吉木萨尔凹陷芦草沟组致密油分子尺寸及结构特征

致密油分子尺寸及流动性的研究对致密油藏评价及开发具有重要意义.为明确吉木萨尔凹陷芦草沟组致密油的分子尺寸及其对原油流动的影响，综合核磁共振、红外光谱、元素分析和相对分子质量测定等结果，计算了典型井致密油不同馏分段的分子结构参数，采用Chemoffice软件模拟了相应的分子结构.结果显示致密油组分主要集中在350~500℃馏分段，平均分子中含有多环环烷烃和多环芳烃结构，平均分子尺度为1.232~4.026 nm，表明原油分子在纳米孔喉中占有率较高，影响孔喉流动下限. 

Molecular Size and Structure Characteristics of Tight Oil of Lucaogou Formation in Jimusar Depression

The study of the size and fluidity of tight oil is of great significance for the evaluation and development of tight reservoirs. In order to determine the molecular size and its influence on mobility of tight oil of Lucaogou Formation in Jimusar depression, the average structure parameters of different fractions of Ji 174 tight oil were calculated on the basis of 1H-NMR, IR, elemental analysis and molecular weight measurement. According to the parameters, the molecular structures of several fractions from Ji 174 tight oil were simulated by using the Chemoffice software. The results show that the components of the tight oil are mainly concentrated in the fraction from 350 to 500℃, and there are polycyclic naphthene and polycyclic aromatic structures in the average molecules with the sizes of 1.232-4.026 nm. It is the large molecular scale that leads to high shares of oil molecules in nano-pore-throat and affects the pore throat flow limit of the reservoir.