Laboratory investigation of hydraulic fracture propagation using real-time ultrasonic measurement in shale formations with random natural fractures

The significance of natural fractures in unconventional shale hydrocarbon formations has opened new research frontiers in hydraulic fracturing. Among many of its unique contributions to gas production, the interaction between natural fractures and hydraulic fractures has long been experimentally and computationally investigated. Here, we experimentally investigated the evolution of the fracturing network with a self-developed ultrasonic testing system. Laboratory experiments are proposed to study the propagation of hydraulic fracture in naturally fractured model blocks that contain random micro-fractures. Our analysis suggests that the total fracture width obtained by ultrasonic pulse velocity (UPV) can reflect the dynamic evolution of the fracturing network. The nonlinear fracturing network evolution process is closely related to the variation of the total fracture width. It is suggested from the total fracture width that the maximum fracture network can be realized with greater natural fracture density, large injection rate, and smaller stress ratio. The study presents a better insight into the response of random naturally fractured shale formation under hydraulic fracturing treatment by analyzing the variation of UPV in real time.     

A conceptual evolutionary aseismic decision support framework for hospitals

In this paper, aconceptual evolutionary framework for aseismic decision support for hospitalsthat attempts to integrate a range of engineering and sociotechnical models is presented. Genetic algorithms are applied to find the optimal decision sets. A case study is completed to demonstrate how the frameworkmay applytoa specific hospital.The simulations show that the proposed evolutionary decision support framework is able to discover robust policy sets in either uncertain or fixed environments. The framework also qualitatively identifies some of the characteristicbehavior of the critical care organization. Thus, by utilizing the proposedframework, the decision makers are able to make more informed decisions, especially toenhance the seismic safety of the hospitals.     

从岩石化学特点看板溪群的沉积大地构造背景

将板溪群和冷家溪群杂砂岩全岩岩石化学分析结果在SiO_2-K_2O/Na_2O图解、SiO_2/Al_2O_3-K_2O/(Na_2O+CaO)图解、Na_2O-K_2O图解以及(K_2O+Na_2O)—Al_2O_3图解上投点,发现多数板溪群杂砂岩样品点落在被动大陆边缘区,而冷家溪群杂砂岩样品点则多落入活动大陆边缘区。因此认为,板溪群沉积于被动大陆边缘,而冷家溪群沉积于活动大陆边缘,它们形成于不同的地质演化阶段。     

Optimization of concurrent mining and reclamation plans for single coal seam: a case study in northern Anhui, China

The extraction of underground ore body inevitably causes a large amount of land subsidence. Current reclamation technologies in China mainly focus on stable subsided land, which means most of the affected lands are submerged into water because of the high groundwater table in some areas, leading to the loss of soils and inefficient reclamation. Therefore, a new technology for reclaiming unstable subsiding land is being studied for restoring farmland as much as possible, based on a case study in northern Anhui, China. In consideration of the mining plan, subsidence processes in various stages were analyzed and some related factors such as vertical subsidence, post-mining slope, water area, and land use condition were also simulated. Due to mining activities, useful farmland has gradually decreased to merely 14.4 % of the pre-mining area. In this study, the following stages were modeled from pre-mining to post-mining: (1) percentage of farmland was 100 % in stage (a) (pre-mining), (2) 72.5 % in stage (b), (3) 67.3 % in stage (c), and (4) 14.4 % in stage (d) (post-mining). The results show that 86.6 % of cultivated land was submerged into water and lost its capacity for cultivation after coal mining. Reclamation plans for stages (b), (c), and (d) were made by a traditional reclamation method called “Digging Deep to Fill Shallow”. Based on scenario simulation of reclamation, the farmland reclamation percentages were improved to 78.3, 73.3, and 40.70 %, respectively. Taking the percentage of reclaimed farmland as the preferred standard, concurrent mining and reclamation for stage (b) and (c) could increase farmland reclamation percentages to 37.6 and 32.6 %, respectively, compared with the farmland reclamation percentage of post-mining [reclaiming the land in stage (d)]. The results reveal that optimum reclamation time should be at stage (b). Therefore, under current technical conditions, concurrent mining and reclamation could enhance the quantity of cultivated land and provide better land protection and food security in the mined areas with high groundwater table.     

