Conventional petroleum exploration targets have become increasingly complex recently. Although geological research of unconventional oil and gas resources has received much attention in recent years, such resources also face many complex geological and scientific problems. In this context, the 8 th International Symposium on Hydrocarbon Accumulation Mechanisms and Petroleum Resources Evaluation was held in Beijing from 21 to 23 October, 2022. Experts presented and discussed their latest research findings on this topic relating to both conventional and unconventional oil and gas resources. They also discussed various development strategies for the petroleum industry taking into account the global objectives of "carbon peaking and carbon neutrality" to mitigate the impacts of climate change. Six significant theoretical advances and some new technologies were introduced at this conference. These advances related to the "Whole Petroleum System" theory, shale oil and gas exploration, deep and ultra-deep petroleum exploitation, clean energy issues, and alternative types of unconventional oil and gas resources. In response to these technological advances, four major current challenges were identified. These challenges related to the petroleum industry's ongoing growth and development in the context of carbon-neutrality goals, the evolution of hydrocarbon laws relating to petroleum accumulations and their exploitation, organic and inorganic effects on petroleum generation and accumulation mechanisms, and artificial intelligence applications related to hydrocarbon prediction.

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Abstract. To explore the effect of various solvents extraction on the chemical property of shales, several lacustrine shales from Chang 7 member of the Upper Triassic Yanchang Formation, Ordos Basin with maturities from marginally mature (Tmax = 439 ℃) to late mature (Tmax = 456 ℃) were extracted by using acetone, tetrahydrofuran (THF), carbon disulfide (CS2), and benzene, respectively. Fourier transform infrared spectroscopy (FTIR) was employed to examine the functional groups of the samples before and after extraction with different solvents. The results showed that the extraction yield from shale with THF is significantly higher than that of other solvents, which may be related to the properties of the THF, including the aromatic structure, high boiling point, excellent Hansen solubility parameters, and strong polarity. The TOC-normalized yield of the mature sample J1 is significantly higher than that of other samples, which may be related to that the J1 sample is at the peak of hydrocarbon generation, thus a large number of kerogens were cracked into oil and bitumen. The aromaticity of organic matter (OM) increases with the increase of maturity. The length of the aliphatic chains of the organic matter first increased with the increase of maturity before late maturity stage, and then decreased in late maturity stage. The extraction of shales with solvents hardly changes the length of aliphatic chains. Higher aromaticity is observed in shale residues after THF extractions than other solvents (i.e., acetone, CS2, benzene).