城市地区充水薄层煤炭采空区瞬变电磁法探测效能分析

本文通过瞬变电磁法对薄层充水采空区进行实地探测,并使用天然源面波法进行二次探测,通过天然源面波法的探测结果和钻探的结果验证了瞬变电磁法对薄层充水采空区探测的可行性。通过数值模拟,构建不同采空区含水率、不同深度和不同厚度的薄层充水采空区的电阻率模型,研究了瞬变电磁法对薄层充水采空区的探测效果。研究结果表明,瞬变电磁法可以对薄层充水采空区进行有效的探测;随着薄层充水采空区含水率的降低,瞬变电磁法探测出的异常区范围和电阻率异常幅值变小,当采空区未充水时,瞬变电磁法无法对采空区进行有效的探测;随着薄层充水采空区深度的增加,瞬变电磁法探测出的异常范围和电阻率异常幅值变小,在本文模拟的工况条件下,100 m为探测的极限深度;随着薄层充水采空区厚度的降低,探测出的异常区范围和电阻率异常幅值变小。     

复杂地形结构下瞬变电磁三维正演模拟-以大西洋洋中脊TAG热液区为例

如何确定海底多金属硫化物的空间分布并对其进行资源量评价至关重要.瞬变电磁法是陆地金属矿床勘探的重要手段,但海底的崎岖地形、硫化物的复杂结构以及不稳定的近底观测条件为瞬变电磁在海洋中的应用提出了挑战.为验证瞬变电磁方法对热液区硫化物的勘探应用潜力,本文采用了有限元方法,结合大西洋洋中脊TAG热液区实测地形数据和硫化物深部...     

深海多金属硫化物瞬变电磁激电效应初探

瞬变电磁法是深海多金属硫化物勘探的有效手段。海底多金属硫化物中高品位的金属组分会引起极强的激电效应,且对瞬变电磁响应产生显著影响。本文通过实验室测量和数值模拟对深海多金属硫化物的激电效应进行了探讨和分析。首先对西南印度洋中脊热液区的岩矿石样品进行了较为系统的电性测试,典型硫化物的复电阻率在频率域有最大达160 mrad相位移动,时间域与频率域的测量结果表明,极化率参数可以很好地区分硫化矿物与围岩。利用Cole-Cole模型对实测复电阻率进行解释,得到复电阻率的特征参数,分析各参数与块状硫化物组分和结构的关系,并根据极化率参数对典型硫化物进行了分类。将典型硫化物的激电参数用于计算层状介质的瞬变电磁响应,计算结果表明,在海底多金属硫化物矿床瞬变电磁法响应的最佳观测时窗内可同时观测到激电效应的影响。虽然在采集时窗晚期瞬变响应发生畸变,但在信号接收早期,激电效应能有效增强瞬变电磁法对深海多金属硫化物的探测能力,为瞬变电磁实测数据提供解释依据。     

复杂地形结构下瞬变电磁三维正演模拟

如何确定海底多金属硫化物的空间分布并对其进行资源量评价至关重要。瞬变电磁法是陆地金属矿床勘探的重要手段,但海底的崎岖地形、硫化物的复杂结构以及不稳定的近底观测条件为瞬变电磁在海洋中的应用提出了挑战。为验证瞬变电磁方法对热液区硫化物的勘探应用潜力,本文采用了有限元方法,结合大西洋洋中脊TAG热液区实测地形数据和硫化物深部剖面进行三维正演模拟,通过对比仪器在不同位置、姿态、离底高度的正演模拟结果发现:重叠回线探测装置在离底高度小于60 m时,可以有效探测到TAG丘体的高电导率异常。海底复杂地形以及仪器拖曳方式都会对二次场早期响应产生干扰,同时仪器姿态变化也会改变所探测到的响应,这表明,应结合研究区域的海底地形、仪器海底定位以及姿态数据才能更好的对实测瞬变电磁数据进行合理解释。     

