Research on Asphaltene Deposition During the Process of CO 2 Flooding Huang Lei 1 Shen Pingping 1...

Research on Asphaltene Deposition During the Process of CO2 Flooding

Huang Lei1 Shen Pingping1 Jia Ying2 Li Shi1

1.State Key Laboratory of EOR (Research institute of Petroleum Exploration and Development,Petrochina) 2.Exploration and Production R

esearch Institute, Sinopec

For IEA EOR MeetingCNPC

1 、 Research Background

2 、 Asphaltene Precipitation Experiment study for CO2 Injecti

on

3 、 Asphaltene Precipitation Model for CO2 Injection Process

4 、 Compositional simulator Considering Asphaltene Deposit

ion

5 、 Conclusion

contentCNPC

Asphaltene deposition in the well hole

Asphaltene deposition in the pipe line

Research BackgroundCNPC

Asphaltene Precipitation:

Asphaltene component to be s

eperated from oil and get togeth

er to form another phase differen

t from oil phase

Asphaltene deposition:

the process of precipitated as

phaltene settling onto the surfac

e of porous media

Two Basic Concept

AsphalteneResinsaromatic

sAlkanesCO2

CO2 Injection

Asphaltene Precipitation

Asphaltene Deposition

Research BackgroundCNPC


2 、 Asphaltene Precipitation Experiment study for CO2 Injecti

on

3 、 Asphaltene Precipitation Model for CO2 Injection Process

4 、 Compositional simulator Considering Asphaltene Deposit

ion

5 、 Conclusion

contentCNPC

The Basic Properties and Composition of Experiment OilSampling

Separator Sampling

Reservoir Pressure （ MPa ） 32

Reservoir Temperatue（℃） 110

Bubble Point （ MPa ） 4

DOR （ m3/m3 ） 12.9

FVF 1.088

Density@Pr,Tr (g/cm3) 0.8219

Viscosity@Pr,Tr(mPa.s) 7.02

Dead Oil Density (g/cm3) 0.886

CO2 0.34

C1+N2 11.26

C2 ～ C10 23.43

C11+ 64.97

Wax of Dead oil ( ％ ) 24.69

Asphaltene of Dead oil ( ％ ) 16.79

Evaluation Representative

Asphaltene Precipitation Experiment study for CO2 InjectionCNPC

1

2 3

45

6

7

8

9

10

注：1.恒速驱替泵；2.地层油容器；3. CO2气容器；4.恒温箱；5.激光检测系统；

6.样品筒活塞；7.样品；8.激光发射器；9.激光接收器；10.电磁搅拌系统。

Equipment for Precipitation Onset Point Measure


Equipment for Precipitate quantity measure

13

11

12

1514

4 6

CBA

P3

P5 Õæ

P4

31

600 ml 1000ml

CO2

1000ml

N2

Æø

Ñù

Æ¿

Ôö

Ñ¹

»ú

È¡ÑùÏµÍ³

CO2

P1

D

E

5

P2

2

16

9

107

8

注： 1-3. 手动高压泵 4-16. 高压阀门 P1-P5. 压力表A. 主平衡釜 B. 副釜 C. 转样釜 D. 空气恒温浴 E. 石油醚洗瓶


4. 0E- 12

4. 2E- 12

4. 4E- 12

4. 6E- 12

4. 8E- 12

5. 0E- 12

5. 2E- 12

5. 4E- 12

0. 0 0. 1 0. 2 0. 3 0. 4 0. 5 0. 6 0. 7CO注入 2在原油中的摩尔分数

PT

L ,

w

出现气相

onset

20.0MPa4. 4E- 12

4. 6E- 12

4. 8E- 12

5. 0E- 12

5. 2E- 12

5. 4E- 12

5. 6E- 12

5. 8E- 12

0. 0 0. 1 0. 2 0. 3 0. 4 0. 5 0. 6 0. 7CO注入 2在原油中的摩尔分数

PT

L ,

w

出现气相

onset

26.0MPa4. 4E- 12

4. 6E- 12

4. 8E- 12

5. 0E- 12

5. 2E- 12

5. 4E- 12

5. 6E- 12

5. 8E- 12

