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Quantitative evaluation of gas hydrate reservoir by AVO attributes analysis based on the Brekhovskikh equation

Petroleum Science 2023年第4期20卷 2045-2059页

作者： Yao wang yan-fei wang Key Laboratory of Petroleum Resources Research Institute of Geology and GeophysicsChinese Academy of SciencesBeijing100029China University of Chinese Academy of Sciences Beijing100049China Innovation Academy for Earth Science Chinese Academy of SciencesBeijing100029China

AVO (Amplitude variation with offset) technology is widely used in gas hydrate research. BSR (Bottom simulating reflector), caused by the huge difference in wave impedance between the hydrate reservoir and the underlying free gas reservoir, is the bottom boundary mark of the hydrate reservoir. Analyzing the AVO attributes of BSR can evaluate hydrate reservoirs. However, the Zoeppritz equation which is the theoretical basis of conventional AVO technology has inherent problems: the Zoeppritz equation does not consider the influence of thin layer thickness on reflection coefficients;the approximation of the Zoeppritz equation assumes that the difference of wave impedance between the two sides of the interface is small. These assumptions are not consistent with the occurrence characteristics of natural gas hydrate. The Brekhovskikh equation, which is more suitable for thin-layer reflection coefficient calculation, is used as the theoretical basis for AVO analysis. The reflection coefficients calculated by the Brekhovskikh equation are complex numbers with phase angles. Therefore, attributes of the reflection coefficient and its phase angle changing with offset are used to analyze the hydrate reservoir's porosity, saturation, and thickness. Finally, the random forest algorithm is used to predict the reservoir porosity, hydrate saturation, and thickness of the hydrate reservoir. In the synthetic data, the inversion results based on the four attributes of the Brekhovskikh equation are better than the conventional inversion results based on the two attributes of Zoeppritz, and the thickness can be accurately predicted. The proposed method also achieves good results in the application of Blake Ridge data. According to the method proposed in this paper, the hydrate reservoir in the area has a high porosity (more than 50%), and a medium saturation (between 10% and 20%). The thickness is mainly between 200m and 300m. It is consistent with the previous results obtained by veloci

关键词： Natural gas hydrate Brekhovskikh equation AVO attributes Random forest

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RESEARCH ON IMPROVED CUT-OFF NEGATIVE PRESSURE METHOD FOR UNSTEADY SEEPAGE FLOW WITH FREE SURFACE

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Journal of Hydrodynamics 2005年第5期17卷 521-531页

作者： ZHANG Qian-fei wang yan-ming Shanghai Municipal Engineering Design Institute Shanghai 200092 China

The cut-off negative pressure method is one of effective approaches to solve the seepage flow with free surface. According to the characteristics of this method, however, it has been found out that the deficiency of the algorithms is to easily cause inaccurate simulation in the vicinity of free surface owing to the penalty function with only one controlling penalty parameter. Therefore, an improved cut-off pressure method was presented by constructing penalty function with two controlling penalty parameters. The improved algorithms were illustrated to be able to improve the simulation accuracy and raise the convergence speed through considering the effects of the partially saturated or unsaturated elements more reasonably and calculating the nodal external forces more accurately. Finally, the improved cut-off negative pressure method was applied to the simulation of unsteady seepage flow with free surface, and the corresponding program codes were developed with validation of some cases.

关键词： free surface unsteady seepage flow finite element method improved cut-off negative pressure method

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DUAL RECIPROCITY HYBRID BOUNDARY NODE METHOD FOR THREE-DIMENSIONAL ELASTICITY WITH BODY FORCE

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Acta Mechanica Solida Sinica 2008年第3期21卷 267-277页

作者： fei yan Yuanhan wang Yu Miao fei Tan School of Civil Engineering and Mechanics Huazhong University of Science and Technology Wuhan 430074 China

Combining Dual Reciprocity Method （DRM） with Hybrid Boundary Node Method （HBNM）, the Dual Reciprocity Hybrid Boundary Node Method （DRHBNM） is developed for three-dimensional linear elasticity problems with body force. This method can be used to solve the elasticity problems with body force without domain integral, which is inevitable by HBNM. To demonstrate the versatility and the fast convergence of this method, some numerical examples of 3-D elasticity problems with body forces are examined. The computational results show that the present method is effective and can be widely applied in solving practical engineering problems.

关键词： hybrid boundary node method dual reciprocity method body force radial basis function

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Micro-macro fracture mechanism of heterogeneous granite in percussive drilling

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Petroleum Science 2023年第5期20卷 3131-3142页

作者： Wei-Ji Liu yan-fei wang Zhao-wang Dan Xiao-Hua Zhu School of Mechatronic Engineering Southwest Petroleum UniversityChengdu610500SichuanChina Geothermal Energy Research Center Southwest Petroleum UniversityChengdu610500SichuanChina Powerchina Sinohydro Bureau 7 Co. LTDChengdu610500SichuanChina

