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《物探化探计算技术》2019,(6)
目前临界阻尼状态下局部导电体瞬变电磁观测电压表达式存在两种不同的结果,为了探究其原因,对临界阻尼状态下局部导电体观测电压表达式重新进行了推导,并用MATLAB软件对推导结果进行了验证。通过推导证明其中一种表达式存在错误,经过计算发现线圈阻尼系数越小,该表达式计算的观测电压误差越大;时间常数越小,计算的观测电压误差越大。 相似文献
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针对低渗透油田开发过程中存在的时变效应,以室内实验为基础,结合数值模拟方法研究了低渗透油藏渗透率时变效应规律及其对油田开发效果的影响.结果表明,上覆压力越大,渗透率时变伤害率越大,上覆压力增大至一定值之后,上覆压力的变化对渗透率伤害率的影响不大.渗透率越小,渗透率时变伤害率越大.当渗透率小于0.1×10-3 μm2时,渗透率时变伤害明显增大,同时难以恢复到原渗透率条件,裂缝性岩心时变伤害大且伤害后恢复更加困难.时变效应对渗透率的伤害主要集中在井筒附近,无因次半径越小,渗透率伤害越大;在相同的生产压差下,时变效应系数越大,油井产量越低. 相似文献
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通过室内大尺寸非饱和黄土冻结作用下水分迁移试验,开展了土体密度、含水量、冻结温度、冻结方式对非饱和黄土水分迁移影响的研究.试验结果表明:冻结过程中土样温度变化分为3个阶段:急剧降温阶段,缓慢降温阶段,稳定阶段; 干密度越大,稳定冻结锋面的水分迁移量越大,但冻结区的整体水分增量越小; 初始含水量越大,水分迁移量越大,并且在冻结锋面处含水量增幅越大; 在未冻结区,从邻近冻结锋面到暖端,含水量先增大后减小,初始含水量越小,这种现象越明显.此现象是冻结界面抽吸力、温度梯度和基质吸力梯度共同作用的结果.冻结方式直接影响已冻结区的含水量分布和水分迁移总量. 相似文献
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针对可控源音频大地电磁法(CSAMT)野外数据采集中接收电缆线之间、接收电缆线和大地之间存在的电磁耦合效应,通过电磁耦合理论研究和等效电路计算,推导正演模拟计算公式,结合各种模型的正演模拟计算和野外实际数据对比,研究了可控源音频大地法中影响电磁耦合效应的三种因素,包括:电缆线长度、不极化电极接地电阻、信号频率,总结出三种因素对应的电磁耦合特征,即:接收系统中电缆线长度越长,电缆线之间的耦合电容越大,视电阻率曲线在高频段出现下降的趋势越明显,曲线畸变越明显;野外不极化电极上接地电阻越大,视电阻率曲线在高频段表现出下降的趋势越明显,曲线畸变越明显;电路中信号频率越高,感抗和容抗越大,曲线畸变越明显,当信号频率增大到一定的值时,电路中的感应容抗就不再继续增大,曲线趋于稳定。 相似文献
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本文结合标本测定和模拟实验结果,对不同条件下虚分量谱极值频率变化较大的原因进行了分析讨论.认为虚分量谱的“不稳定”实际上是极化体时间常数变化的客观反映.就反演频谱确定时间常数而言,相位谱并不比虚分量谱优越. 相似文献
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非饱和粗颗粒土体的冻结试验研究 总被引：4，自引：2，他引：2
按照实际工程中路基填料的级配要求配制试样,在考虑覆盖层和补水条件下进行室内单向冻结试验,开展了土质、温度梯度和温度边界条件对非饱和粗颗粒填料冻胀特性的影响研究。试验结果表明：土质、温度梯度和温度边界对粗颗粒填料的冻胀特性影响显著。其中混合细粒的冻胀量最大、黏质黄土次之、粉质黏土最小,且其对应的试样顶部、冻结锋面处的含水量及外界补水量均具有相同的大小关系。温度梯度越大,冻胀量越大,试样顶部含水量越高,但冻结锋面处的含水量变化比较小,同时外界补水量越小。试样冷端温度边界越低,冻胀量越小,试样冷端含水量越小,但外界补水量越大。 相似文献
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通过对软土地区某基坑工程实践进行有限元数值模拟,分析了排桩、重力坝两种基坑围护形式下大型坑中坑里面内、外坑之间距离对两坑围护体水平变形的影响。计算数据表明,内外坑距离越大,外坑围护体水平位移越小,当距离大于2~3倍内坑深度后,围护体水平变形可以不用考虑坑中坑的影响。内外坑距离越大,内坑围护体水平位移越小;内坑围护体水平变形受外坑围护体刚度影响,外坑围护体刚度越大,内坑围护体变形越小。 相似文献
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为了定量研究煤层气井解吸特征,文章通过煤样解吸实验获取解吸曲线并进行拟合回归得到了煤样解吸曲线定量表征公式。结果表明：煤样解吸曲线可以用来定量表征;解吸体积常数可表征煤样的最大解吸量,解吸时间常数表征解吸气体体积达到最大解吸气体积一半时所用的解吸时间;煤样初始解吸速率等于解吸体积常数与解吸时间常数之比,煤样解吸速率随着解吸体积常数增加而增加,随着解吸时间常数增加而降低。解吸时间常数与吸附时间成线性正相关关系,解吸时间常数越大,煤样解吸速率越小;在工程上可以用解吸体积常数代替解吸气量和残余气量之和;解吸时间常数随气体压力和裂缝指数增加而降低,随镜质组、惰质组含量增加而先增加后降低,与粘土矿物含量关系不明显;解吸体积常数随气体压力、惰质组含量增加而增加,与粘土矿物含量关系不明显,随着镜质组含量增加而降低,随裂缝指数先降低后增加。 相似文献
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Emily Keeble David I. Whiteside Michael J. Benton 《Proceedings of the Geologists' Association. Geologists' Association》2018,129(2):99-119
