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Practice and understanding of sidetracking horizontal drilling in old wells in Sulige Gas Field, NW China
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作者 ZHANG Jinwu WANG Guoyong +1 位作者 HE Kai YE Chenglin 《Petroleum Exploration and Development》 2019年第2期384-392,共9页
To seek effective ways of lowering development cost and tapping inter-well remaining reserves, sidetracking horizontal wells from old wells in Su10 and Su53 Block were conducted. The engineering and geological problem... To seek effective ways of lowering development cost and tapping inter-well remaining reserves, sidetracking horizontal wells from old wells in Su10 and Su53 Block were conducted. The engineering and geological problems such as leakage, collapse and sticking in slim-hole sidetracking, and difficult evaluation of remaining gas were gradually overcome, and a set of drilling and completion technology, well deployment optimization technology and geo-steering technology suitable for sidetracking horizontal wells in tight sandstone gas reservoirs have been worked out. By making full use of the old well, sidetracking horizontal wells can greatly reduce development costs, enhance the producing degree of inter-well remaining reserves, and get production 3-5 times of that of adjacent vertical wells.Its production effect is influenced by encountered sandstone length, the position of the horizontal segment in the reservoir, produced effective reservoir thickness, gas saturation, controlled reserves and fracturing effect, etc. Up to now, in Block Su10 and Su53, 12 sidetracking horizontal wells have been drilled, which have an average drilling cycle of 49 days, average horizontal section length of 689 m,average effective drilling ratio of 61.5%, average well-head pressure of 16.2 MPa, and daily output of 4.7×10~4 m^3 at the initial stage after production. By the end of 2017, the average yield increment was more than 1 000×10~4 m^3 with good effect. With the increase of low yield old wells, wells in the enrichment regions tend to be saturated and the rest gas-bearing areas are lower in grade, therefore, sidetracking horizontal well can be used for optimization of well pattern, well deployment mode and exploitation of remaining oil areas. 展开更多
关键词 SULIGE Gas Field SIDETRACKING horizontal well TIGHT SANDSTONE old well stimulation RESERVES producing
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Renewal Needs and Solutions for Urban Old Communities under the Guidance of Resilient Security
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作者 ZHOU Xu LIU Zihan +1 位作者 SUN Ziin YANG Peizhe 《Journal of Landscape Research》 2024年第5期15-18,26,共5页
The renewal strategy guided by resilient security aims to enhance the community’s resistance and resilience to natural disasters and other emergency situations,ensuring that the community can quickly restore normal f... The renewal strategy guided by resilient security aims to enhance the community’s resistance and resilience to natural disasters and other emergency situations,ensuring that the community can quickly restore normal functions in the face of shocks.By enhancing the resilience of the community,residents’sense of security and satisfaction can be improved,while promoting the long-term stability and prosperity of the city.Using methods such as literature review,case analysis,and demand investigation,this paper investigates the needs and strategies for the renewal of urban old communities,and explores the demand analysis and solutions for the renewal of urban old communities under the guidance of resilient security.This paper aims to address the lack of resilience in old communities caused by outdated construction,aging infrastructure,and insufficient public services,as well as how to improve the adaptability,resilience,and transformation ability of communities through renovation and transformation. 展开更多
关键词 Resilient security old community Community renewal Demand analysis Implementation path
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Improving the Quality of Public Space in Old Residential Areas Based on Superposition and Intervention:A Case Study of Baihuazhou District of Nanchang City
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作者 LI Shengnan 《Journal of Landscape Research》 2024年第4期13-16,20,共5页
