The fluid–solid coupling effect is more pronounced in the process of deep coal seam development compared to shallow coalbed methane, exerting a greater influence on production, and cannot be disregarded. Throughout the extraction process, the interaction between effective stress and gas desorption triggers deformation within the coal seam, leading to dynamic changes in both porosity and permeability. This paper has developed a fully coupled gas flow and deformation model that contains the coal matrix and discrete fractures to describe the dynamic gas seepage behavior and deformation of deep coal seams within a coupled wellbore–hydraulic fractures–matrix system. The model's validity is corroborated through the examination of fracture aperture, employing the finite element numerical simulation capabilities of COMSOL Multiphysics. Subsequent to the model's validation, an in-depth investigation into the permeability and production variations under diverse parametric conditions is conducted. This analysis also encompasses the assessment of hydraulic fracture geometry's impact. The simulation outcomes reveal that the permeability alterations during coal seam development are subject to the counteracting influences of gas desorption and effective stress. Moreover, it is observed that an increase in the Langmuir volume strain constant and initial porosity correlates with enhanced production, whereas a diminution in the hydraulic fracture compression coefficient leads to increased cumulative production. Notably, the optimal production is attained when hydraulic fractures are oriented vertically yet asymmetrically relative to the horizontal well.

Well-documented outcrops around the Emeishan Large Igneous Province (ELIP) in South China, eastern Tethys, encompassing the end-Guadalupian mass extinction have been investigated. Correlatable sections recording the event exhibit very similar lithological characters, positive-then-negative C isotope excursions and massive biotic demise. Detailed analyses of the fossil record and carbon isotopic variations were carried out on the Guadalupian–Wuchiapingian Boundary sections over the inner, middle, outer zones of the ELIP and its margin. Due to a pronounced decrease in marine habitat area and the environmental and ecological change over this part of the Tethys, the biota crisis records show the loss of numerous tropical invertebrate taxa, and exhibit fewer genera and smaller testing sizes and low productivity. The biota crisis was a sustainable and gradual reduction in diversity over the Capitanian. The associated carbon isotopic data reveal unusually high δ¹³C(carb) values before the late Capitanian, representing higher primary productivity (or buried rate) and more ¹³C-enriched CO₂ released by hydrothermal carbonate breakdown from the upper crust into the sediments at that time. Subsequently, an accelerated negative excursion across the boundary and the gradual excursion with low carbon isotope amplitude favours an increased influx of light ¹²C sourced by the volcanism around the eastern Tethys. The very similar time–space relation between the biota crisis and the Emeishan volcanism confirms that volcanic eruptions may have triggered the biota crisis event in South China. Intensive volcanism could result in detrimental environmental and ecological stresses, habitat loss, organic material splitting, or the emission of light carbon and thermal fluid (or aerosol), implying that the losses of the shallow-marine invertebrates either occurred geologically instantaneously or in a series of closely spaced crises coinciding with the initial phase of ELIP formation. These findings in South China may reveal the causal relation between mass extinctions and LIPs in a global context.

The remains of trilobites and other species were unexpectedly discovered in a volcanic ash layer beneath the Permian–Triassic Boundary (PTB). Based on a biostratigraphic investigation of the Zhongliangshan section in Chongqing, South China, the quantity of the species gradually decreased with subsequent volcanism. This finding provides an opportunity to further understand the disappearance of trilobites and the evolution of the mass extinction event. The temporal coincidence between the volcanic eruption event and the loss of trilobites and other species supports the idea of a cause-and-effect relationship. The species remains in the ash bed appeared before the disappearance of Clarkina yini and the climax of the negative carbon isotope excursion, which implies that the onset of the mass extinction occurred at the end-Permian. The explosive volcanic events caused massive releases of CO₂, toxic gases and volcanic ash and resulted in loss of habitat for certain species in the Tethys domain. This phenomenon may have led to the abrupt death of trilobites and the catastrophic collapse of biodiversity.

Lacustrine depositional systems are more sensitive to climatic fluctuations than marine systems, producing significant stratigraphic and sedimentological heterogeneity that affects shale oil distribution. However, the mechanisms linking paleoclimatic variability to shale oil enrichment remain insufficiently constrained. This study investigates the coupling between hydrological variations, organic matter enrichment, and pore structure development under different climatic conditions in the Second Member of the Funing Formation from Well A1 in the Qintong Depression. Using a combination of total organic carbon (TOC) analysis, total sulfur (TS) analysis, X-ray diffraction (XRD), high-resolution geochemical profiling, field-emission scanning electron microscopy (FE-SEM), and helium porosimetry, we reveal how paleoclimate influences shale oil accumulation. The Second Member of the Funing Formation is subdivided into four stratigraphic units based on TOC variations, with units 1 and 3 corresponding to extremely arid conditions, unit 2 to arid conditions, and unit 4 to a humid climate. Both arid and humid conditions promoted elevated lacustrine primary productivity and moderate sedimentation rates, thereby favoring efficient organic matter accumulation. Increased water depth and optimal salinity also facilitated bottom-water anoxia, enhancing organic matter preservation. The study demonstrates that climatic variations in terrigenous clastic input and lake salinity affect the mineral composition of the lacustrine shale, influencing pore development. Under arid conditions, favorable mineralogical proportions enhances the formation of intercrystalline pores within the clay matrix, improving hydrocarbon storage potential. This research establishes that paleoclimate plays a critical role in shale oil enrichment by influencing both organic matter accumulation and pore structure. Among the analyzed units, unit 2, deposited under arid conditions, shows the most favorable source–reservoir characteristics and is identified as the most promising interval for future shale oil exploration.