川西地区雷口坡组顶部不整合面特征及其对储层的影响     

王文楷  许国明  淡永  宋晓波  王琼仙  冯霞  张露 《中国岩溶》2018,37(4):592-601

近年来,川西地区在雷口坡组顶部钻遇优质储层,取得了天然气勘探的重大突破。基于野外露头、钻井岩芯、薄片、录井、测井、常量元素和（碳、氧）同位素等资料的分析,对川西地区雷口坡组顶部不整合面特征及其对储层影响进行了研究。结果表明,不同地区雷顶储层受不整合面的影响存在差异性:彭州地区雷顶发育裂缝型灰岩储层,储层发育不受不整合面影响;新场地区雷顶发育孔隙型白云岩储层,不整合面对储层有改善作用;回龙地区雷顶发育石膏溶蚀孔、洞型岩溶储层,不整合面对储层发育起控制作用。岩性和微古地貌是影响川西地区古岩溶作用发育的决定性因素。回龙地区广泛发育的规模性岩溶储层是川西雷口坡组下一步勘探的有利目标。   相似文献   

Deep mantle roots and continental emergence: implications for whole-Earth elemental cycling,long-term climate,and the Cambrian explosion     

Cin-Ty A. Lee  Jeremy Caves  Hehe Jiang  Wenrong Cao  Adrian Lenardic  N. Ryan McKenzie 《International Geology Review》2018,60(4):431-448

Elevations on Earth are dominantly controlled by crustal buoyancy, primarily through variations in crustal thickness: continents ride higher than ocean basins because they are underlain by thicker crust. Mountain building, where crust is magmatically or tectonically thickened, is thus key to making continents. However, most of the continents have long passed their mountain building origins, having since subsided back to near sea level. The elevations of the old, stable continents are lower than that expected for their crustal thicknesses, requiring a subcrustal component of negative buoyancy that develops after mountain building. While initial subsidence is driven by crustal erosion, thermal relaxation through growth of a cold thermal boundary layer provides the negative buoyancy that causes continents to subside further. The maximum thickness of this thermal boundary layer is controlled by the thickness of a chemically and rheologically distinct continental mantle root, formed during large-scale mantle melting billions of years ago. The final resting elevation of a stabilized continent is controlled by the thickness of this thermal boundary layer and the temperature of the Earth’s mantle, such that continents ride higher in a cooler mantle and lower in a hot mantle. Constrained by the thermal history of the Earth, continents are predicted to have been mostly below sea level for most of Earth’s history, with areas of land being confined to narrow strips of active mountain building. Large-scale emergence of stable continents occurred late in Earth’s history (Neoproterozoic) over a 100–300 million year transition, irreversibly altering the surface of the Earth in terms of weathering, climate, biogeochemical cycling and the evolution of life. Climate during the transition would be expected to be unstable, swinging back and forth between icehouse and greenhouse states as higher order fluctuations in mantle dynamics would cause the Earth to fluctuate rapidly between water and terrestrial worlds.  相似文献   

西秦岭北缘一个新生代伸展型角度不整合及其地质意义     

郭进京  张琛  吉夏  赵海涛  刘重庆  陆宏宇  王凯旋 《地质通报》2018,37(10):1831-1841

通过对西秦岭北缘漳县地区渐新统—中新统含盐红层地层与下伏造山带地层之间的角度不整合及其之上的砾岩、地层序列、沉积旋回等特征研究,提出了该角度不整合为伸展型角度不整合的认识。该伸展型角度不整合的存在指示了西秦岭北缘漳县渐新统—中新统含盐红层盆地具有伸展断陷盆地的属性,意味着在渐新世—中新世漳县含盐盆地形成和沉积充填时期,青藏高原东北缘(至少西秦岭北缘)一直处于伸展构造环境。这与印度板块与欧亚板块碰撞汇聚动力学作用向东北缘扩展形成的以挤压缩短和隆升为主的构造环境不协调,也就是说,青藏高原东北缘在渐新世—中新世可能尚未卷入现今青藏高原构造系统。  相似文献   

