The Shanxi Formation layers in the northeast of the Zhoukou Depression, Southern North China Basin, mainly consist of dark mudstone interbed with tight stone and widely developed coal seam, which is a promising target for unconventional oil and gas exploration. A series of geochemical and geological methods were used to analyze the characterization and controls of the pores structural heterogeneity in low-thermal-maturity shale. These methods include the Rock-Eval analysis, total organic carbon (TOC) analysis, scanning electron microscope observation with an energy-dispersive spectrometer (SEM-EDS), X-ray diffraction, and low-pressure N2 adsorption. Based on these measurements, the pore diameter, specific surface area (SSA), and fractal dimension (D) were calculated, and then, the pore structure heterogeneity was analyzed. The result shows the pores of Shanxi Formation shale are mainly interparticle pores with low porosity and low permeability, and the pore structure is highly complex. The average fractal dimension of the micropore and the macropore are both 2.77, but that of the mesopore is 2.65, indicating a less-complex mesopore structure than the micropore and macropore. The S2, S1, and TOC exhibit no clear correlation with SSA and fractal dimension of pores, which proved the little impact of organic matter on the heterogeneity of pore structure in the low-maturity shale of the research area. The illite has a strong effect on the pore structural heterogeneity of Shanxi Formation shale. The samples with high content of illite show higher SSA, better physical properties, and low fractal dimension, reflecting low pore structural heterogeneity. However, the quartz and clay minerals show a slight correlation with SSA and no obvious relationship with the fractal dimension, indicating a little effect of them on the pore structure heterogeneity. The pore structural heterogeneity decreases along with the increase in porosity, while the permeability influenced by a variety of reasons under the compaction shows a poor relationship with SSA and fractal dimension. On the whole, the pore structural heterogeneity decreases for low-thermal-maturity shale with high content of illite and high porosity, which should be considered to be the better unconventional oil and gas reservoir in the research area.

Pore structural characteristics and methane adsorption capacity are two significant aspects affecting shale gas potential, but the impact of deposition and burial processes on these two aspects is not clear. Hence, the shale samples of Taiyuan Formation deposited continuously and experienced multi-stage tectonic uplift in Fuyang-Bozhou area of Southern North China Basin were collected in this study. Based on the total organic carbon content analysis, mineral composition determination, low-pressure CO2 and N2 adsorption, high-pressure methane adsorption and argon ion polishing-field emission scanning electron microscope observation. The impact of depositional and burial processes variation on shale reservoir physical properties and adsorption performance is studied. The results display that the pore types of shale samples which were continues deposited and experienced multi-stage tectonic uplift have no obvious differences, while the pore volume as well as specific surface area (SSA) of micropores and mesopores of shale samples under multi-stage tectonic uplift are larger significantly. Meanwhile, the roughness of shale pores increases also. The decrease of loading pressure caused by multi-stage tectonic uplift may be the main factor for the pore structure changes of shale sample. Compared with the continuous deposited samples, the shale samples under multi-stage tectonic uplift have stronger methane adsorption capacity, which is relevant to the greater SSA of micropores as well as mesopores. This study provides an example and new revelation for the influence of depositional and burial processes on shale pore structure and methane adsorption capacity.

Background: Chronic diabetes mellitus compromises the vascular system, which causes organ injury, including in the lung. Due to the strong compensatory ability of the lung, it always shows subclinical symptoms. Once sepsis occurs, the degree of lung injury is more severe under hyperglycaemia. α7nAChRs play an important role in regulating inflammation and metabolism. Our previous study demonstrated that PNU282987, an α7nAChR agonist, could improve endothelial progenitor cell functions. In this study, we examined the role of diabetes mellitus during sepsis and whether α7nAChR activation combined with endothelial progenitor cell transplantation can protect the lung from septic and diabetic impairments. Methods: Type 2 diabetic model rats were induced by a high-fat diet and streptozotocin. Then, these rats were exposed to lipopolysaccharide in a two-hit manner to cause sepsis. The oxygenation index, wet-to-dry ratio and histopathological score of the lungs were tested after PNU282987 treatment and EPC transplantation. IL-6, IL-8, TNF-α and IL-10 levels were measured by ELISA. Caspase-3, Bax, Bcl-2, NF-κB, phosphorylated JAK2 and phosphorylated STAT3 levels were measured by western blotting to investigate apoptosis and the underlying mechanism. Results:Sepsis caused obvious lung injury, which was exacerbated by diabetic conditions. α7nAChR activation and endothelial progenitor cell injection reduced injury in diabetic rats with sepsis, alleviating inflammation and decreasing apoptosis. This treatment was more effective when PNU282987 and endothelial progenitor cells were administered together. The JAK2/STAT3 signalling pathway was activated during this process, and the phosphorylation of NF-κB was inhibited. Conclusion: Activating α7nAChRs and endothelial progenitor cell transplantation alleviated the lung injury in diabetic rats with sepsis. Combining PNU282987 with endothelial progenitor cell transplantation showed better results than either treatment alone. During this process, the JAK2/STAT3 signalling pathway was activated, and NF-κB was inhibited.