基于干涉成像的微震定位方法

提出了一种基于光学干涉原理,用地震波代替光波进行地震成像的一种新的成像方法:地震干涉成像方法。用这种方法进行微震定位的特点是不需要进行初至拾取,观测系统也可以使用任意阵列检波器。模拟了一个地下震源的二维时间延迟记录,编制了基于C语言的震源定位程序,对接收的记录使用此方法进行成像。通过程序运行结果验证了此方法的可行性,且定位效果明显。     

基于低频信息补偿的数据驱动Marchenko成像

基于常规地震干涉法和地震超越干涉法,提出了SI和BSI的结合方法SIBSI,即在SI被动源低频信息提取的基础上,重构主动源BSI地震数据,并利用BSI进行格林函数重构和面向目标的Marchenko成像.研究了基于频率优势的主动源低频重构方法,在完整保留了主动源信号高频信息的基础上,有效重构了低频信息,拓宽了地震数据的频带范围.讨论了含有自由表面多次波的地震数据在Marchenko成像中应用的方法.设计了一个含有高阻抗地层的模型,在该模型上使用SI低频信息重构BSI主动源地震数据,最后与纯主动源地震数据的格林函数重构和Marchenko成像进行了对比,证明了本文所提出方法的有效性、抗噪性以及在提高成像效果中的优势.     

地震波干涉法研究进展综述

地震波干涉法的提出与应用丰富了对地震波传播规律的认识和研究,被认为是地球物理发展的一大进展.其基本原理是对不同位置接收到的地震波信号进行相关而得到新的地震信号,该信号能反映原始地震波信号所不能反映的信息.本文详细介绍了地震波干涉法的原理及其在地球物理学特别是地震勘探领域中的应用.首先,重点介绍了地震波干涉法理论的提出、发展和完善的过程;其次,讨论了目前应用的地震波干涉法的不同的数学实现方式;最后,介绍了用地震波干涉法的数值实现过程以及用地震波干涉法进行成像的研究进展.     

Walkaway VSP数据的联合相干成像(英文)

本文将相干成像用于WVSP数据的一次反射波和下行地表多次波的成像中,通过对叠加次数分布的分析,发现一次反射波相干成像的成像范围小但在井位置处的叠加次数高;下行地表多次波相干成像的成像范围大而在井位置处的叠加次数少。基于此,本文尝试利用一种WVSP的联合相干成像方法来解决这一问题。该方法利用WVSP的直达波与下行地表多次波和直达波与一次反射波来进行联合相干成像。这种联合相干成像方法在有效拓宽成像面积的同时增加了覆盖次数(特别是在井旁),使干涉记录中的虚假同相轴得到了有效地压制,提高了成像剖面的信噪比,使成像结果更加可靠。正演模拟得到的WVSP合成记录和野外实际采集到的WVSP数据处理结果均表明这种方法的有效性。     

反褶积干涉成像及其在随钻地震数据处理中的应用

随钻地震是石油工程领域的一项新技术,是利用钻头破岩的连续随机振动信号进行钻前预测,通常需要利用钻头震源函数与地面记录互相关进行处理,而地下数千米震源函数的获取难度很大,成为制约随钻地震技术的一个关键问题.反褶积干涉成像是在互相关基础上发展起来的,可以利用随机噪音获得地震台站间的格林函数,对地下构造和速度结构成像,同时这种方法不依赖于震源函数信息.本文回顾了干涉成像的发展历程,分析了互相关干涉和反褶积干涉的原理、方法和特点,结合随钻地震数据处理需要,结合实例分析了反褶积干涉应用于随钻地震数据处理的前景,为发展新型随钻地震技术提供了重要参考信息.     

全干涉成像的微地震定位方法研究

基于偏移成像的微地震定位方法由于可避免走时拾取误差以及可实现自动化定位等优点被广泛应用.绕射叠加方法将能量沿走时曲线聚焦到空间网格点上,进行成像时需要搜索发震时刻.干涉成像方法利用互相关提取的走时差信息可避免搜索发震时刻,但定位结果受数据信噪比的影响较大.为了进一步提高干涉成像法的定位精度,本文提出一种同时使用互相关和自相关道集的全干涉成像方法,增加的自相关道集提取的S-P走时差可降低震源-检波器方向的定位误差,提高定位精度.单井监测的理论测试和实际数据的研究结果表明,全干涉成像的定位精度高于仅使用互相关道集的干涉成像方法,同时计算效率高于绕射叠加方法.     

基于瞬时相位的微地震干涉定位方法研究

波形叠加定位法具有自动性和抗噪性等优点,已被广泛应用于微地震事件定位.当该类方法采用特征函数变换原始波形以克服初至极性变化影响时,会降低成像分辨率.而将相位加权叠加法应用于微地震成像时,虽然提高了成像分辨率,但并未考虑复杂震源机制对定位的影响.为了校正波形极性,并提高干涉成像法的分辨率和压制噪声的能力,本文重新组合了原...     

