正构烷烃分布模式判断柴西主力烃源岩

Identification of chief hydrocarbon source rocks based on n-alkane distribution patterns in western Qaidam Basin

宋振响 周世新 穆亚蓬 陈昭

Song Zhenxiang Zhou Shixin Mu Yapeng Chen Zhao

中国石油化工股份有限公司, 石油勘探开发研究院, 无锡石油地质研究所, 江苏, 无锡, 214151 2. 中国科学院, 地质与地球物理研究所, 气体地球化学重点实验室, 兰州, 730000 3. 河南省有色金属地质矿产局, 第二地质大队, 郑州, 450016

Wuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214151, China 2. Key Laboratory of Gas Geochemistry, Institute of Geology and Geophysics, Chinese Academy of Sciences, Lanzhou, Gansu 730000, China 3. No. 2 Geological Party, He'nan Bureau of Geological Survey for Nonferrous Metals, Zhengzhou, He'nan 450016, China

柴西原油正构烷烃分布多呈偶奇优势(CPI<1),而烃源岩样品则多呈奇偶优势分布,只有少数呈偶奇优势分布。从正构烷烃分布模式出发,结合单体烃碳同位素分析,对柴西原油和烃源岩进行对比,以确定柴西原油形成的主力烃源岩。研究表明,柴西深层主力烃源层为E23,次要烃源层为E1+2和N31;浅层主力烃源层为N1,次要烃源层为N2。从生烃性能角度看,正构烷烃分布呈偶奇优势的烃源岩样品,其有机碳、氯仿沥青"A"、总烃含量、转化系数等都比呈奇偶优势分布的样品高,生烃性能较好,应为柴西主力烃源岩。

The n-alkane distribution of crude oils from the western Qaidam Basin is characterized by even-to-odd (C18—C28) predominance. Source rocks from the region are mainly characterized by odd-to-even predominance. Based on n-alkane distribution pattern, combined with single molecule carbon isotope analysis, comparing crude oil with source rock, it was discussed in this paper the main source rocks in the western Qaidam Basin. The correlation of n-alkane distribution and single molecule carbon isotope analysis illustrated that the chief hydrocarbon source layer was E23 and the secondary layers were E1+2 and N31 in deep region. Meanwhile, the chief hydrocarbon source layer was N1 and the secondary layer was N2 in shallow region. Hydrocarbon potential analysis showed that those samples with even-to-odd (C18—C28) predominance possessed higher TOC, bitumen "A", total hydrocarbon content and conversion ratio, displaying huge hydrocarbon generating potential.

国家自然科学基金项目(40572088);中国科学院知识创新工程重要方向项目(KZCX2-YW-Q05-03-05)

https://doi.org/10.11781/sysydz201102182