共查询到20条相似文献，搜索用时 15 毫秒
1.
Surface reflection seismic techniques have the capability of mapping subsurface geological features without disturbing the rock mass. They also have an added capability of penetrating to a much deeper depth than any other geophysical technique, including the ground probing radar. However, the successful application of reflection seismic techniques in crystalline rocks has in general been more difficult than in sedimentary basins, because of the irregular geometry and low acoustic impedance contrasts across geological boundaries. In this paper, we describe the imaging of fracture zones in crystalline rocks. Effective data processing, carefully modified from the conventional approaches, was applied on two high-resolution field data previously collected by different contractors. The strategy included enhancement of the signal hidden under the large-amplitude scattering noise, through pre- and post-stack processing such as shot f-k filtering, residual statics and careful muting after NMO correction. Two sets of low S/N test data from Canada and Sweden are analyzed in this research. The reflected energy in these data sets appeared to be more closely related to fracturing than to lithologic boundaries. The major fracture zones at shallow depth have been mapped with the desired resolution and can be correlated to the available well-log and seismic crosshole tomographic data. Once the surface waves were removed, shallow reflectors in the fracture zones could be identified and analyzed on the field records. Focusing analysis of the seismic image was performed in the constant-offset section to investigate the trends of major fracture zones. The complex attributes were also analyzed to determine whether they could be applied to the shallow fracture zones. Instantaneous frequency plots outline the intense fracturing zone and instantaneous phase plots identify the major and minor fractures, and other coherent events with different dip attitudes which interfere with each other. 相似文献
2.
三维地震技术对沉积学的发展有着重要的推动作用,主要体现在分析方法和概念上.高精度的三维地震数据可以通过对沉积要素的直接成像来重建三维的沉积古环境,也可以通过对不同地质历史时期的古沉积环境进行成像来研究沉积演化史.地震数据联合测井数据也可以通过预测岩石性质分布来定量描述沉积岩的非均质性.在成岩作用分析工作中,高分辨率的地震成像用优于10 m的纵向分辨率在上千平方千米的范围内描述成岩界面的几何形态,是一种在整个盆地范围内研究成岩作用过程的新方法.应用三维地震技术解决沉积问题这一领域未来发展潜力巨大.对相关的方法、工作流程和研究实例进行了论述. 相似文献
3.
郭西娜 《物探化探计算技术》1998,20(1):42-46
本文针对浅层地震勘探和数据处理的特点,系统地介绍了浅层地震勘探数据处理微机软件系统的能量均衡原理、实现过程和程序流程及该系统在能量均衡处理技术方面的一些新的突破：如首尾能量补偿,最大振幅能量限制等功能。该系统使得浅层地震勘探数据处理真正实现了既能完成常规的滑比或ＡＧＣ处理,又能对首尾能量进行必要的补偿等特殊处理,从而使浅层地震勘探的时间剖面图得到更好的修饰。 相似文献
4.
Ayman Fazea Al-Lehyani Abdullatif Abdulrahman Al-Shuhail 《Arabian Journal of Geosciences》2014,7(2):757-771
Near-surface diffractors are one of the problems in land seismic exploration. They can scatter the surface wave energy emanating from the seismic source and contaminate the signal received by seismic receivers. The scattered energy from the near-surface diffractors manifests itself on seismic shot gathers as strong hyperbolic events, called diffractions, masking the weakly reflected body waves. Diffractions present complications to most of surface-wave suppression schemes, especially when they have been scattered by scatterers outside the receiver line. Different methods have been used to eliminate diffractions from seismic data, including geophone arrays, filtering, and inverse scattering. Each of those methods has its own limitations. In this study, we present processing algorithms to map and attenuate near-surface diffractors of surface waves in seismic shot gathers. The mapping algorithm is based on semblance measurements and time–offset relations, while the attenuation algorithm is based on the least-square fitting of a source wavelet. The algorithms are applied on synthetic data from two different models. The first model has three near-surface diffractors, while the second model has three clusters of near-surface diffractors. Each cluster consists of three near-surface diffractors with a different geometry for each cluster. The results show that the proposed algorithms are successful in locating and attenuating most near-surface diffractors, except when the separation between individual diffractors is below the wavelength of the diffracted surface wave. 相似文献
5.
