The permeability of faults within siliciclastic petroleum reservoirs of the North Sea and Norwegian Continental Shelf

Faulting in Middle Jurassic reservoirs occurred at shallow depth during regional extension. Clean sandstones (<15% clay) deformed without significant grain fracturing and permeability reduction. Faults in impure sandstones (15–40% clay) experienced significant syn-deformation compaction and permeability reduction. Enhanced compaction during deeper burial reduced their permeabilities further from an average of 0.05 mD at <2.5 km to 0.001 mD at >4 km. Clay-rich sediments (>40% clay) deformed to produce clay smears with very low permeabilities (<0.001 mD). Faulting in the Rotliegendes occurred at greater depth during both basin extension and inversion. Extensional faulting produced cataclasites with permeability reductions of <10–>10⁶; their permeabilities range from 0.2 to 0.0001 mD and are inversely related to their maximum burial depth. Faults formed or reactivated during inversion experienced permeability increase. These results can be extrapolated to other hydrocarbon reservoirs if differences in stress and temperature history are taken into account.The permeability of most (>80%) faults is not sufficiently low, compared to their wallrock, to retard single-phase fluid flow on a km-scale. Nevertheless, most faults could retard the flow of a non-wetting phase if present at low saturations. It may be necessary to incorporate the two-phase fluid flow properties of fault rocks into reservoir simulators using upscaling or pseudoisation techniques. Fault property data should be calibrated against production data before it can be used confidently.     

On a sequence of remarkable fine structures in the type IV burst of 24 April, 1985

During the type IV burst on 24 April, 1985 we observed at 234 MHz an untypical, strong, nearly six hours lasting continuum emission incorporating several groups of broadband pulsations, zebra patterns, fiber bursts, and a new fine structure phenomenon. The power spectra of the groups of broadband pulsations reveal no simple structure. There is only one common periodic component between 0.3 s and 0.4 s. Slowly drifting chains of narrowband fiber bursts are described as a new fine structure by spectrograms and simultaneously recorded single frequency intensity profiles. A qualitative model of this new fine structure is suggested.     

无线射频识别双向认证协议及性能分析

针对姚华桢等人提出的射频识别认证协议易遭受读写器ID揭露,中间人攻击和假冒攻击等安全脆弱性,提出一种基于NTRU公钥密码算法的改进双向认证协议,并用GNY逻辑进行了形式化分析.协议不仅具有一次一密的特点,而且在实现双向认证的同时也完成了会话密钥的交换,并将主要的计算放在读写器上,有效降低了服务器的压力;解决了当前协议中存在的位置跟踪,前向安全性等隐私泄漏问题.分析结果表明,该协议不仅能够可抵抗重传,假冒,拒绝服务等多种恶意攻击,而且具有计算复杂度低,通信量小,效率高等特点,适合在低成本标签实现.     

基于TileStache的多源投影矢量数据瓦片生成技术研究

瓦片技术的出现改变了传统Web GIS的服务架构,提高了地图数据请求响应的效率。针对多种地图投影类型或地理坐标的矢量数据在瓦片划分过程中遇到的问题,本文基于OGR地理数据模型,设计了多投影数据转换Python模块,扩展至开源应用程序Tile Stache,得到适用于多源投影矢量地理数据的瓦片生成工具OTile Tool;从而实现矢量地理数据瓦片的快速生成,为网络地理信息系统提供了表达地理信息的Geo JSON格式瓦片数据。     

