单点高密度地震勘探技术研究综述

常规组合采集方法存在组内干扰等缺点,不能满足高精度地震勘探的需要.为此,单点高密度地震勘探技术受到越来越广泛的关注.该技术采用点激发、点接收、小道距、大道数的采集方式,在室内进行数字组合等处理,与常规组合勘探相比可以提高施工效率;消除组内干扰;提高噪声压制的精度;输出多种组合数据;提高地震资料的分辨率和成像精度,改善油藏特征描述等,很好地适应日益复杂的勘探形势的需要.该技术的理论研究已经取得了很多进展,实际应用效果也比较好.尤其是WesternGeco公司,走在该技术的发展前沿,进行了许多成功的陆上和海上勘探试验.但是该技术存在信噪比低,数据量大等问题,其具体实施方法还有待进一步研究.     

陆上高分辨率地震勘探检波器性能及应用效果分析(英文)

地震检波器的性能是高分辨率地震数据采集中的一个重要因素,对资料的品质影响很大。为此,作者在不同类型地区对目前在高分辨率地震勘探中常用的动圈式检波器、涡流检波器和数字检波器的性能进行了对比试验。通过野外工作的实际,总结了动圈式检波器、涡流检波器和数字检波器在不同表层地质条件地区的应用效果,提出了适合该类地区高分辨率地震检波器的性能指标,指出合理选择检波器类型和检波器的联接方式,能提高地震资料的信噪比和分辨率。     

重震联合中速度-密度耦合研究综述

基于物性参数耦合的多地球物理数据联合反演方法是21世纪初发展起来的新技术,速度-密度耦合约束下的重震联合反演是其重要分支之一.相比于传统的重震资料综合解释,基于速度-密度耦合的重震联合反演能够减少主观因素的干扰,发挥地震和重力数据的互补作用,产生精度和一致性更高的速度-密度模型.结合国内外现状,本文较为全面地介绍了现有的速度-密度耦合方式,并讨论了速度-密度耦合约束下重震联合反演策略和目标函数的构建及求解等相关问题.不同反演策略和耦合方式的适用性不同,没有绝对的优劣之分.根据研究区的实际情况,在合适的速度-密度耦合约束下开展重震联合反演研究和应用是下一步工作的重点.     

Assessment of seismic resistance of masonry structures including boundary conditions

The paper is devoted to the investigation of seismic response of the masonry structure and describes experiences with modelling of boundary conditions during the test of large heavy model on 6DOF shaking table. The main aim of the research was how to increase dynamic resistance capacity of old masonry buildings including the medium and strong seismic effects. The results of theoretical and numerical analyses are compared including initial forecasting calculations made before any test started. The emphasis is given to the boundary conditions reached during the excitation of the large masonry model via shaking table. Strengthening and retrofitting procedures and their effects are discussed when special fibre mortar is used for repair and strengthening of masonry parts of structure.     

Wave equation datuming applied to marine OBS data and to land high resolution seismic profiling

One key step in seismic data processing flows is the computation of static corrections, which relocate shots and receivers at the same datum plane and remove near surface weathering effects. We applied a standard static correction and a wave equation datuming and compared the obtained results in two case studies: 1) a sparse ocean bottom seismometers dataset for deep crustal prospecting; 2) a high resolution land reflection dataset for hydrogeological investigation. In both cases, a detailed velocity field, obtained by tomographic inversion of the first breaks, was adopted to relocate shots and receivers to the datum plane. The results emphasize the importance of wave equation datuming to properly handle complex near surface conditions. In the first dataset, the deployed ocean bottom seismometers were relocated to the sea level (shot positions) and a standard processing sequence was subsequently applied to the output. In the second dataset, the application of wave equation datuming allowed us to remove the coherent noise, such as ground roll, and to improve the image quality with respect to the application of static correction. The comparison of the two approaches evidences that the main reflecting markers are better resolved when the wave equation datuming procedure is adopted.     