0. 0 0. 1 0. 2 0. 3 0. 4 0. 5 0. 6 0. 7CO注入 2在原油中的摩尔分数

PT

L ,

w

出现气相

onset

20.0MPa 23.0MPa 26.0MPa

4. 4E- 12

4. 6E- 12

4. 8E- 12

5. 0E- 12

5. 2E- 12

5. 4E- 12

5. 6E- 12

5. 8E- 12

0. 0 0. 1 0. 2 0. 3 0. 4 0. 5 0. 6 0. 7 0. 8CO注入 2在原油中的摩尔分数

PT

L ,

w

出现气相

onset

29.0MPa5. 4E- 12

5. 6E- 12

5. 8E- 12

6. 0E- 12

6. 2E- 12

6. 4E- 12

6. 6E- 12

0. 0 0. 1 0. 2 0. 3 0. 4 0. 5 0. 6 0. 7 0. 8CO注入 2在原油中的摩尔分数

PT

L ,

w

出现气相

onset

32.0MPa5. 2E- 12

5. 4E- 12

5. 6E- 12

5. 8E- 12

6. 0E- 12

6. 2E- 12

6. 4E- 12

0. 0 0. 1 0. 2 0. 3 0. 4 0. 5 0. 6 0. 7 0. 8CO注入 2在原油中的摩尔分数

PT

L ,

w出现气相

onset

35.0MPa

29.0MPa 35.0MPa32.0MPa

CNPC

PLT response of asphaltene Precipitation process

Asphaltene Precipitation Experiment study for CO2 Injection

injection pressure

MPa

CO2

content@onset

mol%

CO2 content

@vapering

mol%

Asphaltene in oil wt%

Asphaltene Precipitation

wt%

noCO2 16.79 0

23.00 0.27 0.60 11.32 5.47

26.00 0.30 0.64 10.31 6.48

29.00 0.33 0.68 9.85 6.94

32.00 0.36 0.71 9.52 7.27

35.00 0.39 0.73 9.13 7.66

Result of Asphaltene Precipitation Experiment

0

10

20

30

40

50

60

70

0 0. 2 0. 4 0. 6 0. 8 1

CO2 , mol %摩尔分数

MPa

压力，

临界点

沥青质沉淀初始点实验值

饱和压力实验值

饱和压力线

沥青质沉淀初始线

Onset line

saturation line

Critical point

CNPC

Asphaltene Precipitation Experiment study for CO2 Injection


2 、 Asphaltene Precipitation Experiment study for CO2 Injec

tion

3 、 Asphaltene Precipitation Model for CO2 Injection Proce

ss

4 、 Compositional simulator Considering Asphaltene Depo

sition and its Application

5 、 Conclusion

contentCNPC

Presumption

Because precipitated asphaltene is composed of heavy polarity an

d non-ideality molecules, which is solid-like precipitated liquid with

strong viscosity under reservoir condition. Thus, equation of state i

ncorporating association （ AEOS ） is used to describe the phas

e behavior of asphaltene

Ignoring resin component ， Precipitated Asphaltene is composed

of asphaltene component

asphaltene component do not behave association in oil phase

During the process of asphaltene precipitation, no crystal formed

Asphaltene Precipitation Model for CO2 Injection ProcessCNPC

Because precipitated asphaltene is composed of heavy polarity

and non-ideality molecules, the compress factor of association

compound established by Anderko is introduced to describe the

non-ideality of precipitated asphaltene

where1 phch ZZZ

2

1 1 4 /ch

aa

ZRTK V

Compressible factor of Asphaltene


1 2

ln ( 1) ln( 1) ln2 2 1 2

ph

ch ph ch ph

ph

Z BAZ Z Z Z

B Z B

1 2ln ( , , , ) ( , , )ch chZ V T B Z V T

Fugacity Calculation for Asphaltene Phase


where

0 1Vn

0 1Sn

0 1S Vn n

1

1

10

1 1

1

1 1

VLNi i

S VL Vi i

SN

LS S VL VN N

K z

n K n

z n

K n K n

Vapor/liquid/Asphaltene equilibrium model:


