary throughout the heavy oil eld. Thus a method to determine the gas solubility and the in-situ vis osity from NMR logs

ould be very useful in heavy oil and bitumen reservoir development. n this ork vis osity and laboratory NMR measure-ments as a fun tion of dissolved gas on entrations ere performed on re ombined live heavy oils. The effe ts of three different gases 4 2 and 2 6 on the vis os-ity of t o different samples ere investigated in a series of saturation pressures. The orrelations bet een the saturation pressure gas solubility NMR T2 and live oil vis osity are established to resolve the differen es bet een NMR log and laboratory data. The ndings onstitute a method for evalua-tion of in-situ heavy oil vis osity through NMR ell logging.

EQUIPMENTS AND MATERIALS

The NMR spe trometer used in this ork as a lo eld Maran- operating at a proton resonan e fre uen y of

2. M . 4 -mm NMR probe ith a 4 -mm s eet spot in length and minimum e ho spa ing of .2 ms as used for

Viscosity Evaluation for NMR Well Logging of Live Heavy Oils

PETROPHYSICS 23February 2012

most NMR measurements. The typi al applied idth of 2 pulse as .3 s and that of pulse as 15.5 s. Another 5 -mm NMR probe ith a minimum e ho spa ing of .4 ms

as used for stati gradient measurements. The temperature of the magneti eld system as ontrolled at 3 ith an error of .1 . A pressure vessel manufa tured by T M as used for all high pressure e periments. The main body of this pressure vessel as made ith and as ustomi ed to

t the 4 mm probe and the ompatible temperature ontrol system. t had an internal diameter of 22 mm and the total volume of its sample hamber as 2 ml. The syntheti heavy oil sample used in this ork as the rook eld vis osity standard 36 1 per ent

A oil ommer ially available from the rook eld om-pany hi h has a vis osity of 361 at 25 . This is even more vis ous than the Athabas a bitumen used in our previous ork ang et al. 2 . The three pure gases 2 4 and 2 6 used in this

ork ere provided by Matheson Tri- as ith produ t grade of ltra igh urity.

EXPERIMENTS AND RESULTS

Viscosity of heavy oil samples

The vis osities of the bitumen sample and the rook-eld vis osity standard 36 ere measured at differ-

ent temperatures by using the rook eld vis ometer -. The sample temperature as ontrolled by an oil bath

AA 35 onne ted to the vis ometer sample holder. The temperature for the vis osity measurements ranged from 1 to . pe i ations of the rook eld vis om-eter - limited the lo est temperature that the bitu-men sample vis osity measurement ould be performed at to 2 . When the sample temperature as further lo ered to 1 the bitumen vis osity as beyond the apability of

rook eld vis ometer 3. 1 6 . M measurements ere performed on the t o heavy oil samples at temperature from 1 to at 1 inter-

vals. At ea h temperature the measurements ere repeated three times to ensure the reliability of e perimental data. The T2 values at different temperatures ere evalu-ated ith the interpretation method developed in our pre-vious ork ang et al. 2 . The relationship bet een the vis osity temperature ratio and T2 of the t o heavy oil samples is sho n in ig. 1. Although the orrelations are still linear on a log-log s ale they learly deviate from pre-viously reported orrelations Morriss et al. 1 hang et al. 1 o et al. 2 2 .

Investigations on recombined live oils at differentpressures

The investigations on the re ombined live oils satu-rated ith 2 4 and 2 6 ere performed at different pressures. uring the e periments ith ea h gas the pro edure

as generally divided into t o stages the pressuri ation stage and the depressuri ation stage. irst the highly pres-suri ed gas as introdu ed into the losed pressure vessel. After the gas-oil system rea hed e uilibrium at the highest pressure level the system pressure ould be depressuri ed to several lo er levels step by step. At ea h lo er pressure the e uilibrium as a hieved as ell. uring the entire pro ess NMR measurements ere performed periodi ally to tra k the T2 hange. roper num-ber of s ans N as hosen to make the signal-to-noise ratio NR e ual to 1 . a h measurement as repeated 6 times to ensure reliability of e perimental data. The system pressure inside the vessel as monitored by using enso-Metri s pressure transdu er Model 6 2 Ma . 5 psig . The investigations on the re ombined live oils rst started ith rook eld oil.

CO2

The rook eld oil as rst re ombined ith 2. n this ase the gas pressure inside the vessel as initially raised to 2 psia by in e ting 2 from the top of the pres-

Fig. 1 Relationship between T2 and viscosity/tempera-ture ratio for the two heavy oils.

0.01

0.1

1

10

1.E+00 1.E+01 1.E+02 1.E+03 1.E+04

T2

(mse

c)

Viscosity/Temperature (cP/K)

Brookfield oil

Bitumen

T2 = 37.92*(T / Visc)0.6815

R2 = 0.9956

T2 = 4.252*(T / Visc)0.4493

R2 = 0.9972

Fig. 2 T2 2 as a func-tion of time.

0

1

2

3

4

0.1 1 10 100 1000 10000

Am

plit

ude f

T2 Relaxation Time Distribution (msec)

0 hr

21 hr

71 hr

116 hr

260 hr

568 hr

PETROPHYSICS24

Yang et al.

February 2012

sure vessel. Then the gas sour e as ut off and no more gas as added into the system after ards. The oil sample volume as 15 ml.

The pressure vessel as verti ally pla ed in the 3 air bath after gas in e tion. n this manner gas transferred into the oil ithout generated onve tion. The T2 distribution of

rook eld oil ith dissolved 2 as measured as a fun -tion of time and the results are displayed in Fig. 2. As sho n in Fig. 2 the oil T2 peak markedly moves to larger values ith time. t indi ates that a signi ant amount of 2 is dissolved into the heavy oil even ithout any generated onve tion. The 2 is dissolved at the gas-liq-uid interfa e in reases the oil density and reates a natural onve tion pattern until the oil is gas saturated augen et

al. 2 . The re orded system pressure and the hange of T2during the pressuri ation stage are displayed in Fig. 3. As

2 gradually dissolved into the oil the pressure in the vapor phase kept de reasing hile the oil T2 ontinuously in reased as more 2 as dissolved. As sho n in Fig. 3 both vapor pressure and oil T2 started leveling up after 4 hours. Theoreti ally the ultimate pressure at equilibrium an be measured hen the rook eld oil is ompletely saturated

ith 2. o ever in pra ti e the 2 phases may take an e tremely long time to really rea h the equilibrated state. Therefore as an appro imation e assumed that the 2-

rook eld oil system rea hed quasi-equilibrium after 56 hours and then moved to the ne t stage depressuri ation. The re orded pressure at 56 hours as .4 psia

hile the T2 of rook eld oil saturated ith 2 as 4. 1 ms. After ards the depressuri ation as ondu ted by de reasing the pressure by 2 psi at a time till the pressure inside the vessel rea hed appro imately 1 psia. The pres-sure vessel as kept verti al inside the 3 air bath during the entire depressuri ation pro ess. The hanges of pressure

and live oil T2 ere monitored in a similar ay to the pres-suri ation phase. The NMR T2 and pressure measurements ere e tended for at least an e tra t o days after the 2 saturated oil rst rea hed its equilibrated value at ea h pressure level. This ensured that the T2 and pressure measurements ere are at equilibrium. The evolutions of oil T2 and gas pressure for the 2saturated rook eld oil as a fun tion of time at four differ-ent lo er pressure levels are displayed in Fig. 4. The values of pressure and live oil T2 at equilibrium are sho n in ea h subplot respe tively. The time hen the 2 saturated oil

rst rea hed equilibrium at ea h pressure level is indi ated by the verti al dashed line. The T2 distributions for the 2 saturated oil at different pressures are sho n in Fig. 5. As the 2 as depressur-

Fig. 5 T2 2 -ferent pressures.

