共查询到20条相似文献，搜索用时 750 毫秒
1.
2.
为了避免单一物探方法在地质反演解释中存在的多解性弊端,本文介绍了以电成像法为主、浅层地震反射波法为辅的综合物探方法对隐伏断层进行探测的应用实例,首先,通过电成像法查找断层破碎带的位置走向,然后利用浅层地震反射波法精确查明断层的产状、性质、位置及断距等地质参数,并对两种方法的探测成果进行综合对比分析,推断该隐伏断层为走向近东西向,倾向近南北向的正断层,断层落差约4.2m,其上断点埋深约17.9m。经钻孔验证表明,电成像与浅层地震联合方法在浅覆盖区隐伏断层探测中具有精确、可靠、经济的优势,该方法具有较强的应用价值。 相似文献
3.
LiuJiangping XiaJianghai ChenChao ZhangSuxin 《中国地质大学学报(英文版)》2003,14(4):363-367
The application of the seismic reflection method is often limited in complex terrain areas.The problem is the incorrect correction of time-shift caused by topography. To apply normal moveout(NMO) correction to reflection data correctly, static corrections are necessary to be applied in advance for the compensation of the time distortions of topography and the time-delays from near-surface weathered layers. For environment and engineering investigation, weathered layers are our targets so that the static correction mainly serves the adjustment of time-shift due to an undulating surface. In practice,seismic reflected raypaths are assumed to be almost vertical through the near-surface layers because they have much lower velocities than layers below. This assumption is typically acceptable in most cases since it results in little residual error for small elevation changes and small offsets in reflection events. Although static algorithms based on choosing a floating datum related to common midpoint gathers or residual surface-consistent functions are available and effective, errors caused by the assumption of vertical raypaths often generate pseudo indications of structures. This paper presents the comparison of applying corrections based on the vertical raypaths and bias (non-vertical) raypaths. It also provides an approach of combining elevation and NMO corrections. The advantages of the approach are demonstrated by a synthetic example of multi-coverage seismic reflection surveys on rough topography. 相似文献
4.
The Madurai Block in southern India is considered to represent the eroded roots of an arc-accretionary complex that developed during the subduction–collision tectonics associated with the closure of the Mozambique Ocean and final suturing of the crustal fragments within the Gondwana supercontinent in the Late Neoproterozoic–Cambrian. Here we present a magnetotelluric (MT) model covering the main collisional suture (Palghat–Cauvery Suture Zone) in the north into the central part of the Madurai Block in the south comprising data from 11 stations. Together with a synthesis of the available seismic reflection data along a N–S transect further south within the Madurai Block, we evaluate the crustal architecture and its implications on the tectonic development of this region. According to our model, the predominantly south dipping seismic reflectors beneath the Madurai Block define a prominent south-dipping lithological layering with northward vergence resembling a thrust sequence. We interpret these stacked layers as imbricate structures or mega duplexes developed during subduction–accretion tectonics. The layered nature and stacking of contrasting velocity domains as imaged from the seismic profile, and the presence of thick (>20 km) low resistivity layers ‘floating’ within high resistivity domains as seen from MT model, suggest the subduction of a moderately thick oceanic crust. We identify several low resistivity domains beneath the Madurai Block from the MT model which probably represent eclogitised remnants of oceanic lithosphere. Their metamorphosed and exhumed equivalents in association with ultrahigh-temperature metamorphic orogens have been identified from surface geological studies. Both seismic reflections and MT model confirm a southward subduction polarity with a progressive accretion history during the northward migration of the trench prior to the final collisional assembly of the crustal blocks along the Palghat–Cauvery Suture Zone, the trace of the Gondwana suture in southern India. 相似文献
5.
6.
对一种能增强工程地震勘探数据质量的新叠加技术——零偏移距共反射面叠加进行了研究。目前模拟零偏移距剖面常规方法存在需要精确宏速度模型及不能对地下反射界面产生最佳照明的问题,而零偏移距共反射面叠加具有完全数据驱动、与宏速度模型无关、能够产生对地下反射界面最佳照明及提高模拟零偏移距剖面成像质量的优势。针对零偏移距共反射面叠加还未在国内工程地震勘探中进行广泛应用的现状,详细介绍了零偏移距共反射面叠加基本原理及其实现过程,并使用一套人工合成断层模型数据及来自某高速公路段附近一条二维测线的实际工程地震勘探数据进行了测试计算。理论模型试算结果及在工程地震勘探实际资料处理中的应用表明零偏移距共反射面叠加可提高地震数据信噪比,增强地震反射同相轴连续性,改善模拟零偏移距剖面质量,是一种非常有发展前景的工程地震成像方法。 相似文献
7.
浅层反射地震资料中面波一般比较发育,对有效信号形成干扰,现有压制面波等相千干扰的处理手段主要适用于中深部、深部地震勘探,但并不适用于浅层反射地震资料的处理。为此提出了倾角中值滤波法。该方法是基于叠前地震单炮道集上反射波与强线性干扰在￡吨域视速度上的差异,在多组视倾角范围内,求取一个最佳视倾角,将最佳视倾角的振幅序列的中值视为相干干扰,利用“减去法”,达到信噪分离。通过模型与实际资料的处理,汪明该方法能够有效分离强线性干扰,并保留了强线性干扰的特性,提高了资料的信噪比,保真度高,是浅层高分辨率地震勘探的一种理想的叠前信噪分离技术。 相似文献
8.
