Distribution and properties of high molecular weight hydrocarbons in crude oils and oil reservoir of Shengli oil field, China

With the development of high temperature gas chromatography (HTGC), it is possible to examine high molecular weight hydrocarbons (HMWHCs) up to about C120. Utilizing the difference in solubility between HMWHCs and middle-low molecular weight ones, HMWHCs were separated from other components and concentrated. In order to keep the comparability of indies between conventional methods and HTGC, all samples from Shengli oil field of China were analyzed by several kinds of instruments. The contents and distribution characteristics of HMWHCs in various types of oils and the ability of anti-biodegradation of HMWHCs were summarized. The ubiquitous occurrence of HMWHCs was found. The ability of anti-biodegradation of HMWHCs is approximately equivalent to that of regular steranes. Dense sampling and analyses with HTGC and conventional instruments revealed the low mobility and heterogeneity of HMWHCs in oil reservoir of Gaoxie 73 well. The contents of HMWHCs in oil layers were obviously more than that in oils produced.