0

1

2

3

4

0.1 1 10 100 1000 1000

Am

plit

ude f


780 psia

638 psia

452 psia

273 psia

122 psia

14.7 psia

0

Fig. 3 Vapor pressure decay and oil T2 increase with 2

0.1

1

10

760

780

800

820

840

860

880

900

0 200 400 600

T2 of C

O2

Dissolved B

rookfield Oil

(msec)

Syst

em P

ress

ure

(psi

a)

Time (Hour)

Pressure

T2

Fig. 4 Evolution of T2 2 saturated

during depressurization stage.

600

700

1

10

0 50 100 150 200

Pressu

re (psia)

T2

of B

roo

kfie

ld O

il (m

sec)

Time (Hour)

T2 Pressure

Peq = 638.1 psiaT2 = 3.06 msec

60

160

0.1

1

0 50 100 150

Pressu

re (psia)

T2

of B

rook

fiel

d O

il (m

sec)

Time (Hour)

T2 Pressure


400

500

1

10

0 50 100 150 200

Pressu

re (psia)

T2

of B

rook

fiel

d O

il (m

sec)

Time (Hour)

T2 Pressure


200

300

0.1

1

10

0 20 40 60 80

Pressure (p

sia)

T2

of B

rook

fiel

d O

il (m

sec)

Time (Hour)

T2 Pressure




i ed from psia to 122 psia the oil T2 peak signi antly de reases from large to smaller values. Moreover even

hen the gas pressure is only 122 psia the T2 of live oil is still markedly different from the oil ithout 2.

CH4

n the ase of 4- rook eld oil the gas pressure inside the losed vessel as initially 6 psia and the oil sample volume as 15 ml. The pressure vessel as verti ally pla ed in the 3 air bath after the introdu tion of pressuri ed 4. n this manner only diffusion o urred bet een gas and oil. The T2 distribution of rook eld oil ith 4 as measured as a fun tion of time and the results are displayed in Fig. 6. As sho n in Fig. 6 the position of the live rook eld oil peak did not hange signi antly during the entire 16 hour measurement time. The e tremely slo dissolution of

4 is due to the small diffusivity of 4 into heavy oil hang et al. 2 preti et al. 2 2 . onsequently if it

o urred only by diffusion bet een the oil and gas phases 4 saturation ould take an unreasonably long time.

Therefore it as ne essary to boost the saturation pro-ess by generating onve tion on the 4-oil system. n

order to generate onve tion the pressure vessel as pla ed on a support stand at room temperature and repeatedly turned from verti al to hori ontal and then ba k to verti al as sho n in Fig. . The interval bet een ea h a tion from verti al to hori ontal or from hori ontal to verti al as about 6 minutes. The vessel as put ba k into the Maran spe trometer every night and verti ally pla ed in the 3 air bath over-night. The system pressure and the T2 of 4 dissolved oil

ere measured every subsequent morning. The T2 distribution of 4 dissolved rook eld oil as measured as a fun tion of time in the period of onve tion and is displayed in Fig. .

n ontrast to the observations from Fig. 6 ith the assis-tan e of onve tion the oil T2 peak in reases to larger val-ues. n Fig. the T2 distribution has a small peak at around 1 se . This is believed to be the response of high pressure

4 vapor inside the pressure vessel. The T2 of pressuri ed 4 as found to be around 1 se at 1 psia private om-

muni ation ith r. Ar un urup . The T2 of 4 dissolved oil rst rea hed equilibrium plateau value after 2 6 hours as sho n in Fig. . The e periments ontinued for t o e tra days and no signi ant hanges for either pressure or T2 ere observed. Therefore

the system as onsidered to be equilibrated at that point. uring the 2 6 hours the generated onve tion made the

pressure de rease by about 34 psi from 6 psia to 52 psia. orrespondingly the solution of 4 in reased the oil T2

from .36 ms to .6 ms.n omparison ith the observations from the ase of

2- rook eld oil the dissolution of 4 in reased T2 mu h less than 2 did. The T2 rose from .36 ms to .6 ms at

52 psia in the ase of 4-oil hile the equilibrated T2 as 4. 1 ms at psia for 2-oil. Therefore in order to reate enough differen e for reliable measurement e depressur-i ed the 4- rook eld oil mi ture dire tly from 52 psia to 1 psia. We follo ed the same e perimental pro edures as in the 2 ase. The pressure hange as re orded and the T2 measurement as performed periodi ally.

Fig. 6 T2 4 as a func-tion of diffusion time.

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

0.1 1 10 100 1000 100

Am

plit

ude f


0hr

4hr

19hr

42hr

101hr

168hr

00

Fig. 7 Demonstration of generating convection

Fig. 8 T2 4 as a func-tion of time in convection.

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0.1 1 10 100 1000 10000

Am

plit

ude f


0 hr

9 hr

85 hr

129 hr

177 hr

206 hr

251 hr

PETROPHYSICS26

Yang et al.

February 2012

The hanges of T2 and the re orded pressure for the 4saturated rook eld oil at 111 psia are displayed in Fig. . The shift of live oil T2 distribution at three different pressure levels is displayed in Fig. 1 . As the 4 as depressuri ed from 52 psia to 111 psia the T2 peak signi antly shifted to shorter values. o ever the T2 of 4 saturated rook eld oil at 111 psia still is remarkably different from the T2 of dead oil.

C2H6

n the ase of 2 6- rook eld oil the gas pressure inside the vessel as rst raised to 551 psia by in e ting

2 6 from the top of the pressure vessel. This pressure as less than the riti al pressure of 2 6 hi h is 6. psia. The oil sample volume as 13 ml. After the initial gas in e tion the diffusion behavior of

2 6 inside the rook eld oil at 3 as rst investigated. The T2 distribution hange as a fun tion of time during the diffusion period is sho n in Fig. 11.

An interesting nding as that hen 2 6 gradually dissolved into the oil the T2 distribution of oil be ame bi-modal. This is be ause the dissolved 2 6 de reases the vis-osity of oil signi antly in reasing T2 of oil ith 2 6 to

1 ms. Mean hile the T2 of oil ithout gas still remained at its original value of 1 ms. As more 2 6 dissolved into the rook eld oil the area of the peak representing the 2 6saturated oil in reased hile the area of the peak of oil ith-out gas shrank orrespondingly.

The e planation for the bi-modal of T2 distribution sho n in Fig. 11 as veri ed by the stati gradient M measurement sli e measurement on the oil sample ith the 5 -mm probe. The applied e ho spa ing as .4 ms. The sample volume in this ase as 13 ml resulting in 3.4 m in length in the pressure vessel. A regular M measurement

as rst made on the entire sample. After ards the sli e measurements ere performed at three different positions along the sample. The available sli e thi kness as appro i-mately 1 m. The midline position of ea h sli e is displayed in Fig. 12.

osition 1 enter of the entire sample position 2 1.5 m

Fig. 9 T2 4as a function of time during depressurization stage.

40

90

140

0.1

1

0 20 40 60 80 100 120

Pressure (psia)

T2

of B

rook

fiel

d O

il (m

sec)

Time (Hour)

T2 Pressure

Peq = 111 psia

T2 = 0.39 msec

Time (Hour)

Fig. 10 T2 4different pressure levels.

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0.1 1 10 100 1000 10000

Am

plit

ude f


14.7psia

111psia

852psia

Fig. 11 T2 2 6 as a function of time in diffusion.

