辽西深反射地震勘探采集试验

深反射地震勘探是目前研究和分析地下深部构造最有效的方法之一。为了查明辽西地区深部构造信息,在该地区布设一条16.9 km的深反射地震剖面。由于该地区的地震地质资料有限,为了能够获取深部地层的地震反射信号,开展了辽西地区的深反射地震勘探采集参数试验。本次地震采集参数试验采用炸药震源、428XL地震仪和SG-10低频检波器,固定采集参数为：采样间隔1 ms、道间距20 m、记录长度15 s。采集参数试验主要针对激发因素（激发深度、药量、组合井激发）和接收因素（组合低频检波器）进行了较为全面的试验工作。依据采集的地震记录确定所研究的主要目的层为6.5 s反射信号,通过对不同激发因素和接受因素单炮记录中目的层信号能量及信噪比的比较,确定适合于该地区的最佳激发参数和接收参数为：井深15 m、药量12 kg;井组合采用单井和三井组合相结合;检波器组合采用点组合方式。研究结果表明,在辽西地区,通过增加激发深度、增加药量、采用组合井激发和组合低频检波器、延长记录时间等措施可以获得地下更深部的反射信息。     

垦东地区海陆过渡带地震采集技术应用

分析了垦东地区海陆过渡带勘探的难点,针对地震波激发和接收条件差、干扰波发育等特点,在海陆过渡带地震波的激发、接收以及测量等方面进行研究:优选了气枪震源和炸药震源激发参数;改进了检波器及检波器固定方法,从而提高了检波器与地表的耦合效果;对检波器进行实时定位监测。采用上述措施,提高了地震采集资料的信噪比和分辨率,顺利完成了该区的地震采集任务。     

倾斜检波器与地表双自由度耦合效应

煤田地震数据采集过程中,存在同一检波点位置重复插拔布设检波器的情况,检波器多次插拔布设存在倾角差异,导致检波器与地表耦合条件变化,影响地震数据采集质量。将检波器倾角参数引入检波器与地表耦合系统。从振动力学的角度推导倾斜检波器“双自由度耦合振动系统”,研究检波器倾角、检波器与地表相对阻尼系数、地表介质参数对耦合系统的影响,分析相同检波点位置重复布设检波器对地震数据采集的影响机理。研究结果表明,检波器倾角的增加将衰减检波器与地表耦合系统的幅频响应,提高耦合系统的谐振频率,说明本次倾斜检波器与地表耦合系统模型构建合理,结果可用于指导和规范地震数据采集工作。     

基于可控震源的中浅部地震勘探参数选择

可控震源已经广泛应用在石油、煤田等地震勘探工作中,相应的技术手段也较为成熟,但涉及高频检波器采集的较少,尤其是使用可控震源进行中浅部地震勘探时参数的选择缺乏参考依据。为了研究如何在中浅部地震勘探中获取高品质数据,在雄安地区开展了一系列“可控震源激发、高频检波器接收试验。本文在大量试验数据的基础上,采用原始单炮定性分析与频谱定量分析相结合的方式,从原始数据信噪比与分辨率的角度出发,系统论述了可控震源震动次数、扫描长度、初始频率、终止频率、驱动幅度、斜坡长度以及检波器自然频率等参数的选择对数据质量的影响;明确了所涉及参数的选择要点及依据,提出了高截止频率的概念;最后,总结了中浅部地震勘探参数选择的策略,对以后中浅部可控震源地震勘探具有一定的借鉴意义。     

检波器组合对高分辨率地震勘探的影响

基于检波器组合各点为平面简谐波同相叠加的假设,地震勘探野外施工多将检波器组合作为压制噪音提高原始资料信噪比的一种主要手段,但实际野外地震地质因素难以满足假设条件,导致由多个检波器组合叠加的地震信号存在一定程度的畸变,进而影响到信号的振幅和频率。通过对组合基距及组内距的计算,论证了检波器组合对信号频率及振幅的影响程度。实际资料分析证明,检波器组合在噪音压制的同时也会损伤到有效信号,尤其高频信息成份;过大的检波器组合基距,不仅会降低原始资料信噪比,甚至还会降低原始资料频率。据此提出在高信噪比地区,采集地震数据宜采用较小检波器组合基距,以提高原始资料的分辨率。     

