An Experimental Study on Hydrodynamic Retention of Low and High Molecular Weight Sulfonated Polyacrylamide Polymer

Abstract

Polymers are often added with water as a viscosifier to improve oil recovery from hydrocarbon reservoirs. Polymer might be lost wholly or partially from the injected polymer solution by adsorption on the grain surfaces, mechanical entrapment in pores, and hydrodynamic retention in stagnant zones. Therefore, having a clear picture of polymer losses (and retention) is very important for designing a technically and economically successful polymer flood project. The polymer adsorption and mechanical entrapment are discussed more in depth in the literature, though the effect of hydrodynamic retention can be just as significant. This research investigates the effect of the hydrodynamic retention for low and high molecular weight (AN 113 VLM and AN 113 VHM) sulfonated polyacrylamide polymer. Two high permeability Bentheimer core plugs from outcrops were used to perform polymer corefloods. Polymer retention was first determined by injecting 1 cm3/min, followed by polymer core floods at 3, 5, and 8 cm3/min to determine the hydrodynamic retention (incremental retention). A higher molecular weight polymer (AN 113 VHM) showed higher polymer retention. In contrast, hydrodynamic retention for lower molecular weight (AN 113 VLM) was significantly higher than that of the higher molecular weight polymer. Other important observations were the reversibility of the hydrodynamic retention, no permanent permeability reduction, the shear thinning behavior in a rheometer, and shear thickening behavior in core floods.

Effect of Silica Nanoparticles on Polymer Adsorption Reduction on Marcellus Shale

“…Consequently, a decrease occurs in the hydrodynamic size of the polymer, and there is thereby a reduction in polymer viscosity. 17,39 Nevertheless, it is possible that the addition of some nanoparticles can cause the polymer chains to physically adsorb on the nanoparticle surfaces. 40,41 Figure 6 shows a comparison for the polymer rheology with and without silica nanoparticle solution.…”

“…It is generally understood that shear thinning is due to the more significant breakage/destruction of the entanglements between the polymer molecules at a higher shear rate. Consequently, a decrease occurs in the hydrodynamic size of the polymer, and there is thereby a reduction in polymer viscosity. , Nevertheless, it is possible that the addition of some nanoparticles can cause the polymer chains to physically adsorb on the nanoparticle surfaces. , Figure shows a comparison for the polymer rheology with and without silica nanoparticle solution. Overall, it is possible to say that polymers with higher molecular weights are more sensitive to shear, as the viscosity of the higher molecular weight decreased almost 10 times with shear.…”

Experimental and Numerical Investigation of Polymer Pore-Clogging in Micromodels

“…One of the reasons is that retention mechanisms are typically indirectly inferred from differential pressure and effluent concentration profiles during core-flooding experiments. Therefore, they fail to differentiate between different mechanisms and capture their individual effect on rocks (Al-Hajri et al, 2019;Broseta et al, 1995;Li et al, 2017;Szabo, 1975;Zhang and Seright, 2014).…”

Novel Approach to Model and Visualize the Transport of Polymer Molecules in Porous Media Using Microfluidics

“…But despite all the efforts, these mechanisms that stand behind polymer entrapment are not fully understood yet. One of the reasons is that retention mechanisms are typically indirectly inferred (from differential pressure and effluent concentration profiles during core-flooding experiments) hence, fail to differentiate between different mechanisms and to capture their individual effect on rocks (Al-Hajri et al, 2019;Broseta, Medjahed, Lecourtier, & Robin, 1995;Szabo, 1975;Zhang & Seright, 2014). Therefore, a mechanistic understanding of polymer/pore-network interactions calls for a direct method to be studied.…”