0

1

2

3

0.1 1 10 100 1000 10000

Am

plit

ude f


0 hr

45 hr

109 hr

132 hr

300 hr

468 hr

733 hr

Fig. 12 Static gradient T2 2 6 dis-solved oil sample.

0

0.5

1

1.5

0.1 1 10 100 1000 10000

Am

pli

tud

e f

T2 Relaxation Time (msec)

T2 Distribution of Entire Sample

Slice at Sample Center

Slice 1.5cm Down from Center

Slice 2.1cm Down from Center

#1

#2

#3



do n from the sample enter and position 3 2.1 m do n from the sample enter. n position 2 part of the bottom part of the sli e as outside of the sample region hile in position 3 only a small part at the top of the sli e as

ithin the sample region. The results of the sli ed T2 mea-surements are displayed in Fig. 12 here the area for ea h peak appro imately indi ates the sample si e for ea h sli e measurement. omparing the T2 distribution from ea h sli e measure-ment ith the T2 distribution of the entire oil sample it is learly sho n that the sample in position 1 as the 2 6

saturated oil hile the sample of position 3 as the oil ithout 2 6. The T2 distribution resulting from position 2

represents the ombination of 2 6 saturated oil and dead oil. After 33 hours of diffusion onve tion as introdu ed to the 2 6- rook eld oil system by using the same method as for the 4 ase. The hange of T2 distribution as a fun tion of time during the onve tion stage is displayed in Fig. 13. The last measurement made during diffusion hi h lasted 33 hours is also plotted in Fig. 13 as a ben hmark.

omparing Fig. 11 and Fig. 13 e nd that the onve -tion signi antly boosted the dissolution of 2 6 into Brook-

eld oil. As sho n in Fig. 13 16 hours after the generation of onve tion hours in total after the initial pressuri a-tion the T2 peak for dead oil ompletely disappeared as the entire oil sample as saturated by 2 6. The e periment ontinued for another 6 hours and no signi ant hange for

either pressure or T2 as observed. n Fig. 11 and Fig. 13 the relatively smaller peaks lo ated at appro imately 1 se are believed to be the T2 response of dissolved 2 6 inside the oil sample at the pres-ent pressure level. The T2 of pressuri ed 2 6 as found to be 1 .4 se at 56 psig and . se at 4 5 psig private om-muni ation ith r. Ar un urup . arameters of the NMR measurements ere arefully sele ted to avoid T2 ontribu-tion from 2 6 vapor Fig. 11 and Fig. 13 .

After the Brook eld oil as saturated ith 2 6 at 4 psia the depressuri ation as ondu ted by de reasing the pressure by 1 psi at a time until the pressure inside the vessel rea hed appro imately 1 psia. The pressure vessel

as kept verti al inside the 3 air bath during the entire depressuri ation pro ess. The hanges of pressure and live oil T2 ere monitored in a similar ay to the previous t o ases. The measured T2 and re orded pressure hanges as a fun tion of time for the 2 6 saturated Brook eld oil at four lo er pressure levels are displayed in Fig. 14. The T2 peak shift of 2 6 saturated oil at different pressures is sho n in Fig. 15. t is lear that the live oil T2 is signi antly larger than that of the dead oil even at the lo est pressure level. The T2 peak from dissolved 2 6 appro imately at 1 se at 4 psia de reases to smaller values as equilibrium pressure de reases Fig. 15 . Mean hile the area of the dis-

Fig. 13 T2 2 6 as a function of time in convection.

0

1

2

3

0.1 1 10 100 1000 10000

Am

plit

ude f


733 hr

757 hr

805 hr

900 hr

Fig. 14 T2 2 6oil as a function of time at different pressures during depressurization stage.

220

320

1

10

0 50 100 150

Pressure (psia)

T2

of B

rook

fiel

d O

il (m

sec)

Time (Hour)

T2 Pressure

Peq = 287 psiaT2 = 3.45 msec

330

430

1

10

100

0 50 100 150

Pressure (psia)

T2

of B

rook

fiel

d O

il (m

sec)

Time (Hour)

T2 Pressure


120

220

1

10

0 50 100 150 200

Pressure (psia)

T2

of B

rook

fiel

d O

il (m

sec)

Time (Hour)

T2 Pressure


40

140

0.1

1

10

0 50 100 150 200

Pressure (psia)

T2

of B

rook

fiel

d O

il (m

sec)

Time (Hour)

T2 Pressure


Fig. 15 T2 2 6different pressure levels.

0

1

2

3

0.1 1 10 100 1000 10000

Am

plit

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14.7 psia

106 psia

189 psia

287 psia

393 psia

480 psia

PETROPHYSICS28

Yang et al.

February 2012

solved 2 6 T2 peak shrinks as ell indi ating the de rease of dissolved amount of 2 6 inside the oil sample.

sing appropriate pressure hanges vapor phase vol-ume and temperature the solubility of ea h gas in Brook-

eld oil at ea h pressure level as al ulated by using the q. A.1 or q. A.2 sho n in Appendi A. The ompress-

ibility fa tor z for ea h gas an be found in referen e books A 1 3 NB 1 4 NB 1 6 .

Mean hile an e trapolation as performed at ea h pressure level as sho n in Appendi B for all three gases in order to orre t the effe t of temperature hange on the initial pressure reading. The relationship bet een the solubility of ea h gas

hi h as al ulated ith either the orre ted pressure data via e trapolation or the original re orded data and the or-responding T2 is plotted in Fig. 16. The T2 of dead Brook-

eld oil is indi ated by symbols. ere the solubility is e pressed in the unit of mole gas ml oil. As displayed in Fig. 16 a and Fig. 16 b solubilities of 2 and 4 al ulated from the orre ted pressure data are signi antly smaller than those al ulated from the origi-nally re orded data at ea h pressure level. bviously for both 2 and 4 the solubilities al ulated ith un or-re ted pressure trends deviate further from the value of dead oil T2 than the results al ulated ith orre ted pressures. Fig. 16 sho s the relationship bet een the solubil-ity of 2 6 in Brook eld oil and its orresponding T2. The e trapolation of 2 6 solubility al ulated from the or-re ted data is mu h loser to the value of dead oil T2 hile the trend of solubility al ulated from the original pressure

data deviates signi antly. spe ially at 1 6 psia the solu-bility al ulated from the originally re orded pressure data is near ero. o ever as sho n in Fig. 15 the 2 6 satu-rated oil T2 is markedly larger than the dead oil T2. This is unreasonable and also implies that orre tion of the re orded pressure data is ne essary. The relationship bet een the gas on entration in oil and the orresponding pressure at equilibrium is displayed in Fig. 1 for different gases. The al ulation results are from the orre ted pressure data. enry s la is employed to t the pressure vs. gas on entration data and the esti-mated enry s onstant for ea h gas in the Brook eld oil is displayed by the orresponding tted fun tion in the plot. As sho n in Fig. 1 a the al ulated solubility val-ues in the ases of 2 6-oil and 4-oil follo enry s la

ell. o ever the originally al ulated solubility of 2 deviates signi antly. The e trapolation of the 2 data does not pass through the origin. nstead at -a is y it has an inter ept of . 1 mol gas ml oil indi ated by the red solid dot . imilar deviation as also observed for the relationship bet een live oil T2 and solubility for 2 as sho n in Fig. 16 d . The proposed e planation for this deviation is that dur-ing the pressuri ation stage in the ase of 2-oil psia at 3 besides the original t o phases vapor 2 and liquid oil a third phase hi h is 2-ri h liquid ith presen e of heavy-hydro arbon omponents may be formed inside the