最优性价比的观测系统设计方法研究

三维观测系统优化设计是野外地震采集工作的一个重要环节,影响着后期地震资料采集处理解释的各个工作环节.因此,高质量的观测系统设计是地震勘探工作的关键,然而在无限制的追求高信噪比、高分辨率的地震资料,高难度的野外施工的同时,这往往会带来较大的成本投入.鉴于以上存在的问题,文章着重分析质量最优和成本最优的观测系统设计,通过寻找观测系统参数与采集质量和采集成本的关系,结合二者的优点,提出了最优性价比的观测系统优化设计方法,并通过一个实际工区的试验,体现出该方法的应用效果,为高质量的观测系统设计提供新的思路和方法.     

Flow resistance adjustments of channel and bars in the middle reaches of the Yangtze River in response to the operation of the Three Gorges Dam

Journal of Geographical Sciences - Since the Three Gorges Dam (TGD) was put into operation, the flood water level at an identical discharge rate has not displayed a decreasing trend along the...     

连作马铃薯根系分泌物鉴定及其对尖孢镰孢菌(Fusarium oxysporum)的作用

为了揭示马铃薯连作化感物质与枯萎病之间的关系,通过水培和田间长期定位试验相结合方法,收集不同连作年限马铃薯根系分泌物,采用GC-TOF-MS进行分离鉴定.结果表明:在检测到的马铃薯根系分泌的48种物质中有机酸占30种.比较轮作、连作5年和连作10年马铃薯根系分泌物中有机酸的相对含量,发现苹果酸和棕榈酸的差异比较大.马铃...     

甘肃礼县王河金矿地电提取找矿方法实验研究

王河金矿地电提取找矿方法的实验研究表明,在已知矿体上方,地电提取Ａｕ、Ａｇ、ＣｕＰｂ都出现了不同程度的异常,且提取时加玉水的异常循环与矿体的赋存位置的吻合程度比不加王水的好,说明在黄土覆盖地区用该方法寻找隐伏矿体是可行的。     

Zircon U–Pb ages and O–Nd isotopic composition of basement rocks in the North Qinling Terrain, central China: evidence for provenance and evolution

The Qinling Group was previously interpreted as the oldest Precambrian basement unit of the North Qinling Terrain, recording its formation and early crustal evolution. The Qinling Group consists predominantly of gneisses, amphibolites, and marbles, which underwent multi-phase deformation and metamorphism. In order to better constrain the provenance and tectonic setting of this group and the evolution of the North Qinling orogenic belt, in situ U–Pb dating and oxygen isotopic analysis of zircons in combination with whole-rock geochemistry and Sr–Nd isotope analysis was performed on the two dominant rock types, amphibolite and felsic gneiss. Felsic gneisses exhibit enrichment of LREEs and LILEs (Rb, Ba, Th, K, Pb), negative Eu anomalies and depletion of HFSEs (Nb, Ta, P, Ti). The rocks have slightly elevated δ¹⁸O values (6.5–9.3 ‰) and initial ε _Nd values of ?4.6 corresponding to two-stage Nd model age of 1.99 Ga. Amphibolites are also enriched in LILEs and LREEs and depleted in Nb and Ta and have homogeneous δ¹⁸O values (5.0–6.0 ‰), but higher initial ε _Nd values (2.8–3.3) and younger two-stage Nd model ages (1.29–1.24 Ga) compared to the gneisses. The zircon age record indicates that the gneisses and amphibolites were formed in a ~960 Ma volcanic arc environment rather than in a rift setting as previously suggested. A major metamorphic event took place during the Early Paleozoic. Based on the age spectrum of detrital zircons, the Qinling Group is interpreted as an autonomous geological unit, which was mainly derived mostly from 1,000 to 900 Ma old granitoid rocks. The North Qinling Terrain can be regarded as a remnant of the Grenville orogenic belt with an early Neoproterozoic evolution different from that of the North and South China blocks.     

基于手机邮箱监控天气雷达运行状态的方法

介绍了一种新的短信报警方法,通过巧妙应用中国移动的139邮箱业务,同样能完成对雷达状态的监控,并详细阐述了该方法的原理,最后对两种方法的优劣势进行了对比分析,为台站在设计监控软件时能有多种选择。