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Tight oil reservoirs are complex geological materials composed of solid matrix, pore structure, and mixed multiple phases of fluids, particularly for oil reservoirs suffering from high content of in situ pressurized water found in China. In this regard, a coupled model considering two-phase flow of oil and water, as well as deformation and damage evolution of porous media, is proposed and validated using associated results, including the oil depletion process, analytical solution of stress shadow effect, and physical experiments on multi-fracture interactions and fracture propagation in unsaturated seepage fields. Then, the proposed model is used to study the behavior of multi-fracture interactions in an unsaturated reservoir in presence of water and oil. The results show that conspicuous interactions exist among multiple induced fractures. Interaction behavior varies from extracted geological profiles of the reservoir due to in situ stress anisotropy. The differential pressures of water and that of oil in different regions of reservoir affect interactions and trajectories of multi-fractures to a considerable degree. The absolute value of reservoir average pressure is a dominant factor affecting fracture interactions and in favor of enhancing fracture network complexity. In addition, difference of reservoir average pressures in different regions of reservoir would promote the fracturing effectiveness. Factors affecting fracture interactions and reservoir treatment effectiveness are quantitatively estimated through stimulated reservoir area. This study confirms the significance of incorporating the two-phase flow process in analyses of multi-fracture interactions and fracture trajectory predictions during tight sandstone oil reservoir developments.

Due to the heterogeneity of rock masses and the variability of in situ stress, the traditional linear inversion method is insufficiently accurate to achieve high accuracy of the in situ stress field. To address this challenge, nonlinear stress boundaries for a numerical model are determined through regression analysis of a series of nonlinear coefficient matrices, which are derived from the bubbling method. Considering the randomness and flexibility of the bubbling method, a parametric study is conducted to determine recommended ranges for these parameters, including the standard deviation () of bubble radii, the non-uniform coefficient matrix number () for nonlinear stress boundaries, and the number (m) and positions of in situ stress measurement points. A model case study provides a reference for the selection of these parameters. Additionally, when the nonlinear in situ stress inversion method is employed, stress distortion inevitably occurs near model boundaries, aligning with the Saint Venant's principle. Two strategies are proposed accordingly: employing a systematic reduction of nonlinear coefficients to achieve high inversion accuracy while minimizing significant stress distortion, and excluding regions with severe stress distortion near the model edges while utilizing the central part of the model for subsequent simulations. These two strategies have been successfully implemented in the nonlinear in situ stress inversion of the Xincheng Gold Mine and have achieved higher inversion accuracy than the linear method. Specifically, the linear and nonlinear inversion methods yield root mean square errors (RMSE) of 4.15 and 3.2, and inversion relative errors () of 22.08% and 17.55%, respectively. Therefore, the nonlinear inversion method outperforms the traditional multiple linear regression method, even in the presence of a systematic reduction in the nonlinear stress boundaries.

Towards increasingly severe worldwide pollution of industrial solid waste red mud (RM) released from aluminum industry, constitutional valuable element Al has been successfully separated for a novel mild rotating hydrothermal synthesis (150 °C, 12 h, 5 Hz) of the uniform hierarchical porous flowerlike boehmite (γ-AlOOH) microspheres in the presence of appropriate urea, which exhibit distinctly small average diameter (1.52 μm) and narrow particle size distribution (PSD: 1.12-1.97 μm), as well as high specific surface area (129.37 m2g-1). On the one hand, the rotating hydrothermal synthesis promotes the mass and heat transfer, enabling γ-AlOOH microspheres at a lower temperature within a shorter time. On the other hand, moderate rotation provides predominant shear force, rendering the uniform γ-AlOOH microspheres with small average diameter and narrow PSD. The optimal AlOOH-U2M-R5Hz microspheres demonstrate satisfactory adsorption performance for Congo Red (CR) and Methyl Blue (MB), with the maximum adsorption capacities of 602.4 and 1208.7 mg g-1, respectively. Various isotherm models of Langmuir, Freundlich, Temkin and Dubinin-Radushkevich are utilized, adsorption kinetics are analyzed, adsorption mechanism is uncovered based on hydrogen bonding and electrostatic attraction. The increase in the temperature or the presence of coexisting cations facilitates the adsorption of CR, whereas coexisting anions weaken the adsorption of CR on the AlOOH-U2M-R5Hz microspheres. Furthermore, the excellent recycling performances and especially dynamic adsorption (retainment of removal efficiency of approx. 99.0% within 1000 min) as well as authentic water bodies (e.g. tap water and river water) simulated wastewater treatment undoubtedly indicate great practical applications of the AlOOH-U2M-R5Hz microspheres, towards cleaner aluminum production and cost-effective sustainable solution to anionic dye-bearing wastewater.

A facile eco-friendly hydrothermal route (180°C, 12.0h) has been developed for the first time to the uniform hierarchical porous MgBO2(OH) microspheres without the aid of any organic additive, surfactant or template, by using the abundant MgCl2·6H2O, H3BO3and NaOH as the raw materials. The as-obtained porous microspheres exhibit a specific surface area of 94.752mg·g−1, pore volume of 0.814cm3·g−1, and ca. 84.0% of which have a diameter of 2.25–3.40μm. The thermal decomposition of the porous MgBO2(OH) microspheres (650°C, 2.5°C·min−1) leads to the porous Mg2B2O5microspheres with well-retained morphology. When utilized as the adsorbents for the removal of CR from mimic waste water, the present porous MgBO2(OH) microspheres exhibit satisfactory adsorption capacity, with the maximum adsorption capacity qmof 309.1mg·g−1, much higher than that derived from most of the referenced adsorbents. This opens a new window for the facile green hydrothermal synthesis of the hierarchical porous MgBO2(OH) microspheres, and extends the potential application of the 3D hierarchical porous metal borates as high-efficiency adsorbents for organic dyes removal.