Application and Challenge of Flow Improver for the Development of
Heavy Oil and Waxy Crude
Fusheng Zhang
1,2*
, Baoshan Guan
1,2
, Guoliang Liu
1,2
, Xuening Li
1,2
, Zhuoyan Zhu
1,2
and Huimin Su
1,2
1
Research Institute of Petroleum Exploration and Development, PetroChina, No.20 Xueyuan Road, Beijing 100083, China
2
Key Laboratory of Oilfield Chemistry, CNPC, No. 20 Xueyuan Road, Beijing 100083, China
Keywords: Heavy oil, Waxy crude, Development , Flow improver, Application
Abstract: This paper outlined the composition of some flow improvers and their applications in long-distance pipeline
transportation in China, thereafter compared the effectiveness of using oil-based and water-based viscosity
reducers in both low-viscosity and high-viscosity heavy oil wells in China. At the end, this paper summarized
challenge in the research of viscosity reducer for the heavy oil formation drive.
1 INTRODUCTION
Generally speaking, the production of crude oil has
three stages: formation drive, wellbore lifting and
pipeline transportation. According to its viscosity,
crude oil can be classified as conventional oil, heavy
oil, extra heavy oil and bitumen (Li et al., 1990).
The conventional crude oil in China normally
features high wax content (Wang,1995), high pour
point and viscosity, and poor flow. Because of high
resin and asphaltene content, heavy oil, extra heavy
oil and bitumen generally have even higher viscosity
and poorer flow. In order to improve the flow of
crude oil meanwhile ensure safety in production,
heating is commonly used in the production of heavy
oil. Flow improvers are generally believed to have
the potential to greatly improve the flow of crude oil;
furthermore, they could be far more energy-efficient
and economic.
After years of arduous work, Scientists
worldwide have made great progress in the research
of flow improvers (Barasha et al., 2018; Pranab and
Moumita, 2014; Hafiz and Khidr, 2007; Zhang et al.,
2014; Khidr, 2011; Deshmukh and Bharambe, 2009;
Nassar, 2008; Du et al., 2012; Ahmed et al., 2014), a
series of which were developed and proved to be
suitable for the pipeline transportation and wellbore
lift of crude oil. Flow improvers have been widely
used in pipelines and wellbores (Bai et al., 2016; Qin
et al., 2012; Luo et al., 2015; Liu et al., 2017; Jiang et
al., 2013; Ma et al., 2017), and moreover brought
forth substantial economic and social benefits.
In reservoir conditions, for conventional crude oil,
its flow is generally good, which poses little problem
to formation drive, water flooding is used. In
comparison, for heavy oil, extra heavy oil and
bitumen, because its flow is poor, thermal technology
is mainly used to solve the difficulties of formation
drive. For normal heavy oil, water flooding is used,
but the oil recovery of water flooding is only 5-25%,
the main reasons is the higher viscosity of normal
heavy oil, so the study of viscosity reducer for
normal heavy oil has great significance to improve
oil recovery of its water flooding.
2 APPLICATION OF FLOW
IMPROVER IN CRUDE OIL
PIPELINE
To combat flow loss in pipeline transportation, for
conventional crude oil, heating combined with flow
improvers are commonly used; while for heavy oil,
extra heavy oil and bitumen, heating is commonly
used.
2.1 Composition of China's Crude Oil
Transported by Some Pipelines
China's onshore oil pipeline has a total length of over
23,400 kilometers (Zhang, 2016). Pipelines are the
main means of transportation for crude oil,
accounting for over 80%. For some major oil
Zhang, F., Guan, B., Liu, G., Li, X., Zhu, Z. and Su, H.
Application and Challenge of Flow Improver for the Development of Heavy Oil and Waxy Crude.
DOI: 10.5220/0008185900770082
In The Second International Conference on Materials Chemistry and Environmental Protection (MEEP 2018), pages 77-82
ISBN: 978-989-758-360-5
Copyright
c
 2019 by SCITEPRESS – Science and Technology Publications, Lda. All rights reserved
77

pipelines of China, crude oil has high wax, resin and
asphaltene content, which brings about great
challenges for pipeline transportation (Table 1).
2.2 Application Results in Crude Oil
Pipeline
Based on studies of pour point depressing
mechanisms (Zhang and Wang, 1995), flow
improvers (Zhang et al., 1999a; Zhang et al., 1999b;
Cao and Li, 2004; Li et al., 1989; Wang, 2013; Li,
2010; Dang et al., 1996; Bi, 1992) was developed and
has demonstrated good adaptability and modification
results for crude oil transported by some pipelines
such as Luning, Zhongluo and Pulin et al. in China
(Table 2).
Table 2 shows that flow improvers produced
good pour point depression and viscosity reduction
results. With treatment of 10-100mg/kg, pour point
dropped 12℃-23℃, and viscosity dropped 16%-98%.
Through its applications in the pipelines, we have
seen great savings in fuels and transportation costs,
and moreover significant economic and social
benefits. On the other hand, operational safety and
adaptability of pipeline transportation have been
improved.
