共查询到19条相似文献，搜索用时 93 毫秒
1.
倾斜观测载荷干扰源最小"安静"距离理论分析 总被引：5，自引：0，他引：5
作为一种高精度的形变观测,钻孔倾斜观测点必须尽可能避开干扰源。河流、湖泊、仓库(货场、列车编组站)和铁路,是几种主要的影响钻孔倾斜观测的地面载荷变化干扰源。中对这些地面载荷变化干扰影响分别建立了不同的模型,提出了针对一定的干扰限定指标,估计观测点到干扰源的最小“安静”距离的方法。 相似文献
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探地雷达天线分为两种,一种是屏蔽的,一种是非屏蔽的.屏蔽天线一般不会接收到地面干扰波,但非屏蔽的天线在接收地下反射波的同时也会接收到诸如墙体、汽车、高压线、路灯杆、钻机等产生的地面干扰波.在市区内进行探地雷达探测如何消除这些干扰波就显得非常重要.由于地面干扰波的频率和有效反射波的频率一致,采用频率域滤波方法难以将其消除.研究发现地面干扰波的二维频谱和有效反射波的二维频谱明显分离,可采用二维滤波的方式进行处理.通过人机交互的方式在二维频谱图上用任意截取法滤波可以很好地消除探地雷达地面干扰波.实际应用效果说明这种处理方法比较有效. 相似文献
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地震台站地电场观测会受到各种因素的干扰,必须快速发现并消除干扰源,以保障观测数据的正常输出。2019年5月17日—6月4日,昌黎地震台地电场观测受不明原因干扰,观测数据产生畸变,与已知干扰类型数据特征进行对比分析,发现与常见干扰源所致数据变化形态特征不同;按照干扰数据变化特征,假设干扰源与观测台站的相对位置关系,布设简易的野外观测点,成功定位本次观测干扰源。最终确认,昌黎台地电场干扰由位于台站东南方向的铁件铸造厂变压器电缆漏电所致。此次干扰源排查,可为同类地电台站观测数据干扰分析提供参考。 相似文献
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地震勘探中应用地面爆炸,往往产生严重的声波、地面波和浅层的干扰,而有效波能量的強度常比較微弱。“地形爆炸”就是鉴于以上情况而作出的某些改进。它的基本特点是利用地形特点而使干扰的能量减少到最低的水平,尽量提高有效波能量水平。 相似文献
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《地球物理学进展》2015,(6)
在地震勘探中,鄂尔多斯盆地伊陕斜坡苏里格西地区的第四纪小型河湖沉积盆地会产生一种强干扰波.为了探索该干扰波特征及形成机理,通过对大量的试验资料对比分析,综合研究了该沉积体的沉积规律、岩性特征及干扰波速度特点,频谱特性和时距曲线.结果表明,该干扰波形成机理有如下特点:(1)该干扰波能量强,呈"八字胡"状;(2)该沉积体为第四纪河湖相沉积,岩性、速度成层分布,是形成该干扰波主要原因;(3)该干扰波频谱在0~300 Hz,近道主频在50 Hz,中道主频在65Hz,远道主频在20Hz,第270道高频主瓣在870ms,中低频主瓣在920ms;(4)干扰波时距曲线为双曲线. 相似文献
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2008年11月10日在青海柴达木盆地北缘发生了大柴旦M_W6.3地震,为了研究该地震的区域地震波传播与地面运动特征,本文利用地质资料和地壳速度结构研究成果,构建了柴达木盆地及周边区域三维传播介质模型,采用有限差分方法模拟了大柴旦地震波场传播过程以及地面运动分布特征.结果表明,柴达木盆地对波场传播有明显影响,表现为地震波传入盆地后在边界产生次生面波,盆地沉积物对地震波具有围陷作用,地震地面运动在盆地内振幅增大、持时延长.模拟结果给出的地震地面运动峰值速度分布以及理论地震图均和观测结果符合较好,反映数值模拟较好地给出了观测地面运动的主要特征以及传播介质模型的合理性. 相似文献
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以昌黎何家庄井、卢龙崔庄井的水位观测数据和中层水温观测数据为对象，针对日常观测中记录的场地环境干扰进行基础数据分析，发现昌黎何家庄井主要干扰源为同层水位超采，卢龙崔庄井主要干扰源为桃林口水库放水。通过同井观测的水位与中层水温相关性、水位日变幅在正常与非正常情况下的变化特征，可得不同井孔的变化特征，为今后此类干扰判别提供依据。 相似文献
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针对密山地震台观测数据存在的类似尖脉冲干扰,通过3次对比测试及工频干扰测试获取的数据资料进行分析,确定干扰存在的客观性,初步确定干扰信号的基本分布状态,排除部分干扰源方位. 相似文献
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《地震地质》2016,(4)
在水平层状介质模型下,采用有限元数值计算方法建立三维模型,分析了地电阻率测区中位于地表的金属导线和局部电性异常体对观测产生的干扰形态和幅度随时间的变化特征。分析结果显示:1)低阻干扰源位于影响系数为正的区域时,将引起地电阻率观测值的下降变化,位于影响系数为负的区域时,将引起观测值的上升变化,高阻干扰源对观测的影响与之相反;2)地表干扰源影响的动态特征表现为,在浅层介质电阻率较低时对观测的干扰幅度要大于浅层介质电阻率较高时;3)对于正常年变的测道,低阻干扰源位于影响系数为正的区域时引起年变幅度增大,位于影响系数为负的区域时引起年变幅度减小,高阻干扰源对年变形态的影响与之相反;对于反常年变的测道,干扰源对年变形态的影响则与对正常年变测道的影响相反;4)金属导线对观测的干扰幅度受自身电阻率和横截面积影响:电阻率越低干扰幅度越大;有效横截面积越大干扰幅度越大。 相似文献
11.
