Geochemical Characteristics and Reservoir Formation of Cambrian Heavy Oil of Well Tadong 2 in Tarim Basin

Key words: 
• oilsource rock correlation

Abstract: Studying the geochemical characteristics and formation history of heavy oil from Well Tadong 2 is of great importance to clarify the oil accumulation of Tarim marine crude oil. The writer synthetically apply the isotope mass spectrogram, chromatogram and chromatogrammass spectrogram methods to the research of molecular fossil characteristic of heavy oil from Well Tadong 2 , and results reveal that heavy oil from Well Tadong 2 is characterized by high gammacerane , high C28 sterane ,low rearranged sterane and high C27triaromatic steroid, these characteristics are similar to that of CambrianLower Ordovician source rock , which demonstrate that Cambrian crude oil come from CambrianLower Ordovician source rock; condensed compounds (fluoranthene, pyrene, benzo\[a\]anthracene, bow, benzo fluoranthene, benzopyrene) with high abundance are detected in the heavy oil of Well Tadong 2, and carbon isotope value of whole oil evidently lean to heavier, all foregoing characteristics revealing that hydrocarbons in crude oil become densification by thermal alteration. Homogenization temperature of fluid inclusion and burialthermal evolution history imply that accumulation period of heavy oil from Well Tadong 2 may be at 450~440 Ma. 