Ordos Basin is an important continental shale gas exploration site in China. The micropore structure of the shale reservoir is of great importance for shale gas evaluation. The Taiyuan Formation of the lower Permian is the main exploration interval for this area. To examine the nanometer pore structures in the Taiyuan Formation shale reservoirs in the Lin-Xing area, Northern Shaanxi, the microscopic pore structure characteristics were analyzed via nitrogen adsorption experiments. The pore structure parameters, such as specific surface area, pore volume, and aperture distribution, of shale were calculated; the significance of the pore structure for shale gas storage was analyzed; and the main controlling factors of pore development were assessed. The results indicated the surface area and hole volume of the shale sample to be 0.141–2.188 m²/g and 0.001398–0.008718 cm³/g, respectively. According to the IUPAC (International Union of Pure and Applied Chemistry) classification, mesopores and macropores were dominant in the pore structure, with the presence of a certain number of micropores. The adsorption curves were similar to the standard IV (a)-type isotherm line, and the hysteresis loop type was mainly similar to H3 and H4 types, indicating that most pores are dominated by open type pores, such as parallel plate-shaped pores and wedge-shaped slit pores. The micropores and mesopores provide the vast majority of the specific surface area, functioning as the main area for the adsorption of gas in the shale. The mesopores and macropores provide the vast majority of the pore volume, functioning as the main storage areas for the gas in the shale. Total organic carbon had no notable linear correlation with the total pore volume and the specific surface area. Vitrinite reflectance (Ro) had no notable correlation with the specific surface area, but did have a low “U” curve correlation with the total pore volume. There was no relationship between the quartz content and specific surface area and total pore volume. In addition, there was no notable correlation between the clay mineral content and total specific surface area and total pore volume.

Biomarker compounds that derived from early living organisms play an important role in oil and gas geochemistry and exploration since they can record the diagenetic evolution of the parent materials of crude oil and reflect the organic geochemical characteristics of crude oil and source rocks. To offer scientific basis for oil exploration and exploitation for study area, gas chromatography-mass spectrometry method is applied to study the biomarker compounds of crude oil in Southwestern Yishan Slope of Ordos Basin, through qualitatively and quantitatively analyzing separated materials. The crude oil of Yanchang Formation and the source rocks of Yan’an and Yanchang Formation were collected in order to systematically analyze the characteristics of the biomarker compounds in saturated hydrocarbon fractions and clarify the organic geochemical characteristics of crude oil. The distribution and composition of various types of hydrocarbon biomarker compounds in crude oil suggest that the parent materials of crude oil are composed of hydrobiont and terrigenous plants, and the crude oil is mature oil which is formed in the weak reducing fresh water environment. Oil source correlation results show that the crude oil of Yanchang Formation in Yishan Slope is sourced from the source rocks of Chang 7 subformation.

Over-mature shale has undergone complex geological processes, e.g., diagenesis, deep thermolysis, epigenesis, and metamorphism. During this series of processes, the internal components of shale are transformed coordinatively, and the special pore structure with a complex genesis in the over-mature shale is formed. The study of the special pore structure of over-mature shale and its main controlling factors can provide theoretical support for shale gas exploration and development. In this study, the over-mature shale of the Longtan Formation in the Laochang area, eastern Yunnan Province, China, was tested and analyzed to determine the total organic carbon content, kerogen microscopic composition, and its vitrinite reflectance. Moreover, the mineral composition and pore characteristics of the shale were tested using X-ray diffraction, the argon ion polishing field emission scanning electron microscopy technique, and the low temperature nitrogen adsorption experiment. The results show that the compositions of Longtan Formation shales have a low rigid clastic particles content, high clay content, and abundant metasomatic ankerite, and that the organic matter, dominated by type III, is highly mature. At the same time, the shale pore structure is characterized by a large average pore size, well-developed macropores, and a high number of micropores and mesopores. By analyzing the transformation of the mineral composition of shale during thermal evolution, the controlling factors of pore structure are determined. During the evolution of shale, the intergranular pores (mainly large pores) between rigid minerals are destroyed in large quantities. After a short period, a large number of dissolved pores with the pore size of macropores are formed in the acid-resistant minerals under the action of organic acid. These dissolved pores, together with the remaining intergranular pores of rigid minerals and micro-fractures, form most of the macropores of shale. There is a large amount of ankerite in over-mature shale formed during metasomatism, which occludes some pores of shale. However, intragranular pores and cleavage-sheets develop in ankerite, contributing some porosity to the shale reservoir. Inter-clay pores and organic matter pores constitute most shale micro and mesopores, and between which inter-clay pores take dominance.