Table1: Some pipeline parameters and composition of transported crude oil in China.
Pipeline
Pipeline length
/km
Design throughput
/10
4
ton/y
Wax
/%
Resin and asphaltene
/%
Luning
652.6
2000
20.60
23.70
Zhongluo
290.1
500
24.59
6.81
Pulin
241.9
350
21.40
8.00
Weijing
226.4
350
30.80
9.90
Donghuang
251.1
1000
18.30
21.60
Donglin
171.3
1000
19.10
20.80
Mahuining
270.0
470
17.90
20.10
Huage
438.8
300
22.60
11.80
Kushan
476.0
1000
8.84
6.47
Dongxin
93.0
540
19.60
21.50
Hongjing
210.1
350
14.80
13.27
Table 2: Effect of flow improvers on some pipeline's crude oils in China
Pipeline
Dosage
/mg/kg
Pour point /℃
Pour point
reduction
/℃
Viscosity(30℃) /mPa.s
Viscosity
reduction
/%
Before
treatment
After
treatment
Before
treatment
After
treatment
Luning
40
24
5
19
935
300
68
Zhongluo
50
33
13
20
1172
60
95
Pulin
50
33
15
18
763
19
98
Weijing
50
37
23
14
1720
119
93
Donghuang
50
17
4
13
396
334
16
Donglin
50
23
3
20
408
314
23
Mahuining
100
18
-5
23
1716
①
41
①
97
Huage
100
33
15
18
2365
②
256
②
89
Kushan
11
1
-11
12
293
③
32
③
89
Dongxin
10
27
10
17
2418
④
476
④
80
Hongjing
50
33
22
11
192
⑤
48
⑤
75
Note: ①8℃; ②20℃; ③2℃; ④20℃; ⑤35℃
MEEP 2018 - The Second International Conference on Materials Chemistry and Environmental Protection
78

3 APPLICATION OF VISCOSITY
REDUCERS IN HEAVY OIL
WELLBORE LIFTING
According to the characteristics of heavy oil in China
and based on studies of viscosity reduction
mechanisms (Zhang and Wang,1995), both oil-based
and water-based viscosity reducers were developed
and used in the wellbore lifting of heavy oil (Zhang et
al.,1999c).
3.1 The Application of Oil-based
Viscosity Reducers in Wellbore
Lifting
Oil-based viscosity reducer is composed of the
macromolecule polymers containing the strong polar
groups. The groups with strong polarity in its
molecules and those in the molecules of resin and
asphaltene form hydrogen bonds, which have good
viscosity-reducing effect for heavy oil. Therefore,
oil-based viscosity reducers are suitable for the
production of heavy oil with low water content and
low viscosity. Viscosity of some heavy oil with low
viscosity was significantly reduced, results are
shown in Table 3.
Table 3 shows that dosage of 250-300mg/kg, the
viscosity of above-mentioned heavy oil dropped
46%-91%.
In the early production stage of Block 104-5, oil
production were well under expectation. Great
production improvements were achieved after the
treatment of oil-based viscosity reducers, as shown in
Table 4.
Table 4 shows that after the treatment of oil-based
viscosity reducers in Block 104-5, both oil
production time and rates were increased. Production
improvements were obvious that daily oil production
rate increased from 20 tons to 230 tons.
3.2 The Application of Water-based
Viscosity Reducers in Wellbore
Lifting
Water-based viscosity reducer is composed of
surfactants and emulsion stabilizers. It is able to turn
an oil-water system into an O/W emulsion, reducing
the viscosity of heavy oil by over 90%.
In the wellbore lifting process, the viscosity
reducer can be used alone by injecting into the
bottomhole or with steam stimulation. The viscosity
reduction effect is shown in Table 5.
Water-based viscosity reducer was used in a
number of oil wells in Wa-38 block of Xinglongtai
oil production plant at Liaohe. The application results
are shown in Table 6.
Table 6 shows that both production days and
production rates of Wa38 block increased
significantly. According to the statistical data from
15 Wells provided by the oil production plant,
accumulative incremental reached 35,870 tons, and
return on investment is as high as 26:1.
Table 3: Viscosity-reducing effect of oil-soluble viscosity reducer for some heavy oils.
Oil sample
Dosage
/mg/kg
Viscosity (40℃) /mPa.s
Viscosity reduction /%
Before treatment
After treatment
104-5 Block,
Jidong
Oilfield
106-5
300
5500
1100
80.0
104-5
300
1600
448
72.0
109-6
300
910
490
46.2
109-7
300
1230
650
47.2
Namazhuang Huabei oilfield
250
1513
123
91.0
Erlian oilfield
300
2620
360
86.3
Kelamayi
300
2300
460
80.0
Application and Challenge of Flow Improver for the Development of Heavy Oil and Waxy Crude
79

Table 4: Application results in Block 104-5 of Jidong Oilfield.