槽波地震勘探仪器的发展现状

高性能槽波地震勘探仪器的研制能够有力推进槽波地震勘探方法在煤矿地质构造勘察等领域的有效应用。通过分析槽波地震勘探实例,对比国内外多款新型槽波地震仪采集站,结果表明：无线遥测式地震仪是槽波地震勘探仪器的主要发展方向;新型采集站都使用有Δ-Σ技术的24位AD转换器,前置增益都是多倍率。地震仪器采集站的性能满足槽波地震勘探需要,但是地震检波器的性能制约了槽波地震仪整机性能的提高。分析6种不同类型地震检波器的原理和性能,目前地震检波器主要是围绕提高灵敏度,拓宽频率响应范围和增强抗干扰能力3个方面进行研究。其中高性能压电式地震检波器在槽波地震勘探中有较好应用前景,进一步介绍了一种压电地震检波器芯体及测试结果。     

高分辨率三维地震采集技术研究

对松辽盆地南部的地层品质因素和地层衰减系数，尤其是近地表的地层品质因素和地层衰减系数进行研究，进而研究了野外地震采集的激发和接受等各个因素。研究结果表明：高分辨率地震采集的小药量激发理论在松辽盆地南部是不适用的；保证激发深度在浅水面之下0．5m是非常重要的；地层品质因素和地层衰减系数的研究不但可以确定检波器的最佳埋置深度，而且有助于确定对地震数据进行高分辨率处理的最佳流程和参数。最后有针对性地设计了有利于高分辨率三维地震采集的观测系统和各种采集参数；形成了一套适合松辽盆地南部地区的高分辨率三地震采集方法；应用后提高了三维地震采集数据的质量。     

二维地震采集参数的选择——以潮水盆地HW勘查区为例

HW勘查区位于潮水盆地南部,地貌形态为山前冲洪积倾斜戈壁平原和低矮丘陵,表浅层坚硬、疏松的砂砾石层给该区煤层地震勘探有效探测带来极大困难,选择有效的采集参数是保障该区地震勘探效果的关键.参考邻区地震勘探经验,通过理论分析和试验,得出了针对不同地段采取不同井深、药量、井组合及井间距的激发参数,结合勘查区地质特点,选择多个检波器线性组合和高覆盖次数观测系统.所选择的采集参数经过精细施工,取得了较好的地震效果,为今后类似地区进行煤田地震勘探提供了有参考价值的经验和实例.     

地震检波器技术与发展研究

地震勘探数据采集的关键器件是检波器,分为模拟检波器和数字检波器。在分析了各种模拟检波器特点之后,再对数字检波器进行研究。这里展示了基于MEMS(Micro Electro Me-chanical systems)技术的数字检波所代表的机电合一、微型化、宽频谱线性响应的发展方向。同时指出,由于目前MEMS数字检波器的不完善,在今后一段时间内,基于电磁感应机理的数字检波器,将与基于MEMS技术的数字检波器长期共存与互补。     

涡阳-凤台地区地震活动和地震构造

本文运用深浅部构造对比研究，结合历史地震资料、中强震观测资料分析和地震活动性分析结果，探讨中强震过渡区地震构造环境和地震韵律的研究途径，以涡阳～凤台地区为例，对其进行综合剖析，推演未来中强震发生的空间部位，并预测该地区未来可能发生地震的震源深度、震级、地震长轴衰减方向、发生时间等参数。     

Local adaptive parameterization for the history matching of 3D seismic data

Matching seismic data in assisted history matching processes can be a challenging task. One main idea is to bring flexibility in the choice of the parameters to be perturbed, focusing on the information provided by seismic data. Local parameterization techniques such as pilot-point or gradual deformation methods can be introduced, considering their high adaptability. However, the choice of the spatial supports associated to the perturbed parameters is crucial to successfully reduce the seismic mismatch. The information related to seismic data is sometimes considered to initialize such local methods. Recent attempts to define the regions adaptively have been proposed, focusing on the mismatch between simulated and reference seismic data. However, the regions are defined manually for each optimization process. Therefore, we propose to drive the definition of the parameter support by performing an automatic definition of the regions to be perturbed from the residual maps related to the 3D seismic data. Two methods are developed in this paper. The first one consists in clustering the residual map with classification algorithms. The second method proposes to drive the generation of pilot point locations in an adaptive way. Residual maps, after proper normalization, are considered as probability density functions of the pilot point locations. Both procedures lead to a complete adaptive and highly flexible perturbation technique for 3D seismic matching. A synthetic study based on the PUNQ test case is introduced to illustrate the potential of these adaptive strategies.     