提出了一种变有害奇异值为更有利于横向储层预测有效信息的提取方法———瞬空参数法（SIPA）,并与时间域中基于复数道分析的常规瞬时参数法进行了对比。瞬空参数法是通过将地震数据沿层重组后,构成沿层变化的反射振幅信号道,以它为实数道进行瞬空复数道分析,计算出瞬空参数。横向振幅的变化点正是不满足解析条件和性质的奇点,这些奇点所对应的奇异值,刚好对应沿层横向地质结构的突变点。又由于瞬空相位和瞬空波数沿层方向的相对变化率大于振幅的相对变化率,因此利用瞬空参数进行断层、裂缝、缝洞发育带、河道、地层尖灭点等各种岩性突变点更有效。通过瞬空参数应用效果的数值模拟和Y地区的资料处理,以及裂缝性储层预测的实际效果,证明了上述结论的正确性。 相似文献
9.
10.
Recent studies have demonstrated a plausible link between surface and near-surface tectonic features and the vertical projection of the Commerce geophysical lineament (CGL). The CGL is a 5- to 10-km-wide zone of basement magnetic and gravity anomalies traceable for more than 600 km, extending from Arkansas through southeast Missouri and southern Illinois and into Indiana. Twelve kilometers of high-resolution seismic reflection data, collected at four sites along a 175-km segment of the CGL projection, are interpreted to show varying amounts of deformation involving Tertiary and some Quaternary sediments. Some of the locally anomalous geomorphic features in the northern Mississippi embayment region (i.e., paleoliquefaction features, anomalous directional changes in stream channels, and areas of linear bluff escarpments) overlying the CGL can be correlated with specific faults and/or narrow zones of deformed (faulted and folded) strata that are imaged on high-resolution seismic reflection data. There is an observable change in near-surface deformation style and complexity progressing from the southwest to the northeast along the trace of the CGL. The seismic reflection data collaborate mapping evidence which suggests that this region has undergone a complex history of deformation, some of which is documented to be as young as Quaternary, during multiple episodes of reactivation under varying stress fields. This work, along with that of other studies presented in this volume, points to the existence of at least one major crustal feature outside the currently defined zone of seismic activity (New Madrid Seismic Zone) that should be considered as a significant potential source zone for seismogenic activity within the midcontinent region of the United States. 相似文献
11.
We applied a type of depth migration for converted seismic phases to active and passive seismic data sets from the Campi Flegrei volcanic region in southern Italy. The migration method is based on the diffraction summation migration technique. Travel times to grid points in a volume were calculated in smooth P and S-velocity models and trace energy near the calculated converted phase time was stacked over multiple sources at one receiver. Weighting factors based on Snell's Law at an arbitrarily oriented local interface were applied to better focus trace energy. PP reflection images from the active data set provide increased detail to images of the caldera rim from other studies. The migrated images also show features near 2–3 km in depth beneath Pozzuoli City, which may be associated with an over-pressured gas volume, as suggested by other geophysical investigations. Possible deeper features near 4 km depth may be related to the presence of the carbonate basement or may image a previously undetected feature, such as a small body of strongly thermometamorphosed volcanic rock. The current passive earthquake data set from the 1984 ground uplift episode was not well suited to the converted phases analysis due to narrow P–S windows and high noise levels in the traces. However, two stations provide confirmation and extension of imaged features in the active data. 相似文献
12.
13.
《Physics and Chemistry of the Earth, Part A: Solid Earth and Geodesy》1999,24(5):467-474
In the context of a reflection seismic AVA (Amplitude vs. Angle) analysis, data from the western Mediterranean Ridge have been analysed to obtain estimates on the reflection coefficient and the AVA gradient. The study put particular emphasis on the role of the Messinian evaporites, which display a characteristic amplitude signature on the AVA-sections. From the seismic attributes obtained from the Zoeppritz equations it could be infered that the material contrast at the salt/sediment interface of the Messinian evaporites is sufficient to generate converted waves, which are strong enough to survive the processes of NMO-correction and CMP stack. This mode conversion could subsequently be modelled by dynamic Ray-tracing to identify which events on the stacked data are likely to be based on converted waves and thus present some pitfalls for an imprudent interpreter. 相似文献
14.
煤矿采空区塌陷是一个重要的地质问题,由于采空塌陷区地震、地质条件的复杂性,传统三维地震勘探探测方法难以准确查明采空区边界。本研究提出一种基于四维地震特征的煤矿采空区识别方法,并以淮南煤田张集煤矿为靶区开展采空区探测。该方法从模型驱动入手,通过建立煤层开采前、后地质模型及进行正演模拟,利用模型地震叠前时间偏移剖面回溯分析采空区引起的地震特征差异。根据模型数据采空区的地震反射特征,指导识别实际地震数据中的采空区,并通过地震解释圈定采空区范围。张集煤矿的实际四维地震数据分析结果显示,采空区域反射波连续性变差,采空区边界出现同相轴错断现象;因此,利用采空区四维地震特征差异能够有效识别煤矿采空区,并能准确圈定采空区的范围。 相似文献
15.
