Construction of multi-mineral digital rocks for upscaling the numerical simulation of tight rock physical properties

Tight sandstone reservoirs are characterized by multi-scale pore space and high clay content, resulting in intricate rock physical responses. In this work, multi-scale imaging techniques, including computed tomography and stitched scanning electron microscopy, are applied to identify the large intergranular pores and micropores within major minerals. The pore structure of tight sandstones is quantitatively investigated using multi-scale images. Besides, multi-mineral digital rocks are constructed by performing registration and segmentation processing on the images obtained from microcomputed tomography and energy-dispersive scanning electron microscopy. These digital rocks are treated as composite materials consisting of different mineral types and micro-porosities, which enables the upscaling of the numerical simulation of rock physics properties. The results reveal that residual intergranular pores are interconnected through micropores within clay minerals, which significantly influences the electrical conductivities and permeabilities of tight sandstones. The proposed upscaling method can effectively couple the contribution of formation brine in multi-scale pores and clay minerals to bulk rock physics properties. This approach is suitable for the numerical simulation of diverse rock physical properties and can be applied to various tight reservoirs.Document Type: PerspectiveCited as: Hu, J., Xiao, Z., Ni, H., Liu, X. Construction of multi-mineral digital rocks for upscaling the numerical simulation of tight rock physical properties. Advances in Geo-Energy Research, 2023, 9(1): 68-70. https://doi.org/10.46690/ager.2023.07.0

Estimation of mechanics parameters of rock in consideration of confining pressure using monitoring while drilling data

During the drilling process, high-strength rock can lead to various issues such as drilling suppression, bit wear, and increased operational costs. To ensure safe and efficient drilling operations, it is crucial to accurately predict the strength parameters of the rock and recommend modifications to operational procedures. This paper proposes a low-cost and fast measurement method for predicting the strength parameters of rock in the field. To evaluate the effectiveness of this method, a drilling process monitoring experiment was conducted on sandstone, limestone, and granite. The experiment studied the effect of confining pressure on the response of cutting with an impregnated diamond bit. By analyzing the relationship between the thrust force, torque force, and penetration depth under different confining pressures, the researchers developed an analytical model for drilling that considers confining pressure, compressed crushed zone, and bit geometry. The results show that the confining pressure has a significant effect on the cutting response. As the confining pressure increases, the thrust force, torque force, and penetration depth at the cutting point also increase. Furthermore, a new measurement method was proposed to determine the strength parameters, such as cohesion, internal friction angle, and unconfined compressive strength. The estimated strength parameters for the three rock types using the drilling method were in good agreement with those of the standard laboratory test, with an error range of 10%. This method of estimating rock strength parameters is a practical tool for engineers. It can continuously and quickly obtain the drilling parameters of in-situ rocks

Improvement of the Microstructure and X-ray Performance of Ultrathin Ru/C Multilayer Mirror after High Temperature Treatment

Ru/C multilayer mirrors with a period of 2.5 nm and 150 bilayers were studied under high-temperature annealing and long-term storage. A general increase in the reflectivity was observed after annealing at different temperatures from 300 to 700 °C, during which a maximum enhancement of around 14% was obtained at 600 °C. The highest reflectance measured at 8 keV reached 69% after 600 °C annealing. This was accompanied by a 6% expansion of the layer period, which could be mainly attributed to carbon layers. The surface roughness was not affected by the annealing, whereas the polycrystallization of Ru with crystallographic planes parallel to the layer interfaces was enhanced. Combining the transmission-electron microscopy measurements, it was found that the interdiffusion at the C-on-Ru interface was significantly suppressed. The decreased interdiffusion, enhanced optical contrast, and larger multilayer period were the main reasons for the increased reflectance. The 600 °C annealed Ru/C multilayer remained intact after 13 months of storage in air, which also demonstrated significant temporal stability

Microstructure evolution and hard x-ray reflectance of ultrathin Ru/C multilayer mirrors with different layer thicknesses

Nanoscale Ru/C multilayers are essential reflective optics in the hard x-ray region of 7–20 keV. To understand the layer growth behavior and develop ultrathin Ru/C multilayer mirrors with periods smaller than 3.0 nm, multilayers with different periods of 6.2–1.5 nm were fabricated and studied. It is found that the average interface width started to increase obviously when the period became smaller than 2.5 nm while the surface roughness of different multilayers remained almost the same. The intrinsic stress of the multilayer gradually decreased with decreasing period and reached a very low value of −82 MPa at d  = 2.3 nm. High reflectance of 54% and 65% (at E  = 8.04 keV) were demonstrated for the multilayers with periods of 2.5 nm and 3.0 nm, respectively, whereas that for 1.9 nm period was significantly lower. To further analyze the layer microstructure, x-ray diffraction and transmission electron microscopy were used. The polycrystallized structure of Ru remained similar for the multilayers with period less than 2.5 nm, while a non-continuous layer growth and severe intermixing between Ru and C were observed for the multilayer with period of 1.9 nm. The increased intermixing between Ru and C was found to be the main reason for the larger interface width and lower reflectance of the multilayers with period smaller than 2.5 nm. It also indicated that the layer thickness threshold for a Ru/C multilayer growing with good layer quality is 1.0–1.2 nm

Supplementary document for On-chip Ultracompact Multimode Vortex Beam Emitter Based on Vertical Modes - 6054031.pdf

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Downregulation of homeobox gene Barx2 increases gastric cancer proliferation and metastasis and predicts poor patient outcomes

Barx2 is a Bar family homeodomain transcription factor shown to play a critical role in cell adhesion and cytoskeleton remodeling, key processes in carcinogenesis and metastasis. Using quantitative real-time PCR, Western blotting, and immunohistochemistry, we found that Barx2 is expressed at lower levels in human gastric cancer (GC) tissues than in adjacent normal mucosa. In a multivariate analysis, Barx2 expression emerged as an independent prognostic factor for disease-free and overall survival. Kaplan-Meier survival analysis showed a trend toward even shorter overall survival in the patient group with Barx2-negative tumors, independent of advanced UICC stage and tumor relapse. Using in vitro and in vivo assays, we demonstrated that under normal conditions Barx2 inhibited GC cell proliferation and invasiveness through inhibition of the Wnt/beta-catenin signaling pathway. These findings indicate that reduction or loss of Barx2 dis-inhibits GC cell proliferation and invasion, and that reduction in Barx2 could serve as an independent prognostic biomarker for poor outcome in GC patients.Funding Agencies|National Natural Science Foundation of China [81272750]</p