沁水煤层气山地地震采集技术管理

沁水煤层气山地地震采集是我们在经过多年山地采集经验的基础上完成的。施工按国际标准化的管理模式进行项目管理,从招标、投标、施工作业组织管理、技术质量管理要求到作业过程的质量控制、工程量和质量的认定,包括山地采集的基本方法(激电井深、药量的选择,测量方法,仪器及其参数的选择)及采集质量与现场技术管理及技术质量监督等方面,采用了适合中国国情与国际标准有机结合的方法。体现了在复杂的山区实施地震采集项目采用先进地震采集技术管理的特色。     

震区隧道洞口段注浆措施的减震效果数值模拟分析

为研究注浆措施在地震区隧道洞口段的减震效果,基于围岩-结构三维模型,改变注浆的范围及参数,采用有限差分法软件FLAC-3D,分析了某隧道洞口段的动力响应。采用人工拟合地震波、黏性边界条件,输入三个方向的地震波,模拟了原设计、全环间隔注浆措施、局部加强注浆措施三种工况。研究分析了各工况的内力、位移、周边围岩塑性区等,并与全环间隔注浆、局部加强注浆两种减震措施的效果作了对比,得出了地震区隧道洞口段的动力响应规律、减震措施的有效范围及全环间隔注浆措施能起到阻尼减震的效果、局部加强注浆措施能改善衬砌结构内力分布的作用等结论。对高烈度地震区隧道洞口段抗减震措施研究有一定的借鉴意义。     

昆仑山前地震勘探方法及应用效果

由于昆仑山前带地表条件及地下构造复杂,地震施工难度大,采集的资料品质低,噪声干扰严重,静校正问题严重,地下地层纵横向速度变化剧烈,资料处理难度较大,成像困难。针对这些难点,合理地设计采集参数,并采用灵活多变的观测系统进行采集,大大提高了原始资料的信噪比。通过有针对性地使用静校正技术、噪声压制技术以及构造成像技术,较好地解决了山地地震资料成像问题,最终剖面构造形态清晰,断层接触关系清楚。     

考虑冻土效应的桥梁桩-土动力相互作用研究现状与展望

冻土和地震是我国西部高寒高烈度地区桥梁工程建设中主要面临的两大挑战。冻土区线路工程广泛采用桩基础桥梁, 土体冻结后会显著影响地震作用下桩-土动力相互作用过程, 给桩基础桥梁抗震分析带来困难。首先系统总结和分析了冻土对桥梁结构地震响应的影响、 桩-冻土相互作用效应及其计算模型等方面的研究现状, 进而对相关成果进行了科学分析。研究表明： 冻土的存在对桥梁结构地震反应的影响是显著的, 桩基础桥梁抗震设计中不考虑冻土效应是不合理的。目前还存在的问题包括： 冻土区桥梁结构地震反应的研究中, 未充分考虑冻土效应; 现有桩-土相互作用模型无法有效应用于冻土领域; 地震作用下桩-冻土体系相互作用机理及其破坏特征不明确。在此基础上, 提出了考虑冻土效应后桥梁桩-土动力相互作用为今后需要重点研究的方向。     

Influence of slow active faults in probabilistic seismic hazard assessment: the northwestern margin of the València trough

Areas of low strain rate are typically characterized by low to moderate seismicity. The earthquake catalogs for these regions do not usually include large earthquakes because of their long recurrence periods. In cases where the recurrence period of large earthquakes is much longer than the catalog time span, probabilistic seismic hazard is underestimated. The information provided by geological and paleo-seismological studies can potentially improve seismic hazard estimation through renewal models, which assume characteristic earthquakes. In this work, we compare the differences produced when active faults in the northwestern margin of the València trough are introduced in hazard analysis. The differences between the models demonstrate that the introduction of faults in zones characterized by low seismic activity can give rise to significant changes in the hazard values and location. The earthquake and fault seismic parameters (recurrence interval, segmentation or fault length that controls the maximum magnitude earthquake and time elapsed since the last event or T_e) were studied to ascertain their effect on the final hazard results. The most critical parameter is the recurrence interval, where shorter recurrences produce higher hazard values. The next most important parameter is the fault segmentation. Higher hazard values are obtained when the fault has segments capable of producing big earthquakes. Finally, the least critical parameter is the time elapsed since the last event (T_e), when longer T_e produces higher hazard values.     

