Introduction to ArtificiaI Intelligence in Higher Education
Polymer flooding
1. Bohai Bay, China
Present by : Behzad Hosseinzadeh
1
Polymer Flooding
Number of slides:17 Winter-1392 EOR course
2. Reservoir Location
• Bohai Sea, also known as Bohai Gulf, Bohai, or
Bo Hai, is the innermost gulf of the Yellow Sea
on the coast of Northeastern and North China.
2
Reservoir Location
Rock and reservoir
properties
Challenges
Use PHP instead of
HAWP
HAWP
- Vicosification
- Solubility
-Mechanical
degradation
-Long-term
thermal
stability
• Treatment HAWP
Operations
Results
3. Reservoir Location
• SZ36-1 oilfield is located at the coast of
Liaodong, Bohai Bay, China 9
• It is estimated that around 70% of oil reserve in
China offshore oilfields are heavy oil
• 64% of them are discovered in Bohai bay.
• The oil recovery by water flooding is only 18 –
25%, which is far below than that of the onshore the
average oil recovery of 32 –40%.
• It was put into operation since 1993
• Sea water with high salinity of 32,423mg/L was
initially injected for about 8 years.
• Then water from Guantao formation with salinity
of 9048mg/L was injected.
• The history of water injection makes the salinity of
produced water higher than that of the original
formation water, especially of Ca 2+ and Mg 2+ .
3
Reservoir Location
Rock and reservoir
properties
Challenges
Use PHP instead of
HAWP
HAWP
- Vicosification
- Solubility
-Mechanical
degradation
-Long-term
thermal
stability
• Treatment HAWP
Operations
Results
4. Rock and reservoir
properties
4
Reservoir Location
Rock and reservoir
properties
Challenges
Use PHP instead of
HAWP
HAWP
- Vicosification
- Solubility
-Mechanical
degradation
-Long-term
thermal
stability
• Treatment HAWP
Operations
Results
5. Rock and reservoir
properties
o Distributioned and good connectivity
o sedimentary rhythmic feature
o reservoir rocks are feldspathic quartz sand
composed mainly of fine sands
o The crude oil in SZ36-1 oilfield is highly viscous
o It is characterzed as high desity, low sulphur
content, low wax content and high gum and
bitumen contents.
5
Reservoir Location
Rock and reservoir
properties
Challenges
Use PHP instead of
HAWP
HAWP
- Vicosification
- Solubility
-Mechanical
degradation
-Long-term
thermal
stability
• Treatment HAWP
Operations
Results
6. Challenges
High salinity and hardness of the make-up water (Ca
2+ and Mg 2+ : 600 – 1,200mg/L), and high viscosity
of oil (in average of 70mPa·s), which require the
polymer to be salt resistant and good viscosification.
Limited spacing of platform does not allow big
volume installation for polymer resolving, so
development of fast-resolving polymer is necessary.
Drilling and completion by wire wrapped screen
gravel-packed sand control and large displacement of
offshore oilfields require strong anti-mechanical
degradation ability of polymer.
Long-term stability of polymer in the formation
is required because of the large well spacing and
thick pay zone.
Treatment of produced fluid to meet the
environmental requirements should fast and
complete in the platform. So the effect of polymer to
the produced fluid should be considered in the
polymer design.
6
Reservoir Location
Rock and reservoir
properties
Challenges
Use PHP instead of
HAWP
HAWP
- Vicosification
- Solubility
-Mechanical
degradation
-Long-term
thermal
stability
• Treatment HAWP
Operations
Results
7. Use PHP instead of HAWP
Partially hydrolyzed Polyacrylamide (PHP) is a
long chain high molecular weight polymer with
great visocification
Partially hydrolyzed Polyacrylamide (PHP) is a
long chain high molecular weight polymer with
great visocification
a kind of Hydrophobically Associating Water-
soluble Polymer (HAWP) is being designed and
synethesized with less sensitive to sanility
and high viscosification as a driving agent for
offshore polymer flooding.
7
Reservoir Location
Rock and reservoir
properties
Challenges
Use PHP instead of
HAWP
HAWP
- Vicosification
- Solubility
-Mechanical
degradation
-Long-term
thermal
stability
• Treatment HAWP
Operations
Results
8. Characteristics of HAWP
Overcoming the five main challenges is crucial
for a successful offshore polymer flooding. HAWP
is discussed and shows its characteristics
satisfying the requirement of offshore operation.