Pant-y-ffynnon Quarry in South Wales yielded a rich cache of fossils in the early 1950s, including articulated specimens of new species (the small sauropodomorph dinosaur Pantydraco caducus and the crocodylomorph Terrestrisuchus gracilis), but no substantial study of the wider fauna of the Pant-y-ffynnon fissure systems has been published. Here, our overview of existing specimens, a few described but mostly undescribed, as well as freshly processed material, provides a comprehensive picture of the Pant-y-ffynnon palaeo-island of the Late Triassic. This was an island with a relatively impoverished fauna dominated by small clevosaurs (rhynchocephalians), including a new species, Clevosaurus cambrica, described here from a partially articulated specimen and isolated bones. The new species has a dental morphology that is intermediate between the Late Triassic Clevosaurus hudsoni, from Cromhall Quarry to the east, and the younger C. convallis from Pant Quarry to the west, suggesting adaptive radiation of clevosaurs in the palaeo-archipelago. The larger reptiles on the palaeo-island do not exceed 1.5?m in length, including a small carnivorous crocodylomorph, Terrestrisuchus, and a possible example of insular dwarfism in the basal dinosaur Pantydraco. 相似文献
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Gilles Serge Odin 《Comptes Rendus Geoscience》2002,334(6):409-414
Lithostratigraphy, physicochemical stratigraphy, biostratigraphy, and geochronology of the 77–70 Ma old series bracketing the Campanian–Maastrichtian boundary have been investigated by 70 experts. For the first time, direct relationships between macro- and microfossils have been established, as well as direct and indirect relationships between chemo-physical and biostratigraphical tools. A combination of criteria for selecting the boundary level, duration estimates, uncertainties on durations and on the location of biohorizons have been considered; new chronostratigraphic units are proposed. The geological site at Tercis is accepted by the Commission on Stratigraphy as the international reference for the stratigraphy of the studied interval. To cite this article: G.S. Odin, C. R. Geoscience 334 (2002) 409–414. 相似文献
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The effect of water on accessory phase solubility in subaluminous and peralkaline granitic melts 总被引：4，自引：0，他引：4
The solubilities of columbite, tantalite, wolframite, rutile, zircon and hafnon were determined as a function of the water contents in peralkaline and subaluminous granite melts. All experiments were conducted at 1035 °C and 2 kbar and the water contents of the melts ranged from nominally dry to approximately 6 wt.% H2O. Accessory phase solubilities are not affected by the water content of the peralkaline melt. By contrast, solubilities are affected by the water content of the subaluminous melt, where the solubilities of all the accessory phases examined increase with the water content of the melt, up to 2 wt.% H2O. At higher water contents, solubilities are nearly constant. It can be concluded that water is not an important control of accessory phase solubility, although the water content will affect diffusivities of components in the melt, thus whether or not accessory phases will be present as restite material. The solubility behaviour in the subaluminous and peralkaline melts supports previous spectroscopic studies, which have observed differences in the coordination of high field strength elements in dry vs. wet subaluminous granitic glasses, but not for peralkaline granitic glasses. Lastly, the fact that wolframite solubility increases with increasing water content in the subaluminous melt suggests that tungsten dissolved as a hexavalent species. 相似文献
