Abstract
In practical applications, the chemical and physical adsorption of a polymer solution greatly affects its action mode and effect. Understanding the adsorption mechanism and its influencing factors can help to optimize the application mode and ensure application efficiency. Three types of polymer solutions—partially hydrolyzed polyacrylamide (HPAM), hydrophobically associating polymer (AP-P4), and dendrimer hydrophobically associating polymer (DHAP), which are viscoelastic liquids—were used as sorbates to study their adsorption by a sorbent such as quartz sand. The effects of the solution concentration, contact time, particle size of quartz sand, solid–liquid ratio, and fluid movement on the adsorption capacity of the polymer solutions were examined. The results showed that HPAM presents a typical Langmuir monolayer adsorption characteristic, and its adsorption capacity (per unit area) is 1.17–1.62 μg/cm2. The association enhances the interactions of the AP-P4 and DHAP solutions, and they present multilayer characteristics of first-order chemical adsorption and secondary physical molecule adsorption. Moreover, the dendrite structure further increases the adsorption thickness of DHAP. Hence, the adsorption thicknesses of AP-P4 and DHAP are four and six times that of HPAM, respectively. The adsorption of the three polymers is consistent with the influence of fluid motion and decreases with increasing fluid velocity. However, the larger the thickness of the adsorption layer, the clearer the influence of the flow, and the higher the decrease in adsorption capacity. Optimizing the injection rate is an effective method to control the applications of a polymer in porous media.
Highlights
Polymer flooding has been broadly applied as a major enhanced oil recovery (EOR) technology in numerous oilfields worldwide [1,2,3]
The decrease in the displacement phase permeability is caused by the comprehensive outcomes of polymer solution adsorption and retention in porous media [7]
Adsorption kinetic model is more feasible to study adsorption characteristics and influencing factors based on static adsorption methods
Summary
Polymer flooding has been broadly applied as a major enhanced oil recovery (EOR) technology in numerous oilfields worldwide [1,2,3]. There are two main methods for the study of polymer solution adsorption: static and dynamic adsorption [10,11,12,13]. Adsorption kinetic model is more feasible to study adsorption characteristics and influencing factors based on static adsorption methods. The model assumes that the adsorption rate is directly proportional to the square of the adsorbate concentration, and the limiting factor of the adsorption rate is the adsorption mechanism. The model assumes that the driving force of the adsorption process is from the concentration gradient of the adsorbate in the solution. The absorbance of each polymer solution was measured using a UV spectrophotometer, and the adsorption capacity was calculated using the standard curve data.
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