Polymer flooding by hydrolyzed polyacrylamide (HPAM) is a well-known enhanced oil recovery (EOR) technique which is mainly applied to viscosify the pushing fluid and improve the mobility ratio; however, the role of this polymer on the rock wettability alteration, one of three main recovery mechanisms, has remained a topic of debate. In this study, the adsorption of hydrolyzed-polyacrylamide on the carbonate surface was investigated by molecular dynamic simulation considering a simple Young model based on the surface tensions of each phase to calculate the water contact angle and then continued by an experimental procedure after aging carbonate slices in the oil and polymer solutions. Dreiding and Universal force fields were selected for the simulation of water and HPAM boxes, respectively, to calculate non-bonding/bonding energies and surface tension for the water, polymer, and three-phase system including calcite rock. The polymer adsorbing decreased the final water contact angle to about 130 and 140 degrees at the ambient and reservoir temperatures, respectively, to provide a moderately oil-wet state and a good agreement with the experimental results for the surface wettability alteration toward the water wetting. However, the theory and laboratory observations showed a different relation between the polymer adsorption and increasing temperature. Lennard-Jones potentials showed the polymer surface desorption at the increased kinetic energy of molecules due to the molecular distance whereas in the experiment condition the tendency of polymer adsorption on the calcite surface increased with temperature, probably because of ion exchange and thermal decarboxylation phenomenon. These findings make an opportunity to further molecular dynamic investigations of different polymers as a wettability modifier through the EOR process.

水解聚丙烯酰胺（HPAM）驱聚合物是一种众所周知的增强采油率（EOR）技术，主要用于增稠推动液的粘度和提高流动率。然而，这种聚合物在岩石润湿性改变（三种主要采收机理之一）中的作用一直是争论的话题。在这项研究中，通过分子动力学模拟研究了水解聚丙烯酰胺在碳酸盐表面上的吸附，该动力学基于每个相的表面张力，基于简单的杨模型，计算了水接触角，然后在碳酸盐切片老化后通过实验程序继续进行。在油和聚合物溶液中。选择了Dreiding和Universal力场分别模拟水箱和HPAM箱，计算水，聚合物和包括方解石岩石的三相系统的非键合/键合能和表面张力。吸附的聚合物分别在环境温度和储层温度下将最终水接触角分别降低至约130度和140度，以提供适度的油湿状态，并与针对水润湿的表面润湿性改变的实验结果良好吻合。然而，理论和实验室观察表明聚合物吸附与温度升高之间存在不同的关系。Lennard-Jones势表明，随着分子距离的增加，在分子动能增加时聚合物表面解吸，而在实验条件下，方解石表面上聚合物的吸附趋势随温度的升高而增加，可能是由于离子交换和热脱羧现象。这些发现为通过EOR方法对作为润湿性调节剂的不同聚合物进行进一步的分子动力学研究提供了机会。