Well
number
Production efficiency
/%
Time of continuous production
/d
Production
/ton/d
Before
treatment
After
treatment
Incre-
ment
Before
treatment
After
treatment
Incre-
ment
Before
treatment
After
treatment
Incre-
ment
104-6
40
94
54
110
254
144
3.7
4.4
0.7
109-6
43
96
53
81
118
37
5.5
8.3
2.8
111-6
97
98
1
119
129
10
8.4
9.5
1.1
111-7
96
97
1
44
200
156
10.4
10.7
0.3
Table 5: Effect of water-based viscosity reducer for some heavy oils.
Oil sample
Dosage
/mg/kg
Oil :Water
/w:w
Viscosity /mPa.s
Viscosity reduction
/%
Before treatment
After treatment
Shengli oilfield
100
6:4
59600 (60℃)
30 (30℃)
>99.95
Jidong oilfield
100
6:4
22750 (40℃)
50 (40℃)
99.80
Kelamayi
oilfield
100
6:4
12050 (30℃)
44 (30℃)
99.60
Wa 38 Union,
Liaohe oilfield
100
7:3
77600 (50℃)
50 (30℃)
>99.94
150
7:3
77600 (50℃)
49 (30℃)
>99.94
200
7:3
77600 (50℃)
55 (30℃)
>99.93
Table 6: Application results in Wa-38 Block of Liaohe oilfield.
Well
number
Steam
cycle
/round
Recovery
water
/%
Increment of
water recovery
/%
Oil
production
/ton
Increment of
oil production
/ton
Production
time
/day
Increment of
production
time
/day
3542
2
45.9
8.1
2283
1780
148.3
83.1
3
54.0
4063
231.4
37430
1
47.5
77.5
2069
404
168.1
25.6
2
125.0
2473
193.7
37435
2
35
29.0
1761
247
243.7
5.0
3
64
2008
148.7
3124
5
27.7
58.5
1824
1476
137.5
65.8
6
86.2
3300
203.3
36432
2
37.8
35.5
2064
80
179.5
31.7
3
73.8
2144
211.2
3743
2
29.9
25.2
470
1143
58.5
137.4
3
55.1
1613
195.9
4 VISCOSITY REDUCER FOR
HEAVY OIL FORMATION
DRIVE
For conventional crude oil with the low in-situ
viscosity, water flooding is mainly used as formation
drive. For heavy oil with high viscosity, thermal
recovery is used, which includes steam stimulation,
steam flooding, in-situ combustion and SAGD. For
heavy oil with low viscosity, water flooding is used.
In terms of heavy oil, those that can be developed
by water flooding accounts for 30.1% of total
reserves and 18% of total production. Because of the
thickness of oil and the heterogeneity of reservoir,
water flooding in normal heavy oil reservoirs could
only yield 5-25% final oil recovery.
In an effort to improve oil recovery factor of
water flooding in heavy oil reservoirs, most
MEEP 2018 - The Second International Conference on Materials Chemistry and Environmental Protection
80

researchers home and abroad previously focused
their studies on alkaline flooding, polymer flooding,
surfactant flooding and combination flooding etc.
Their theoretical research has some merits (Liao and
Tang, 2018; Qu, 2013; Tang et al., 2012; Zhou, 2017;
Chen, 2013; Jin et al., 2005), besides some
technologies proposed were put into field tests. In
No.3 oil production plant of Dagang oilfield in China,
a small-scale field test using viscosity reducer was
implemented. Due to the failure for the small
molecule viscosity reducers to form stable O/W
emulsions under low in-situ shear rate, incremental
oil production was found to be nominal.
Studies show that the key to improving water
drive recovery factor in heavy oil reservoirs is to
enlarge swept volume. Reducing viscosity of heavy
oil and raising viscosity of displacement phase are
effective ways to achieve this. Now that there is no
research conducted home or abroad on heavy oil
water flooding EOR technologies that could reduce
heavy oil viscosity meanwhile raising displacement
phase viscosity under low in-situ shear stress. This
could possibly be achieved by macromolecular
viscosity reducers according to the theory of
molecular design. The synergism could greatly
improve the recovery factor of water flooding in
heavy oil reservoirs. Therefore, macromolecular
viscosity reducer is one of the key technologies to
replace water flooding in the near future. It is of great
significance to water flooding EOR of heavy oil and
has a promising prospect and range of applications.
5 CONCLUSIONS AND
PROPOSALS
Flow improver which has good pour
point-depressing and viscosity-reducing effects for
the waxy crude oil, had been used in Luning,
Zhongluo and Pulin, et al. pipelines and improved
safety and adaptability in operations.
Oil-based viscosity reducer which has good
viscosity reducing effect for heavy oil with low
viscosity, had used to wellbore lifting of low
viscosity heavy oil. While water-based viscosity
reducer which has good viscosity reducing effect on
heavy oil with high viscosity, had used to wellbore
lifting of extra heavy oil.
More research needs to be diverted to and focused
on viscosity reducers for formation drive, including
studies of viscosity reducing mechanisms, evaluation
system and molecular structure design.
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