Judgement of asphaltene precipitation is as follows:

if ， asphaltene would precipitate ；

if ， asphaltene would not precipitate ；

if ， asphaltene begin to precipitate 。

Where is content of heavy components in oil.

ln lnNo sf f

ln lnNo sf f

ln lnNo sf f

Nof

Phase stability analysis of precipitated asphaltene:


Regression Result for Asphaltene Pricipitation onset point

Asphaltene Precipitation Model for CO2 Injection Process

0

20

40

60

80

100

120

0 0. 1 0. 2 0. 3 0. 4 0. 5 0. 6 0. 7 0. 8 0. 9 1

CO2 , %摩尔百分含量

MPa

压力，

计算饱和压力线

临界点

沥青质沉淀初始点计算值

沥青质沉淀消失点计算值

沥青质沉淀初始点实验值

饱和压力实验值

CO2,mole%

cal.Pb point

cal.onset line

cal.disappearance line

expl.onset line

exp.Pb line

critical point

CNPC

When injection pressure is constant, precipitated asphaltene increases with the increase of injected C

O2 before CO2-oil system reaches saturation. Precipitated asphaltene reaches maximum at saturation

state, and then precipitated asphaltene decreases with the increase of injected CO2

When the CO2 mole percents of CO2-oil system are constant, precipitated asphaltene reaches maxi

mum at saturation pressure.

The higher system pressure, the more maximum quantities of precipitated asphaltene

Asphaltene Precipitation Model for CO2 Injection Process

0. 0

1. 0

2. 0

3. 0

4. 0

5. 0

6. 0

7. 0

8. 0

9. 0

20 30 40 50 60 70 80 90

CO2 %摩尔百分数，

wt沥青质沉淀量，

％

23MPa 31MPa

26MPa 29MPa

35MPa 37MPa

0

1

2

3

4

5

6

7

8

0 10 20 30 40 50 60压力，MPa

沥青质沉淀量，

wt％

0

10

20

30

40

50

60

70

气相摩尔百分数，％

0. 6CO2沥青质沉淀量0. 64CO2沥青质沉淀量

0. 68CO2沥青质沉淀量0. 71CO2沥青质沉淀量0. 73CO2沥青质沉淀量0. 6CO2气相摩尔分数

0. 64CO2气相摩尔分数0. 68CO2气相摩尔分数0. 71CO2气相摩尔分数

0. 73CO2气相摩尔分数

the relationship between asphaltene precipitation and CO2 mole percent at fixed pressure

the relationship between asphaltene precipitation, gas phase mole percent and pressure at varied CO2 mole percent