基于常规复数道分析方法计算地震信号瞬时特征参数,用于常规地震剖面解释中,其精度完全可以满足要求。但对高分辨率地震勘探,特别是对薄层的研究,其精度就不够了。在充分研究常规复数道分析算法及应用效果的基础上,提出了能够用于高分辨率资料解释的新复数道分析的方法。模型算例和实际资料处理结果表明,该方法可以有效地提高地震资料的分辨率。 相似文献
16.
The braided channel sedimentary sand is a kind of common oil reservoir, which is characteristic of poor regularity structure and complicated oil water relation. Seismic trace can be remodeled by wavelet decomposition, namely seismic trace is decomposed into a series of different attribute wavelets. The different reflection is obtained by the different attribute wavelets, thus prediction accuracy of braided channel sedimentary sand is improved. The seismic signal treated by matching pursuit method has good focusing capability of instantaneous spectrum, based on which the seismic signal is simply and rapidly remodeled by time frequency decomposition. The seismic data of Kendong 701 area were processed based on matching pursuit time frequency decomposition. The results showed that the interpretability of oil reservoir was improved and the seismic reflection characteristics and drilling data were well related. The braided channel sedimentary sands of Minghuazheng and Guantao group strata in Kendong 701 area were predicted, and the results showed that the reservoir distribution had the obvious braided channel features. Based on the predictions, three wells were located and the prediction and drilled results were consistent. 相似文献
17.
龙口煤矿主要为新生界古近系含煤建造,共含煤1、煤2、煤3、煤4四层煤,煤2为全区稳定可采煤层。以往的地震勘探剖面上反映煤2反射特征明显,断点干脆。在新采集的海上三维地震剖面上,煤2局部存夹矸,致使煤2反射波表现异常。通过正演模拟,总结出夹矸层厚度与频率的相互关系及其反射波特征。从实际资料的处理中,可以看出,经保幅处理后的叠前时间偏移剖面,比常规时间叠加剖面更能准确的反映出夹矸层的透镜体反射特征,特别是透镜体的上、下部同相轴反射波组强弱之分更加明显。实际采掘数据表明,地震剖面解释的夹矸分布范围,与实际情况吻合较好。 相似文献
18.
地震勘探资源频率域叠加方法研究 总被引：1，自引：1，他引：1
在叠前共深度点道集内各地震道的动、静校正误差很小的情况下，地震资料时间域水平叠加方法有较好的叠加结果。但是，如果动、静校正的误差较大时，叠加效果将受到影响，即叠后振幅和分辨率都会降低。因此，提出一种频率域叠加方法。该方法既具有常规水平叠加方法能提高信噪比的优点，又能将共深度点道集内的走时时差消除，达到内相叠回的目的。几个比较叠加方法效果的有噪CDP道集叠加的例子证明了该方法的效果。 相似文献
19.
Improved supervirtual interferometry (SVI) method that enhance the signal-to-noise ratio (SNR) of noisy seismic refraction data is presented. This 3D supervirtual algorithm is helpful in removal of side lobes caused by convolution in the conventional 3D SVI method. In this study, we extend the supervirtual seismic refraction interferometry method to 3D geometries commonly used in active seismic exploration. To achieve this objective, synthetic 3D seismic refraction data were created using single patch orthogonal geometry. Simple two-layers velocity model was used. A zero phase wavelet was convolved with the refraction travel time to create the seismic wiggle trace. The refraction arrival is computed using the equation for horizontal refractor case and is not adapted for dipping refractor. Noise of Gaussian distribution with zero mean and 0.25 standard deviation was added to simulate a case of moderate ambient noise. The supervirtual algorithm, consisting of crosscorrelation, alignment, summation, and first arrival calculation is performed. By aligning and summation of all the correlogram, the stationary position of source-receiver pairs as required in the 2D supervirtual method are eliminated in this case. Synthetic data presented in this study shows accurate first arrivals after the application of the 3D SVI and traces with much better SNR than the actual traces. 相似文献
20.
以山西潞安矿区地层为参照,建立圆锥状陷落柱模型,模型区域为[0,1000]×[0,600]。分别在模型（0,0）、（250,0）和（500,0）三点激发,101道接收,道距10m。采用高斯射线束法对陷落柱模型进行地震射线追踪,模拟结果表明陷落柱柱面产生的反射波只有小部分能为地表所接收,难以形成能量可观的连续的反射波。另外根据射线路径,提出了延迟反射波（包括“反射—透射波”和“透射—反射波”）的概念,认为延迟反射波是在地表一定范围内可以接收到的陷落柱的特征波,它对CMP道集、水平叠加及偏移处理均会造成影响,从而影响陷落柱的地震解释精度。延迟反射波很可能就是实际揭露陷落柱规模小于地震资料解释结果的原因之一。 相似文献