Do hydrolyzed polyacrylamide molecules change viscosity in high-salinity formation-water?

In this paper, molecular dynamics simulations were conducted to investigate the molecular configuration and network of hydrolyzed polyacrylamide (HPAM) molecules in high-salinity formation-water and the viscosity changes from the microscopic dense to dilute phase.

Does calcium concentration affect molecular configuration and viscosity of polyacrylamide molecules?

Partially hydrolyzed polyacrylamide molecules in high-salinity formation-water solution are simulated using the molecular dynamics method to investigate the impact of calcium concentration on molecular configuration, network, and viscosity from microscopic dense to dilute phases. The key results are as follows:

What is the apparent viscosity of HPAM in formation-water?

The apparent viscosity of HPAM in formation-water will increase around 2–3 times when the concentration is more than such a threshold. Our SEM image shows that HPAM molecules in formation-water are strongly microscopically heterogeneous, comprising the dense to dilute phase.

Does polymer flooding affect viscosity in high-salinity formation-water?

According to the reports from oilfields in which polymer flooding has been applied, 5–4 it is a big challenge to maintain the polymer’s viscosity in high-salinity formation-water. Polyacrylamides, including partially hydrolyzed polyacrylamide (HPAM), are commonly used for polymer flooding.

How do you calculate apparent viscosities of HPAM solution?

Since the simulation for each case is nano-scale homogeneous, the HPAM solution is a Newton fluid, and apparent viscosities are calculated as follows: where τ and γ are the shear stress and shear rate, respectively. F and A are the driving force applied along the x direction and the area of the x direction, respectively.

How does NaCl affect the intrinsic viscosity of HPAM molecule?

Chen et al.9 simulated one HPAM molecule in aqueous solution with different concentrations of NaCl. Their results illustrated that a HPAM molecule became more coiled and the intrinsic viscosity of HPAM decreased as the concentration of NaCl increased.