2-heavy oil system. The - - three-phase-equilibrium has been observed in both 2 Alkane system rr et al. 1 1 ni k et al. 1 5 and 2 rude oil system rr et al. 1 1 yegh et al. 1 at near- riti al ondition. The e tra tion of heavy hydro arbon omponents as heavy as

24 into 2-ri h phase as reported by rr et al. 1 1 . More importantly the oe isting three phases ere found to be able to form more easily ith heavier omponent in the

2 oil binary mi ture rr et al. 1 1 . uring the pressuri ation stage of 2-oil system in this study after the in e tion of the pressuri ed 2 had eased the stripping of hydro arbons from the oil by 2 and the

Fig. 16oil and its corresponding T2 for three different gases.

y = 0.28e1820.9x

R² = 1

y = 0.25e1556x

R² = 1

0.1

1.0

0.E+00 2.E-04 4.E-04 6.E-04 8.E-04

T2of

Liv

e B

rook

fiel

d O

il (m

sec)

Solubility in Brookfield Oil (mol gas/ mL oil)

Dead Oil T2

with corrected data

with original dataCH4

(b)

y = 0.49e1404.3x

R² = 0.997

y = 0.94e1007.8x

R² = 0.992

0.1

1

10

100

0.E+00 1.E-03 2.E-03 3.E-03

T2

of L

ive

Bro

okfi

eld

Oil

(mse

c)


Dead oil T2

with corrected data

with original data

C2H6(c)

y = 0.11e1192.6x

R² = 0.9923

y = 0.09e991.37x

R² = 0.996

0.1

1

10

0.E+00 1.E-03 2.E-03 3.E-03 4.E-03 5.E-03

T2

of L

ive

Bro

okfi

eld

Oil

(mse

c)

Solubility in Brookfield Oil (mol / mL oil)

Dead oil T2

with corrected data

with original dataCO2

(a)

y = 0.49e1404.3x

R² = 0.997

y = 0.28e1820.9x

R² = 1

y = 0.94e1007.8x

R² = 0.992

0.1

1

10

100

0.E+00 1.E-03 2.E-03 3.E-03 4.E-03

T2

of L

ive

Bro

okfi

eld

Oil

(mse

c)


Dead oil T2

C2H6-Oil

CH4-Oil

CO2-Oil

(d)

Fig. 17 Relationship between the gas concentration in Brook-

2

2



dissolution of 2 into oil o urred simultaneously. As more heavy hydro arbon omponents ere present in the 2vapor phase a 2-ri h liquid phase ould have gradually formed inside the pressure vessel. o ever simply by moni-toring the pressure hange in vapor phase e annot tell the differen e bet een the pressure de ay from the dissolution of

2 into oil and the pressure de ay aused by ondensation of 2 into the 2-ri h liquid phase. The usti ation of the proposed interpretation of the t o liquid phases is dem-onstrated in Appendi by sho ing that the z fa tor of 2

ith the ad ustment mat hes ith enry s la .The re orded pressure de ay due to the ondensation of

2 in the se ond liquid phase as mistaken as that aused by the solution of 2 into the oil phase. As a result the al-ulated solubility of 2 at the highest pressure level ould

be signi antly larger than its true value. ubsequently as the pressure de reases the 2-oil system moved a ay from the three- oe isting-phases region and the data for the pressure differen e at ea h lo er pressure level ould be orre tly obtained. o ever based on the method for solubility al ulation in this ork Appen-di A any impa t on the solubility at the highest pressure

ill uniformly affe t the al ulation of solubility at ea h lo er pressure. onsequently as sho n in Fig. 1 a the al ulated solubility of 2 in Brook eld oil appears to be

overestimated ith a onstant value at ea h pressure level but still linearly orrelates the pressure at equilibrium and the solubility in the oil. n order to orre t the overestimation of 2 solubility

e uniformly subtra ted the e ess value at the inter ept of -a is from the originally al ulated solubility at ea h pres-

sure and re-plotted the orre ted 2 data in Fig. 1 b . t is lear that the orre ted 2 data no follo s the enry s

la ell.

The orre ted 2 data are also employed in the rela-tionship of live oil T2 and 2 solubility. omparing Fig. 16 d and Fig. 1 as the solubility of 2 as orre ted via the method demonstrated in Fig. 1 the data trend of T2vs. orre ted solubility of 2 no e trapolates ell to the dead oil value. The relationship bet een live oil T2 and its orresponding gas solubility is losely linear on a semi-log

s ale for all three gases. Furthermore an interesting nding in Fig. 1 is that the relationship bet een live oil T2 and gas solubility appears to losely follo a similar trend regard-less of the gas type used for saturation.

The vis osity of live Brook eld oil ith different gases as measured at different pressures by using a apillary

vis ometer. All the measurements ere performed at room temperature 22 . The relationship bet een uid vis osity and o rate measured pressure drop and tube dimension is governed by the Hagen-Poiseuille equation

ere is oil vis osity Q is o rate L is length of tube and R is inner radius of the tube. The apillary vis ometer as rst tested ith dead Brook eld oil at four different o rates. The average value obtained by using the apillary vis ometer as 46 6 at room temperature. Mean hile the vis osity measured

ith the Brook eld vis ometer at the same temperature as 4 1 only a 2.5 per ent differen e from the average value from the apillary vis ometer. The vis osity of live Brook eld oil saturated by 2 6

as measured at ve different pressure levels. n the ase of

Fig. 18 2 in T2 -

2value.

T2 o

f Liv

e B

rook

eld

Oil

(mse

c)

Fig. 19 Relationship between the T2the viscosity/temperature ratio.

0.1

1

10

100

1.E+00 1.E+01 1.E+02 1.E+03 1.E+04

T2

Rel

axat

ion

Tim

e (m

sec)


C2H6-Oil

CO2-Oil

CH4-Oil

Dead Oil at 22C

Dead Brookfield Oil at Different T

μ =P0 PL( ) R4

8 Q L .

PETROPHYSICS30

Yang et al.

February 2012

either 2-oil or 4 -oil the live oil vis osity measurement as performed at one pressure level. The measured vis os-

ity values of Brook eld oil under different onditions are summari ed in Fig. 1 and the data of dead oil vis osity at different temperatures are also plotted for omparison. The investigation on the vis osity of live Brook eld oil sho s that regardless of the gas type used for saturation the live oil T2 orrelates ith vis osity temperature ratio on a log-log s ale. More importantly as displayed in Fig. 1 the hanges of T2 and vis osity temperature ratio aused by solution gas follo the same trend as those aused by tem-perature variations on the dead oil. The investigations on the re ombined live bitumen ere ondu ted ith the same pro edures developed in the ase

of Brook eld oil.

C2H6 saturated bitumen

The re ombination e periments on bitumen rst started ith 2 6. The total bitumen sample volume in this ork as 13 ml. The vessel ontaining bitumen and 2 6 as rst

pla ed verti ally in the 3 air bath so that only diffusion o urred to the 2 6 dissolution into bitumen. The pressure hange during the diffusion stage as re orded and as

used for the e trapolation required to remove the tempera-ture effe t on the initial pressure reading Appendi B . As sho n in Fig. 2 the pressure de reases sharply

ithin the initial 4 minutes. This is mainly due to the sig-ni ant temperature hange after pressuri ed gas in e tion. After the rst 6 minutes the re orded pressure started to level out. The diffusion stage lasted for 13 minutes and the onve tion as introdu ed to the 2 6-bitumen system immediately after ards. The T2 response of 2 6 dissolved bitumen during the entire pressuri ation stage as measured as a fun tion of time and is displayed in Fig. 21. The e peri-mental pro edures are similar to those used in the Brook eld oil ase.

imilar to the observations in the ork on 2 6-Brook-eld oil the bimodal peak for the T2 distribution of bitumen

also appeared as the dissolution of 2 6 gradually pro eeded. The relatively small peaks at appro imately T2 2 se are the responses from the dissolved 2 6 inside the bitumen sample at the present pressure level. ere the sele tion of NMR parameters as the same as for the ork on Brook-

eld oil therefore the ontribution from 2 6 vapor to T2 is negligible. As sho n in Fig. 21 the dissolution of 2 6 in bitumen rea hed saturation after 3 hours. The measurements for both T2 and pressure ontinued for an e tra 121 hours there-after and no signi ant hanges ere observed. The T2 peak of 2 6 saturated bitumen is mu h broader than in the T2 distribution of 2 6-Brook eld oil. Further-more even after omplete saturation of 2 6 the bitumen

Fig. 20 2 6- bitumen during the diffusion stage.