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Muriel Rocher Stéphane Baize Stéphane Jaillet Edward Marc Cushing Yannick Lozac&#x;h Francis Lemeille 《Comptes Rendus Geoscience》2003,335(8):701-708
Calcite samples were extracted both from the rock matrix and the superficial coating of a karstified fault plane of an underground quarry, located in the eastern border of the Paris basin. The karstification is dated as Quaternary. Analysis of mechanical calcite twinning reveals that only the calcite matrix has also undergone a compression trending WNW that can be attributed to the Mio-Pliocene alpine collision. Both coating and matrix have undergone a strike-slip regime with σ1 roughly trending north–south, that could correspond to the regional present-day state of stress, a strike-slip compression rather trending NNW, modified by local phenomena. To cite this article: M. Rocher et al., C. R. Geoscience 335 (2003). 相似文献
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正20141520 Bo Ying(Key Laboratory of Metallogeny and Mineral Assessment,MLR,Beijing 100037,China);Liu Chenglin Saline Spring Hydrochemical Characteristics and Indicators for Potassium Exploration in Southwestern and Northern Tarim Basin,Xinjiang(Acta Geoscientica Sinica,ISSN1006-3021,CN11-3474/P,34(5),2013,p.594-602,5 illus.,3 tables,28 refs.) 相似文献
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正20141243Chen Ge(Hangzhou Research Institute of Petroleum Geology,PetroChina,Hangzhou 310023,China);Si Chunsong Study on Sedimentary Numerical Simulation Method of Fan Delta Sand Body(Journal of Geology, 相似文献
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正20142599Chen Sanming(Guangxi Key Laboratory of Concealed Deposits Exploration,Guilin University of Technology,Guilin541004,China);He Yuzhou Block Model and Reserves Estimation of Panzhihua Iron Deposit Based on 3D Geological Modeling(Journal of Guilin University of Technology,ISSN1674-9057,CN45-1375/N,33(4),2013,p.610-615,9illus.,1table,15refs.) 相似文献
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正20140594 Bai Daoyuan(Hunan Institute of Geology Survey,Changsha 410016,China);Zhong Xiang Faults in the Jingzhou Basin and Their Tectonic Settings(Geotectonica et Metallogenia,ISSN1001-1552,CN44-1595/P,37(2),2013,p.173-183,6illus.,59refs.)Key words:basin evolution,tectonic setting,South China In the Upper Paleozoic and Jurassic se- 相似文献
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正20141912Cao Hui(State Key Laboratory for Continental Tectonics and Dynamics,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China)Gravitational Collapse and Folding during Orogenesis:A Comparative Study of FIA Trends and Fold Axial Plane Traces(Geology in China,ISSN1000-3657,CN11-1167/P,40(6),2013,p.1818-1828,9illus.,35refs.,with 相似文献