Abstract: Using carbon isotope, biological marker compound and other geochemical analysis methods, it is conformed that the Cambrian-Lower Ordovician source rocks and the paleo-oil reservoir cracking gas are the key factors for forming the large-sized condensate gas field in Tazhong No.1 slope-break zone; using inclusion and reservoir geochemical analysis technologies, combined with the source rock evolution history, structural history and deposition-reservoir evolution history to study the period of time and the migration of the hydrocarbon accumulation, this paper presents that Tazhong No.1 fault, the late deep strike-slip faults and multi-stage unconformities in process of shape of Tazhong paleo-uplift are the main transporting systems, thus clarifying the dynamic process of hydrocarbon accumulation in late Caledonian episode, paleo-oil reservoir adjustment, oil-gas transfer and generation from source rocks in late Hercynian episode, as well as multi-stage oil-gas charging processes of cracking gas in Himalayan paleo-reservoir into early oil reservoirs. In particular, this paper points out that the heterogeneity of reef-shoal complex and the diversity of transporting system are the key factors resulting in complex fluid distribution, hence develops the multi-stage charging and multi-stage adjusting hydrocarbon accumulation models. This study shows the characteristics of gas rich in outer zone and oil rich in inner zone of Tazhong No.1 slope-break zone, which enriches the theory of hydrocarbon accumulation in marine carbonate rocks in Tarim basin.

Key words: Tarim basin, Tazhong No.1 slope-break zone, reef-shoal complex, giant condensate field, multiple oil sources, multi-stage hydrocarbon accumulation