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Abstract: The Lower Palaeozoic deep marine strata of the Tarim Basin are rich in petroleum resources and show bright prospect of exploration. The Tarim Basin is a typical multicycle superimposed cratonic basin. The Tarim Basin experienced a number of significant structural changes, resulting in a complex reservoiring process of oil and gas with the characteristics of “multi-source hydrocarbon supply, multi-stage reservoir, and mixed adjustment”. The Cambrian-Ordovician hydrocarbon source rock in the Tarim Basin can be divided into three sets of source rocks: the Mid-Lower Cambrian, Mid-Lower Ordovician, and Upper Ordovician ones. The low geothermal gradient in the Tarim Basin contributed to the late oil generation of Cambrian and Ordovician oil-gas source rocks. The oil and gas of ultra-deep marine carbonates in the Tarim Basin generally commonly originated from multiple source rocks. The ultra-deep carbonate reservoirs in the Tarim Basin include four types, namely, reef-bank reservoir, dolomite reservoir, karst reservoir, and fracture reservoir, which are jointly controlled by factors of structure, strata sequence, facies, and fluid. The ultra-deep carbonate reservoirs in the Tarim Basin experienced multiple oil and gas accumulation period. The first accumulation period occurred in the late Caledonian period, the second one in the late Hercynian period, and the third one in the Himalayan period. The petroleum reservoir in the Tarim Basin is characterized by obvious multi-stage sealing and layered enrichment. Many types of pathways of migration were developed in the Tarim Basin, such as unconformities, faults, fractures, permeable transport layers, and volcanic piercement. The validity of pathways of hydrocarbons migration mainly depends on the location of source rocks and the matching relation between the period of hydrocarbon generation and migration and the formation of pathways. The formation and distribution of petroleum reservoir in the Tarim Basin is mainly controlled by factors of palaeouplift, palaeoslope, hydrocarbon source, regional seal, and structural balance zone.

Keyword: Main control factors, Hydrocarbon accumulation, Ultra-deep marine carbonates, Tarim Basin