The conventional rotary rock breaking method faces a technical bottleneck in improving the rate of penetration(ROP)in deep hard *** drilling is the most potential approach to increase rock-breaking efficiency and ***,the rock-breaking mechanism of percussive drilling is still unclear enough,especially the micro-fracture mechanism of rock under confining pressure(under lateral pressure and hydraulic pressure).In this paper,the impact rock breaking experiments by four kinds of Polycrystalline Diamond Compact(PDC)cutters are carried out using a drop-weight impact testing machine and an acoustic emission(AE)recording system,the influence of parameters such as cutter shape,rake angle,and impact energy on rock-breaking are systematically *** study includes a numerical simulation to examine the process of crack initiation,propagation,and cuttings formation during the impact process with the consideration of confining *** results show the conicalshaped cutter is the most aggressive with high breaking *** penetration depth of the cutter is mainly influenced by the impact energy and cutter shape than the rake angle of the *** exists critical impact energy makes the rock breaking efficiency the *** critical impact energy is about 40 J when using the conical-shaped cutter with a rake angle of 15°.The rock mainly failed in tensile mode,and the inter-grain crack is the main *** pressure can inhibit the formation of horizontal cracks,while lateral pressure can inhibit the formation of vertical cracks and reduce the proportion of tensile *** research results can provide some reference and basis for improving the rock-breaking efficiency in deep hard formations.

关键词： Percussive drilling PFC Rock fragmentation characteristics Rock breaking efficiency

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Single-cell analysis identifies phospholysine phosphohistidine inorganic pyrophosphate phosphatase as a target in ulcerative colitis

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World Journal of Gastroenterology 2023年第48期29卷 6222-6234页

作者： yan-fei wang Ruo-Yu He Chan Xu Xiao-Ling Li yan-fei Cao Department of Gastroenterology The Third Affiliated Hospital of Zhejiang Chinese Medical UniversityNo.219 Moganshan RoadXihu DistrictHangzhou 310005Zhejiang ProvinceChina Clinical laboratory The Third Affiliated Hospital of Zhejiang Chinese Medical UniversityNo.219 Moganshan RoadXihu DistrictHangzhou 310005Zhejiang ProvinceChina Elder Medicine Department The Third Affiliated Hospital of Zhejiang Chinese Medical UniversityNo.219 Moganshan RoadXihu DistrictHangzhou 310005Zhejiang ProvinceChina

BACKGROUND Ulcerative colitis(UC)is a chronic gastrointestinal disorder characterized by inflammation and ulceration,representing a significant predisposition to colorectal *** advances in single-cell RNA sequencing(scRNA-seq)technology offer a promising avenue for dissecting the complex cellular interactions and molecular signatures driving UC *** To utilize scRNA-seq technology to dissect the complex cellular interactions and molecular signatures that underlie UC *** In this research,we integrated and analyzed the scRNA-seq data from UC ***,we conducted mRNA and protein level assays as well as pathology-related staining tests on clinical patient *** In this study,we identified the sustained upregulation of inflammatory response pathways during UC progression,characterized the features of damaged endothelial cells in ***,we uncovered the downregulation of phospholysine phosphohistidine inorganic pyrophosphate phosphatase(LHPP)has a negative correlation with signal transducer and activator of transcription *** downregulation of LHPP in UC patient tissues and plasma suggests that LHPP may serve as a potential therapeutic target for *** paper highlights the importance of LHPP as a potential key target in UC and unveils its potential role in inflammation *** The findings suggest that LHPP may serve as a potential therapeutic target for UC,emphasizing its importance as a potential key target in UC and unveiling its role in inflammation regulation.

关键词： Ulcerative colitis Single-cell RNA sequencing Phospholysine phosphohistidine inorganic pyrophosphate phosphatase

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Convergence and Optimality of Adaptive Regularization for Ill-posed Deconvolution Problems in Infinite Spaces

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Acta Mathematicae Applicatae Sinica 2006年第3期22卷 429-436页

作者： yan-fei wang Qing-hua Ma State Key Laboratory of Remote Sensing Science Jointly Sponsored by the Institute of Remote Sensing Applications Chinese Academy of Sciences and Beijing Normal University P.O.Box 9718 Beijing 100101 China Department of Information Sciences College of Arts and Science of Beijing Union University Beijing 100038China

The adaptive regularization method is first proposed by Ryzhikov et al. in [6] for the deconvolution in elimination of multiples which appear frequently in geoscience and remote sensing. They have done experiments to show that this method is very effective. This method is better than the Tikhonov regularization in the sense that it is adaptive, i.e., it automatically eliminates the small eigenvalues of the operator when the operator is near singular. In this paper, we give theoretical analysis about the adaptive regularization. We introduce an a priori strategy and an a posteriori strategy for choosing the regularization parameter, and prove regularities of the adaptive regularization for both strategies. For the former, we show that the order of the convergence rate can approach O（｜｜n｜｜^4v/4v＋1） for some 0 〈 v 〈 1, while for the latter, the order of the convergence rate can be at most O（｜｜n｜｜^2v/2v＋1） for some 0 〈 v 〈 1.

