The crystallization behavior of wax molecules is the root cause of wax deposition. In this study, molecular dynamics simulations were used to investigate the aggregational crystallization behavior of wax molecules in a crude oil system. The results show that wax molecules produce ordered wax crystal structures from the disordered liquid phase crude oil system under van der Waals forces at low temperatures. The crystallization of wax molecules consists of three main processes: carbon chain extension, nucleation of wax molecules and wax crystal growth. The lower the temperature of the crude oil system and the lower the cooling rate, the higher the degree of aggregation of wax molecules, the smaller the number of wax crystals and the larger the crystal size. In addition, asphaltene molecules are found to aggregate by face-to-face stacking and T-shaped stacking at low temperatures. Based on the spatial steric hindrance effect, the asphaltene aggregates prevent further aggregation between wax crystal clusters. Asphaltenes lead to an increase in the liquid content of the wax deposit layer, causing the yield stress of the deposit to decrease and the structural strength to weaken.

蜡分子的结晶行为是蜡沉积的根本原因。在这项研究中，分子动力学模拟用于研究原油系统中蜡分子的聚集结晶行为。结果表明，蜡分子在低温范德华力作用下，从无序液相原油体系中产生有序的蜡晶体结构。蜡分子的结晶包括三个主要过程：碳链延伸、蜡分子成核和蜡晶体生长。原油体系温度越低，冷却速度越低，蜡分子的聚集程度越高，蜡晶体的数量越少，晶体尺寸越大。此外，发现沥青质分子在低温下通过面对面堆积和T形堆积而聚集。基于空间位阻效应，沥青质聚集体阻止蜡晶簇之间的进一步聚集。沥青质导致蜡沉积层的液体含量增加，导致沉积的屈服应力降低，结构强度减弱。