Constraining the Period of Hydrocarbon Accumulation by Fluid Inclusion, Molecular Biomarker and ESR Dating Techniques: A Case Study from the Tazhong 45 Well, Tarim Basin
摘要
///Two distinct generations of hydrocarbon inclusions are found in vein fluorite from the Ordovician carbonate reservoirs in the Tazhong 45 well,Tarim Basin. Based on an integrated investigation, it is concluded that: 1) the fluorite vein was formed by a deep fluoride-rich fluid brought into the Ordovician carbonate formation through deep faults during the Permian; 2) the fluoride-rich fluid was a low temperature hydrothermal fluid probably generated from an acidic magmatic activity in the region during the Late Hercynian; 3) the charge of mature liquid hydrocarbons from the Middle-Upper Ordovician source rock was concomitant with the fluorite crystallization in the Tazhong 45 carbonate reservoirs; 4) the second generation of hydrocarbon inclusions distributed along the fluorite fractures were formed at around 23 Ma during the Himalayan stage; 5) the late charged hydrocarbons were derived primarily from highly mature Cambrian source rocks in the Tarim Basin; and 6) the second hydrocarbon charge in the Tazhong 45 well coincided with a basin-wide hydrocarbon expulsion and accumulation of primarily high maturity oil.