背景噪声提取体波方法研究进展

地球深部结构探测是地球物理学的核心领域,而地震体波可以深入地球内部且分辨率较高,是研究地球内部结构不可或缺的技术手段。基于背景噪声提取高信噪比体波信号技术的迅速发展,极大地促进了地震学的发展和应用范围,使其在地球深部结构成像、城市浅层空间探测等领域日益发挥出重要作用。本文详细综述了如何利用地震干涉法及台阵处理技术提取出用于研究不同探测尺度（局部、区域、全球）的各类体波信号。其中,地震干涉法通过对地震台站记录到的波形信号进行互相关,抵消掉重合的射线路径,最后得到台站对之间的地震记录;而台阵处理方法是基于接收器台阵发展起来的数据处理手段,该技术不仅能够进一步提高信噪比（SNR）,而且能够获得方位信息。一般来讲,背景噪声中包含的体波信号能量远低于面波信号能量,提取难度大。本文着重介绍了Bin-叠加法、双波束方法（DBF）以及相位加权叠加法（PWS）,并对3种方法的适用条件进行了总结。      

VSP地震干涉成像及应用研究

受井中检波器串级数局限,垂直地震剖面(VSP)反射波成像范围窄,且不能对井中最浅接收点上方区域有效成像.虽然多次波成像能扩大成像范围,但在实际应用中尚有诸多困难和挑战.本文根据Wapenaar的地震干涉理论,基于上下行波场分离技术,研发了VSP地震干涉成像方法.该方法将VSP自由表面多次波重建为在地表震源位置激发(虚震源)接收的拟地面地震反射波,然后偏移成像,以达到对多次波间接成像的目的.通过数值模型实验,测试了VSP干涉成像的极限分辨率,并讨论了主要采集参数的影响,结果表明:该方法的垂向和水平极限分辨率分别达约10m和20m,且能分辨深度达6500m处的50m×100m溶洞;采用12至24道井中检波器串采集的VSP资料,其干涉成像结果显著优于VSP反射波成像,与相应的地面地震成像效果相当.将本文方法应用于新疆地区采集的VSP资料,结果表明:与VSP反射波成像相比,成像同相轴更加连续,成像范围显著扩大;与地面地震成像相比,成像结果相当,尤其在浅中部甚至更好.新方法不仅无需进行井中接收点静校正,且能显著增大成像范围,有利于成像同相轴的追踪对比、地震属性提取和地质解释,尤其对中国新疆地区深部缝洞型储层的成像,具有广泛的实际应用前景.     

地面与井中观测条件下的微地震干涉逆时定位算法

勘探和开发非常规油气藏已经成为国际油气工业界的新热点.由于这类油藏具有低渗透率的特点,开采过程中往往需要多级压裂形成能够使烃类自由流动的裂隙.通过定位分析压裂过程中诱导的微地震震源能够帮助人们刻画裂缝属性(走向、密度等),评价压裂效果,分析断裂模式,推定震源机制等.微地震定位可以采用波动方程逆时聚焦方法实现.由于微地震数据信噪比低,加之速度模型不准确、稀疏观测等诸多因素使得定位的精度大打折扣.本文将波动方程逆时聚焦定位原理与干涉"成像"原理相结合,探讨多源微地震信号的干涉逆时定位算法,尤其扩展该算法到三维多分量地面、井中以及井地联合观测条件下.通过理论合成数据与实际射孔资料的数值试验,展示了该微地震定位算法的精度优势与抗噪特点,并指出波场聚焦微地震定位方法在实际应用中的制约因素与应对策略.     

Contribution to the knowledge of the magmatic evolution by the study of the variation of the coefficient of viscosity

The determination of the coefficient of viscosity of eruptive products gives useful elements to the knowledge of possible variations of composition and physical conditions of the magmas.     

Pictorial Series of the Manifestations of the Dynamics of the Earth

Studia Geophysica et Geodaetica -     

Evolution of the Source of the Active Region of the Sun

Geomagnetism and Aeronomy - The magnetic evolution of the active region of the Sun at the level of the photosphere has been studied. Magnetic synoptic maps of the 2007 Kitt Peak Observatory were...     

Magnetic stratigraphy of the Ordovician in the lower reach of the Kotuy River: the age of the Bysy-Yuryakh stratum and the rate of geomagnetic reversals on the eve of the superchron

Until recently, the existing data prevented the geophysicists from accurately dating the Bysy-Yuryakh stratum, which outcrops in the middle reach of the Kotuy River, constraining the time of its formation to a wide interval from the end of the Late Cambrian to the beginning of the Silurian. The obtained paleomagnetic data unambiguously correlate the Bysy-Yuryakh stratum to the Nyaian regional stage and constrain its formation, at least a considerable part of it, by the Tremadocian. This result perfectly agrees with the data on the Bysy-Yuryakh conodonts studied in this work and yields a spectacular example of the successful application of paleomagnetic studies in solving important tasks of stratigraphy and, correspondingly, petroleum geology. Within the Bysy-Yuryakh stratum, we revealed a large normal-polarity interval corresponding to the long (>1 Ma) period when the geomagnetic reversals were absent. This result, in combination with the data for the Tremadocian and Middle–Upper Cambrian sequences of the other regions, indicates that (1) the rate of occurrence of the geomagnetic reversals on the eve of the Ordovician Moyero superchron of reversed polarity was at most one reversal per Ma; (2) the superchron does not switch on instantaneously but is preceded by a certain gradual change in the operation conditions of the dynamo mechanism which, inter alia, manifests itself by the reduction of the frequency of geomagnetic reversals with the approach of the superchron. This finding supports the views according to which a process preparing the establishment of the superchrons takes place at the core–mantle boundary.     