To support carbon peaking and neutrality goals in the city transportation sector, this paper accounts for CO₂ emissions from the transport sector in Xuzhou City, North Jiangsu Province, from 1995 to 2023. This study explores the relationship between transport-related carbon emissions and economic growth, using the TAPIO decoupling index. Meanwhile, a carbon emission prediction model based on the STIRPAT framework is constructed, with scenario analysis applied to forecast future emissions. Results show three decoupling stages: the first, dominated by weak and expansive negative decoupling, reflects extensive economic growth; the second features weak decoupling with expansive coupling, indicating a more environmentally coordinated phase; the third transitions from expansive negative decoupling and weak decoupling to strong decoupling and expansive coupling, suggesting a shift in development patterns. Under the baseline, low-carbon, and enhanced low-carbon scenarios, by 2030, the CO₂ emissions of the transportation industry in Xuzhou will be 10,154,700 tons, 9,072,500 tons, and 8,835,000 tons, respectively, and the CO₂ emissions under the low-carbon scenario and the enhanced low-carbon scenario will be reduced by 10.66% and 13.00%, respectively. Based on these findings, the study proposes carbon reduction strategies for Xuzhou’s transport sector, focusing on policy regulation, energy use, and structural adjustments.

The geochemistry of the fatty acids in the modern sediments in the Northern South Yellow Sea is still poorly studied, and studies on the geochemistry of the fatty acids in relatively long-core sediment samples are lacking. Thus, the fatty acids in the core sediments in the Northern South Yellow Sea were separated and identified to study their components and distribution characteristics, and the sources of organic matter and the early diagenetic evolution of the fatty acids in the sediments were discussed. The results show that saturated straight-chain fatty acids (methyl ester) have the highest content in the core sediments in the Northern South Yellow Sea, which account for 83.89% of the total fatty acids (methyl ester). nC_16:0 is dominant, accounting for 30.48% of the n-saturated fatty acids (methyl ester). Unsaturated fatty acids (methyl ester) account for 7.59% of the total fatty acids (methyl ester). Binary unsaturated fatty acids (methyl ester) can only be detected in some samples, which are low in content and dominated by C_18:2. Based on the components and distribution of the fatty acids (methyl ester) in the core sediments in the Northern South Yellow Sea, combined with the characteristics of other lipid biomarker compounds, the actual geological background, and previous research results, it is considered that the sources of organic matter in the core sediments are marine–terrestrial mixed materials, with terrestrial materials dominating. The fatty acids’ (methyl ester) CPI, the relative content of short-chain saturated fatty acids (methyl ester), and the unsaturated fatty acids (methyl ester) in the core sediments show non-obvious variation as the burial depth increases, reflecting that the fatty acids in the core sediments are strongly degraded at the early diagenetic stage, and this degradation is controlled by various complicated factors.

Huaqing area is an important area for oil and gas exploration and development in the Ordos Basin, within which, the Chang 9 oil group of Triassic Yanchang Formation is one of the main intervals for exploration and development (Zhang et al., 2011). Fluid inclusions record abundant oil and gas accumulation information and important oil and gas migration and accumulation history information(Parnell et al., 1998; Parnell, 2010; Jiang et al., 2018). The occurrence, distribution and intersection of the fluid inclusions in diagenetic minerals were observed under microscope. The accurate formation periods of inclusions are key to determine hydrocarbon accumulation periods (Burrus et al., 1985; Zhou et al., 2000; Zhao, 2002). In addition, the fluorescence color and brightness of organic inclusions observed by fluorescence microscopy could be used to roughly identify the oil and gas evolution stages (Zhang et al., 2010). Therefore, the occurrence, distribution and fluorescence characteristics of oil and gas inclusions were important evidence for judging the hydrocarbon accumulation periods. The fluid inclusions in sandstone reservoirs of Chang 9 oil group in Huaqing Area were observed in detail, and the observation results revealed that fluid inclusions were widespread in Chang 9 sandstone and exhibited various types. Through comprehensive analyses, it was considered that the fluid inclusions in Chang 9 sandstone reservoirs indicated three hydrocarbon accumulation periods.