电磁方法在海底多金属硫化物探测中的应用

海底硫化物矿体的三维展布是当前大洋调查急需解决的关键问题,在陆地上电磁方法一直是解决矿产资源三维问题的重要手段之一。2011年我国自主研发了调查海底多金属硫化物的瞬变电磁设备,并于2011年6月在中国大洋第22航次第5航段中的大西洋中脊“贝利珠”热液区( 13.2°S、14.4°W)进行了试验,取得了我国首批海底热液区的瞬变电磁资料。本文对这批资料进行初步分析,阐述一种新的海底硫化物探测方法及其试用结果,得到的视电阻率断面与热液区的实际有很好的对应关系,从2条测线的实测结果来看,设备的探测深度达到海底面以下50~100 m。在本次试用过程中,较好验证了自主研发的深海瞬变电磁设备、获得的数据以及探测深度的可靠性。     

海洋调查中可应用电法吗?

大地电磁法在国内外是行之有效的探测技术,在石油勘探、防灾科学技术及地震监测等方面用处颇大,可补助传统地震波探测的不足或限制。但是,在以往的海洋勘测和调查研究中多用海洋重力、海磁、航磁及广泛采用地震波勘探诸方法,在海洋中电法却长期无用武之地。这是因为,...     

南黄海沉积层地震反射特征模拟分析与勘探技术选择的思考

基于AVO和地震波吸收衰减的地震反射振幅理论模拟分析,在获得了南黄海盆地主要反射界面的地震反射振幅与偏移距关系的基础上,分析了常规地震勘探面临的主要困难,提出了在采用大容量、长排列地震勘探的同时,应适时采用立体气枪震源、上下缆和双检地震等先进的地震勘探技术,同时开展大地电磁、OBS等勘探技术,以获得深部地层的有效地球物理信息。     

井间地震资料解释方法--以垦71区块井间地震为例

垦71区块井间地震代表胜利油田地震勘探工作进入一个新的时期。通过合成记录的制作以及井间地震反射波成像资料与常规地震资料的对比，对垦71区块井间地震资料的可靠性进行了评价。通过粗化处理和测井约束反演，探讨了井间地震资料的综合解释方法。     

测井约束的海洋CSEM反演及其在南黄海中部隆起区勘探应用

海洋可控源电磁法(Controlled-Source ElectroMagnetic,CSEM)对于油气储藏饱和度判别具有较高的敏感性,这为其用于油气储藏检测奠定了基础.但是海洋CSEM相较于地震勘探而言对异常体的垂向分辨率较低,这为海洋CSEM资料反演异常体垂向结构带来困难.由于测井数据具有垂向分辨率高的特点,蕴含丰...     

波罗的海地震的危险性

俄罗斯等国积累了地震分区和评价地震高危地区的重要经验。地台属于地震程度较小的地区,更不用说在地台范围内的海区了。但波罗的海及其东部,实际上处于专家们的视线之外。在2004年9月21日,加里宁格勒强度(I)为6·5的4·9级(M)地震发生之后,这个工作上的不到位特别明显地暴露出     

Fuzzy Probabilistic Analysis of Seismic Stability of Coastal Embankment

The stability of slope is affected by a number of factors, some of which have not only random property but also fuzzy characteristic. Therefore, the analysis of slope stability is really an uncertain problem. The customary safety factor does not in reality reflect stability scientifically, quantitatively and practically. In order to obtain more practical results, the slope stability is treated as a fuzzy random event for the evaluation of its fuzzy probability. Finally, the seismic stability of an existing coastal embankment is analyzed by means of the suggested fuzzy probabilistic method. It may be seen that the results of analysis can more fully represent the numerical assessment of the degree of slope seismic stability.     