A simple ground‐motion prediction model for cumulative absolute velocity and model validation     

Wenqi Du  Gang Wang 《地震工程与结构动力学》2013,42(8):1189-1202

Cumulative absolute velocity (CAV) is an important ground motion intensity measure used in seismic hazard analysis. Based on the Next Generation Attenuation strong motion database, a simple ground‐motion prediction equation is proposed for the geometric mean of as‐recorded horizontal components of CAVs using mixed regression analysis. The proposed model employs only four parameters and has a simple functional form. Validation tests are conducted to compare the proposed model with the recently developed Campbell–Bozorgnia (CB10) model using subsets of the strong motion database, as well as several recent earthquakes that are not used in developing the model. It is found that the predictive capability of the proposed model is comparable with the CB10 model, which employs a complex functional form and more parameters. The study also corroborates previous findings that CAV has higher predictability than other intensity measures such as the peak ground acceleration. The high predictability of CAV warrants the use of the proposed simple model as an alternative in seismic hazard analysis. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Response‐only modal identification of structures using strong motion data     

S. F. Ghahari  F. Abazarsa  M. A. Ghannad  E. Taciroglu 《地震工程与结构动力学》2013,42(8):1221-1242

Dynamic characteristics of structures — viz. natural frequencies, damping ratios, and mode shapes — are central to earthquake‐resistant design. These values identified from field measurements are useful for model validation and health‐monitoring. Most system identification methods require input excitations motions to be measured and the structural response; however, the true input motions are seldom recordable. For example, when soil–structure interaction effects are non‐negligible, neither the free‐field motions nor the recorded responses of the foundations may be assumed as ‘input’. Even in the absence of soil–structure interaction, in many instances, the foundation responses are not recorded (or are recorded with a low signal‐to‐noise ratio). Unfortunately, existing output‐only methods are limited to free vibration data, or weak stationary ambient excitations. However, it is well‐known that the dynamic characteristics of most civil structures are amplitude‐dependent; thus, parameters identified from low‐amplitude responses do not match well with those from strong excitations, which arguably are more pertinent to seismic design. In this study, we present a new identification method through which a structure's dynamic characteristics can be extracted using only seismic response (output) signals. In this method, first, the response signals’ spatial time‐frequency distributions are used for blindly identifying the classical mode shapes and the modal coordinate signals. Second, cross‐relations among the modal coordinates are employed to determine the system's natural frequencies and damping ratios on the premise of linear behavior for the system. We use simulated (but realistic) data to verify the method, and also apply it to a real‐life data set to demonstrate its utility. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Blind modal identification of output‐only structures in time‐domain based on complexity pursuit     

Yongchao Yang  Satish Nagarajaiah 《地震工程与结构动力学》2013,42(13):1885-1905

Output‐only modal identification is needed when only structural responses are available. As a powerful unsupervised learning algorithm, blind source separation (BSS) technique is able to recover the hidden sources and the unknown mixing process using only the observed mixtures. This paper proposes a new time‐domain output‐only modal identification method based on a novel BSS learning algorithm, complexity pursuit (CP). The proposed concept—independent ‘physical systems’ living on the modal coordinates—connects the targeted constituent sources (and their mixing process) targeted by the CP learning rule and the modal responses (and the mode matrix), which can then be directly extracted by the CP algorithm from the measured free or ambient system responses. Numerical simulation results show that the CP method realizes accurate and robust modal identification even in the closely spaced mode and the highly damped mode cases subject to non‐stationary ambient excitation and provides excellent approximation to the non‐diagonalizable highly damped (complex) modes. Experimental and real‐world seismic‐excited structure examples are also presented to demonstrate its capability of blindly extracting modal information from system responses. The proposed CP is shown to yield clear physical interpretation in modal identification; it is computational efficient, user‐friendly, and automatic, requiring little expertise interactions for implementations. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

