Composition and origin of molecular compounds in the condensate oils of the Dabei gas field, Tarim Basin, NW China

• 作者: CHEN Weiyan CHI Linxian LI Tingting YAN Huihui YANG Haijun ZHANG Zhiyao ZHAO Kun ZHU Guangyou
• 来源期刊: 石油勘探与开发:英文版
• 学科: 工学
• 关键词: CONDENSATE oil molecular compound adamantanes comprehensive two-dimensional GAS chromatography Dabei GAS field KUQA DEPRESSION TARIM Basin
• 年，卷（期）: 2019,（3）
• 页码范围: 504-517
• 页数: 14页
• 分类号: TE

摘要

The Dabei gas field in the Kuqa Depression of the Tarim Basin is the most complex and deep continental condensate gas field in China. Comprehensive two-dimensional gas chromatography?time of flight mass spectrometer (GC×GC-TOFMS) analysis was conducted on five condensate oil samples from this field. The results show that the samples have n-alkane series in complete preservation and rich adamantanes. According to the methyladamantane index, the condensate oil is the product of the source rock with vitrinite reflectance (Ro) of 1.3%–1.6%. According to the gas maturity calculated through carbon isotope and vitrinite reflectance, the natural gas is corresponding to Ro of 1.3%–1.7%, reflecting that the natural gas and condensate oil are basically formed during the same period at the high maturity stage of source rock. The Dabei gas field has favorable geological conditions for hydrocarbon accumulation: thick salt rock in the Paleogene acts as a regional high-quality caprock directly overlying the high-quality sandstone reservoir of the Cretaceous, the coal source rocks have high hydrocarbon generation intensity and provide continuous oil and gas, and the subsalt thrust structures develop in rows with rich faults, providing migration pathways for oil and gas migration. These factors together controlled the formation of the Dabei gas field.