非纵弯线气枪震源陆地反射资料叠加成像

为探索大容量气枪震源在深部地震探测中的应用,2015年10月在安徽铜陵段开展气枪流动激发试验。该试验采用沿长江航道激发、岸边固定排列接收的工作方式,因受长江航道及江岸地形的影响,加上原始记录中干扰波发育、静校正问题突出等,基于常规的共中心点叠加的数据处理方法已不再适用。为此,开展了针对性的数据处理方法研究。本文采用初至波层析静校正、叠前多域多道集去噪以及非纵弯线共反射面元叠加等一系列处理技术,结果显示所获测线经过区域的深部构造叠加剖面较清晰。     

Seismic velocity structure around the Hyuganada region, Southwest Japan, derived from seismic tomography using land and OBS data and its implications for interplate coupling and vertical crustal uplift

The Hyuganada region, a forearc region of Southwest Japan, is characterized by several interesting geological and geophysical features, i.e., significant aseismic crustal uplift of 120 m during the past 120 thousand years at the Miyazaki Plain, negative free-air gravity anomalies with the maximum magnitude of −130 mgal, and relatively less cohesive interplate coupling compared with that for off the Shikoku and Kii Peninsula. In order to examine the causes of these observations, we determined a detailed three-dimensional seismic velocity structure based on the seismic data observed by ocean bottom seismometers (OBS) and land stations. P- and S-wave tomographic velocity structures clearly indicate the subducting slab and also the zones of high Poisson's ratio at 25–35 km depth along the coastline of the northeastern part of the Hyuganada. The region with high Poisson's ratio may correspond to the serpentinized mantle wedge as suggested for other mantle wedges, and appears to be coincident with the zone for observed aseismic slips such as the slow-slip and after-slip events. Also, the detection may be related to a relatively weak interplate coupling in the Hyuganada region. The tomographic structures also indicate low velocity zones with a horizontal scale comparable to the Kyushu-Palau Ridge in and around the subducting slab. If we assume that the low velocity zones correspond to the subducted Kyushu-Palau Ridge, then the predicted gravity anomaly due to the density contrast between the low velocity zones and the surrounding region can explain about 60% of the gravity anomaly in the Hyuganada region. The buoyancy is probably an important factor for the crustal uplift observed in the Miyazaki Plain, the steep bending of the subducting slab and the normal fault-type earthquakes around the Hyuganada region.     

The effects of near-surface conditions on anisotropy parameter estimations from 4C seismic data

We present a study of anisotropic parameter estimation in the near‐surface layers for P‐wave and converted‐wave (C‐wave) data. Near‐surface data is affected by apparent anisotropy due to a vertical velocity compaction gradient. We have carried out a modelling study, which showed that a velocity gradient introduces apparent anisotropy into an isotropic medium. Thus, parameter estimation will give anomalous values that affect the imaging of the target area. The parameter estimation technique is also influenced by phase reversals with diminishing amplitude, leading to erroneous parameters. In a modelling study using a near‐surface model, we have observed phase reversals in near‐surface PP reflections. The values of the P‐wave anisotropy parameter η estimated from these events are about an order of magnitude larger than the model values. Next, we use C‐wave data to estimate the effect of anisotropy (χ) and compute η from these values. These calculated η‐values are closer to the model values, and NMO correction with both η‐values shows a better correction for the calculated value. Hence, we believe that calculating η from χ gives a better representation of the anisotropy than picked η from the P‐wave. Finally, we extract the anisotropy parameters η and χ from real data from the Alba Field in the North Sea. Comparing the results with reference values from a model built according to well‐log, VSP and surface data, we find that the parameters show differences of up to an order of magnitude. The η‐values calculated from the C‐wave anisotropy parameter χ fit the reference values much better and show values of the same order of magnitude.     

检波器-大地耦合系统特性的振动力学解释、模态参数识别及其对地震资料的影响与消除

检波器-大地耦合系统处于地震数据采集的最前端,是地震采集中的基本问题.“耦合是指两个系统之间的相互作用.检波器和大地的耦舍是影响能量转换的重要因素之一,取决于两者之间接触的牢固程度,以及检波器的重量和接触面积等;该耦合系统中存在着自然谐振并有滤波效应”(R.E.Sheriff).多年来,对耦舍响应的研究主要集中在理论研究以及检波器耦合效果对比两个方面,并以感性描述、现象罗列居多.笔者在研究过程中设计了检波器-大地耦舍响应的测定方法,并实际测量了检波器-大地耦合响应.结果表明,检波器-大地耦合响应可以用“单自由度有阻尼的自由振动系统”来描述,涉及到“固有频率”以及“阻尼比”两个参数,并可用参数扫描法对其振动模态进行参数识别.当检波器埋置效果差时,耦合响应使得地震子波相位增加,分辨率降低;高频成分增加,信噪比降低(主要在高频端).根据测得的耦合响应对检波器接收到的数据进行“耦合反褶积”,将地震数据“还原为”地表下数十厘米处的介质振动,从而消除耦合响应,可以增强地震信号的“保真度”,提高信噪比与分辨率.由于地表介质的多变性,每一个检波器对应的耦合响应均不同,同一检波器组合中多个检波器的耦合响应存在一定差异;其中只要有一个检波器埋置差,其整体的耦合效果就会显著变差;因为耦合响应对地震数据的影响非常深刻并难以忽略,所以合成地震记录时也应该考虑耦合响应的影响.     