关于地震预警的几个问题   总被引：1，自引：1，他引：0  

张晁军  李卫东  林捷  许洪华  陈会忠 《中国地震》2013,29(2):198-209

地震预警是建立在高密度地震台网基础上的新技术,本文就地震预警的一些基本概念、关键技术、预警效果、预警部署及其在防震减灾方面的作用等进行了讨论,指出了地震预警存在的问题,以及需要研究的方向,并首次提出了预警能力、预警无效区、预警受益区、预警反应时间的概念.地震预警能力受预警系统的制约,实际地震预警能力除与台网密度、预警模式、自动处理系统、数据传输模式、发布系统等因素有关外,还与地震破裂性质有关.同时强调地震预警部署是复杂的社会工程,需要全社会的共同参与.  相似文献   

滇西施甸地区晚泛非运动的地层学和岩石学响应     

黄勇  郝家栩  白龙  邓贵标  张国祥  黄文俊 《中国区域地质》2012,(2):306-313

保山地块的寒武系露头少,研究范围有限。长期以来,地学界对寒武系与奥陶系之间的接触关系存在较大争议,有人认为是整合接触,有人认为是假整合接触,囿于过去的工作精度,目前尚无定论。近年来,在保山施甸地区开展1∶5万区调工作时发现,区内普遍缺失早奥陶世沉积,仅在施甸半坡一带有中奥陶统,在大寨一带,中上奥陶统蒲缥组直接平行不整合在上寒武统保山组之上,结合晚寒武世—早奥陶世业已存在的岩浆活动,认为这是晚泛非运动的远程响应。  相似文献   

Study on the Recovery of Erosion Quantity of Unconformities of Paleogene-Neogene in Bohai Sea Area     

LI Rufeng  ZHANG Gangxiong  RUAN Xiaofei 《地质论评》2012,58(3)

应用盆地波动过程分析方法,对渤海海域9个不同坳陷内的18口典型井古近系和新近系进行了沉积—剥蚀过程分析,分解出了760Ma、220Ma、70Ma和30Ma四个低频波动周期,以及18Ma、8Ma和2Ma三个高频波动周期.通过分析反映"组"、"段"级别的、以18Ma和8Ma为周期的波动曲线特征,预测了孔店期—沙河街期沉积—剥蚀过程;系统地计算出了古近纪—新近纪地层中主要不整合的剥蚀量,确定了与油气成藏密切相关的孔店组末期、东营组末期和馆陶组末期地层剥蚀厚度分别为:0～516m、0 ～213m和0～682m.通过波动曲线特征对比分析,确定了研究区构造转换带分别是孔店期位于渤中、沙河街期和东营期位于BZ13-1-2井区和LD10-1-1井区、馆陶期位于LD10-1-1井区、明化镇期位于BZ3-1-3D井区;定量地恢复了与油气运聚密切相关的孔店晚期、东营晚期和馆陶晚期不整合剥蚀量平面分布,再现了关键时期沉降沉积区和隆起剥蚀区区域分布规律.上述认识对于深入研究渤海海域古近系—新近系油气分布规律,开拓沙河街组及其以下层系油气勘探新领域具有重要意义.  相似文献   

利用测井资料研究阿雷斯油田地层构造特征和油气水分布规律     

杜旭东  赵齐辉  庄维  韩桂芹  吴国海 《世界地质》2012,31(1):162-170

利用测井资料对比分析了阿雷斯油田和南阿雷斯构造的地层特点,并确定了4 个标志层,认为白垩系和上侏罗统的阿克萨布拉克组的地层分布比较稳定,层内小层地质特征可对比性高,该组与下伏侏罗统地层为不整合接触关系; 库姆科尔组应为中下侏罗统残余地层。详细分析了其南侧的南阿雷斯构造相应层位之间的地层关系,认为阿克萨布拉克组与库姆科尔组之间不整合特征明显,阿雷斯油田的阿克萨布拉克组与其下伏侏罗系地层存在不整合关系。基于上述不整合地层关系的认识,认为阿雷斯油田中下侏罗统油藏类型为多个地层不整合油藏。目前钻遇基底的出油井为单独成藏,受古隆起控制。  相似文献