Asp

ha

lten

e P

recip

itatio

n,w

t%

Ga

s mo

le%

Asp

ha

lten

e P

recip

itatio

n,w

t%

CO2,mole% pressure,MPa

CNPC


2 、 Asphaltene Precipitation Experiment study for CO2 Inject

ion

3 、 Asphaltene Precipitation Model for CO2 Injection Proces

s

4 、 Compositional simulator Considering Asphaltene Depos

ition

5 、 Conclusion

contentCNPC

0 ,

,c

isfsf o c

i ny

N N i n

1

0fn

w wrww w wk

kw

Skkq

t

where ，

Conservation Equation for Component i

1

( ) 0f

j ij jnjrj

j ij isf j i ik ijj k jj

y Skk

y y q yt

0

o g srgroo o g g t

o g

N N Nkkkkq

t

Compositional simulator Considering Asphaltene Deposition

Conservation Equation for Water

Conservation Equation for Oil and Gas

CNPC

Precipitated Asphaltnene is made of three parts ： deposit onto the p

orous media surface through adsorption ； deposit through mecha

nical entrapment ； suspended in the oil phase

adoption by unit rock volume

surface adsorption by unit rock mass follows a Langmuir isotherm ：

saN

sfN

s sa se sfN N N N

s

saRsa

~1

M

WN

＝

,max

1sa a sf

saa sf

W K CW

K C

oo

ssf6

sf

10

MN

MNC ＝

mechanical entrapment ： 0sf

ses

ˆ m

CN

v

＝

seN

suspended content in oil phase ：

CNPC


Plugging Equations

0 0 0

ˆ 11 1 exp 1 1

exp -1

K E KE G

K G K

＝

ssesaˆ uNN ＋－＝

Using following equations established by Cernansky

&Siroky （ 1985 ） to describe plugging process

CNPC


Sequnia

l

Core length(c

m)

Perm

( mD )

Soi( ％ ) Pex(MPa)

dp(MPa)

Injection

PV

Exp. Re

(%)

New method

Cal. Re

(%)

Conventional methed

Cal. Re

(%)

1 43.16 8.92 0.5494 19 5 3.31 59.76 58.47 63.28

2 42.85 8.91 0.5527 24 6.4 3.11 64.38 64.12 67.85

3 45.82 8.69 0.5561 29 8 3.11 78.07 80.13 82.77

4 43.16 8.92 0.5524 34 10 2.88 79.24 82.04 84.32

2m

Recovery factor matching for core flooding

CNPC


Asphaltene deposition front is consistent with gas front, which indicate

s that CO2 injection lead to asphaltene pricipitate

0

0. 1

0. 2

0. 3

0. 4

0. 5

0. 6

0. 7

0. 8

0. 9

0 2 4 6 8 10 12 14 16 18 20网格块

g沉积沥青质质量，

0

10

20

30

40

50

60

%饱和度，

沥青质沉积量

气体饱和度

0

0. 1

0. 2

0. 3

0. 4

0. 5

0. 6

0. 7

0. 8

0. 9

0 2 4 6 8 10 12 14 16 18 20网格块


0

10

20

30

40

50

60

%饱和度，

沥青质沉积量

气体饱和度

0

0. 1

0. 2

0. 3

0. 4

0. 5

0. 6

0. 7

0. 8

0. 9

0 2 4 6 8 10 12 14 16 18 20网格块


0

10

20

30

40

50

60

%饱和度。

沥青质沉积量

气体饱和度

0

0. 1

0. 2

0. 3

0. 4

0. 5

0. 6

0. 7

0. 8

0. 9

0 2 4 6 8 10 12 14 16 18 20网格块

kg沉积沥青质质量，

0

10

20

30

40

50

60

70

%饱和度，

沥青质沉积量

气体饱和度

0.1HCPV0.2HCPV

0.3HCPV 0.4HCPV

CNPC


0

5

10

15

20

0 0. 2 0. 4 0. 6 0. 8 1 1. 2 1. 4 1. 6

PV, d

,g沉积沥青质质量

25MPa

29. 4MPa35MPa

As pressure rises ， more asphaltene deposition lefted in core.

CNPC



2 、 Asphaltene Precipitation Experiment study for CO2 Injec

tion

3 、 Asphaltene Precipitation Model for CO2 Injection Proces

s

4 、 Compositional simulator Considering Asphaltene Depo

sition

5 、 Conclusion

contentCNPC

AEOS can describe Asphaltene Precipitation behavior.

For a fixed pressure system, precipitated asphaltene increases

with the increase of injected CO2 before system reaches satura

tion, then precipitated asphaltene decreases with the increase.

When system composition is fixed, precipitated asphaltene rea

ch its climax near saturation pressure.

Asphaltene Precipitation should be considered in CO2 injection

process of high Asphaltene content oil.

Asphaltene deposition front is consistent with CO2 front.

As pressure rises ， more asphaltene deposition lefted in core.

ConclusionCNPC

Research on Asphaltene Deposition During the Process of CO 2 Flooding Huang Lei 1 Shen Pingping 1...

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