Vicosification
Solubility
Mechanical degradation
Long-term thermal stability
Treatment of produced fluid contained HAWP
8
Reservoir Location
Rock and reservoir
properties
Challenges
Use PHP instead of
HAWP
HAWP
- Vicosification
- Solubility
-Mechanical
degradation
-Long-term
thermal
stability
• Treatment HAWP
Operations
Results
9. Vicosification
The use of water soluble polymers to increase
the water viscosity has been shown to be an
effective way to improve the sweep efficiency and
hence increasing the oil recovery.
The experimental result shows that visosocity of
HAWP increased significantly with the increase of
concentration of polymer solution. (test on J3 well
of SZ36-1 oilfield)
C* = increased sharply with the increase of polymer
concentration.
9
C*
Reservoir Location
Rock and reservoir
properties
Challenges
Use PHP instead of
HAWP
HAWP
- Vicosification
- Solubility
-Mechanical
degradation
-Long-term
thermal
stability
• Treatment HAWP
Operations
Results
10. Solubility
Because there is a small portion of
hydrophobic comonomer introduced into
HAWP, the resolving of HAWP become
conditional.
Experimental result shows higher polymer
concentration and higher temperature are
favorable for the resolving of HAWP.
There is a critical resolving temperature for
HAWP about 37 °C.
10
Reservoir Location
Rock and reservoir
properties
Challenges
Use PHP instead of
HAWP
HAWP
- Vicosification
- Solubility
-Mechanical
degradation
-Long-term
thermal
stability
• Treatment HAWP
Operations
Results
11. Mechanical degradation
It is known that when a polymer solution is
exposed to high shear conditions the
molecule may be scissored.
High shear conditions occur:
during mixing of polymer solutions, or during the
conveyance of a polymer solution in pumps and
chokes, or during injection in perforations, or in the
formation near the well bore where the polymer
solution is flowing at high velocities.
11
Reservoir Location
Rock and reservoir
properties
Challenges
Use PHP instead of
HAWP
HAWP
- Vicosification
- Solubility
-Mechanical
degradation
-Long-term
thermal
stability
• Treatment HAWP
Operations
Results
12. Long-term thermal stability
Normally a polymer flooding project would last
for years, which requires polymer stable
throughout these long periods.
When polymer solution is kept for a longer
period at high temperature
it can degrade and lose its viscosity.
12
Reservoir Location
Rock and reservoir
properties
Challenges
Use PHP instead of
HAWP
HAWP
- Vicosification
- Solubility
-Mechanical
degradation
-Long-term
thermal
stability
• Treatment HAWP
Operations
Results
13. Treatment of produced
fluid contained HAWP
Produced fluid containing polymer should be
treated in the limited spacing of
platforms, while meeting the requirement of
reinjection to the well or discharge to the sea.
Problem :
Existence of polymers, the contained oil in the
produced water increased a lot, which would lead to
the hard demulsification and increamental of
viscosity of produced fluid.
Solution :
A new demulsifier and assitant-demulsifier for
offshore application has been developed to
dehydrate water from the oil-water emulsions 13
Reservoir Location
Rock and reservoir
properties
Challenges
Use PHP instead of
HAWP
HAWP
- Vicosification
- Solubility
-Mechanical
degradation
-Long-term
thermal
stability
• Treatment HAWP
Operations
Results
14. Treatment of produced
fluid contained HAWP
14
Reservoir Location
Rock and reservoir
properties
Challenges
Use PHP instead of
HAWP
HAWP
- Vicosification
- Solubility
-Mechanical
degradation
-Long-term
thermal
stability
• Treatment HAWP
Operations
Results
15. Operation
Area was decided with a five-spot pattern.
Since October 2005, polymer flooding for well
group has been carried out.
The project is designed to continuous inject
HAWP for 3 years
Total polymer consumed 3,142.7tons
15
Reservoir Location
Rock and reservoir
properties
Challenges
Use PHP instead of
HAWP
HAWP
- Vicosification
- Solubility
-Mechanical
degradation
-Long-term
thermal
stability
• Treatment HAWP
Operations
Results
16. Result
water cut decreased and oil production increased in
the corresponding wells.
The accumulated oil reached 25,000m 3 and
water cut decreased from 95% to 54% until the end
of the test (in J3 well of SZ36-1 ).
Until Feb. 2007, the total incremental oil by
polymer flooding reached 12,000m 3 , and total
production kept stable (group wells)/
16
Reservoir Location
Rock and reservoir
properties
Challenges
Use PHP instead of
HAWP
HAWP
- Vicosification
- Solubility
-Mechanical
degradation
-Long-term
thermal
stability
• Treatment HAWP
Operations
Results