基于Dreamlet变换的地震数据压缩理论与方法

为达到更加有效地表示地震数据的目的,仅仅将地震数据当作普通的图像数据处理是远远不够的,地震数据中蕴含的地震波的运动学特性也应作为重要因素而被考虑到.本文讨论了利用Dreamlet变换方法实现地震数据压缩的方法,并针对地震数据本身所蕴含的频散关系特性进一步提出了多尺度Dreamlet变换压缩方法.Dreamlet变换由2个一维局部谐波变换的张量积构成,它在提供地震波场时间-空间局部化性质的同时可以保留波场的运动学特性.通过对二维SEG/EAGE叠前、叠后数据的算例说明了Dreamlet变换用于地震数据压缩的有效性.利用压缩后的数据进行成像的结果更表明,与Curvelet变换方法相比,Dreamlet与多尺度Dreamlet方法可以提供更高的压缩比;在相同压缩比的条件下,使用Dreamlet与多尺度Dreamlet方法压缩重建后的数据进行成像能更好地保留成像结果中的重要结构.     

基于Dreamlet变换的地震数据压缩理论与方法

为达到更加有效地表示地震数据的目的,仅仅将地震数据当作普通的图像数据处理是远远不够的,地震数据中蕴含的地震波的运动学特性也应作为重要因素而被考虑到.本文讨论了利用Dreamlet变换方法实现地震数据压缩的方法,并针对地震数据本身所蕴含的频散关系特性进一步提出了多尺度Dreamlet变换压缩方法.Dreamlet变换由2个一维局部谐波变换的张量积构成,它在提供地震波场时间-空间局部化性质的同时可以保留波场的运动学特性.通过对二维SEG/EAGE叠前、叠后数据的算例说明了Dreamlet变换用于地震数据压缩的有效性.利用压缩后的数据进行成像的结果更表明,与Curvelet变换方法相比,Dreamlet与多尺度Dreamlet方法可以提供更高的压缩比;在相同压缩比的条件下,使用Dreamlet与多尺度Dreamlet方法压缩重建后的数据进行成像能更好地保留成像结果中的重要结构.     

地震属性参数在札达—泉水沟深地震测深资料预处理与震相识别中的应用

地震属性分析技术在地球物理勘探领域的广泛应用,启发研究人员将其应用于人工源宽角反射/折射深地震测深剖面的资料预处理和震相识别。采用札达—泉水沟深地震测深资料,提取振幅、信噪比、主频、瞬时带宽、瞬时高频能量等地震属性参数,分析不同参数的物理含义,挑选其中对界面变化敏感的参数,对深地震测深资料进行预处理,并利用P波和S波的联合扫描,提高震相识别的准确性。走时互换结果显示,采用地震属性参数可有效提高震相拾取的准确性,进而提高后续地壳速度结构反演结果的精度。     

浅层地震资料解释陷阱(英文)

高分辨率浅层地震方法是在近地表调查中使用最为广泛的方法。然而,在许多情况下,地震资料的解释经常会出现错误。在本文中,我们介绍了三个例子,分析了造成P波,SH波,多道的面波(MASW)地震资料解释的错误原因,大都是由于在表面或地下条件约束不确当引起的。第一个例子是P波反射剖面上的一个波的特征被解释为浅层断裂带,但后来证实它是由高水平的背景噪音引起的,因为采集测线通过了一个公路交叉口。第二个例子是SH波反射地震剖面上一个波特征被解释为是逆倾向滑断层,但有针对性的钻探表明,它是一个侵入到基岩面的一个深层局部侵蚀。最后,第三个例子,MASW调查剖面上,一个陡倾特征一开始被解释为基岩谷。然而,后来的钻探表明这是一个非常软的湖泊沉积物,后者严重损坏了应用面波频段。虽然最初的解释是不正确的,但这刺激地球物理学家和地质学家之间的讨论,并强调地球物理数据采集的时候,采集之前以及采集之后需要科学家之间有意义的合作与讨论。     

陆地地震勘探随机噪声统计特性

在地震勘探随机噪声压制领域,噪声通常被假设为平稳、高斯随机过程的信息.然而,在某些情况下,这样的假设并不准确.本文应用现代统计检验方法对地震勘探随机噪声的平稳性、高斯性和线性进行了研究.结果表明地震勘探随机噪声并不是传统意义上认为的平稳随机过程,其平稳性受到噪声时长和采集环境复杂程度的影响.发现噪声时间越长,采集环境越复杂,随机噪声的平稳性越差,但是对于短时长随机噪声而言,其可以近似认为是平稳的.同时,采集环境的复杂程度也影响着随机噪声的高斯性和线性特性,环境条件越复杂,随机噪声高斯性越好,线性特性越差,但总的来说随机噪声可以归为线性非高斯随机过程.