《Tectonophysics》1987,140(1):103-113
A simple coherence measure—the semblance coefficient—has been used to sample the lithosphere beneath the NORSAR array in terms of its ability to produce coherent seismic energy. The data set is comprised of two samples of teleseismic P-coda waves (south of Honshu and Hindu-Kush events) and two samples of microseismic noise data with duration of about one hour each.Concerning the constitution of the earth structure there are two possibilities for coherent energy to be present in noise-like wavefields. The first is tied to scattering effects and the second may be brought about by seismic emission effects. The emissive component represents the seismic response of the medium to variations in the background stress field which may arise from various sources: passing seismic waves (body or surface), free oscillations of the Earth, tides, an abnormal level of heat flow, or geodynamic processes in general.The presence of a well known source of seismic signal—Hunderfossen dam—in the vicinity of NORSAR area provided an opportunity to test the data processing algorithm. Results obtained for two independent microseismic data samples point to the same location in close vicinity to the dam.For P-coda data the signal energy from the upper mantle areas, as indicated by the maximum of semblance measure values at the depth around 116 km, reaches about 3.8% and 5% of the total P-coda energy for Honshu and Hindu-Kush events, respectively. For microseismic noise data this value is about 1% at a depth around 100 km. Comparison with the results of holographic studies supports the assumption that, in the case of microseismic data, the detected signal energy is of emissive nature, while for P-coda data we need more coda samples to make a sound judgement about the nature (scattering or emission) of the detected signals. 相似文献
6.
A. V. Klyuchevskii V. M. Dem’yanovich S. Demberel B. Lkhagvadorj 《Doklady Earth Sciences》2012,443(2):484-488
The information about strong earthquakes of Mongolia for the instrumental period of observations has been generalized in a
sketch of the energy of seismotectonic deformations in the lithosphere. This sketch has been correlated with the map of general
seismic zoning of Mongolia. The derived results characterize the energy of seismotectonic deformations in the lithosphere
in terms of absolute units, which is favorable for projecting and building activities. The approach to energy estimation being
developed is recommended for further development of modern engineering and building technologies in the framework of the regional
seismic safety problem. 相似文献
7.
Three-dimensional seismic mapping of the upper mantle beneath Fennoscandia (Baltic Shield) using an ACH-type of inversion technique in combination with P-wave travel-time residual observations from the local seismograph network gave the following results. The central parts of the Baltic Shield are characterized by relatively high seismic velocities down to approximately 300 km. Those parts of the shield most affected by the Caledonide orogeny exhibit relatively low velocities particularly in the uppermost 100 km depth interval. The lower part of the upper mantle (300–600 km) does not exhibit pronounced seismic velocity anomalies and in this respect is in contrast to results from similar studies in regions subjected to neotectonic processes like parts of central and southeastern Europe. The seismic anomaly pattern in the presumed thickened lithosphere is in quantitative agreement with similar ones derived from surface wave dispersion analysis and inversion of electrical measurements. The general orientation of these anomalies coincides with that of the glacial uplift. 相似文献
8.
三维地震勘探中叠加速度成图 总被引：3，自引：1，他引：2
速度参数和成图方法和选取对于提高三维地震反射层构造图的精度是很重要的,文章提出了由地震资料的叠加速度来获得界面平均速度,并利用钻井资料对界面平均速度校正,得出了符合地质规律的平均速度,提高了作图精度。该方法成功地应用于华北某煤田勘探区的三维资料解释中,弥补了传统时深转换方法的不足,收到了很好的效果,所绘制的构造图深度同巷道资料吻合。 相似文献
9.
1984年以来,我们在计算机上建立了地震层位和速度、重磁等地质数据库应用系统,配备了相应的数据处理、绘图软件包;目前正在建立沉积数据库。这些工作已成为地矿部石油普查勘探数据库系统的一部分。 相似文献
10.
测井约束下的神经网络地震储层参数反演 总被引：4，自引：0，他引：4
针对目前大多数地震反演方法基于褶积模型及相应假设条件的现状,本文提出了在假定储层参数与地震资料之间存在某种非线性映射的情况下,以测井作为约束条件,利用Ｅｌｍａｎ局部递归神经网络法,建立地震数据到地层参数的映射模型,将地震数据直接由已知井点向外递推地层速度、孔隙度和泥质含量的方法。文中给出了方法原理、处理流程及应用实例。 相似文献
11.