With the development of cities,China has entered an era of stock planning.The functions of old residential areas in urban development can no longer meet the needs of residents in the new era for a better life,and new ... With the development of cities,China has entered an era of stock planning.The functions of old residential areas in urban development can no longer meet the needs of residents in the new era for a better life,and new standards have been put forward for the quality of public spaces for living.This paper analyzes and sorts out the characteristics and problems of the public space in the old residential areas of Baihuazhou district.Combining superposition and intervention techniques,the spatial,historical,cultural and other characteristic elements of the residential areas are preserved to the greatest extent.The public space in the old residential areas of Baihuazhou District is updated and reconstructed in order to achieve the goal of improving the quality of its public space. 展开更多
关键词 Superposition and intervention old residential area Public space Quality improvement Baihuazhou District
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Analysis of Safety Assessment and Testing of Heavy Traffic Vehicles on Old Bridges Without Data
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作者 Qing Yang Jiang Feng 《Journal of World Architecture》 2024年第1期35-39,共5页
This article presents a real-life project that aimed to evaluate the safety of traffic vehicles on old bridges without any prior data.The project involved various safety inspections,including conventional,static,and d... This article presents a real-life project that aimed to evaluate the safety of traffic vehicles on old bridges without any prior data.The project involved various safety inspections,including conventional,static,and dynamic load inspections and safety assessments.After conducting these tests,it was concluded that the structure of the old bridge is relatively safe,with only a few bumps.The bridge could function normally following appropriate treatment.The analysis provides valuable insights into the assessment of the quality and safety of such bridges to ensure the safe driving of heavy vehicles. 展开更多
关键词 old bridge Absence of data Heavy vehicles Safety inspection Safety assessment
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Research on the Index System of Old Neighborhood Renovation Based on Green Building Evaluation Standard
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作者 Yufei Que 《Journal of Architectural Research and Development》 2024年第3期140-146,共7页
With the advancement of the transformation,the contradiction between the residents’demand for a better living environment and the convenience of living in the settlements comes to the fore.Effective identification,or... With the advancement of the transformation,the contradiction between the residents’demand for a better living environment and the convenience of living in the settlements comes to the fore.Effective identification,organic integration,timely adoption,and correct decision-making for the transformation of old neighborhoods are pressing issues in the transformation of old neighborhoods.Therefore,this paper takes the green building evaluation standards of various countries as the research basis and support for the construction of the transformation strategy of old neighborhoods.Through the collection and comparative analysis of the indicators of green building evaluation standards,the index system of transformation is formed,and it also provides a certain foundation for the subsequent related research. 展开更多
关键词 old neighborhoods Green building evaluation standards RENOVATION CRITERIA
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Research on the feasibility of storage and estimation model of storage capacity of CO_(2)in fissures of coal mine old goaf 被引量:4
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作者 Yang Ding Shugang Li +4 位作者 Bing Zhu Haifei Lin Jingfei Zhang Junhong Tan Wenbin Chen 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2023年第6期675-686,共12页
The concept of the carbon cycle in the old goaf of a coal mine based on CO_(2)utilization and storage was put forward adhering to the principle of low-carbon development,utilization of space resources in old goafs,and... The concept of the carbon cycle in the old goaf of a coal mine based on CO_(2)utilization and storage was put forward adhering to the principle of low-carbon development,utilization of space resources in old goafs,and associated gas resources development.Firstly,the evolution characteristics of overburden fissures in the goaf of the case was studied using a two-dimensional physical similarity simulation test,the sealing performance of the caprocks after stabilization was analyzed,and the fissures were counted and classi-fied.Then,the process of gaseous CO_(2)injection in the connected fissure was simulated by Ansys Fluent software,and the migration law and distribution characteristics of CO_(2)under the condition of gaseous CO_(2)injection were analyzed.Finally,the estimation models of free CO_(2)storage capacity in the old goaf were constructed considering the proportion of connected fissure and the effectiveness of CO_(2)injection.The CO_(2)storage capacity in the old