Susceptibility assessment of regional submarine landslides triggered by seismic actions

Submarine landslide and even its evolution to high-speed sliding masses can seriously threaten the safety of ocean engineering. Earthquakes are the most frequent trigger factors for landslides, and thus, seismic instability evaluation of submarine slopes has become a hot topic. However, the mechanism of submarine slope failures triggered by earthquakes is enormously complex. Although certain satisfactory results have been achieved in specific slopes, submarine landslides are still difficult to monitor and control, meaning that prevention-oriented research remains the mainstream. Regional slide predictive analyses of vast submarine slopes should be emphasized, but relevant research is notably rare. In this paper, a regional assessment methodology for submarine slope instabilities under seismic loads is proposed, and susceptibility mapping of landslides is established. First, considering the quasi-static bidirectional seismic action and the marine soil strength-weakening effect, an infinite slope sliding mode is used to establish the stability evaluation formula for a multiple soil-layer slope. Second, according to water depth data and GIS techniques, slope gradients are investigated, and the safety factors of submarine slopes located at specific stations are acquired. Furthermore, discrete stations are taken as sample points, and susceptibility mapping of submarine landslides is achieved using the inverse distance weighted and GIS techniques. Finally, regional seismic instability assessments of submarine slopes are conducted in the northeastern South China Sea, and various factors that influence submarine landslides are briefly discussed. This study offers an important basis for the development of marine resources and the risk assessments in ocean engineering.     

Large-scale seafloor stability evaluation of the northern continental slope of South China Sea

Abstract

With the continuous expansion of energy demand, the deep-water continental slope in the northern South China Sea has become one of the significant offshore oil and gas exploration regions. The frequent occurrence of marine geological hazards in this region, especially submarine landslides, can cause serious damage to engineering facilities. However, there have been few studies on the stability of the northern continental slope of the South China Sea; these studies mainly focused on a specific submarine slope or small-range evaluation, resulting in a lack of large-scale and quantitative understanding. Hence, considering the variation in the physical and mechanical properties of marine soils with depth, formulas for calculating the safety factor of submarine slopes by an infinite sliding model are established, and the factors affecting slope stability such as soil properties, slope gradient and horizontal seismic action are systematically investigated. Using GIS techniques, the terrain slope gradients and a historical seismic database of the northern South China Sea are obtained. Combined with soil mechanical parameters, a regional stability evaluation of the northern continental slope is carried out. Furthermore, the distribution of risk zones is given. On the whole, under strong seismic action, large-scale submarine slope instability occurs and must be highly considered when assessing risk. This achievement is of great significance to engineering sites, route selection and engineering risk assessment.     

Dynamic Risk Analysis of Permanent Deformation of Sea Embankment

For evaluation of the permanent deformation of a sea embankment under stochastic earthquake excitation, a robust dynamic risk analytical method is presented based on conventional permanent deformation analysis and stochastic seismic response analysis. This method can predict not only the mean value of maximum permanent deformation but also the reliability corresponding to different deformation control standards. The earthquake motion is modelled as a stationary Gaussian filtered white noise random process. The predicted average maximum horizontal permanent displacement is in agreement with the conventional result. Further studied are the reliability of permanent deformation due to stochastic wave details at one seismic motion level and the risk of permanent deformation due to stochastic seismic strength, i. e., the maximum acceleration in a long period. Therefore, it is possible to make the optimal design in terms of safety and economy according to the importance of a sea embankment. It is suggested tha     

连云港海底航道安全海洋环境综合评价

海底航道安全与海洋环境相关,随着海洋调查观测技术的进步,航道观测信息增多,有些信息往往难以定量,如何利用这些资料评估海底航道安全日益重要。本研究在综合分析连云港海底航道安全海洋环境主要影响因素的基础上,基于航道地形环境、航道地质环境、海洋动力环境、极端事件对航道安全的影响程度,建立了连云港海底航道安全海洋环境模糊综合评价模型,运用模糊综合评价法对航道安全海洋环境进行了定量评估,依据评价结果,连云港海底航道安全海洋环境定量评价为2.63,等级介于比较安全与一般危险之间,对航道海洋环境立体监测与安全评价体系建设具有实践意义。     

气枪组合震源模拟分析及其应用

在海洋地震勘探中,气枪组合震源得到广泛应用.目前气枪组合震源通常是采用模拟技术,得到震源的远场子波后,通过评价远场子波的参数来评价震源的性能.文章对气枪组合震源性能评价标准进行了简单叙述,对采用震源模拟软件模拟一系列震源进行评价后,优选了3 000 CI,并应用于实际地震勘探中,达到勘探地质目的,取得了良好的资料.     