二连盆地内的凹陷窄而狭长,断裂发育,构造变化剧烈,速度横向变化快,常规作图方法难以满足精细构造解释的要求.采用叠前时间偏移后的叠加速度谱生成速度模型,并用井震标定速度进行校正,形成高精度的变速三维速度场,用它对地震层位作时深转换,较大地提高了构造成图的精度. 相似文献
12.
三角洲沉积的结构-成因分类与编图方法 总被引：6，自引：0，他引：6
地质学中各类沉积体系的分类方案历来受到广大学者重视,尤其是三角洲做为沉积学研究与油气勘探开发的重点与热点,近年来人们越来越强调对其进行结构-成因分类。本文回顾了三角洲沉积体系研究的发展历程,指出了其存在的主要问题,进而系统论述了三角洲的结构-成因分类的具体含义与分类方案,阐明了这种分类方法的优点。同时,又提出了一套能够反映三角洲结构-成因特点的沉积相编图方法及编图中应注意的一些具体问题。这种编图方法从高分辨层序地层对比与沉积微相导向的小层对比出发,强调在恰当的编图单元约束下,注重岩相组合与沉积序列进行沉积类型识别,采用岩、电、震结合的方法进行多参数套合编图,使沉积相图能够更好地反映砂体的粒度粗细、分布特征及沉积成因,以便使储层的预测性得到充分体现。 相似文献
13.
本文在特殊地质填图的过程中研究了哈密地区砂岩的地震波速,利用ZBL-U520非金属超声检测仪和Autolab2000多功能岩石物性设备,在0~200 MPa(约0~7000 m地下深度)下研究了密度、孔隙度和压力三个因素对砂岩地震波速的影响。研究发现:砂岩的波速与密度呈正相关关系,但与孔隙度呈负相关关系;纵波与密度和孔隙度的线性关系好于横波;波速与压力呈对数关系。此外,本文还分析了ZBL-U520与Autolab2000两种仪器测试方法的适用性。最后针对地质填图的特点给出建议:在特殊地质填图中,不仅要按照规范采集标本,测试其在常温常压下的岩石波速,还应该适当考察不同地层压力状态下的速度特征,才能更全面地认识填图区地震波的性质。 相似文献
14.
Seismically induced landslide displacements: a predictive model 总被引：27，自引：0，他引：27
Newmark's model for predicting earthquake-induced landslide displacements provides a simple way to predict the coseismic displacements affecting a sliding mass subject to earthquake loading. In this model, seismic slope stability is measured in terms of critical acceleration, which depends on the mechanical soil properties, pore-pressure distribution, and slope geometry. The triggering seismic forces are investigated in terms of energy radiation from the source, propagation, and site effects, based on 190 accelerometric recordings from 17 Italian earthquakes with magnitudes between 4.5 and 6.8. The method is based on the calibration of relations having the general form of an attenuation law that relates the energy of the seismic forces to the dynamic shear resistances of the sliding mass to propagate the expected landslide displacements as an inverse function of the distance from the fault rupture; the amount of displacement computed through these relations provides a criterion to predict the occurrence of slope failures. Finally, maps showing, in a deterministic and a probabilistic way, the potential of seismically induced landslide displacements are displayed as a tool to provide seismic landslide scenarios and earthquake-induced landslide hazard maps, respectively. 相似文献
15.
A seismic refraction experiment was conducted in an area at a site where joints had been mapped in detail in order to determine whether velocity anisotropy could be correlated with joint directions. The purpose was to assess the possibility of using seismic refraction techniques for mapping joint directions in alluvium-covered areas.The results of the experiment show that a velocity anisotropy can be detected by simple seismic refraction measurements, and that the anisotropy can be correlated with the dominant joints. It is believed that the technique is applicable to the determination of joint directions in alluvium-covered areas. 相似文献
16.