515

520

525

530

535

0 20 40 60 80 100 120 140

Pres

sure

l (ps

ia)

Time (min)

Initial diffusion stage

Fig. 21 T2 2 6 during pressurization stage.

0.0

0.5

1.0

1.5

0.1 1 10 100 1000 10000

Am

plitu

de f


Dead Oil

23 hrs

120 hrs

141 hrs

213 hrs

308 hrs

391 hrs

429 hrs

Fig. 22 T2 2 6 saturated bitumen dur-ing depressurization stage.

330

350

370

390

1

10

0 20 40 60 80 100 120

Pressure (psia)

T 2of

bitu

men

(mse

c)

Time (Hour)

T2 Pressure

Peq = 370 psia

160

180

200

220

0.1

1

10

0 20 40 60 80

Pressure (psia)

T 2of

bitu

men

(mse

c)

Time (Hour)

T2 Pressure

Peq = 200 psia

60

80

100

120

0.1

1

10

0 20 40 60 80 100 120

Pressure (psia)

T 2of

bitu

men

(mse

c)

Time (Hour)

T2 Pressure

Peq = 106 psia

230

250

270

290

1

10

0 20 40 60 80 100

Pressure (psia)

T 2of

bitu

men

(mse

c)

Time (Hour)

T2 Pressure

Peq = 278 psia



still has a ertain amount of omponents rela ing faster than the rst applied e ho spa ing .2 ms . This is be ause the bitumen sample has mu h more omple omponents and even higher vis osity than syntheti Brook eld oil. After the bitumen as saturated ith 2 6 at 4 5 psia the depressuri ation as ondu ted by de reasing the pres-sure by 1 psi at a time till the pressure inside the vessel de reased to appro imately 1 psia. The measurements of pressure and T2 during the depressuri ation stage ere per-formed in the same ay as for the ork on the Brook eld oil. The re orded pressure and T2 for the 2 6 saturated bitu-men at different pressure levels are displayed in Fig. 22. The T2 values sho n in ea h plot are evaluated through regular

M data ithout spe i ed M and lognormal distribution model. [The mean value of T2 for ea h pressure as supple-mented ith F measurements ang et al. 2 . The T2distributions of 2 6 saturated bitumen from regular M data interpretations are displayed in Fig. 23. As rude oil the ma or bitumen T2 spe tra peaks are mu h broader than those of the syntheti Brook eld oil.

CO2 saturated bitumen

The gas-oil mi ing e periments for the 2 saturated bitumen ere ondu ted in the same ay as for the 2 6-bitumen. Due to sample loss during the previous measure-ments the total bitumen volume used in the 2-bitumen ase as .5 ml.

At the beginning of the mi ing e periment the pressure vessel as pla ed in the 3 air bath until no signi ant temperature-related pressure de ay as observed. n this manner enough pressure data as olle ted for e trapola-tion during the diffusion stage. After ards the onve tion

as introdu ed to the 2-bitumen system via ro king of the vessel as sho n in Fig. . The T2 distribution hanges of bitumen during the 2dissolution pro ess are sho n in Fig. 24. The number of s ans N as ad usted to rea h NR 1 . The applied

idth of 2 pulse and pulse ere tuned before ea h mea-surement. As sho n in Fig. 24 the 2 dissolved in bitumen rea hed equilibrium after 3 1 hours. Thereafter the gas dis-solution e periment ontinued for an e tra hours and no signi ant hange of either T2 distribution or pressure in the vapor phase as observed. quilibrium as on rmed at this point. After the bitumen sample as saturated ith 2 at psia the depressuri ation as ondu ted by de reasing the pressure by 15 psi at a time till the pressure inside the ves-sel de reased to appro imately 1 psia. The re orded pres-sure and T2 for the 2 saturated bitumen at different pres-sure levels are displayed in Fig. 25. The verti al dashed lines in the plot indi ate the time hen 2-bitumen rst rea hed equilibrium at ea h pressure. The T2 distributions of 2 saturated bitumen at differ-ent pressure levels are displayed in Fig. 26. All the distribu-tions sho n in the plot are from regular M data inter-pretations.

Fig. 23 T2 -ferent pressure levels.

0.0

0.5

1.0

1.5

0.1 1 10 100 1000 10000

Am

plit

ude f


Dead oil

106psia

200psia

278psia

370psia

475psia

Fig. 24 T2 2 during pressurization stage.

0.0

0.2

0.4

0.6

0.8

1.0

0.1 1 10 100 1000 1000

Am

plitu

de f


Dead Oil

21 hrs

97 hrs

174 hrs

284 hrs

391 hrs

470 hrs

00

Fig. 25 T2 -ing depressurization stage.

380

390

400

410

420

0.1

1

10

0 10 20 30 40 50

Pressure (psia)

T2

of b

itum

en (m

sec)

Time (Hour)

T2 Pressure

Peq = 414 psia

90

100

110

120

130

140

0.1

1

0 10 20 30 40 50 60 70

Pressure (psia)

T2

of b

itum

en (m

sec)

Time (Hour)

T2 Pressure

Peq = 120 psia

270

280

290

300

310

0.1

1

10

0 10 20 30 40 50 60 70

Pressure (psia)

T2

of b

itum

en (m

sec)

Time (Hour)

T2 Pressure

Peq = 300 psia

550

560

570

580

590

1

10

0 10 20 30 40 50 60

Pressure (psia)

T2

of b

itum

en (m

sec)

Time (Hour)

T2 Pressure

Peq = 583 psia

PETROPHYSICS32

Yang et al.

February 2012

The T1 distributions of the 2 saturated bitumen at the same equilibrated pressures ere also obtained and sho n in Fig. 2 . An inversion re overy sequen e ith 2 differ-ent re overy times logarithmi ally spa ed bet een 3 se and 5 se as employed for the measurements. The T1 dis-tributions for live bitumen at different pressure levels are displayed in Fig. 2 . The variations of T1 distribution ith pressure are mu h smaller than the T2 hange of live bitumen as sho n in Fig. 26. n other ords the hange of bitumen vis osity

aused by the hange of 2 solubility at different pres-sure has mu h more effe t on the T2 response than on T1. This observation mat hes the results obtained in previous

ork on other heavy oil samples irasaki et al. 2 3 .

CH4 saturated bitumen

The same e perimental pro edures for both diffusion and onve tion ere applied in the ase of 4-bitumen. The total sample volume used in measurements as .6 ml.

