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The applications of electromagnetics have increased in the past two decades because of an improved understanding of the methods, improved service availability, and the increased focus of exploration in the more complex reservoir characterization issues. For electromagnetic methods surface applications for hydrocarbon Exploration and Production are still a special case, while applications in borehole and airborne research and for engineering and environmental objectives are routine. In the past, electromagnetic techniques, in particular deep transient electromagnetics, made up a completely different discipline in geophysics, although many of the principles are similar to the seismic one. With an understanding of the specific problems related to data processing initially and then acquisition, the inclusion of principles learned from seismics happened almost naturally. Initially, the data processing was very similar to seismic full-waveform processing. The hardware was also changed to include multichannel acquisition systems, and the field procedures became very similar to seismic surveying. As a consequence, the integration and synergism of the interpretation process is becoming almost automatic. The long-offset transient electromagnetic (LOTEM) technique will be summarized from the viewpoint of its similarity to seismics. The complete concept of the method will also be reviewed. An interpretation case history that integrates seismic and LOTEM from a hydrocarbon area in China clearly demonstrates the limitations and benefits of the method. 相似文献
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Exploration in the basalt covered areas of the Faroes offshore has always suffered from poor seismic imaging below the basalt. Long offset 2D and 3D seismic data were acquired and a significant improvement in the seismic image below top basalt has been achieved. Deep towing of the source and receiver cables helped by extending the seismic bandwidth towards lower frequencies. Bubble‐tuned rather than conventional peak‐tuned source arrays gave little, if any, incremental benefit. The improvement in the imaging comes primarily from the approach to processing the data. High frequencies (dominantly noise) are filtered out of the data early in the processing to concentrate on the low frequency data. Careful multiple removal is important with several passes of demultiple being applied to the data using both Surface‐Related Multiple Elimination (SRME) and Radon techniques. Velocity analysis is performed as an iterative process taking into account the geological model. Reprocessing legacy 2D surveys, acquired with wide‐ranging parameters, using these processing techniques improved these datasets significantly, indicating that sub‐basalt imaging seems to be more sensitive to processing than to the choice of acquisition parameters. 相似文献
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在复杂的山区煤田三维地震勘探中,受地形和地表、地质条件的限制,使野外地震数据采集技术成为关健。文中结合在新安煤田三维地震勘探过程中遇到的复杂条件(地形极其复杂,相对高差大、潜水面变化不定、地表岩性横向变化大等),通过野外的试验对比,选择良好的地震激发和接收条件,应用非线性观测系统理论等多项技术措施,以保证野外地震记录的质量,从而更好地为下一步的地震数据处理与解释服务。研究结果表明:本勘探区内三维地震数据采集中,所采用的技术方法得当,效果明显,而且对具有相似地表、地质条件的地区具有借鉴作用 相似文献
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在山区地震勘探中,由于复杂多变的岩性及地表的剧烈起伏影响地震成像的品质,本文以裴沟矿井31采区为例,首先在数据采集阶段针对不同地表条件采用不同设备成孔,保证原始数据质量;其次在资料处理阶段通过＂两步＂静校正方法解决山区高程及岩性变化引起的成像问题,获得高质量的处理成果。经过矿井生产的初步验证可知,所采用的技术手段正确,所取得的地质成果精度较高。 相似文献
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矿产资源勘探尤其是金属矿勘探具有地质条件复杂、勘探深度大、分辨率要求高等特点.常规地震勘探技术与装备难以满足复杂地形高精度三维地震勘探需求.针对该技术难题,研发一套高保真、高分辨率轻便分布式混合遥测地震勘探系统迫在眉睫.鉴于此本文开发了信号高保真高分辨率数据采集技术、实时通讯及采集单元无址链接技术和多媒介混合遥测技术等一系列关键技术.成功研制出SE863单站单道分布式混合遥测地震数据采集系统,该系统由31位高分辨率采集单元链、集3 G/4 G无线通讯及有线通讯的交叉数据管理站、便携式主控站以及测控软件组成.支持二维、三维高密度地震反射波勘探、散射成像、天然源透射成像等地震数据采集工作.利用该套系统与428XL地震数据采集系统进行同步对比,并将该系统交付第三方使用完成了1 km2三维地震勘探实验,结果表明该系统设备轻便、性能稳定、分辨率高、数据质量好,是我国具有完全自主知识产权的高精度轻便分布式地震勘探技术装备,大大增强了我国地震勘探技术核心竞争力. 相似文献
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The complexity feature of crust-mantle boundary in Zhangbei seismic region and its tectonic implication 总被引：1，自引：0，他引：1
The ProP waveform data obtained from a deep seismic sounding profile, which ran through Zhangbei seismic region, were processed by means of both seismic wave complexity coefficient and frequency spectrum analysis methods, and the complexity characteristics of crest-mantle boundary beneath the studied area and its adjacent region were determined. The results show that the place below epicenter can be taken as boundary, the northern side of which is Inner Mongolia axis with small complexity coefficient and the southern side of which is Huai＇an basin with large complexity coefficient. The different spectrum patterns at the two sides of the epicenter were inferred from spectrum analysis. In the epicentral area, there have been