Rheology of a New Sulfonic Associative Polymer in Porous Media

Abstract

For hydrophobically associative polymers, incorporating a small fraction of hydrophobic monomer into a hydrolyzed polyacrylamide (HPAM) polymer can promote intermolecular associations and thereby enhance viscosities and resistance factors. In this paper, we investigate the behavior of a new associative polymer in porous media. The tetra-polymer has low hydrophobic-monomer content and a molecular weight (Mw) of 12-17 million g/mol. Total anionic content is 15-25 mol%, including a few percent of a sulfonic monomer. This polymer is compared with a conventional HPAM with 18-20 million g/mol Mw and 35-40% anionic content. Rheological properties (viscosity vs. concentration; and shear rate and elastic and loss moduli vs. frequency) were similar for the two polymers [in a 2.52% total dissolved solids (TDS) brine at 25°C]. For both polymers in cores with permeabilities from 300 to 13,000 md, no face plugging or internal-filter-cake formation was observed, and resistance factors correlated well using the capillary-bundle parameter. For the HPAM polymer in these cores, low-flux resistance factors were consistent with low-shear-rate viscosities. In contrast, over the same permeability range, the associative polymer provided low-flux resistance factors that were two to three times the values expected from viscosities. Moderate shear degradation did not eliminate this effect-nor did flow through a few feet of porous rock. Propagation experiments in long cores (up to 157 cm) suggest that the unexpectedly high resistance factors could propagate deep into a reservoir-thereby providing enhanced displacement compared with conventional HPAM polymers. Compared with HPAM, the new polymer shows a significantly higher level of shear thinning at low fluxes and a lower degree of shear thickening at high fluxes.

Review on Polymer Flooding: Rheology, Adsorption, Stability, and Field Applications of Various Polymer Systems

“…Similarly, a small decrease in the concentration due to polymer retention on rock surface will lead to decrease in the viscosity which will make it insufficient for the desired mobility control. 45 Solubility of HMA polymers is also not as good as that of the un-modified counterpart. 147 The mechanism of oil recovery and behavior in porous media of HMA polymers is not well understood and needs further investigations.…”

“…HPAM, the structure of which is shown in Fig. 2, is the most widely used polymer for cEOR applications [45][46][47][48][49][50] and a number of publications have reported its evaluation under different conditions. [51][52][53][54][55][56][57][58][59][60][61][62] In the following sections, the thermal stability, rheology, and adsorption of HPAM on rock surface will be discussed.…”

Complexation of Surfactant/β‐Cyclodextrin to Inhibit Surfactant Adsorption onto Sand, Kaolin, and Shale for Applications in Enhanced Oil Recovery Processes. Part III: Oil Displacement Evaluation

“…where u is flux (cm/h), t is time (h), A is cross sectional area of the sandpack (cm 2 ), / (fraction) is porosity, and k is permeability (md) [46][47][48]. The capillary bundle parameter can be also interpreted as volume of fluid injected normalized for porosity and permeability; which allowed comparing the experimental performance between sandpacks having the same mineral composition.…”

Viscoelasticity of a Supramolecular Polymer Network and its Relevance for Enhanced Oil Recovery

“…The performance of the baseline and the SAP network as mobility control agents in porous media was analyzed by plotting the effective viscosity or resistance factor (RF) [63][64][65][66][67][68] of the polymer system during flow through porous media as a function of the volume of fluid injected expressed as a fraction of pore volume (PV), which was normalized for porosity and permeability to compare the displacement tests on the same reference. The capillary bundle parameter model was applied for data normalization [66,[69][70][71]. Polymer retention in porous media after the post-polymer brine injection was determined by the residual resistance factor, RRF [59, 62-65, 67, 68, 70-74].…”