The T2 distributions measured during the 4 dissolu-tion pro ess are sho n in Fig. 2 as a fun tion of time. The number of s ans N as ad usted to rea h NR = 1 . The applied idth of 2 pulse and pulse ere tuned before ea h measurement. As sho n in Fig. 2 the T2 hanges aused by the dis-solved 4 are signi antly smaller than those observed

ith the other t o gases. 4 rea hed saturation in bitumen after 331 hours. The measurements ontinued for an e tra

hours thereafter and no signi ant hanges of T2 distribu-tion and pressure ere observed. As mentioned in the 4-Brook eld oil the smaller T2 peaks at appro imately 1 se are from the 4 vapor inside the vessel. Due to the mu h smaller solubility of 4 in bitumen the depressuri ation as only ondu ted at t o pressures Fig. 2 . The T2 distributions of 4 saturated bitumen at

different pressure levels are displayed in Fig. 3 . All the dis-tributions are from regular M data interpretations. The minor peaks bet een 1 ms and 1 ms are from free 4in the vapor phase. As the pressure de reases the gas peak moves to smaller T2 value and shrinks to smaller area.

Solubilities of three different gases in bitumen

The solubility of ea h gas in the bitumen as al ulated by using q. A.1 and q. A.2 . The relationship bet een

Fig. 26 T2 2 saturated bitumen at differ-ent pressure levels.

0.0

0.2

0.4

0.6

0.8

1.0

0.1 1 10 100 1000 10000

Am

plit

ude f


Dead oil

120 psia

300 psia

414 psia

583 psia

709 psia


0

0.2

0.4

0.6

0.8

1

0.1 1 10 100 1000 10000

Am

plit

ude f

T1 Relaxation Times (msec)

T1 at 709 psia

T1 at 583 psia

T1 at 414 psia

T1 at 300 psia

T1 at 120 psia

Fig. 28 T2 4 dur-ing pressurization stage.

0

0.2

0.4

0.6

0.8

1

0.1 1 10 100 1000 10000

Am

plit

ude f


Dead oil

19 hrs

141 hrs

263hrs

331hrs

428hrs

Fig. 29 T2 4 saturated bitumen dur-ing depressurization stage.

490

500

510

520

530

540

0.1

1

0 20 40 60 80

Pressure (psia)

T2of

bit

um

en (

mse

c)

Time (Hour)

T2 Pressure

Peq = 517 psia

110

120

130

140

150

0.1

1

0 20 40 60 80

Pressure (psia)

T2

of b

itum

en (m

sec)

Time (Hour)

T2 Pressure

Peq = 131 psia



gas on entration in bitumen and its orresponding equili-brated pressure is plotted in Fig. 31. enry s la is employed to t the pressure vs. gas on-entration data for all three gases. The t o solid lines are

the tted urves to the 2 6-bitumen and 4-bitumen data respe tively. The dashed line is the tting to the 2-bitu-men data. The tted fun tions are displayed in the plot. As sho n in Fig. 31 a the behaviors of the three gases in the bitumen are quite similar to those in Brook eld oil Fig. 1 .

2 6 and 4 losely follo enry s la hile 2 signi -antly deviates from it. The al ulated solubilities for 2 in

bitumen appear not to e trapolate to ero. The proposed e planation for this phenomenon has been dis ussed in the ork on Brook eld oil. The usti a-tion of the interpretation is sho n in Appendi . n order to orre t the overestimation for the al ulated 2 solubil-ity in bitumen e uniformly subtra t the e ess value at the inter ept of -a is from the originally al ulated solu-bility at ea h pressure and re-plot the orre ted 2 data in Fig. 31 b . t is lear that the orre ted 2 data follo s the

enry s la ell. The orre ted 2 data are also employed in the rela-tionship of live bitumen T2 and 2 solubility. As sho n in Fig. 32 a the originally al ulated data from 2-bitumen signi antly deviate from the dead oil values. o ever as the solubility of 2 as orre ted via the method sho n in Fig. 31 the data trend of T2 vs. orre ted solubility of

2 e trapolates ell to the dead bitumen value. The rela-tionship bet een live bitumen T2 and its orresponding gas solubility is losely linear on a semi-log s ale for all three gases. Furthermore similar to the observations in the ork on Brook eld oil the relationship bet een the live oil T2 and gas solubility sho n in Fig. 32 b appears to losely follo similar trend regardless of the gas type used for saturation.

Viscosity measurements on live bitumen

The vis osity of live bitumen ith different gases as measured using the same method as for Brook eld oil. The

vis osity measurements on the 2 6 saturated bitumen ere performed at three pressure levels. o ever due to the lim-ited volume of available bitumen sample the vis osity of live bitumen saturated by either 4 or 2 as only mea-sured at one pressure level. The results for live bitumen vis-osity ith three different gases are sho n in Fig. 33.

omparing Fig. 33 ith Fig. 1 e an nd that although the rude bitumen sample is totally different from syntheti Brook eld oil the live oil T2 still orrelates ith the vis osity temperature ratio on a log-log s ale regardless of the gas type used for saturation. As in the ase of Brook-

eld oil e observe that the hanges of T2 and vis ositytemperature ratio aused by solution gas follo the same trend as those aused by temperature variations on the dead bitumen. Data from other referen e papers inegar et al. 1 1

aTorra a et al. 1 M ann et al. 1 hang 2 2 are employed to ompare the bitumen and Brook eld oil data obtained in this ork and sho n in Fig. 34. ere the rela ation time and vis osity temperature ratio are normal-i ed ith respe t to 2 M ang et al. 2 irasaki et al. 2 3 .


0

0.2

0.4

0.6

0.8

1

0.1 1 10 100 1000 10000

Am

plitu

def


Dead oil

131 psia

517 psia

914 psia

Fig. 31 Relationship between the gas concentration in Bitu-

2 -2-Bitumen is corrected

Fig. 32 Relationship between the gas solubility in bitumen and its corresponding T2 2-bitumen

2-

PETROPHYSICS34

Yang et al.

February 2012

The bitumen data are highlighted in red hile the data from Brook eld oil are highlighted in blue. As sho n in Fig. 34 the T2 data from the syntheti Brook eld oil devi-ate from the rude oil data. o ever either T2 or T1 data obtained from the bitumen follo ell the trend of referen e data from other rude oils.

Relationship between pressure and live oil T2

The equilibrium pressure orrelates ell ith the live oil T2 of the t o heavy oils. t is found that the relationship bet een pressure and T2 is losely linear on a semi-log s ale for all three reservoir gases as sho n in Fig. 35. t is lear that 2 6 has the most signi ant in uen e on T2 hile 4e erts the least T2 hange at the same pressure level. More-over the data trends from any of the three gases e trapolate

ell to the dead oil T2 value indi ated by an .

CONCLUSIONS

The T2 of live oil is signi antly larger than the T2 of dead oil even at the lo est pressure level in this ork 1 psia . The relationships bet een equilibrium pressure and live oil T2 of both t o heavy oils are found to be losely linear on a semi-log s ale for all three reservoir gases. 2 6has the most signi ant in uen e on the T2 hile 4 e erts the least T2 hange at the same pressure level. The al ulated solubilities of both 4 and 2 6 in the t o different heavy oils follo enry s la ell. o ever the al ulation for 2 is signi antly overestimated. This may be due to a 2-ri h liquid phase here heavy-hydro-arbon omponents ould have formed inside the vessel at

the highest pressures. The relationship bet een al ulated gas solubility and the orresponding live oil T2 is found to be losely linear on a semi-log s ale for all three gases. With the orre tion by

enry s la in the ases of 2 the relationship bet een the live oil T2 and gas solubility appears to losely follo similar trend for ea h oil regardless of the gas type used for saturation. The hanges of T2 and vis osity temperature ratio aused by solution gas follo the same trend as those aused

by temperature variations on dead oil. Moreover this nding holds for both syntheti and rude oils. n this manner the vis osity of live heavy oil an be evaluated from the NMR response of dead oil ith the orrelation of T2 ith vis ositytemperature.