Interplanetary acceleration of energetic particles at 1 and 5 AU

Energetic particle (0.1 to 100 MeV protons) acceleration is studied by using high resolution interplanetary magnetic field and plasma measurements at 1 AU (HEOS-2) and at 5 AU (Pioneer 10). Energy changes of a particle population are followed by computing test particle trajectories and the energy changes through the particle interaction with the time varying magnetic field. The results show that considerable particle acceleration takes place throughout the interplanetary medium, both in the corotating interaction regions (CIR) (5 AU), and in quiet regions (1 AU). Although shocks may contribute to acceleration we suggest statistical acceleration within the CIRs is sufficient to explain most energetic particle observations (e.g., McDonaldet al., 1975; Barnes and Simpson, 1976).The first and second order statistical acceleration coefficients which include transit time damping and Alfvén resonance interactions, are found to be well represented byD _T 8.5×10^–6 T ^0.5 MeV s^–1 andD _TT 4×10^–6 T ^1.5 MeV² s^–1 at 5 AU.By comparison, Fisk's estimates (1976), based on quasi-linear theory for transit-time damping, gaveD _TT 5×10^–7 T MeV² s^–1 at 1 AU.     

中国西北极端降水事件年内非均匀性特征分析

 基于中国西北五省（区）1960—2004年112个台站逐日降水资料,根据百分位值方法定义了不同台站的极端降水阈值,引入了表征时间分配特征的新参数——极端降水事件集中度和集中期,对中国西北极端降水事件的年内非均匀性特征进行了分析,结果表明：西北年极端降水事件集中度及集中期的平均和异常空间分布都存在很大的区域差异,并且其异常空间分布均可分为6个关键区;而从时间演变来看,各个关键区年极端降水事件的集中度与集中期均表现出了显著的年代际振荡特征,但各分区年代际变化特征并不一致;另外西北东、西部年极端降水事件集中度与集中期表现出反向的变化趋势。     

荒漠人工植被区浅层土壤水分空间变化特征分析

研究土壤水分的空间变异及时间动态特征有助于在水文过程与生态格局之间建立定量的联系,由于土壤水分对整个地球系统的重要性,它的时间和空间变化日益引起水文界的广泛关注。干旱荒漠区年降水量稀少,土壤水分在整个生物过程中的作用就显得尤为重要。试验于2005年4月到10月在中国科学院沙坡头沙漠试验研究站人工植被区进行,主要观测1956年植被区表层（0—15 cm）和亚表层（15—30 cm）土壤水分的空间格局与动态分布及其相关影响因素。结果表明:人工植被区表层土壤水分含量明显高于亚表层,其空间变异程度为中等,空间分布的时间差异性显著;降雨是引起干旱沙地表层土壤水分空间变异的决定因素,植物根系是引起亚表层水分空间变异的重要因素。从不同微地形来看,土壤水分含量值表现为丘间低地＞背风坡＞迎风坡,变异程度丘间低地小于迎风坡和背风坡;地形是决定背风坡表层和亚表层以及迎风坡亚表层土壤水分空间分布的主要因素,而迎风坡表层土壤水分变化受风力等环境因子的影响较大。     

1980-2010年安徽省土壤有机碳密度及储量时空变化分析

利用安徽省第二次土壤普查资料和2010-2011年土壤调查数据,运用GIS技术,研究1980-2010年安徽省表层（0~20 cm）和1 m土体中土壤有机碳（SOC）密度和储量的时空变化,并探讨土地利用变化对SOC储量变化的影响。研究表明：① 1980-2010年安徽省表层和1 m土体中SOC密度平均减少0.37 kg/m²和1.63 kg/m²,但耕地的SOC密度增加。② 1980-2010年,全省SOC密度空间变化呈现北增南减的趋势,且增加幅度由北向南依次减小。表层和1 m土体的SOC密度增加的面积为56.97%和58.21%。③ 1980-2010年,全省表层SOC储量减少34.23×10⁹ kg,1 m土体中SOC储量减少197.26×10⁹ kg。淮北平原、江淮丘陵岗地和沿江平原的SOC储量增加,皖西大别山区和皖南丘陵山区减少。④ 非耕地转换为耕地,比保持用地类型不变或变为其他非耕地类型,SOC密度和储量减少较慢。耕地类型内部转换（水田和旱地间转换）比保持类型不变的SOC密度和储量增加较多。研究成果为区域土壤固碳潜力、土壤肥力变化等研究提供科学依据。