goaf of the case coal mine was estimated.The results showed that a caprock group of“hard-thickness low-permeability hard-thickness”was formed after the caprock-fissures system in the goaf of the case tended to be stable vertically.The connected fissure,occlude cracks,and micro-fractures in the goaf accounted for 85.5%,8.5%,and 6%of the total fissures,respectively.Gaseous CO_(2)first migrated to the bottom of the connected fissure after CO_(2)was injected into the goaf,then spread horizontally along the bottom of the connected fissure after reaching the bottom,and finally spread longitudinally after filling the bottom of the entire connected fissure.The theoretical and effective storage capacities of free CO_(2)at normal temperature and pressure in the old goaf of the case were 9757 and 7477 t,respectively.The effective storage capacity of free CO_(2)at normal temperature and pressure in the old goaf after all minefield mined was 193404 t.The research can provide some reference for the coal mining industry to help the goal of“carbon peaking and carbon neutrality”. 展开更多
关键词 Carbon cycle old goaf FISSURE CO_(2)storage FEASIBILITY Storage capacity
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Structural Damage Identification System Suitable for Old Arch Bridge in Rural Regions: Random Forest Approach 被引量:1
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作者 Yu Zhang Zhihua Xiong +2 位作者 Zhuoxi Liang Jiachen She Chicheng Ma 《Computer Modeling in Engineering & Sciences》 SCIE EI 2023年第7期447-469,共23页
A huge number of old arch bridges located in rural regions are at the peak of maintenance.The health monitoring technology of the long-span bridge is hardly applicable to the small-span bridge,owing to the absence of ... A huge number of old arch bridges located in rural regions are at the peak of maintenance.The health monitoring technology of the long-span bridge is hardly applicable to the small-span bridge,owing to the absence of technical resources and sufficient funds in rural regions.There is an urgent need for an economical,fast,and accurate damage identification solution.The authors proposed a damage identification system of an old arch bridge implemented with amachine learning algorithm,which took the vehicle-induced response as the excitation.A damage index was defined based on wavelet packet theory,and a machine learning sample database collecting the denoised response was constructed.Through comparing three machine learning algorithms:Back-Propagation Neural Network(BPNN),Support Vector Machine(SVM),and Random Forest(R.F.),the R.F.damage identification model were found to have a better recognition ability.Finally,the Particle Swarm Optimization(PSO)algorithm was used to optimize the number of subtrees and split features of the R.F.model.The PSO optimized R.F.model was capable of the identification of different damage levels of old arch bridges with sensitive damage index.The proposed framework is practical and promising for the old bridge’s structural damage identification in rural regions. 展开更多
关键词 old arch bridge damage identification machine learning random forest particle swarm optimization
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Chemical and physical studies of metallic alloy-based old Indian coins with LIBS coupled with multivariate analysis
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作者 Vikas GUPTA Abhishekh Kumar RAI +3 位作者 Tejmani KUMAR Rajendhar JUNJURI G Manoj KUMAR A K RAI 《Plasma Science and Technology》 SCIE EI CAS CSCD 2023年第9期91-103,共13页
The present work aims to demonstrate the capabilities of Laser-induced Breakdown Spectroscopy(LIBS)coupled with a multivariate technique for rapid quantification and classification of old Indian coins made of various ... The present work aims to demonstrate the capabilities of Laser-induced Breakdown Spectroscopy(LIBS)coupled with a multivariate technique for rapid quantification and classification of old Indian coins made of various alloys.Thirteen old Indian coins in different years of circulation,(1922–1986)were selected for the study.The concentrations were determined by Calibration free LIBS(CF-LIBS)method.The concentration of cuprum(Cu)is negligible,and aluminum(Al)is maximum in the first five coins,and vice-versa in the remaining eight coins.Two different multivariate methods,Principal Component Analysis(PCA)and Soft Independent Modelling of Class Analogy(SIMCA)have been used to classify and identify the coins.PCA classified all thirteen samples into four main alloy categories.The discernment of unknown samples to their probable class membership of alloy was performed using SIMCA.The surface hardness(Brinell hardness number)is linearly correlated with the plasma temperature and LIBS intensity ratios.The sample surface of the first and fifth coin belongs to Al-alloy,having the least surface hardness,and it became harder for Cu–Ni alloy,Ni-brass alloy,and bronze alloy.The hardness of the surface is more for bronze sample twelve.It is also observed that the plasma temperature increases monotonically with the Brinell hardness number.This analysis provides valuable information on fabrication methodology and explains large diversification in the elementary composition of old coins. 展开更多