ACKNOWLEDGMENTS

The authors are grateful to hell ompany and the Ri e onsortium of ro esses in orous Media for their

nan ial support and gratefully a kno ledge arold in-egar for proposing this resear h.

Fig. 33 Relationship between the T2 of bitumen and the viscosity/temperature ratio.

0.01

0.1

1

10

1.E+00 1.E+01 1.E+02 1.E+03 1.E+04

T2

Rel

axat

ion

Tim

e (m

sec)


C2H6-Bitumenl

CO2-Bitumenl

CH4-Bitumen

Dead Bitumen at Different T

Fig. 34 Relationship between normalized T2 and nor-malized viscosity/temperature ratio for different oils.

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05

Nor

mal

ized

Rel

axat

ion

Tim

e (m

sec)

Normalized Viscosity/Temperature (cP/K)

T2[LaTorraca et al](2 MHz)

T1[LaTorraca et al](2 MHz)

T2[McCann et al](2MHz)

T1[McCann et al](2 MHz)

T2[Vinegar et al](2 MHz)

T1[Vinegar et al](80 MHz)

T2[Zhang et al](2 MHz)


T2[Zhang et al](7.5 MHz)

T1[Zhang et al](7.5 MHz)



Corr. by Morriss et al

Dipole-dipole Corr.

T2[Bitumen, Dead](2 MHz)

T2[Bitumen, Live](2 MHz)

T1[Bitumen, Live](2 MHz)

T2[Brookfield, Dead](2 MHz)

T2[Brookfield, Live](2 MHz)

T1

T2

Fig. 35corresponding live oil T2 for different gases.

y = 0.1369e0.0065x

R² = 0.9984y = 0.2064e0.0027x

R² = 0.9887

y = 0.2367e0.0006x

R² = 0.9775

0.1

1

10

0 200 400 600 800 1000

T2of

Liv

e B

itum

en (m

sec)

Pressure (psia)

CO2-Bitumen

CH4-Bitumen

C2H6-Bitumeny = 0.43e0.0071x

R² = 0.9967 y = 0.40e0.0032x

R² = 0.9998

y = 0.36e0.0008x

R² = 1

0.1

1

10

100

0 200 400 600 800 1000

T2

of L

ive

Bro

okfi

eld

Oil

(mse

c)

Pressure (psia)

CO2-Oil

CH4-Oil

C2H6-Oil



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Deleersnyder M. 2 4 n- itu heavy-oils vis osity determinationusing NMR and onventional logs appli ation to a real e am-ple aper 6 3 o iety of etroleum ngineers presented at the nternational Thermal perations and eavy il ym-posium and Western Regional Meeting Bakers eld alifornia Mar h 16 1 .

ni k R. older . D. and Morsi B. . 1 5 riti al and threephase behavior in the arbon dio ide tride ane system Fluid Phase Equilibria vol. 22 no. 2 p. 2 224.augen . B. and Firoo abadi A. 2 Mi ing of t o binarynon-equilibrium phases in one dimension AIChE Journal vol. 55 no. p. 1 3 1 36.irasaki . . o . W. and hang . 2 3 NMR propertiesof petroleum reservoir uids Magnectic Resonance Imaging vol. 21 no. 3 4 p. 26 2 .

A 1 3 International Thermodynamic Tables of theFluid State Carbon Dioxide ergamon ress ondon .

aTorra a . A. Dunn . . Webber . R. and arlson R. M.1 o -Field NMR determinations of the properties of heavy oils and ater-in-oil emulsions Magnetic Resonance Imaging vol. 16 no. 5 p. 65 662.

o . irasaki . . ouse W. . and obayashi R. 2 2 Mi ing rules and orrelations of NMR rela ation time ith vis osity diffusivity and gas oil ratio of methane hydro arbon mi tures SPE Journal vol. no. 1 p. 24 34.

M ann . . inegar A. and irasaki . . 1 NMR analysisof rude oil and pure hydro arbon uids private ommuni a-tion .

Morriss . . Freedman R. traley . ohnston M. inegar . . and Tutun ian . N. 1 ydro arbon saturation and

vis osity estimation from NMR logging in the Belridge Diato-mite The Log Analyst vol. 3 no. 2 p. 44 5 .

NB 1 6 The thermophysi al properties of ethane from to6 at pressures to bar NB Te hni al Note 6 4 Boulder

olorado.NB 1 4 The thermophysi al properties of methane from to

5 at pressures to bar NB Te hni al Note 653 Boulder olorado.

rr F. M. r. u A. D. and ien . . 1 1 hase behavior of2 and rude oil in lo -temperature reservoirs SPE Journal

4 4 2.yegh . . Rao D. N. okal . and Na man . 1 hase beha-viour and physi al properties of indbergh heavy oil 2 mi -tures Journal of Canadian Petroleum Technology vol. 2 no. 6 p. 31 3 .preti . R. and Mehrotra A. . 2 2 Diffusivity of 2 4

2 6 and N2 in Athabas a Bitumen Canadian Journal of Chemical Engineering vol. p. 116 125.inegar . . Tutun ian . N. delstein W. A. and Roemer . B.1 1 Whole ore analysis by 13 NMR SPE Formation Evalu-ation vol. 6 no. 2 p. 1 3 1 .ang . and irasaki . . 2 NMR measurement of bitumenat different temperatures Journal of Magnetic Resonance vol. 1 2 no. 2 p. 2 2 3.

hang . o . W. uang . . irasaki . . obayashi R.and ouse W. . 1 ome eptions to Default NMR Ro k and Fluid roperties aper FF in 3 th Annual ogging

ymposium Transa tions o iety of etrophysi ists and Well og Analysts.

hang . 2 2 Ri e niversity ouston hD Thesis.hang . yndman . and Maini B. 2 Measurement ofgas diffusivity in heavy oils Journal of Petroleum Science and Engineering vol. 25 p. 3 4 .

APPENDIX A

Gas solubility calculation

The method for al ulating gas solubility from pressure data is des ribed as follo s

Pressurization stage

After pressuri ation the pressure inside the losed sys-tem de reases due to the dissolution of gas into the oil. n this stage a ording to mass balan e the gas amount removed from the vapor phase equals the gas amount transferred into the oil phase. n this manner the gas solubility sg in the oil an be al ulated by the follo ing equation

ere Vg is the volume of vapor phase inside the pressure vessel and Voil is the volume of oil sample inside the pres-sure vessel. Assuming the s elling effe t of oil in this ork is negligible both Vg and Voil are onstant. P is the start-ing pressure and Peq is the pressure at equilibrium. z is the ompressibility under the starting pressure P and zeq is the ompressibility under the equilibrium pressure Peq.

Depressurization stage

After ea h depressuri ation the pressure inside the losed system in reases due to the release of dissolved gas

from inside the oil into the gas vapor. n this stage a ording to mass balan e the gas amount transferred into the vapor phase after ea h depressuri ation equals the gas amount removed from the oil phase. n this manner the gas solubil-ity sg in the oil an be al ulated by the follo ing equation

ere sg i is the solubility at urrent pressure level sg i 1 is the solubility at previous pressure level right before the depres-suri ation Vg is the volume of vapor phase inside the pres-sure vessel and Voil is the volume of oil sample inside the pressure vessel. Assuming the s elling effe t of oil in this

ork is negligible both Vg and Voil are onstant. P is the

sg =P0 Vg

z0 R TPeq Vg

zeq R TVoil . A.1

sg , i = sg , i 1

Peq Vg

zeq R TP0 Vg

z0 R TVoil . A.2

PETROPHYSICS36

Yang et al.