RESEARCH ON TIME-DISTANCE INTERPRETATION OF MULTIPLES AND GHOSTS BASED ON MARINE SEISMIC DATA 
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下载免费PDF全文 Currently, the study on the active fault in the land areas is relatively mature, while there is still lack of detection and research on active faults in the sea areas. Marine exploration, which is different from land areas, has a prominent problem due to the existence of strong reflecting interfaces such as water surface and seafloor in the sea, thus the recording is often accompanied by interference of multiples on seafloor reflections. In addition, because of the characteristics of marine seismic exploration, the source exciting in the water and the geophone receiving in the water, ghost wave usually can be recorded simultaneously during the reflected wave propagation. This phenomenon makes it difficult to distinguish the effective waves and the noise, and has always plagued the data and seriously affects the quality of records. In the offshore and other regions of complex structures, such as inclined interfaces, it is difficult to eliminate the interference of multiples accurately by traditional multiples suppression methods, which are based on the horizontal interface assumption. This paper combines the sea area seismic data and its acquisition method, uses simplified model to simulate the multiples based on the time-distance analysis of multiples and their ghost wave in inclined interface. The time-distance characteristics of the multiples and their ghost waves from different interfaces(including the inclined interface)are obtained, and they are consistent with the actual records. The multiples time-distance simulation can help to distinguish the causes of reflected waves, summarize the multiple-wave time-distance characteristics from different interfaces(including inclined interfaces), and analyze the relationship between the characteristics of multiple waves and primary waves. In particular, this simulation has a significant effect on characterizing the internal multiples that are difficult to identify due to inconspicuous periodicity and the multiples of the inclined interface which present the phenomenon that the vertex of the time-distance curve is shifted. On this basis, relying on the time-distance analysis of ghost wave, we analyze the travel time difference characteristics between reflected waves and their accompanying ghost waves. The differences of the travel time characteristics of different orders ghost wave and reflected wave are summarized and the symmetry of the travel time difference between inclined interface and horizontal interface of ghost waves and reflected waves is analyzed. We simulate the distraction of the ghost wave event with the event of the reflected wave and analyze the influence of the ghost wave on the sea area seismic records. These results can improve the practical interpretation of seismic data. At last, the time-distance information is used to synthesize sea area seismic records, which can help us carry out the effective data processing and understand the characteristics of the time-distance and velocity of multiples in different interfaces and the layer artifact caused by multiples. This study combines the time-distance simulation of multiples and their ghost wave with conventional seismic data processing to analyze the pre-stack and post-stack features of multiple waves and their ghost waves in the seismic records of the sea area. The results of this study are conducive to the effective identification of multiples in seismic records in the sea, provide a theoretical basis for multi-wave suppression and prediction, and may facilitate the future study of sea-area seismic activity detection. 相似文献
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本文根据北京台网、大连、长春、牡丹江、海参威等26个台站的记录,选用了从北京地区到阿留申群岛西端的300多个地震,研究了北京-萨哈林剖面的地幔纵向速度分布。 用Herglotz-Wiechert公式计算得出的V-h作为初始模型,计算理论走时曲线,找出了与实际走时曲线符合较好的速度结构。其特点为:上地幔顶部的速度为7.8公里/秒;高速盖层中有正速度梯度;在约60-120公里深度范围内为低速层;130公里以下速度缓慢增大;在370-440公里、600-740公里有两个速度梯度较大的过渡层,其中以370-440公里的正速度梯度最大,与之相应的震中距为19°。在1060公里以下有微弱的正梯度。 用Kaila方法计算了深度为400公里左右的地震震源深度处的速度值,与上述结果一致。 相似文献