On the determination of the non-linearity of the gravimeter scale

Summary The results of two different methods of the determination of the non-linearity of the gravimeter scale are compared; the economy is discussed as well.     

Influence of the topography of the surface of the Earth on vertical sounding of the temperature profile

Atmospheric temperature and humidity fields as well as information on other meteorological parameters are nowadays retrieved from radiance measurements recorded by operational meteorological satellites. Up to now, the inversion procedures used only take into account crude information on the topography of the Earth’s surface. However, the applied radiative transfer codes have to consider the Earth’s surface as the lower boundary of the atmospheric model and, therefore, need a more precise mean elevation and a classification of the roughness of the Earth’s surface. The influence of the topography of the Earth surface on retrieved temperature profiles is studied by using a physico-statistical inversion method. An objective analysis is made of the more precise mean elevation and derivation of roughness parameters using a new high-resolution digital elevation model (DEM) with a resolution of 500 m×500 m. By means of a geomorphological process and a newly developed topography rejection test, areas with a high surface roughness are localized and singled out. The influence of topography on the retrieved temperature profiles is illustrated by case studies. Changes are found predominantly in areas with a high variation of topography. Using the new high-resolution DEM and the topography rejection test, the geographical position of the calculated temperature profiles tends to be shifted towards areas with a small vertical variation of topography. The mean elevation determined by the new elevation model better characterizes the area observed. Hence, the temperature profiles can be calculated down to lower atmospheric levels. Furthermore, a guess profile better describing the atmospheric situation is selected by the more precise elevation. In addition, the temperature profiles obtained near the coast are improved considerably by the more precise determination of the surface property ‘sea’ and ‘land,’ respectively. Integration of an independent physical information such as topography leads, on average, to a slight improvement of the results of the physico-statistical inversion procedure. In some cases, however, significant improvements have been achieved regarding the desired accuracy of temperature profiles of the order of 1 K. In future, the spatial resolution of new high-resolution sounding instrumentation on the next generation of operational meteorological satellites will be increased. To exploit the resolving power of this new instrumentation, the different variation of the topography of the Earth surface, especially in regions with a high variation of topography, can be taken into account more precisely by using a high-resolution DEM.     

The effect of the pollution of the ground layer of the atmosphere on the albedo

Summary A simple model is proposed suitable for studying the effect of the ground layer of the atmosphere, polluted by aerosol, on the albedo. This model is founded on solving the equation of transfer of radiative energy. The numerical results are discussed, particular attention being paid to the analysis of errors due to neglecting the multiple reflection of solar radiation on the aerosol particles. A method which would also include the multiple reflection is proposed, and the conditions under which the presence of the aerosol is responsible for an increase or decrease of the solar radiation balance on the Earth's surface, are analysed.     

On the solution of the reverse problem of geodesics with the help of the chord

Резюме Дается вывод формул для вычислений длины хорды, длины и азимутов нормаляных сечений и длины геодезической линии эллипсоида. Применяются тригонометрические функции данных величин и постоянные принятого ргфгргнц-эллипсоида, что является целесообразным при использовании вычислителQjных машин, особенно автоматов. Рабочие формулы рекомендуются в форме (8–11).

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Dedicated to Professor František Fiala on His 85th Birthday

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Address: Veveři 95, Brno.     

On the maintenance of the axisymmetric part of the flow in the atmosphere

Summary The maintenance of the axisymmetric component of the flow in the atmosphere is investigated by means of a steady-state, quasi-geostrophic formulation of the meteorological equations. It is shown that the meridional variations in the time-averaged axisymmetric variables can be expressed as the sum of three contributions, one being due to the eddy heat transport, another to the eddy momentum transport, and a third to the convective-radiative equilibrium temperature which enters the problem through the specification of a Newtonian form of diabatic heating. The contributions by the large scale eddies are evaluated through the use of observed values for the eddy heat and momentum transports.The contributions from each of the three forcing mechanisms to the temperature and zonal wind fields are invstigated individually and found to be of about equal importance. The sum of the three contributions are also presented for the temperature, the zonal wind, the stream function associated with the mean meridional circulation and the corresponding vertical motion. Although the results fail to reproduce the main observed features of the lower stratosphere, they are found to be in good agreement with observations in the middle latitude troposphere. At any pressure level, for example, the computed mean zonal wind has a jet-like profile and the axis of the jet is found to slope to the south with height, as observed in the atmosphere.Based in part on a thesis submitted by the first author as partial fulfillment of the requirements for the Ph.D. degree at the University of Michigan. — Publication No. 194 from the Department of Meteorology and Oceanography, The University of Michigan.