     

地下爆炸地震耦合效应的静态分析

首先修正了地下爆炸地震耦合效应的准静态理论,然后利用改进之后的理论对剪切模量、材料强度、围压以及孔隙率不同的介质中地下爆炸的震源强度进行了分析.分析结果表明,对于密实硬岩介质来说,在其它条件不变的情况下,介质的剪切模量越大,震源强度越低;介质的强度越大,震源强度越低;震源强度随着埋深的增加而降低.而干燥多孔介质中的干孔隙率也对震源强度有重要影响.     

Geochemical constraints on the model of the composition and thermal conditions of the Moon according to seismic data

A new method of reconstruction of the temperature profile in the lunar mantle from the velocities of seismic P- and S-waves for different models of chemical composition is developed. The procedure of the solution of an inverse problem is realized with the help of the minimization of the Gibbs free energy and the equations of state of a mantle substance, taking into account phase transformations, anharmonicity, and the effects of inelasticity. The geophysical and geochemical constraints on composition and temperature distribution in Moon’s mantle are established. The upper mantle can be composed of olivine pyroxenite, depleted by low-volatile oxides (∼2 wt % of CaO and Al₂O₃). On the contrary, the lower mantle must be enriched by low-volatile oxides (∼4–6 wt % of CaO and Al₂O₃). Its composition can be represented by a mineral association of the olivine + clinopyroxene + garnet or olivine + orthopyroxene + clinopyroxene + garnet type, which is close in composition to pyrolite. The temperature distribution at depths 50–1000 km are approximated by the equation: T(°C) = 351 + 1718[1–exp (−0.00082H)]. The constraints inferred make it possible to conclude that the published values of the velocities of P- and S-waves for the lunar mantle, obtained by processing the data of seismic experiments of the Apollo lunar mission are inconsistent with each other at depths below 300 km. Otherwise, the variations in the velocities of P- and S-waves disturb the symmetry between the petrological model (composition), the temperature profile, and the seismic profile.     

地震前兆数据的管理与服务

简要介绍了中国地震局全国地震前兆台网中心及其前兆数据来源和特点，重点分析了该中心的数据管理、数据服务及应用。全国地震前兆台网中心在剖析地震前兆数据的结构和总结其特点的基础上，选择了自行研制的基于双表数据结构的CAPOmen平台来管理和维护各种前兆数据，并枚举了该平台所具有的一些特点，前兆台网中心还运用Web和FTP等网络传输手段与用户及研究单位进行各种数据交换和共享，提供以CAPOmen 平台为后台数据库管理的基于浏览器的前兆数据查询、浏览、下载及其他服务等。并对地震前兆数据的管理提出几点建议。     

遥测地震台网联网信号及数据传递技术

叙述了遥测地震台网联网中使用的有线、无线电VHF和UHF地震信号及数字数据的传递技术原理及其方法。     

地震波衰减机理及能量补偿研究综述

随着中、浅层油气勘探程度的不断提高,深层油气藏的勘探已经成为当今勘探研究的主要对象,而深层油气勘探要获得突破关键是用于综合研究的地震剖面要有较高的信噪比和分辨率,深层与浅层能量均衡.因此,国内外对地震波衰减机理和补偿方法进行了大量研究.本文综述了基于岩石物理和散射理论的地震波的衰减机理,重点概括了地震波衰减的影响因素,指出衰减与孔隙度、频率、温度、压力、岩性等因素有关,最后分类介绍了各种地震波衰减的能量补偿方法.     

Assessment of seismic hazard in the North Caucasus

The seismicity of the North Caucasus is the highest in the European part of Russia. The detection of potential seismic sources here and long-term prediction of earthquakes are extremely important for the assessment of seismic hazard and seismic risk in this densely populated and industrially developed region of the country. The seismogenic structures of the Iran-Caucasus-Anatolia and Central Asia regions, adjacent to European Russia, are the subjects of this study. These structures are responsible for the specific features of regional seismicity and for the geodynamic interaction with adjacent areas of the Scythian and Turan platforms. The most probable potential sources of earthquakes with magnitudes M = 7.0 ± 0.2 and 7.5 ± 0.2 in the North Caucasus are located. The possible macroseismic effect of one of them is assessed.