The north–south trending Tancheng-Lujiang (Tanlu) fault belt extends from northeast China to the Dabie–Sulu orogenic belt, for a length of more than 3000 km. This fault belt probably has close links with the lithosphere evolution, seismic activity and mineral resource concentration in East China. Surface geological mapping and studies on sedimentation and basin formation have indicated segmentation at the southern, middle and northern domains of the fault. Here we employ geophysical constraints to evaluate these fault segments. Unlike previous geophysical studies focused on laterally varying crust/mantle seismic velocity structure across the fault, in this study we have integrated a variety of geophysical data sets, such as crustal P-wave velocity, earthquake occurrence and released seismic energy, seismogenic layer thickness, surface heat flow and geothermal field, to understand the deep structure and strength of the lithosphere along the Tanlu segmented fault belt. The results demonstrate remarkable crustal-scale north-to-south segmentation this major fault. The geophysical evidence and some geochemical constraints suggest that the Tanlu fault belt probably served as a channel for melt and fluid percolation, and exerted a significant control on the lithosphere evolution in East China. 相似文献
17.
This study deals with detailed mapping of sedimentary features within Torok Formation and Nanushuk Group in the northern part of the National Petroleum Reserve in Alsaka (NPRA). These Cretaceous units correspond to a single depositional regime of a large deltaic system. Seismic reflecting surfaces within the sequence are seen as sigmoidal traces in seismic sections. These horizons can be identified over long distances (up to 160 km) within individual seismic sections and can be correlated between intersecting sections. The study is centered in four different areas in which seismic information is relatively abundant and of good quality. One of the study areas is of special interest because of a large, now-filled ancient submarine canyon, Simpson Canyon. Reflection-time measurements were obtained by digitizing various horizons that were manually traced on seismic sections. Reflection-time measurements have been converted to depth values, corrected for postdepositional tilting, and portrayed as structure contour maps, perspective fish-net diagrams, and isopach maps prepared by computer. Computer mapping procedures are essential to obtain three-dimensional representations of reflecting surfaces. Because the northern NPRA has undergone little tectonic deformation since Cretaceous, horizons that have been mapped provide a close representation of submarine paleotopographic surfaces. A succession of these surfaces reveals progressive changes in the form of deltaic deposits from west to east, suggesting that energy of waves and currents increased as the delta prograded eastward. The succession of surfaces also suggests that Simpson Canyon was affected by at least two events of erosion and refilling. 相似文献
18.
多口钻井证实四川盆地西南部地区发育火成岩,火成岩主要分布在龙潭组内部,火成岩发育区地震资料存在岩下地震同相轴连续性较差、反射能量弱等现象,火成岩下屏蔽效应机理不清、岩下地震反射井震标定能量相位差异大,明确火成岩区地震波传播规律是地震资料采集、处理解释的基础。这里从地震波反射透射基本原理出发,阐述了火成岩地层的反射透射能量及对下伏地层的屏蔽机理,利用波动方程地震模拟及偏移,分析了不同火成岩分布模型对下伏地层地震信号的屏蔽作用,采用低频补偿、逆时偏移等方法改善岩下成像质量。结果表明:火成岩发育会不同程度导致下伏地层地震透射能量的衰减,纵向多套火层岩发育时,下伏地层屏蔽效应明显,发育区地震表现为类似生物礁的外形隆起、内部杂乱反射特征,下部多次反射较多且能量较强。通过低频优势频带保护处理、利用全波场波动方程偏移成像等方式可以改善岩下地震成像质量。 相似文献
19.
20.
地震波形状描述技术及其在地震相分析中的应用 总被引：2，自引：1，他引：1
地震波的波形变化及其分布规律,是重要的地震参数之一。对地震波形中包含的地质信息加以分析和应用,将有利于提高储层预测,油藏描述精度和钻探成功率。以波形的形状进行分类,并进行地震相和沉积相分析,是目前应用较为广泛的一类地震属性分析的方法技术。在这类技术中,其核心是波形的形状描述和刻画技术。这里以Stratimagic软件为例,通过对构成地震波形状的主要参数（振幅、相位、频率）对其波形状变化影响的细致分析和比较,总结出了可以利用地震波的形状变化规律及形状描述方法,探讨了依据该波形形状分类在地震相分析中的效果和意义。 相似文献