Natural hydraulic cracking: numerical model and sensitivity study   总被引：2，自引：0，他引：2  

Xiaorong Luo 《Earth and Planetary Science Letters》2002,201(2):431-446

Natural hydrofracturing caused by overpressure plays an important role in geopressure evolution and hydrocarbon migration in petroliferous basins. Its mechanism is quite well understood in the case of artificial hydraulic fracturing triggered by high-pressure fluid injection in a well. This is not so for natural hydraulic fracturing which is assumed to initiate as micro-cracks with large influence on the permeability of the medium. The mechanism of natural hydraulic cracking, triggered by increasing pore pressure during geological periods, is studied using a fracturing model coupled to the physical processes occurring during basin evolution. In this model, the hydraulic cracking threshold is assumed to lie between the classical failure limit and the beginning of dilatancy. Fluid pressure evolution is calculated iteratively in order to allow dynamic adjustment of permeability so that the fracturing limit is always preserved. The increase of permeability is interpreted on the basis of equivalent fractures. It is found that fracturing is very efficient to keep a stress level at the rock’s hydraulic cracking limit: a fracture permeability one order of magnitude larger than the intrinsic permeability of the rock would be enough. Observations reported from actual basins and model results strongly suggest that natural hydraulic cracking occurs continuously to keep the pressure at the fracturing limit under relaxed stress conditions.  相似文献   

Sedimentary cycles of trace elements in Salawusu River Valley since 150 ka BP   总被引：6，自引：0，他引：6  

Yao Chun-xial  Li Bao-sheng  Jin He-ling  David Dian Zhang  Yan Man-cun  Zhu Yi-zhi  Li Hou-xin  Zhang Yu-hong  Luo Kai-li 《地理学报(英文版)》2002,12(1):65-71

The paper makes some analyses on 11 trace elements in the Milanggouwan stratigraphical section in the Salawusu River valley, which is regarded as a prototype geology-palaeoclimate record since 150 ka BP. The results show that the content and variation of trace elements has experienced remarkably regular changes in the pace with coarse and fine sedimentary cycles of palaeo-aeolian sands to its overlying fluvio-lacustrine facies or/and palaeosols. The trace elements with chemical properties of relatively active (V, Sr, Cu, Ni, As) and relatively stable (P, Pb, Rb, Mn, Nb, Zr) are a manifestation of the corresponding 27 changeable cycles between peak and valley values, appearing a multi-fiuctuational process line of relative gathering and migration since then. The low numerical value distribution of these two types of trace elements in the aeolian sand facies represents erosion and accumulation under wind force during the cold-dry climate. Whereas their enrichments in both fluvio-lacustrine facies and palaeosols are related to the valley’s special low-lying physiognomic position between the Ordos Plateau and the Loess Plateau under the warm and humid climate conditions. The above relatively migrated and gathered change of the trace elements is the result of 27 climatic cycles of cold-dry and warm-humid, which is probably caused by repeated alternations of winter monsoon and summer monsoon in the Mu Us Sandy Land influenced by the climate vicissitudes in northern hemisphere during glacial and interglacial periods since 150 ka BP.  相似文献   

TDP-0844地震前兆数据综合采集器的研制     

刘桂生  张国育  罗新恒 《地震地磁观测与研究》2003,24(4):48-55

介绍了TDP—0844型地震前兆数据综合采集器采用的设计方案及工作原理，及各个功能模块的设计准则，并列出了采集器实现的功能。文章还给出了采集器的部分应用图例，证明该采集器能够满足地震前兆观测需要。  相似文献   

Introduction of structural aseismic research in China in recent four years     

罗奇峰  石春香  曹炳政  杨树龙  熊华  李仕栋 《地震学报(英文版)》2003,16(6):656-675

Introduction Greeting the coming of the 21st century, Professor HU Yu-xian and other Chinese scholars briefed the trend of earthquake engineering in China and aboard (HU, 1999; HU, ZHOU, 1999). The experiences and lessons learning from the destructive earthquakes in China and abroad in re-cent years, the damage action of the large velocity impulse in ground motion in near field in seis-mic design, numerous earthquake examples show that there are many weaknesses in aspects of earthquake p…  相似文献   

地震数据IP传输及存储技术应用     

周超  罗新恒  刘桂生  张哲  曾令国  吴怀壮 《地震地磁观测与研究》2003,24(2):1-9

介绍一种IP传输方案。该方案通过地震数据IP传输及存储单元(ITU)、IP流多串口服务器完成，能实现单个台站与多个台网中心的Internet传输、单个台站与多个台网中心的专线传输、地震台网中心之间的Internet连接、远程数据下载及参数设置等多种传输方式，该传输方案具备实时性、可压缩性、多路服务、安全性、数据在线保存、传输费用低、操作简单等特点。  相似文献   

ADP数字地震前兆综合观测台网系统的设计     

周超  罗新恒  张哲  陈景华  曾令国  李川君 《地震地磁观测与研究》2003,24(2):18-26

介绍了ADP数字地震前兆综合观测台网系统的功能与结构。ADP系统已在广东省地震局连续运行，满足前兆台网综合化、数字化、自动网络化的要求。  相似文献   

ADAPT数字遥测地震台网中传递函数的辨识     

罗新恒  张哲  陈景华  曾令国 《地震地磁观测与研究》2003,24(3):67-74

Adapt系统可以利用脉冲标定波形得到系统的传递函数，它将复杂的传递函数计算过程简化了，用户可以将传递函数的测定作为一种日常工作来做。  相似文献   

武汉基准台超导重力仪重力潮汐观测结果   总被引：11，自引：2，他引：11  

徐建桥  许厚泽  孙和平  罗少聪 《测绘学报》1997,26(4):307-314

本文采用重力残差信号对武汉基准台超导重力仪的原始观测数据（２０秒采样）作预处理，将原始观测信号分解成重力潮汐和残差两部分，在残差信号中消除一些已知的干扰因素的影响。利用ＥＴＥＲＮＡ软件作调和分析，两主波（Ｏ１和Ｍ２）的重力潮汐参数（振幅因子和相位滞后）为：Ｏ１：１．１７８８±０．０００６，－０．５９７５°±０．０２８°；Ｍ２：１．１７１３±０．０００２，－０．５８７３°±０．００８°经海潮改正以后，Ｏ１和Ｍ２波的潮汐参数与Ｗａｈｒ－Ｄｅｈａｎｔ潮汐模型值相比，振幅因子的偏差优于０．１％。  相似文献   

武威地区冬季低温天气的气候分析与预报     

严志明  李岩瑛  罗晓玲 《干旱气象》1997,(4)

通过对１９８０—１９９１年１２—２月武威地区低温天气过程气候特征和天气成因的分析，建立模式预报方程。１９９２—１９９６年试报效果良好，将植入“武威地区冬半年寒潮降温多目标专家系统”，投入业务运行。  相似文献   

1995年7月12日云南孟连中缅边界7.3级地震中短临预报及前兆异常特征（3）     

付虹  陈立德 《地震研究》1997,20(4):345-356

研究了孟连７．３级地震前云南全省及震中距６００ｋｍ范围内跨断层短水准、短基线、地倾斜、水氡、水位、水汞等１３类观测项目，５５个台站，１１个台项测值的中、短、临异常情况。结果表明，震前中、短、临异常台项目分比为３８％，并主要集中在２００－４００ｋｍ范围。中期异常特征为异常时间长、幅度大、短临异常特征为中期异常趋势结束或测反向，部分项目出现“巨变”东家主震中附近异常出现晚而外围出现早、随着地震临近其异  相似文献