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The present-day in-situ stresses affect the drilling design, well pattern deployment, well completion modification, hydraulic fracturing and water injection of tight-oil sandstones. The measurement data of these stresses are commonly unavailable because of their high costs and limited core samples, therefore employing conventional logs for these stress determination is imperative for tight-oil sandstones. Firstly, the suitable calculation models for the present-day in-situ stress calculation by conventional logs were selected according to the geological characteristics of the sixth member of the Yanchang Formation (Chang 6) in Heshui area of the southern Ordos Basin, China. Then, the dynamic rock mechanical parameters were determined by conventional logs, and corrected by the static rock mechanical parameters obtained from the triaxial rock mechanical tests. Moreover, the pore fluid pressure was determined by the empirical formula method. Finally, the maximum and minimum horizontal compressive stresses (σ H and σ h ), and the vertical stress (σ v ) of six wells were calculated according to the selected models of these stresses, respectively. The present-day in-situ stresses, determined by the proposed method in the paper, were verified by those obtained from acoustic emission tests and finite-element numerical simulations with the relative errors of less than 10%. The results show that the magnitudes of σ H , σ h and the horizontal differential stress (σ H−h ) in the study area mainly range from 32 to 43 MPa, 23 to 37 MPa and 5 to 8 MPa, respectively. The magnitude of the three-dimensional present-day in-situ stress increases with the increase of depth. The average gradients of σ H, σ v and σ h are 0.018, 0.014 and 0.015 MPa/m, respectively, that is σ H >σ v >σ h . In this stress state, the hydraulic fractures, with a trend of little expansion towards multiple directions, are commonly developed at a small angle intersecting with the direction of σ H in the study area.

A brief introduction to the composition of the bath solution for electroplating hard chromium was given.Besides, the requirements for quality control of chromium plating bath solution were put forward from three aspects of bath solution preparation, analysis and daily management to ensure the stability and reliability of bath solution, which would guarantee the quality of hard chromium plating for parts.

Blending modification of inorganic fillers is one of the effective means to improve the ablation resistance of resin matrix composites. The reactive inorganic fillers ZrB2 and ZrSi2 were selected to modify the epoxy modified organo silicone resin, and the modified composites were prepared. The effects of ZrB2 and ZrSi2 addition on the mechanical properties, thermal stability and ablative properties of the composites were studied. The results show that the addition of ZrB2 and ZrSi2 can greatly improve the density, hardness, tensile strength and carbon residue rate of the composites, and effectively improve the ablation resistance of the composites. In air atmosphere, ZrB2 began to react at about 660 °C of ZrB2 modified composites, resulting in a significant increase in carbon residue rate of the composites at 800 °C. ZrB2 is obviously superior to ZrSi2 in improving the ablative properties of the composites. In the process of high temperature oxygen-acetylene ablation, ZrB2 can react to generate corresponding oxides, which significantly improves the ablation resistance of the composites, and the linear ablation rate is only 0.021 mm/s. [ABSTRACT FROM AUTHOR]