关键词 LIBS metallic alloy stoichiometric ablation PCA SIMCA old indian coins surface hardness
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An Extended Fuzzy-DEMATEL System for Factor Analyses on Social Capital Selection in the Renovation of Old Residential Communities
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作者 Guoshuai Sun Xiuru Tang +1 位作者 Shuping Wan Jiao Feng 《Computer Modeling in Engineering & Sciences》 SCIE EI 2023年第2期1041-1067,共27页
China has been promoting the renovation of old residential communities vigorously.Due to the financial pressure of the government and the sustainability of the renovation of old residential communities,public-private ... China has been promoting the renovation of old residential communities vigorously.Due to the financial pressure of the government and the sustainability of the renovation of old residential communities,public-private partnerships(PPP)have already gained attention.The selection of social capital is key to improving the efficiency of the PPP model in renovating old residential communities.In order to determine the influencing factors of social capital selection in the renovation of old residential communities,this paper aims to find an effective approach and analyze these factors.In this paper,a fuzzy decision-making and trial evaluation laboratory(fuzzy-DEMATEL)technique is extended and amore suitable systemis developed for the selection of social capital using the existing group decisionmaking theory.In the first stage,grounded theory is used to extract the unabridged key influencing factors for social capital selection in the renovation of old residential communities.Secondly,by considering the impact of expert weights,the key influencing factors are identified.The interactions within these influencing factors are discussed and the credibility of the results is verified by sensitivity analysis.Finally,these key influencing factors are sorted by importance.Based on the results,the government should focus on a technical level,organizationalmanagement abilities,corporate reputation,credit status,etc.This study provides the government with a theoretical basis and a methodology for evaluating social capital selection. 展开更多
关键词 Social capital selection fuzzy-DEMATEL influencing factors renovation of old residential communities grounded theory
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Transformation Design of Old Parks Based on Behavior Psychology: A Case Study of Hefei Xiaoyaojin Park
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作者 GE Juan CAO Menghan +3 位作者 CHEN Jiaxin HU Yueyue LI Quanjun LI Yinan 《Journal of Landscape Research》 2023年第5期35-40,共6页
City park undertakes the function of urban core green island. Hefei Xiaoyaojin Park providesa leisure and entertainment place for Hefei citizens. Although it has been continuously transformed andupgraded, there are st... City park undertakes the function of urban core green island. Hefei Xiaoyaojin Park providesa leisure and entertainment place for Hefei citizens. Although it has been continuously transformed andupgraded, there are still many places to be improved. Through behavior observation and questionnaire,the usage and satisfaction evaluation of tourists in Xiaoyaojin Park were obtained, and the transformationdesign of Xiaoyaojin Park was analyzed from the perspective of behavior psychology by analyzing thebehavior of tourists in different zones of Xiaoyaojin. Based on the premise of exploring the behaviorof tourists in different spaces, a city park environment that meets the needs of tourists can be created bypromoting the cultural context of the Three Kingdoms, improving the plant landscape and infrastructureof the site, optimizing the spatial function, and exploring the park design and transformation strategy that ismore in line with the needs of people, in order to provide new ideas for the future landscape transformationof Xiaoyaojin park, and offer reference suggestions for the future transformation design of old city parks. 展开更多
关键词 Behavior psychology old park City park Environmental optimization
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Application of the Concept of“Endowing the Old with the New”in Urban Renewal
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作者 JI Yuan 《Journal of Landscape Research》 2023年第2期21-26,共6页
