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• Building an integrating sphere-based spectroscopic system to measure the optical properties. • Obtaining the optical properties' parameters of cotton and mulching film. • Selecting the feature bands to detect mulching film using the optical properties of samples. • Analyzing the sources of differences in the optical properties of cotton and mulching film. Cotton is prone to being mixed with mulching film during the harvesting and packing process in China, which can significantly decrease the quality of cotton fiber and impact the quality of subsequent textile products. Mulching film is a translucent material that makes it challenging to detect optically, which presents an urgent challenge for cotton quality testing due to the lack of research on its detection mechanism. In this study, the absorption coefficient (μ a), reduced scattering coefficient (μ s '), and scattering anisotropy factor (g) of cotton lint and mulching film in the spectral region of 400–1120 nm were obtained using an integrating sphere-based spectroscopic measurement system. The accuracy of the system was validated using liquid phantoms made from polystyrene particles and absorbing dyes. The interval random frog (iRF) algorithm was used to select feature bands, and multivariate analysis of variance (MANOVA) was employed to assess the differences between cotton and mulching film in terms of μ a and μ s ' in the selected feature bands. Support vector machine (SVM) and linear discriminant analysis (LDA) were utilized to classify the concatenation of μ a , μ s ' , μ a and μ s ' of cotton and mulching film in full wavelengths and feature bands. The results demonstrated that there were significant differences in μ a , μ s ' and g between cotton and mulching film due to their different chemical compositions, surface morphology, and tensile properties. The selected feature bands were in the blue band (456.1 nm), red bands (605.8 nm, 628.9 nm, 685.6 nm), and near-infrared bands (805.4 nm, 837 nm, 1006.3 nm). The SVM classification results of the concatenation of μ a , μ s ' , μ a and μ s ' for cotton and mulching film were 100 % in both full wavelengths and feature bands. This study makes a significant contribution by reporting the optical properties of cotton and mulching film, which were used to determine the detection sensitive bands. These findings will serve as a theoretical foundation and data set for the development of detection equipment to identify mulching film in the cotton production process. [ABSTRACT FROM AUTHOR]

• Nanoscale pore-fracture structure of HDR reservoir has been firstly reconstructed. • Significant physical properties of HDR reservoir have been revealed. • Nanoscale investigation is necessary for the physical properties of HDR reservoir. • Hydraulic and mechanical apertures of fractures in HDR reservoir have been compared. As a new type of renewable energy, Hot-Dry-Rock (HDR) is gaining increasing attention. The physical properties of rock influenced by the pore-fracture structure are vital for the hydraulic and chemical characteristics of HDR reservoirs. However, the natural pore-fracture structure in HDR has not been sufficiently studied. To fulfill this gap, we used focused ion beam-scanning electron microscopy (FIB-SEM) to construct three-dimensional (3D) digital models for four granite samples from the deep HDR reservoir in Gonghe Basin, Qinghai Province, China, and obtained the nanoscale structure of the pores and fractures in HDR reservoir for the first time. Our analysis based on the 3D models indicates that the heat transfer area in the HDR reservoir is mainly from fractures and crack-like pores, but a large amount of small but regular pores could be neglected when heat transfer in HDR is considered. The permeability of HDR reservoirs at nanoscale varies from 9.414 nD to 0.082 mD, and the high permeability in this study is accompanied by throughgoing fractures. The variation of porosity and permeability of deep HDR at nanoscale in this study is much more severe than that of shallow granites previously studied at microscale. The performance of geothermal field is significantly influenced by the size of throats and the average size and tortuosity of the interconnected pore-fracture network in HDR. The hydraulic aperture could be 32-58% lower than the mechanical aperture of the natural fractures in HDR reservoirs, which is a vital clue for the numerical simulation associated with enhanced geothermal systems. [ABSTRACT FROM AUTHOR]

• Reported a rare casing leakage failure in a shale gas well in western China during pressure testing. • Failure analysis of the casing and investigation of the manufacturing plant revealed that during the steel pipe rolling process, the bolts on the balance cylinder of the continuous pipe mill dropped onto the pipe. The bolt acts as a dissimilar metal substance to destroy the continuity of the metal. • The FEA calculation results show that when the casing is used in the field, under axial tension and internal pressure, the equivalent force at the defect is much greater than the yield strength of the casing. Therefore, the crack at the defect quickly propagated and penetrated the entire wall thickness of the casing, resulting in the final failure of the casing. • In order to avoid the recurrence of such failure accidents, rectification suggestions were put forward. A casing leaked in a shale gas well during pressure testing. A series of experiments including macroscopic observation, non-destructive inspection, physical and chemical inspection, optical microscope, scanning electron microscope (SEM) and energy dispersive spectrometry techniques (EDS) were carried out to analyze the failure accident. The finite simulation analysis (FEA) method was used to analyze the effect of internal pressure on the defective parts of the casing. Based on the experiment result and manufacturing process investigation, the root cause was obtained. During the casing pipe rolling process, the bolts of size M12 × 60 mm on the balance cylinder of the continuous pipe mill were loosened and dropped onto the pipe. Under the dual action of the roller and the mandrel, the bolts are 'inlaid' inside the casing as a dissimilar metal substance. The bolt head almost occupies the entire wall thickness of the casing, resulting in the remaining wall thickness of the casing being less than 1 mm. The dissimilar metal inside the casing destroys the continuity of the pipe and severely reduces the pressure bearing capacity of the casing. The FEA calculation results show that the equivalent stress at the defect is lower than the yield strength of the pipe body during the factory hydraulic test. While, in the field pressure test, the equivalent stress at the defect is far greater than the yield strength of the casing under the action of axial tension and internal pressure. Therefore, the crack at the defect quickly propagated and penetrated the entire wall thickness of the casing, resulting in leakage. In order to avoid similar accidents, suggestions to prevent such failures are proposed. [ABSTRACT FROM AUTHOR]

• O 2 is brought into the well during the injection of N 2 , resulting in oxygen corrosion. • The serious corrosion is resulted in O 2 by greatly promotes the cathodic process. • The perforated screen failed because of the serious oxygen corrosion. The perforated screens of a gas injection huff and puff well broke down in an oilfield in western China. The physical and chemical properties of the failure-perforated screens met the requirements of relevant technical protocols. The injected gas was nitrogen produced by the membrane nitrogen method, which contains approximately 5% O 2. Therefore, a substantial amount of O 2 entered the well during the gas injection, and greatly promoteed the cathodic process of the electrochemical corrosion. High salinity formation water, especially with large amounts of Cl-, further accelerated the corrosion. The significant oxygen corrosion under the well finally led to the failure of the perforated screen. [ABSTRACT FROM AUTHOR]

The article discusses the role of ductile-brittle deformation in gold mineralization in the Hetai Gold Deposit (HDG) in China. Topics include ore-hosting rocks containing mica-quartz schist, quartz-mica schist, and mica quartzite, the phenomenon of dynamic recrystallization from fractography, and silicated mylonites formed in the process of brittle-ductile shearing.