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A large number of primary oil and gas reservoirs have been discovered in Proterozoic strata all over the globe. Proterozoic sequences are widely distributed in China, and the discovery of large Sinian-aged gas reservoirs in the Sichuan Basin and Mesoproterozoic liquid oil seepages in North China shows that attention should be paid to the exploration potential of Proterozoic strata. In this paper, the main controlling factors of Proterozoic source rocks are discussed. Principally, active atmospheric circulation and astronomical cycles may have driven intense upwelling and runoff to provide nutrients; oxygenated oceanic surface waters could have provided suitable environments for the organisms to thrive; volcanic activity and terrestrial weathering caused by continental break-up would have injected large amounts of nutrients into the ocean, leading to persistent blooms of marine organisms; and extensive anoxic deep waters may have created ideal conditions for the preservation of organic matter. Additionally, the appearance of eukaryotes resulted in diversified hydrocarbon parent material, which effectively improved the generation potential for oil and gas. Through the comparison of Formations across different cratons, seven sets of Proterozoic organic-rich source rocks have been recognized in China, which mainly developed during interglacial periods and are also comparable worldwide. The Hongshuizhuang and Xiamaling Formations in North China have already been identified previously as Mesoproterozoic source rocks. The early Proterozoic Changchengian System is highly promising as a potential source rock in the Ordos Basin. In the Upper Yangtze area, the Neoproterozoic Datangpo and Doushantuo Formations are extensively distributed, and represent the major source rocks for Sinian gas reservoirs in the Sichuan Basin. Moreover, the Nanhuan System may contain abundant shales with high organic matter contents in the Tarim Basin, although this possibility still needs to be verified. Indeed, all three cratons may contain source rocks of Proterozoic strata; thus, these strata represent major exploration targets worthy of great attention. [ABSTRACT FROM AUTHOR]

On the basis of the results of simulation experiments, now we better understand the contribution of high carbon number hydrocarbons to diamondoid generation during thermal pyrolysis of crude oil and its sub-fractions (saturated, aromatic, resin, and asphalene fractions). However, little is known about the effect of volatile components in oil on diamondoid generation and diamondoid indices due to the lack of attention to these components in experiments. In this study, the effect of volatile components in oil on diamondoid generation and maturity indices was investigated by the pyrolysis simulation experiments on a normal crude oil from the HD23 well of the Tarim Basin and its residual oil after artificial volatilization, combined with quantitative analysis of diamondoids. The results indicate that the volatile components (≤ nC) in oil have an obvious contribution to the generation of adamantanes, which occurs mainly in the early stage of oil cracking (Easy R<1.0%), and influences the variations in maturity indices of adamantanes; but they have no obvious effect on the generation and maturity indices of diamantanes. Therefore, some secondary alterations e.g., migration, gas washing, and biodegradation, which may result in the loss of light hydrocarbons in oil under actual geological conditions, could affect the identification of adamantanes generated during the late-stage cracking of crude oil, and further influence the practical application of adamantane indices. [ABSTRACT FROM AUTHOR]