关键词： Ill-posed problems adaptive regularization convergence regularity

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Ultrafine-Grained Microstructure and Improved Mechanical Behaviors of Friction Stir Welded Cu and Cu–30Zn Joints

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Acta Metallurgica Sinica(English Letters) 2018年第8期31卷 878-886页

作者： yan-fei wang Jian An Kun Yin Ming-Sai wang Yu-Sheng Li Chong-Xiang Huang School of Aeronautics and Astronautics Sichuan University Nano Structural Materials Center School of Materials Science and Engineering Nanjing University of Science and Technology

Ultra-strong joints of pure Cu and Cu–30Zn alloy were obtained by friction stir welding under flowing water. The effects of heat inputting condition and material characteristics on the morphologies, microstructures and mechanical properties of welding joints were studied. Defect-free stirring zones of pure Cu and Cu–30Zn were characterized by onion-ringed structure and plastic flowing bands, respectively. Both low stacking fault energy and fast cooling condition contributed to the formation of small recrystallized grains less than 1 μm in stirring zones. The welding joints in both materials exhibited enhanced mechanical performances due to ultrafine-grained microstructure in stirring zones and disappearance of soft heataffected-zone. The technique of digital image correlation was used to study the tensile deformation behaviors of welding joints and verify the improved tensile properties.

关键词： Friction stir welding Ultrafine grain Mechanical properties Stacking fault energy Digital image correlation(DIC)

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Investigating microstructure of Longmaxi shale in Shizhu area,Sichuan Basin, by optical microscopy, scanning electron microscopy and micro-computed tomography

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Nuclear Science and Techniques 2017年第11期28卷 226-235页

作者： Yu wang Li-Hua wang Jian-Qiang wang Zheng Jiang Chan Jin yan-fei wang Key Laboratory of Interfacial Physics and Technology Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai 201800 China Shanghai Synchrotron Radiation Facility Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201204 China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China

Microstructure of shale formation is the key to understanding its petrophysical and chemical *** microscopy, scanning electron microscopy and micro-computed tomography(μ-CT) have been combined for characterization of microstructure of Longmaxi(LMX)shale from Shizhu area, Sichan Basin. The results indicate that laminated LMX shale consists of mineral matrix-rich layers and organic matter(OM)-rich layers at micrometer scale in two and three dimensions. Mineral matrix layers,mainly consisting of interparticle pores and intraplatelet pores, are approximately parallel to the bedding ***-rich layer, mainly containing intercrystalline pores,shows a strong preferred orientation parallel to the bedding plane. OM-rich layer, mainly containing OM pores, seems to be discontinuous. In addition, intercrystalline pores are enriched in some layers, while OM pores are distributed irregularly in matrix layers. This vertical heterogeneity of pore microscopic structures in LMX shale is of great importance to understand its petrophysical and chemical properties.

关键词： Micro-computed tomography Pore microstructure Heterogeneity Matrix layers Longmaxi shale

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Improving the Mechanical and Tribological Properties of NiTi Alloys by Combining Cryo-Rolling and Post-Annealing

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Acta Metallurgica Sinica(English Letters) 2022年第2期35卷 317-325页

作者： Yong Wen yan-fei wang Hao Ran Wei Wei Jun-Ming Zhang Chong-Xiang Huang School of Aeronautics and Astronautics Sichuan UniversityChengdu 610065China

By combining cryo-rolling and post-annealing treatments,the nanostructured NiTi alloy is produced.A diff erential scanning calorimetry measurement was used to test the eff ect of the preparation process on phase *** cryo-rolling changes the tensile fracture of NiTi alloy to a ductile ***,the recovered structure exhibits signifi cant strength improvement,while the tensile plasticity is still comparable to that of the coarse-grained *** optimized mechanical performance is due to the strengthening eff ect of refi ned microstructure and the high work hardening capability rendered by moderate dislocation ***-on-plate reciprocating dry-sliding wear test reveals that the nanostructured NiTi alloy also has enhanced wear resistance,which is primarily ascribed to the high content of residue martensite formed during *** results provide an eff ective route to optimize the mechanical and wear properties of NiTi alloys.

关键词： NiTi alloy Phase transformation Strength and ductility Wear resistance Cryogenic rolling

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Three-dimensional regulation of transcription

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Protein & Cell 2015年第4期6卷 241-253页

作者： Jun Cao Zhengyu Luo Qingyu Cheng Qianlan Xu yan Zhang fei wang yan Wu Xiaoyuan Song CAS Key Laboratory of Brain Function and Disease and School of Life Sciences University of Science and Technology ofChina Hefei 230027 China

Cells can adapt to environment and development by reconstructing their transcriptional networks to regulate diverse cellular processes without altering the underly- ing DNA sequences. These alterations, namely epige- netic changes, occur during cell division, differentiation and cell death. Numerous evidences demonstrate that epigenetic changes are governed by various types of determinants, including DNA methylation patterns, his- tone posttranslational modification signatures, histone variants, chromatin remodeling, and recently discovered chromosome conformation characteristics and non- coding RNAs （ncRNAs）. Here, we highlight recent efforts on how the two latter epigenetic factors participate in the sophisticated transcriptional process and describe emerging techniques which permit us to uncover and gain insights into the fascinating genomic regulation.

关键词： transcriptional regulation long non-coding RNAs three-dimensional chromosome interactions,epigenetic changes

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