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Forward modeling is of critical importance for inversion analysis of surface wave methods to obtain shear-wave velocity (VS) profiles of soil sites. The dynamic stiffness matrix (DSM) method can provide forward modeling of Rayleigh surface waves to simulate complex wave propagation in layered soil sites. However, contamination from body waves and interference of multiple Rayleigh wave modes can reduce the accuracy of theoretical dispersion curves, especially at irregular soil sites with embedded low-velocity or high-velocity layers. An analytical method is developed herein to combine the techniques of the multichannel analysis of surface waves method with the DSM method to improve the accuracy of the theoretical dispersion analysis for soil sites. The proposed method implements multichannel analysis of the analytical displacement responses to capture dominant dispersion trends. Comparison of the results obtained with the new method against those from the transfer matrix method and the literature indicates that the new method can (1) effectively minimize the effects of contamination caused by body waves and interference from several Rayleigh wave modes, and (2) generate accurate dominant dispersion trends for soil sites with various stiffness profiles, especially for the high-frequency dispersion characteristics of the profiles with embedded low-velocity layers. 相似文献
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S. N. DOMENICO 《Geophysical Prospecting》1979,27(3):539-563
Inferior reflection quality in the Gulf of Suez at the target depth interval is attributable in part to surficial multiple reflections. An excellent example of the latter is observed on a typical seismic line in the northern portion of the Gulf. An increase in prominence of the multiple reflections appears associated with decreasing depth to a dipping highvelocity layer. Inversion of a second-order polynomial time-distance function, fitted to the observed refraction onset time-distance values, gives the velocity-depth function for sediments between the water bottom and a high-velocity layer. Velocities thus determined increase non-linearly with depth from a value near water velocity at the water bottom. Depths to the high-velocity layer are obtained from the associated head-wave linear time-distance function and by ray tracing in the overlying sediments. As the high-velocity layer approaches the water bottom from sub-water depths exceeding 0.6 km to a depth of 56 m, intensity of the multiple reflections increases to the extent of completely dominating individual records to a time of at least 3 s. The estimated plane-wave normal-incident reflection coefficient at the top of the high-velocity layer increases with decreasing depth to this layer, approaching 0.5 at the shallowest depth. This strong reflection coefficient further substantiates the existence of multiple reflections between the high-velocity layer and water layer. However, existence of water-layer multiples cannot be ruled out. The estimated water-bottom reflection coefficient is approximately 0.3, a substantial value. Multiple reflections of considerably less intensity are apparent where the high-velocity layer is deepest, and it is likely that such are waterlayer multiple reflections. Unfortunately, water-layer multiple reflections and multiple reflections between the water surface and high-velocity layer cannot be separated by their coincidence with time-distance (normal moveout) curves, the configuration of each visibly matching the curves equally well. 相似文献
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本文利用各向异性反射率技术计算理论地震图，提出海底高速薄层会产生沿高速层水平传播的波（简称径向波），这种波在水层中作为P波，在固液界面激发下行横波，该均匀横波以临界角入射高速薄层，在层内作为超临界角的非均匀横波水平传播，再以临界角转换为上行传播的均匀横波，最终在固液界面上行透射转换为水层中P波.高速薄层传播的径向波不同于界面折射波，也不同于具有频散的面波和通道波.理论地震图的研究表明，径向波具有线性时距，能与海底强反射具有同等振幅水平；径向波有其振幅、时距位置和斜率这些观测记录参数，分别对应高速层的厚度、深度和近似的横波速度；径向波可以克服折射波解释中遇到的振幅强弱和高速层速度等困难.径向波可作为探测海底高速薄层的有力工具，对于研究高速层屏蔽、海底反射类型的多样性和相应的资料处理解释有重要意义. 相似文献
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在城市活断层勘探中,对于面波干扰大、地震反射波法难以开展工作的区域,可尝试利用地震折射波法进行探测,并对折射波法探测的原始记录采用时间项、差异时距曲线和有限差分成像等方法进行综合计算、分析,以探索折射波法在城市活断层勘探中的应用成效。文中针对郑州市须水断层西段浅层地震折射波法勘探记录,利用时间项、差异时距曲线和有限差分成像等计算方法,获取剖面速度结构与界面构造;综合震相特征、计算结果等资料确定主要地层的界面深度和构造特征,3种方法都取得了相近的结论。后又通过在测线上4个钻孔资料的验证,认为3种方法的计算结果与钻孔资料相吻合,说明折射波法勘探在城市活断层探测中的应用是可行的 相似文献
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随着地震勘探向浅海、湖泊等流体覆盖层的渗透，存在液体表层或夹层介质中导波的传播研究受到人们重视.在前人研究工作的基础上，本文对存在上覆液体层时的两层、三层以及低速夹层的固体层状介质模型的频散曲线进行了数值计算，分析了当上覆液体表层的厚度变化时多模式导波频散曲线特征.通过与没有液体表层时的完全固体介质模型相对比，研究了存在上覆液体表层时多模式导波频散曲线独特的形态特征，进一步引伸出在滩浅海进行地震勘探中应注意的问题.为在滩浅海及湖泊等表层为液体覆盖层的地区利用导波进行勘探和研究提供一定的研究思路和理论依据. 相似文献
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在地震资料处理中，速度分析和成像技术极为重要.常规地震资料处理方法是利用双曲线方程来描述反射波时距曲线规律，此方程随着地层非均质性、各向异性和排列长度的增加，其误差变大.目前发展的反射波非双曲时距方程，主要有基于层状各向同性模型的非双曲时距方程、基于均匀弱各向异性模型的时距方程、基于速度随炮检距变化模型的时距方程、基于线性连续速度模型的时距方程.本文针对三个典型的模型：层状均匀各向同性模型、层状弱各向异性模型和层状非均匀模型，对这几种时距方程进行了精度比较与分析，得出了一些有益的结论.最后，从不同角度说明了应用这几种方程的合理性. 相似文献