掘进巷道煤体瓦斯特征与震波频率特性研究

通过多次在突出煤层掘进巷道迎头进行震波探测试验,并使用频谱分析和时频分析技术得到各巷道的单道震波信号的频率参数,对比分析各条巷道对应的瓦斯检验参数,建立起煤体瓦斯绝对涌出量与震波频率参数的关系：震波能量主要集中在两个独立的频率域内,高频区和低频区分别对应了震波的主频和次主频;随着煤体瓦斯含量的增大,震波的主频和次主频相应降低,且次主频对瓦斯含量的变化更为灵敏。利用震波频率参数预测掘进巷道迎头附近瓦斯含量,可为瓦斯突出危险性预测提供一种新的参数。     

Estimation of Seismic Landslide Hazard in the Eastern Himalayan Syntaxis Region of Tibetan Plateau

The eastern Himalayan syntaxis is one of the most tectonically active and earthquake-prone regions on Earth where earthquake-induced geological disasters occur frequently and caused great damages. With the planning and construction of Sichuan-Tibet highway, Sichuan-Tibet railway and hydropower development on the Yarlung Zangbo River etc. in recent years, it is very important to evaluate the seismic landslide hazard of this region. In this paper, a seismic landslide hazard map is produced based on seismic geological background analysis and field investigation using Newmark method with 10% PGA exceedance probabilities in future 50 years by considering the influence of river erosion, active faults and seismic amplification for the first time. The results show that the areas prone to seismic landslides are distributed on steep slopes along the drainages and the glacier horns as well as ridges on the mountains. The seismic landslide hazard map produced in this study not only predicts the most prone seismic landslide areas in the future 50 years but also provides a reference for mitigation strategies to reduce the exposure of the new building and planning projects to seismic landslides.     

加蓬盐下复杂构造区井控高精度变速成图的方法研究

随着油气田开发的不断深入,对地震资料解释和构造成图精度的要求越来越高.尤其是在地表复杂、地下结构复杂、陡倾角地层的地区,必须建立高精度速度场,采用变速成图来获得高精度构造图,才能精细落实构造.然而在复杂构造区,速度在纵向和横向上往往变化都很大,采用常规的速度模型,很难得到精确的构造模型.在研究目前针对复杂地区常用的速度建模技术的基础上,提出了充分利用统一校正后的钻井速度、地震速度谱等资料,再结合层位控制法来建立地震测井互相约束的三维速度模型,最后通过时深转换,绘制出构造图的技术方法.该技术在加蓬陆上开发区盐下构造的研究中取得了很好的效果.     

Analysis of seismic hazard in landslide-prone regions: criteria and example for an area of Daunia (southern Italy)

In relation to the assessment of earthquake-induced landslide hazard, this paper discusses general principles and describes implementation criteria for seismic hazard estimates in landslide-prone regions. These criteria were worked out during the preparation of a hazard map belonging to the official Italian geological cartography and they are proposed as guidelines for future compilation of similar maps. In the presented case study, we used a procedure for the assessment of seismic hazard impact on slope stability adopting Arias intensity Ia as seismic shaking parameter and critical acceleration a _c as parameter representing slope strength to failures induced by seismic shaking. According to this procedure, after a preliminary comparison of estimated historical maximum values of Ia with values proposed in literature as landslide-triggering thresholds, a probabilistic approach, based on the Newmark’s model, is adopted: it allows to estimate the minimum critical acceleration a _c required for a slope to keep under a prefixed value, the probability of failures induced by seismic shakings expected in a given time interval. In this way, one can prepare seismic hazard maps where seismic shaking is expressed in an indirect way through a parameter (the critical acceleration) representing the “strength” that seismic shakings mobilise in slope materials (strength demand) with a prefixed exceedance probability. This approach was applied to an area of Daunia (Apulia—southern Italy) affected by frequent landslide phenomena. The obtained results indicate that shakings with a significant slope destabilisation potential can be expected particularly in the north-western part of the area, which is exposed to the seismic activity of Apennine tectonic structures.