The renewal of ancient cities is an important part of the urban renewal work in China.However,there are few studies on the general historical ancient cities at the county level in China,and there is no guidance on the... The renewal of ancient cities is an important part of the urban renewal work in China.However,there are few studies on the general historical ancient cities at the county level in China,and there is no guidance on the renewal path.Through the practice of the renewal design project of Suining County,Xuzhou City,it makes an exploratory study on the renewal concept and mode.It first interprets the connotation and implementation path of the renewal concept of“endowing the old with the new”.Based on the texture analysis of the ancient city of Suining,it finally determines the design theme that tracing the historical context of the ancient city.Using the renewal techniques such as“extraction-transformationactivation”,through the renewal strategies such as“building new space,shaping new landscape,inheriting new culture and pregnant with new environment”,it realizes the regeneration of urban historical context and meets the needs of residents'modern life,so as to provide reference and guidance for the renovation of general historical ancient cities at the county level in China. 展开更多
关键词 Endowing the old with the new Ancient city renewal Update design Application research
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Landscape Upgrading and Transformation of Old Urban Parks from the Perspective of Place Attachment:A Case Study of Nanchang Bayi Park
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作者 Baoyong LI Yuanqing WEN +1 位作者 Bo PENG Huimin TAN 《Meteorological and Environmental Research》 CAS 2023年第2期28-34,41,共8页
On the basis of combing the relevant theories of place attachment, the planning framework of upgrading and reconstruction of old parks based on place attachment was put forward. Taking Nanchang Bayi Park as an example... On the basis of combing the relevant theories of place attachment, the planning framework of upgrading and reconstruction of old parks based on place attachment was put forward. Taking Nanchang Bayi Park as an example, the methods and key points of landscape improvement and transformation of old urban parks based on place attachment were explained to provide new ways and references for the renewal of old urban parks. 展开更多
关键词 Landscape upgrading and transformation old urban parks Place attachment
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Construction of Industrialization Development Model for"1+4+X"Community-Based Elderly Care in Gannan Old Revolutionary Base Area in the Context of Population Aging
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作者 Chenxin YANG Jun XIAO +2 位作者 Liyuan WANG Jiaxin LIU Yangkai LU 《Asian Agricultural Research》 2023年第5期8-10,16,共4页
In the context of controlling population development in a planned way,China entered an aging society in the early 21 st century.In this context,how to meet the needs of the elderly care and form an effective elderly c... In the context of controlling population development in a planned way,China entered an aging society in the early 21 st century.In this context,how to meet the needs of the elderly care and form an effective elderly care model has become a key problem to be solved urgently by local government departments.With the continuous advancement of the elderly care policy,the community-based elderly care has gradually become the mainstream and is in the stage of vigorous promotion.Taking the Gannan old revolutionary base area in Jiangxi Province as an example,this study puts forward"1+4+X"community-based elderly care model based on the policy system of community-based elderly care,the physical and mental health of the elderly,the material space and the construction of evaluation system,and explores how to promote the application of this community model efficiently in the form of industrialization,so as to drive the economic growth of the Gannan old revolutionary base area,promote the employment development and improve the community-based elderly care service. 展开更多
关键词 Community-based elderly care New elderly care model Gannan old revolutionary base area
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Improving the Use of Insecticide-Treated Nets among Children under Five Years Old in Benin, West Africa
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作者 Emmanuel Houessou Tatchémè Filémon Tokponnon 《Advances in Infectious Diseases》 2023年第2期137-158,共22页