Stability of seawalls using modified pseudo-dynamic method under earthquake conditions

By using the modified pseudo-dynamic method for submerged soils this paper explores the seismic stability of seawall for the active condition of earth pressure. Different forces such as seismic active earth pressure, seismic inertia forces of the wall, non-breaking wave pressure, hydrostatic and hydrodynamic pressures are considered in the stability analysis. Limit equilibrium has been used, and expressions for the factor of safety against sliding and overturning mode of failure have been proposed. The proposed methodology overcomes the limitations of existing pseudo-dynamic method for submerged soils. A detailed parametric study has been conducted by varying different parameters and results are presented in the form of design charts for computation of factor of safety against sliding and overturning mode of failures. It was noticed that the influences of soil friction angle, seismic acceleration coefficient, wall inclination and excess pore pressure are significant when compared to the other parameters. The value of factor of safety against the sliding mode of failure is increasing by about 62% when the value of soil frictional angle is increased from 30° to 40°. It was also found that the factor of safety against overturning mode of failure is decreasing by about 22% as the value of excess pore pressure ratio increases from 0 to 0.75. The proposed method with closed-form solutions can be used for the seismic design of seawalls.     

浅海回填区域的地震映象效果分析

地震映象法是近期工程物探在工程地质与环境地质勘察中新出现的1种浅层地震探测方法。本文主要介绍该方法的实用方法技术与主要特点及其实际应用效果。并通过奥运工程勘察实例详细分析了该方法在复杂的浅海人工回填区域中不同的填入物与地质体在时间剖面上所展现的各种不同波形特征。     

The application of high-resolution 3D seismic data to model the distribution of mechanical and hydrogeological properties of a potential host rock for the deep storage of radioactive waste in France

In the context of a deep geological repository of high-level radioactive wastes, the French National Radioactive Waste Management Agency (Andra) has conducted an extensive characterization of the Callovo-Oxfordian argillaceous rock and surrounding formations in the Eastern Paris Basin. As part of this project, an accurate 3D seismic derived geological model is needed. The paper shows the procedure used for building the 3D seismic constrained geological model in depth by combining time-to-depth conversion of seismic horizons, consistent seismic velocity model and elastic impedance in time. It also shows how the 3D model is used for mechanical and hydrogeological studies. The 3D seismic field data example illustrates the potential of the proposed depth conversion procedure for estimating density and velocity distributions, which are consistent with the depth conversion of seismic horizons using the Bayesian Kriging method. The geological model shows good agreement with well log data obtained from a reference well, located closest to the 3D seismic survey area.Modeling of the mechanical parameters such as shear modulus, Young modulus, bulk modulus indicates low variability of parameters confirming the homogeneity of the target formation (Callovo-Oxfordian claystone). 3D modeling of a permeability index (Ik-Seis) computed from seismic attributes (instantaneous frequency, envelope, elastic impedance) and validated at the reference well shows promising potential for supporting hydrogeological simulation and decision making related to safety issues.     

处理解释一体化技术在琼东南盆地深水区的实践

琼东南盆地深水区具有巨大的勘探潜力,但该区地震资料大多为二维资料,且中深层资料品质普遍偏差,对评价古近系影响较大。处理解释一体化技术在琼东南盆地深水区的实践采用的方法是：以陵水凹陷为例,通过对该区地震资料的品质进行分类分析,优选出可能改善的测线进行针对目的层的试处理,对试处理结果和效果进行分析,最后进行批处理。处理解释一体化达到了提高地震资料品质,进而精细研究和评价圈闭目标直至井位研究的目的。实践表明该方法在琼东南盆地深水区的应用是成功的,对于研究陵水凹陷的内部结构和规模及其周缘的凸起结构起到了重要作用。