Smart Brines for minimal surface adsorption in polymer enhanced oil recovery

(1)

0 50 100 150 200 250 Time(min) 1mM 10mM 100mM pH 8 0 50 100 150 200 250 -20 -15 -10 -5 0 f/ 9 Time (min) 1mM 10 mM 100mM pH 6

SMART BRINES FOR MINIMAL SURFACE ADSORPTION IN POLYMER

ENHANCED OIL RECOVERY(EOR)

Materials Science and Technology of Polymers

1

_{, Physics of Complex Fluids}

2

_{, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands,}

DPI, PO BOX 902, 5600 AX Eindhoven, The Netherlands

3

Amrutha Mohan

1,2,3

, I. Siretanu

2

, F. Mugele

2

and G.J. Vancso

1

a.mohan@utwente.nl

PROBLEM STATEMENT

The polymer EOR utilizes high molecular weight polymers to improve the viscosity of the displacing aqueous phase. This polymer-brine solution has a better sweep efficiency than the normal brine solution. But the polymers get adsorbed on the rock surface. Polymer adsorption on the pore surface has a negative impact and therefore needs to be minimized. Here we are investigating polymer adsorption fundamentally through QCM.

CONCLUSIONS

Upon passing the polymer solution, the sensor undergoes frequency shift (∆f) and Dissipation shift (∆D) due to adsorption, density and viscosity effects.. Polymer studied: Flopaam (40 kDa , 2000 ppm solution)

Acknowledgement: The work of Mohan, A. forms part of the research

programme of DPI, Project 807.

The project is sponsored by

SNF and Shell Global Solutions International BV.

DPI, P.O. Box 902, 5600 AX Eindhoven, the Netherlands

The EOR polymers (Flopaam) used in the experiments are provided by SNF.

[1] Wang, L. et al, Colloids Surf. A 2016, 494, 30-38

[2] Hu et. Al. Energy Fuels2019,3,31,127-134

[3] Giannotti, M.I. et al, ChemPhysChem 2007,8,2290-2307

O NH₂ _n C CH CH₂ O _O- _m C CH CH₂

Some factors affecting adhesion:  Charge on the polymer

 Surface charge (charge on the clays)  Ions present in the brine

 pH of the solution

Chemical formula of Flopaam: Random copolymer of Polyacrylamide (70%) (the left,n) and polyacrylic acid (30%) (the right,m)

Polymer Flooding Water Flooding

QCM-D

Topographical features of silica and alumina and their corresponding height profiles[1]

SUBSTRATES

SALTS (1,10,100 mM)

 NaCl

 CaCl₂.2H₂O

pH : 6 and 8

DI WATER SALT SOLUTION SALT + HPAM SALT SOLUTION DI WATER

A B C D E FLOW DIRECTION DISSIPATION FREQUENCY SHIFT

ANALYSIS

Assumptions:

• The system is very dilute the bulk properties of polymer solution≈the bulk properties of salt solution

• Newtonian fluid

• The adsorbed film is rigid and uniform

The frequency shift due to bulk can be calculated using modified Sauerbrey equation[2]

0 0 100 200 300 -30 -25 -20 -15 -10 -5 0 5 ∆ f/n, ∆ D x10 6 Time 5 7 9

• Subtract the bulk shift obtained from salt flush

• average the frequency shifts (diff overtones) • Apply Sauerbrey (if the

deviation is < 5Hz) Apply Sauerbrey to extract mass adsorbed Where C= 17.7 ng/cm2 _Hz SAUERBREY EQUATION Polymer Salt DI 0 50 100 150 200 250 300 mass adsor bed (ng/ cm 2 )

Monovalent salt (NaCl) on Alumina

Flush Regime 1mM (6) 1mM (8) 10mM (6) 10mM (8) 100mM (6) 100mM (8) Polymer Salt DI 0 100 200 300 400 500 600 700 800 mass adsor bed ng/ cm 2 )

Divalent salt (CaCl₂) on Alumina

Flush Regime 1mM (6) 1mM (8) 10mM (6) 10mM (8) 100mM (6) 100mM (8) Polymer Salt DI 0 50 100 150 200 Flush Regime 1mM (6) 1mM (8) 10mM (6) 10mM (8) 100mM (6) 100mM (8)

Monovalent salt (NaCl) on Silica

Mass ad so rb ed * ( ng /cm 2 ) Polymer Salt DI 0 100 200 300 400 500 600 700 800 mass absor bed * ( ng/ cm 2 )

Divalent salt (CaCl₂) on Silica

Flush Regime 1mM (6) 1mM (8) 10mM (6) 10mM (8) 100mM (6) 100mM (8) 0 50 100 150 200 250 300 -10 -8 -6 -4 -2 0 f/ 9 Time(min) 1mM 10mM 100 mM pH 6 0 50 100 150 200 250 300 Time (min) 1mM 10 mM 100 mM pH 8 0 50 100 150 200 250 300 350 400 -40 -30 -20 -10 0 f/ 9 Time (min) 1mM 10 mM 100 mM pH 6 0 50 100 150 200 250 300 350 400 450 1mM 10mM 100mM Time(min) pH 8

ALUMINA

_SILICA

0 50 100 150 200 250 -50 -40 -30 -20 -10 0 f/ 9 Time(min) 1mM 10mM 100mM 0 50 100 150 200 250 300 Time (min) 1mM Ca 10mM Ca 100mM Ca

Smart Brines for minimal surface adsorption in polymer enhanced oil recovery