Study on dispersion property of a novel profile control agent

Yamei Guo EOR Research Center, China University of Petroleum, Beijing

2009.9

Outline Background

Purpose

Methods

Results

Conclusions

Background—studies of LPS

1. Definition: Linked polymer solution (LPS) is a dispersion which is made up of linked polymer coils (LPC) linked by aluminum ions in water.

2. Properties:

SEM photograph of LPC

The size of LPC is about hundreds nanometers

Thermodynamic stable

Good injecting, deformable and plugging property

3. Problems of LPS

High temperature

Prepared with treated water

Oxidation degradation of HPAM over 70ºC

LPC is not formed

To seek a new profile control agent could be prepared with treatedwater and used in the reservoirs at over 70ºC

Purpose

1.Properties of the new profile control agent could have

Good dispersion stability

High temperature tolerance (≥70ºC)

High salinity tolerance (≥50 g∙L-1)

2.Basic properties of sulfomethylated phenol formaldehyde resins—SMP

1. The molecular structure of SMP is consist of benzene rings which

are unable to be degraded at high temperature.

temperature tolerance (≤180ºC)

2. The molecule of SMP has -CH2SO3Na group, more water soluble.

Salinity tolerance (≤150 g∙L-1 NaCl)

Phenolic rings are linked via methylenes at ortho-para positions.Sulfomethylations are mostly linked to premier phenolic rings at double ortho positions.

3.Molecular structure of SMP

Methods

To study dispersion properties of SMP in water by

Coagulation value

Turbidity

Hydrodynamic diameter

Zeta potential

Results of this study1.Dh and zeta potential of molecular aggregates in distilled water

0 50 100 150 200 250

0

10

20

30

In

tens

ity

/ %

Dh / nm

Concentration of SMP /

g∙L-1

Dh

/ nm

Zeta potential /

mV

0.01 106.7 -33.0

0.05 105.4 -36.5

0.1 109.7 -35.3

Dh and zeta potential of SMP (pH=8.2 ， 25ºC)

Hydrodynamic diameter at 0.01g∙L-1 of SMP (25ºC)

The dispersion of SMP in water is a lyophilic colloid

Electrolyte Concentration of electrolyte / mol∙L-1

Coagulation value Ratio of coagulation value

mol∙L-1 g∙L-1

NaCl 4.28 2.23 130.45 1

CaCl2 1.35 0.72 79.92 0.032

MgCl2 1.97 1.48 140.60 0.66

AlCl3 1.29 ×10-1 1.30×10-3 0.17 5.80×10-4

Na2SO4 2.82 1.78 252.76 0.79

2.Coagulation value of SMP solution (25ºC)

The stability of SMP solution is influenced by the positive ions

3. Effect of NaCl on the stability of SMP solution

0 20 40 60 80 100 120 140 160

150

300

450

0 20 40 60 80 100 120 140 160

-10

-34-35-36

0 20 40 60 80 100 120 140 1600

30

60

90

Dh

/ n

m/

mV

concentration / g·L-1

NT

U

1) NaCl , zeta potential , Dh , NTU , the stability of solution

2) The range of Dh is 100 nm ~500 nm when concentration of NaCl is less than 150 g·L-1

The effects of concentrations of NaCl on The stability of SMP solution (pH=8.2 ， 25ºC)

4. Effect of pH on the stability of SMP solution

0 2 4 6 8 10 1230150

-15-30-45

0 2 4 6 8 10 12

100120140160

0 2 4 6 8 10 1206

121824

/ m

VD

h /

nm

pH

NT

U

At pH<3.0, positive charged, pH , H+ , zeta potential , Dh ;

At pH >3.0, negative charged, pH , OH- , zeta potential , Dh ;

At pH=3.0, Dh is the biggest and the absolute value of zeta potential is the least in the solution; At pH=0~12, the turbidity values of solution are small, the solution is stable.

Effects of pH on the stability of SMP solution (25ºC)

Properties LPS SMP

Size of dispersed particles 20nm~2000nm 100nm~500nm

Deformation Well well

Stability Well Well

Preparation Cross linking in fields Synthesis in factories

Salinity tolerance ≤ 50 g∙L-1 ≤ 150 g∙L-1

Temperature tolerance ≤ 70ºC ≥ 95ºC

pH 5~8 3~12

5. Comparison between LPS and SMP solution

Conclusion

1.The hydrodynamic diameter of the SMP molecular aggregates is about 100 nm and the molecular aggregates are negative charged in distilled water.

2.The ratio of critical coagulating concentration (CCC) of NaCl to CaCl2, MgCl2, AlCl3, Na2SO4 for the SMP solution is 1:0.032:0.66:0.00058:0.79.

3.Hydrodynamic diameters of molecular aggregates and turbidity of the SMP solution increase and absolute values of zeta potential of the molecular aggregates decrease with increasing concentrations of NaCl.

4. At pH=0~12, the turbidity values of solution are small, the solution is stable.