Impact Drilling Technology is one of the most effective methods for enhancing the penetration rate and efficiency in hard rock formations. Downhole axial vibration impact tools can provide a stable impact load, but they also increase the complexity of the Bottom Hole Assembly (BHA) motion. Addressing the problem of vibration fatigue in the lower BHA when subjected to high-frequency impact stresses during impact drilling, this study utilizes finite-element impact modules and Design-Life fatigue analysis software to establish a nonlinear dynamic model of the drill string assembly under axial excitation. It investigates the influence patterns of control parameters, such as the impact energy and impact frequency, on BHA vibration damage and rock-breaking efficiency. The results show that the vibration characteristics of the BHA are significantly affected by the impact tool’s control parameters. Increasing the input impact energy intensifies the amplitude of alternating stress in the drill string system. Meanwhile, the equivalent stress fluctuation of the drill string tends to stabilize at high frequencies above 100 Hz, indicating that high-frequency impacts are beneficial for mitigating vibration damage and prolonging the service life of the BHA. This study provides a theoretical basis for reducing the drill string fatigue damage and optimizing the drilling parameters for an improved performance.

Residual coal-fire gas vents form steep thermal and geochemical gradients that create sharply distinct microbial habitats over short distances. We compared the microbial communities of two microhabitats at a residual vent near Kuitun City, Xinjiang: BS1, a gas-emitting fracture at 64 °C, and BS2, adjacent cooler sediment at 43 °C. BS1 had pH 6.8 and total sulfur 5.86 g/kg, whereas BS2 had pH 8.4 and total sulfur 1.90 g/kg. Illumina sequencing of the 16S rRNA gene V3–V4 region yielded 52,327 and 64,212 merged read pairs retained for downstream analyses for BS1 and BS2, respectively. BS1 contained fewer observed amplicon sequence variants (ASVs; 524 versus 1366) and lower Shannon diversity (5.626 versus 6.588). Chloroflexota dominated both communities but was more abundant in BS1 (43.83% versus 36.33%), whereas BS2 contained larger Proteobacteria and Bacteroidota fractions. BS1 was enriched in Pyrinomonas, unclassified Chloroflexota, unclassified Anaerolineae, and Thermorudis, while BS2 was enriched in Thermogemmatispora, Massilia, and Arthrobacter. At this vent, the hot fracture therefore supported a lower-diversity, Chloroflexota-enriched community, whereas cooler sediment supported a richer and more compositionally diverse community. Together with the mineralogical observations, these results reveal sharp site-scale partitioning of bacterial assemblages across a coupled thermal-pH-sulfur gradient.