Background: In Benin, malaria represents the first cause of consultation and hospitalization (48% for children under 5 years old) in health units. It also accounts for 23.1% of deaths recorded in health facilities (Mo... Background: In Benin, malaria represents the first cause of consultation and hospitalization (48% for children under 5 years old) in health units. It also accounts for 23.1% of deaths recorded in health facilities (MoH, 2019). Between the two main components of vector control adopted by Benin government, the mass distribution campaigns of Insecticide-Treated Nets (ITNs) remained the only proven cost-effective way to rapidly achieve high and equitable coverage (WHO, 2017). After the fourth mass distribution campaign conducted in 2017, the Demographic and Health Survey (DHS) data indicated that the percentage of children who slept under an ITN has increased from 20% in 2006 to 70% in 2011-2012 and to 76% in 2017-2018 while the incidence of malaria (tested positive) is increasing rapidly among children under 5 years old, growing from 36.5% in 2009 to 28.8% in 2012 and then to 51.4% in 2019. This study aims to understand this contrast by identifying the origin of the increase in ITN use over time among children under five years old and the factors which determine this use. Methods: Data from the Demographic and Health Survey (DHS) conducted in Benin respectively in 2006 and in 20018 were used during the analysis, which covered 13,445 children under five years old from 2006 DHS and 12,255 children from 2017-2018 DHS. Firstly, the data were analyzed using decomposition method to highlight the origin of the increase of ITN use over time among children under five years old. Secondly, the chi-square test analysis estimated the association between ITN use and some characteristics (wealth index, maternal or caregiver education level and child age). Finally, the logistic regression model was used to identify the main factors, which influence the net use over the study period. Results: This study shows that the improvement of basic conditions is the main origin of behavior change in the use of ITNs among children under five years old. This improvement of the basic conditions consists of making ITNs available in households and informing household members about the benefits of ITN use. So, the free ITN distribution campaigns, routine distribution, awareness campaigns about the benefits of ITN use are the strategies, which increase the household capacities and knowledge, allowing household members to make their children sleep under net. The analysis also shows that region of residence, wealth index of household, household size, religion, and child age continue to determine the ITN use among children under age 5 years old and MNCP will integrate the factors in malaria prevention strategies in order to achieve universal use of ITNs. Conclusions: Although, sleeping under ITN behavior has indeed spread among children under 5 years old, policymakers and other stakeholders should design strategies to maintain and improve the current level of ITN use to reach the collective protection threshold (80% according to WHO). Therefore, to address the challenges of universal use of ITN, the study recommends expanding the routine distribution system to private sector health centers;discussing issues related to health service utilization (particularly ITN use) within a consultation framework at the communal level. In addition, collecting qualitative and quantitative data in the Oueme region will allow better understanding of all aspects of the ITN use gap among children under 5 years. 展开更多
关键词 MALARIA Long-Lasting Insecticidal Net (LLIN) Child under 5 Years old Health Policy BENIN
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大牛地气田老井水锁伤害及解除技术研究
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作者 王锦昌 杨易骏 《石油工业技术监督》 2024年第5期53-59,共7页
大牛地气田开发后期部分老井存在井底积液及近井地带水锁伤害,造成单井产量大幅降低,严重影响气田高效开发。通过建立老井储层水锁评价模型,明确了老井在不同条件下水锁伤害程度;同时以低表面张力、中性润湿为目标,优选出高效XH207C型... 大牛地气田开发后期部分老井存在井底积液及近井地带水锁伤害,造成单井产量大幅降低,严重影响气田高效开发。通过建立老井储层水锁评价模型,明确了老井在不同条件下水锁伤害程度;同时以低表面张力、中性润湿为目标,优选出高效XH207C型解水剂,其与泡排剂、阻垢剂、缓蚀剂等现用药剂配伍性良好,且使盒1、山2层岩心平均渗透率恢复率达130.5%,具有优异解水锁性能。现场应用表明,3口老井解水锁试验后日均增产4 377 m^(3)、累计增产363 226 m^(3),增产有效期为70~103 d,具有良好的增产效果。因此,该水锁解除技术在大牛地气田开发生产中具有一定应用前景。 展开更多
关键词 老井水锁伤害 解水锁剂 优选评价 解水锁技术
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韩城区块煤层气井顶板控底重复压裂技术研究与应用
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作者 王伟 魏振吉 +3 位作者 季亮 张旺 张正朝 赵海峰 《中国科技论文》 CAS 2024年第1期33-42,49,共11页
针对鄂尔多斯盆地韩城区块碎软煤层气老井采用常规重复压裂技术效果不佳的难题,以X井为研究对象,分析了初次压裂改造效果及剩余气产能特征,结合二次加砂与顶板压裂,提出顶板控底重复压裂技术。利用实验与数值模拟软件优化施工参数,优选... 针对鄂尔多斯盆地韩城区块碎软煤层气老井采用常规重复压裂技术效果不佳的难题,以X井为研究对象,分析了初次压裂改造效果及剩余气产能特征,结合二次加砂与顶板压裂,提出顶板控底重复压裂技术。利用实验与数值模拟软件优化施工参数,优选100目石英砂控底并暂堵老缝、40/70目+20/40目石英砂支撑新缝的三级加砂工艺,优化射孔位置为距煤层顶部3~5 m,施工排量为9 m^(3)/min,平均加砂比例为9%,形成增大储层改造体积、提高储层动用程度的顶板控底重复压裂技术。在X井进行现场试验,重复压裂后新增产气量268.1万m^(3),累计应用18口井,平均单井日产气量增加1 210.42 m^(3),有效解决了碎软煤层气老井重复压裂改造效果差的问题,可以满足煤层气老井二次开发及压裂作业降本增效的需求,具有良好的推广应用价值。 展开更多
关键词 煤层气 韩城区块 碎软煤层 老井重复压裂 支撑剂暂堵
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Decreased contrast sensitivity of visual cortical cells to visual stimuli accompanies a reduction of intracortical inhibition in old cats 被引量:2