February 2012

starting pressure and Peq is the pressure at equilibrium. z is the ompressibility under the starting pressure P and zeq is the ompressibility under the equilibrium pressure Peq.

APPENDIX B

Extrapolation for initial pressure

At the beginning of ea h pressuri ation or depressuri a-tion a big pressure hange inside the pressure vessel ithin a relatively short time inevitably o urs. onsequently the system is temporarily either heated by the pressuri ation or ooled by the depressuri ation and then return to the tem-

perature of the air bath 3 . n this manner signi ant pressure u tuation is aused by the temperature hange and displays non-realisti P for solubility al ulations. There-fore the removal of the temperature in uen e on pressure reading at the start of ea h pressure level is ne essary. n this ork e trapolation as employed to make the orre -tion. The ase of 2 6-Brook eld oil is taken to illustrate the e trapolation for the pressure data during the initial period of either pressuri ation or depressuri ation stage. Fig. B.1 sho s the analysis and e trapolation of re orded pressure data for the pressuri ation stage of 2 6-Brook eld oil. The re orded data ithin the initial period hi h ere onsidered to be signi antly in uen ed by temperature hange are sho n by open triangles. The pressure data after

this initial period are displayed by open re tangles and used for e trapolation. The tted fun tion for e trapolation is also displayed in Fig. B.1. imilar analysis and e trapolation ere also performed on the pressure data re orded in the stage of depressuri a-tion and sho n in Fig. B.2. The e trapolation is sho n ith a solid line and the e trapolated value at ea h pressure level is highlighted ith a red solid dot in ea h subplot. The tted fun tions and the orresponding R2 values are also displayed. t is learly sho n that ith the additional effe t of temperature rise-up after ea h rapid depressuri ation the

pressure ithin the initial period open triangles in reases signi antly faster than those thereafter open re tangles .

APPENDIX C

z Factor of CO2 at 30°C with the adjustment to match Henry’s Law

The gas solubility is al ulated via an equation of state ith ompressibility fa tor z as sho n in Appendi A. n

order to remove the overestimation of 2 solubility the ompressibility fa tor z as re-ad usted to orre t the pres-

sure vs. solubility urve of 2 to mat h enry s la Fig. 1 . The solubility al ulation method during the pres-

suri ation stage is e pressed by q. A.1 . The ad ustment on z fa tor an be made on either z initial point or zeqequilibrium point .

The ad ustment on z at the initial pressure as rst per-formed and the re-evaluated value is indi ated as z in Fig.

.1. n order to orre t the al ulated solubility by hang-ing the z fa tor at the initial pressure the re-evaluated value needs to move up to a value of . 3. This value is very unlikely for the ompressibility fa tor of 2 at 3 psia. The ad ustment on ze at the equilibrium pressure sho s that in order to orre t the al ulated solubility to mat h

enry s la the orre ted z fa tor value needs to move do n to a value of .51 indi ated as ze in Fig. .1 at psia. As e dis ussed in the previous paragraphs the pro-posed e planation to the deviation of 2 data from enry s la is the oe isten e of a 2-ri h liquid phase ith the

2 vapor and oil phase. Therefore the estimated value of ze is ontributed by both ze v (z fa tor for 2 vapor phase

Fig. B.12 6

y = -0.3244x + 540.5R² = 0.9951

520

530

540

550

560

0 5 10 15 20 25

Pre

ssur

e (p

sia)

Time (Hour)

Fig. B.22 6

y = 2.2414x + 155.5R² = 0.9955

150

160

170

0 1 2 3 4 5 6

Pre

ssur

e (p

sia)

Time (Hour)

Peq = 189 psia

y = 1.6257x + 78.9R² = 0.9514

70

80

90

0 1 2 3 4 5 6

Pre

ssur

e (p

sia)

Time (Hour)

Peq = 106 psia

y = 1.6301x + 267.2R² = 0.9608

250

260

270

280

290

0 5 10 15 20

Pre

ssur

e (p

sia)

Time (Hour)

Peq = 287 psia

y = 1.3881x + 374.9R² = 0.9257

350

360

370

380

390

400

0 5 10 15 20

Pre

ssur

e (p

sia)

Time (Hour)

Peq = 393 psia

*

*

*



and ze l (z fa tor for 2-ri h liquid phase . As sho n in Fig. .1 the e trapolated value of ze l at psia is highlighted

by a red asterisk hile ze v is indi ated by a bla k asterisk. ze an be al ulated by q. ( .1 and ( .2 .

ere

The sum of mole fra tion of 2 in non-oil phase is onsid-ered as 1.

iven the values for all three z fa tors sho n in q. ( .1 and ombining q. ( .1 and q. ( .2 the mole fra tion of

2 in vapor phase and 2 in 2-ri h liquid phase an be al ulated. The al ulated mole fra tion of 2 in vapor phase is .5 orrespondingly the mole fra tion in 2-ri h liquid phase is .42. ere on the basis of available data in the referen e book ( A 1 3 the estimated density for 2 vapor is .1431 g ml and the density for 2-ri h liquid is .5421 g ml. n this manner the volume fra tion of 2 in either vapor phase or 2-ri h liquid phase is al ulated to be . 4 and .16 respe tively.

In Bitumen 1 -1

The gas solubility is al ulated via an equation of state ith ompressibility fa tor z as sho n in Appendi A. n

order to remove the overestimation of 2 solubility the ompressibility fa tor z as re-ad usted to orre t the pres-

sure vs. solubility urve of 2 to mat h the enry s la (Fig. 31 . The solubility al ulation method during pressur-i ation stage is e pressed by q. (A.1 . The ad ustment on zfa tor an be made on either z (initial point or zeq (equilib-rium point to serve the purpose. Ad usting z at the initial pressure to follo enry s la gives the re-evaluated value z (as sho n in Fig. .2 to be

. 6. This value is very unlikely for the ompressibility fa -tor of 2 at 45 psia. The ad ustment on ze sho s that in order to orre t the al ulated solubility to follo enry s la the orre ted z

fa tor value needs to move do n to a value of .55 (indi-ated as ze in Fig. .2 at psia.

As e dis ussed in the se tion n Brook eld il the estimated value of ze is ontributed by both ze v (z fa tor for

2 vapor phase and ze l (z fa tor for 2-ri h liquid phase . As sho n in Fig. .2 the e trapolated value of ze l at psia is highlighted by a red asterisk hile ze v is indi ated by a bla k asterisk. iven the values for all three z fa tors sho n in q. ( .1 and ombining q. ( .1 and q. ( .2 the mole fra -tion of 2 in vapor phase and 2 in 2-ri h liquid phase an be al ulated. The al ulated mole fra tion of 2 in

vapor phase is .54 and the mole fra tion in 2-ri h liquid phase is .46. n this ase based on the available data in the referen e book ( A 1 3 the estimated density for 2 vapor is .1223 g ml and the density for 2-ri h liquid is .45 6 g ml. n this manner the volume fra tion of 2 in either vapor phase or 2-ri h liquid phase is al ulated to be . 2 and .1 respe tively. These values are lose to the al ula-tions in the ase of 2-Brook eld oil.

Fig. C.1 Analysis of compressibility factor z 2 for 2

Fig. C.2 Analysis of compressibility factor z 2 for 2 in bitumen #10-

*

ze = ze, v xv + ze, l xl ( .1

xv mole fra tion of 2 in vapor phasexl mole fra tion of 2 in 2-ri h liquid phase

xv + xl = 1 ( .2

*

*

*

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