Modeling overpressure development during shale rock compaction coupling poroelasticity and permeability evolution above 3km depth

The evolution of pore pressure including overpressure during sedimentation is an important process to consider when analyzing whether high pore pressure causes rock failure. High pore pressure is caused by under-compaction due to the rapid burial of low-permeability sediments, and as a result, porosity decreases less rapidly with depth than in normally compacted sediments where porosity decreases exponentially with depth. While under-compaction related pore pressure magnitudes have been determined empirically, in most numerical modeling approaches, the pore pressure is either applied as a static magnitude or coupled to a fluid flow simulator. This study simulates the pore pressure evolution during sediment loading and compaction using 3D porous-elastic-plastic finite element analysis. Continuous sedimentary loading is applied, and the resulting compaction process is coupled to the evolution of Poisson ratio and bulk modulus. The models test compacted sandstone and shale beds with varying ranges of physical properties including porosity, permeability, and elasticity for various sedimentation rates and initial physical properties distributions. Initial results show that overpressure occurs in rock layers with a permeability lower than 10-12 m2 when the sedimentation rate is equal to or exceeds 10 mm/year. It also shows that porosity tends to either decrease much slower or temporarily stops decreasing with the development of overpressure. Porous space is easier to be compacted in rocks featuring a lower bulk modulus under the same effective stress. The presented procedure enables to couple the simulation of the effective state of stress both due to the initial burial history of a sedimentary basin therefore provides a better assessment for rock failure analysis --Abstract, page iii

Probing GeV-scale MSSM neutralino dark matter in collider and direct detection experiments

Given the recent constraints from the dark matter (DM) direct detections, we examine a light GeV-scale (2-30 GeV) neutralino DM in the alignment limit of the Minimal Supersymmetric Standard Model (MSSM). In this limit without decoupling, the heavy CP-even scalar $H$ plays the role of the Standard Model (SM) Higgs boson while the other scalar $h$ can be rather light so that the DM can annihilate through the $h$ resonance or into a pair of $h$ to achieve the observed relic density. With the current collider and cosmological constraints, we find that such a light neutralino DM above 6 GeV can be excluded by the XENON-1T (2017) limits while the survivied parameter space below 6 GeV can be fully covered by the future germanium-based light dark matter detections (such as CDEX), by the Higgs coupling precison measurements or by the production process $e^+e^- \to hA$ at an electron-positron collider (Higgs factory).Comment: 15 pages, 5 figures. Discussions and references added, version accepted by PL

The integration of traditional agriculture and new energy gives birth to a new model of green development

Under the background of China's double carbon policy and global climate change, the organic combination of photovoltaic and agriculture has given birth to a new mode of integrated development of traditional agriculture and new energy. This paper summarizes the research and development progress in the field of photovoltaic + agriculture in China from the aspects of the concept of photovoltaic technology, the combination of photovoltaic with agricultural production and the application of photovoltaic in agricultural production. The research shows that the development of photovoltaic technology has reduced the consumption of non renewable energy to a great extent, which has brought great advantages to energy supply and green organic agricultural production in agricultural production; future research can deepen the construction of a perfect and idealized photovoltaic + agriculture model from the theoretical system of photovoltaic combined with agriculture