重油组分密度表征和结构验证的分子模拟

Application of molecular simulation in density characterization and structure validation of heavy oil fractions

经实验推断重油组分平均分子结构后,利用分子模拟技术对重油组分密度和分子结构合理性进行了研究。通过对模型化合物正四十烷、1-十二烷基萘的密度模拟确定了分子模拟所适合的模拟参数和计算流程,在同样的条件下进行重油组分密度的模拟,并与实验值进行比较。结果表明,模型化合物正四十烷、1-十二烷基萘的密度模拟值的相对误差分别为0.27%和0.26%,说明采用的模拟参数和计算流程适于密度模拟表征;在相同模拟条件下,可较为准确地获得重油组分的密度值,与实验值的相对误差约为2%～3%,说明所推断的重油组分平均分子结构是合理可靠的。分子模拟在密度表征的同时也可作为判断所推测平均分子结构合理性的工具。

Average molecular structure of heavy oil fractions was constructed by elemental analysis, molecular weight determination, NMR. And then, the rationality of density and molecular structure was justified with molecular simulation. At first, n-tetracontane and 1-dodeeyl naphthalene were selected as model compounds to do density simulation, which was used to establish the simulation parameters and calculation process. Under the same simulation condition, the density of heavy oil fractions was simulated, and then compared with the experimental value. The result showed that the relative errors of density of ntetracontane and 1-dodecyl naphthalene were 0.27 % and 0.26 % respectively, indicating that the simulated condition was suitable for density characterization. The density values of heavy oil fractions obtained by molecular simulation compared well with the experimental value, and the relative errors were between 2 % and 3%. The consistence of simulation density and experimental density confirmed that the average molecular structure of heavy oil fractions were deduced reasonably. Therefore, molecular simulation could be used as a tool to estimate of density, and the result could justify the average molecular structure of heavy oil fractions.