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作者 周俊 施夏明 +2 位作者 彭青松 化国鹏 华田苗 《Zoological Research》 CAS CSCD 北大核心 2011年第5期533-539,共7页
Psychophysical experiments on human and animal subjects have proven that aged individuals show significantly reduced visual contrast sensitivity compared with young adults.To uncover the possible neural mechanisms,we ... Psychophysical experiments on human and animal subjects have proven that aged individuals show significantly reduced visual contrast sensitivity compared with young adults.To uncover the possible neural mechanisms,we used extracellular single-unit recording techniques to examine the response of V1(primary visual cortex) neurons as a function of visual stimulus contrast in both old and young adult cats(Felis catus).The mean contrast sensitivity of V1 neurons to visual stimuli in old cats decreased significantly relative to young adult cats,consistent with findings reported in old primates.These results indicate that aging can affect contrast sensitivity of visual cortical cells in both primate and non-primate mammalian animals,and might contribute to the reduction of perceptual visual contrast sensitivity in aged individuals.Further,V1 cells of old cats exhibited increased responsiveness,decreased signal-to-noise ratio,and enlarged receptive field(RF) size compared with that of young adult cats,which indicated that decreased contrast sensitivity of V1 neurons accompanied a reduction of intracortical inhibition during senescence. 展开更多
关键词 Contrast sensitivity V1 neurons old cats Young adult cats
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碳纳米葱(OLC)与微米金刚石(MD)烧结制备纳米聚晶金刚石复合材料(nPCD)的表征分析
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作者 李艳国 代利峰 +1 位作者 王志伟 邹芹 《超硬材料工程》 CAS 2024年第5期1-11,共11页
在4~6GPa/1000~1400℃/5~30min条件下,用微米金刚石(MD)和碳纳米葱(OLC)混合物作为原材料制备了纳米聚晶金刚石(nPCD)复合材料。采用XRD、FESEM、HRTEM、Archimedes原理和Vickers硬度计表征了nPCD复合材料的组成、形貌、微观结构、密度... 在4~6GPa/1000~1400℃/5~30min条件下,用微米金刚石(MD)和碳纳米葱(OLC)混合物作为原材料制备了纳米聚晶金刚石(nPCD)复合材料。采用XRD、FESEM、HRTEM、Archimedes原理和Vickers硬度计表征了nPCD复合材料的组成、形貌、微观结构、密度和硬度。研究了MD和烧结参数对nPCD复合材料的组成、微观结构、性能。结果表明,MD在nPCD复合材料中分布均匀。MD作为晶核促进OLC向金刚石的转换。烧结压力的增加提高了nPCD复合材料的密度和硬度。当烧结压力从4GPa提高到6GPa时,nPCD复合材料的密度从2.72g/cm^(3)增加到3.02g/cm^(3),硬度从41.85GPa增加到56GPa。提高烧结温度和延长保持时间使nPCD复合材料的密度和硬度先升高后降低。在nPCD复合材料中nPCD区域具有孪晶结构。孪晶结构的存在提高了nPCD复合材料的硬度。 展开更多
关键词 纳米聚晶金刚石(nPCD) 洋葱状碳(old) 微米金刚石(MD) 高压高温 相变
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英语范畴“old man”认知研究 被引量:1
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作者 唐清 《湖南科技大学学报(社会科学版)》 CSSCI 北大核心 2011年第2期127-129,共3页
以范畴"old man"为案例来诠释从原型范畴理论视角下范畴化"old man"这一自然现象的优势并演绎其动态范畴化过程。通过研究得出成员old man涵括最多的典型特征,为该范畴原型。以该原型为参照点范畴化内部结构,成员ma... 以范畴"old man"为案例来诠释从原型范畴理论视角下范畴化"old man"这一自然现象的优势并演绎其动态范畴化过程。通过研究得出成员old man涵括最多的典型特征,为该范畴原型。以该原型为参照点范畴化内部结构,成员ma-turea、dult隶属性最低,为边缘成员。 展开更多
关键词 原型 范畴化 认知语言学 范畴 old MAN
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Metabolomic-based analysis reveals bile acid-mediated ovarian failure induced by low temperature in zebrafish
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作者 Wen-Hao Li Zhi-Qiang Li +2 位作者 Meng-Di Bu Jia-Zhen Li Liang-Biao Chen 《Zoological Research》 SCIE CSCD 2024年第4期791-804,共14页
As ectotherms, fish are highly sensitive to temperature fluctuations, which can profoundly impact their reproductive cycles. In this study, we investigated the fertility and histological characteristics of zebrafish(D... As ectotherms, fish are highly sensitive to temperature fluctuations, which can profoundly impact their reproductive cycles. In this study, we investigated the fertility and histological characteristics of zebrafish(Danio rerio) ovaries exposed to a temperature gradient ranging from the thermopreferendum temperature of the species,27℃, to lower temperatures of 22℃, 20℃, and 13℃ over a period of two weeks. Comparative metabolomic(six biological replicates for each temperature) and transcriptomic(four biological replicates for each temperature) analyses were conducted under the four temperature conditions. Results indicated that lower temperatures inhibited oocyte development and differential metabolites were involved in steroid hormone production,antioxidant function, and lipid and protein catabolism.Disrupted reproductive hormones, increased proteolysis,and lipid degradation significantly impeded oocyte development and egg maturation. Notably, a significant increase in bile acid content was noted in the ovaries of the cold-treated fish, indicating that bile acids play a critical role in ovarian failure. Overall, these findings provide valuable insights into the mechanisms governing the reproductive response of fish to cold stress. 展开更多
关键词 old stress Ovarian failure METABOLOME ZEBRAFISH
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