Adsorption behavior and shear degradation of ultrahigh‐molecular‐weight hydrolyzed polyacrylamide in a capillary flow

Abstract

Ultrahigh-molecular-weight partially hydrolyzed polyacrylamides (HPAMs) are commonly used in polymer flooding to enhance oil recovery. However, the viscosity of the HPAM solution is susceptible to shear action. Viscosity change affects sweep range and displacement efficiency of the displacement fluid. Here, a macromolecular adsorption model in microcapillary is proposed to reveal the shear variation mechanism at low flow rates. The rheological behaviors of HPAMs with three different molecular weights are investigated using a stainless steel capillary. The shear rate distributions near contraction and within capillary are compared by numerical calculation using the laminar flow model. Experimental and numerical results show that the polymer solution was mechanically degraded at low flow rates, which is in agreement with the results predicted by the adsorption theory model. A new calculation method for the thickness of polymer adsorption layer at lower flow rates is proposed based on the adsorption model proposed in this study. It is found that the viscosity and adsorption of HPAM were changed with flow rate, and their changes are closely related to the displacement efficiency in the micropores of reservoirs. This study provides new perspectives for the selection of polymer injection flow rates and the water shutoff in reservoirs.

Effect of silicon dioxide nanoparticles on the rheology properties of fresh and mechanically degraded hydrolyzed polyacrylamide polymer solutions

“…These extreme deformation rates lead to polymer chain breakage, reducing molecular weight distribution, viscosity, and viscoelastic forces, ultimately diminishing the mobility control potential of polymer solutions. 17 Recent studies, such as that by Al Hashmi et al, 18 have quantified mechanical degradation in hydrolysed polyacrylamide, revealing degradation rates below 20% up to a certain shear rate threshold, beyond which degradation increases. Field applications have reported substantial viscosity reductions of up to 64% in polymer solutions flowing from injector to producer wells.…”

Impact of prolonged water‐gas flow on the performance of polyacrylamide

“…[18][19][20] The thickness of the adsorbed polymer layer and subsequently RPM performance change with time due to other underlying effects, such as the volume of injected fluid, the flowing fluid composition, brine salinity, and the rheological properties of the polymer. 1,[10][11][12][13][14][21][22][23][24][25] Even though the use of polymers as RPM have already been proven, the efficiency period of RPM is still questionable. The performance of RPM may reduce over time due to RPM removal during production of reservoir fluid (water and oil).…”