multi-period magmatic eruptions since Meso-Cenozoic and craters exist at the surface. From the velocity imaging of middle and upper crust in Zhangbei seismic region it can be found that there are crustal low velocity bodies around the craters and also there are low velocity zones, which went into deep crust. It is suggested that the distinct zones of crust-mantle boundary complexity may be the margin, where the magma had intruded due to magma activity in Meso-Cenozoic. The southern side with large complexity coefficient is deep magmatic activity area and the northern side with small complexity coefficient is stable crust-mantle tectonics. The difference of crust-mantle complexity provides deep background for the development of strong earthquake. 相似文献
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三维复杂山地条件下的各种地震波型的走时计算技术,可以直接用于复杂山地区域地震波运动学特性的分析、地震数据采集观测系统的设计以及直接基于三维复杂地表的地震数据处理技术的研发.为了在三维复杂地表条件下准确、灵活且稳定地计算各种地震波型的走时,提出一种多级次群推进迎风混合法.该算法利用不等距迎风差分法简洁稳定地处理三维复杂地表及附近的局部走时计算问题,利用计算精度不错的迎风双线性插值法处理绝大部分均匀正方体网格中的局部走时计算问题,利用群推进法模拟三维复杂地表条件下地震波前的扩展问题,利用多级次算法处理各种类型的地震波的走时计算问题.算法分析和计算实例表明:新方法具有很好的计算精度与效率,且能灵活稳定地处理三维复杂地表复杂介质条件下的多波型走时计算问题. 相似文献
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胜利油田滩浅海地区由于特殊的地表条件和复杂多变的表层结构，既不同于陆上勘探也不同于海上勘探，尤其在两栖地带存在海陆两种施工方式，如何在地震波激发和接收方面采取措施确保资料一致性，及优化观测系统设计以拼接好过渡带的地震资料是施工任务的关键.为此，依托中石化地震勘探重点基础研究实验室，在地震波的激发、接收和观测系统优化设计方面作了大量研究试验工作，形成了一套适用于滩浅海地区的地震勘探技术.通过冀东和垦东等地区应用联合表层调查和检波器精确定位等技术，有效地提高了地震资料的信噪比，改进了成像精度，取得了很好的地震勘探效果. 相似文献
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Tatiana Pertuz Alireza Malehmir Jordan Bos Bojan Brodic Yinshuai Ding Richard de Kunder Paul Marsden 《Geophysical Prospecting》2022,70(1):79-94
A prototype electromagnetic vibrator, referred to here as E-Vib, was upgraded and developed for broadband hardrock and mineral exploration seismic surveys. We selected the iron oxide mine in Blötberget, central Sweden, for a test site in 2019 for the newly developed E-Vib because of the availability of earlier seismic datasets (from 2015 to 2016) for verification of its performance for hardrock imaging purposes. The two-dimensional data acquisition consisted of a fixed geometry with 550 receiver locations spaced at every 5 m, employing both cabled and wireless seismic recorders, along an approximately 2.7 km long profile. The E-Vib operated at every second receiver station (i.e. 10 m spacing) with a linear sweep of 2–180 Hz and with a peak force of 7 kN. The processing workflow took advantage of the broadband signal generated by the E-Vib in this challenging hardrock environment with varying ground conditions. The processed seismic section shows a set of reflections associated with the known iron oxide mineralization and a major crosscutting reflection interpreted to be from a fault system likely to be crosscutting the mineralization. The broadband source data acquisition and subsequent processing helped to improve signal quality and resolution in comparison with the earlier workflows and data where a drophammer seismic source was used as the seismic source. These results suggest new possibilities for the E-Vib source for improved targeting in hardrock geological settings. 相似文献
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在城市浅层地震勘探数据采集中,地震测线经常会遇到河流、桥、交叉路口等地表障碍。为了尽量减小地表障碍造成的影响,需要对观测系统作变观设计。作者分析总结了城市浅层地震勘探中常见障碍以及过障碍变观模式,并开发了浅层地震过障碍变观设计软件,利用此软件可在采集现场快捷地进行过障碍变观。将这种方法应用于实际工作中,有效减小了资料缺失造成的影响,提高了资料的信噪比。该软件能够根据实际工作环境和设备条件在野外现场对观测系统进行灵活变观,设计出合理的过障碍观测系统,有效地提高了变观设计的效率。 相似文献
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Dhananjai Pandey Satish Singh Martin Sinha Lucy MacGregor 《应用地球物理》2007,4(3):183-193
Hydrocarbon exploration interests have renewed the need for developing new sub basalt imaging techniques. One of the most important problems encountered today is seismic imaging below basalt. In recent years, this problem appears to have been overcome partly by using long offset seismic data. However near offset data are yet to be fully utilised due to the complex waveform caused by the surface as well as internal heterogeneity of the basalts. The near normal incidence data, which influence the sub-basalt imaging, are highly useful to understand the internal structure within a basalt layer. The use of converted waves for such targets has been proposed as an alternative in a rather homogeneous basalt layer. With a few synthetic modelling exercises here we highlight the practical difficulties in dealing with more realistic and heterogeneous basalt flow. Full waveform seismograms are computed to understand the effects of intra-trappean sediments on the seismic data. A case study from the Deccan Traps of India is presented in this paper. First, we discuss the effects of intercalated sediments on the overall seismic image. Later, the sonic log data from the field are used to compute the full wave-field response using the reflectivity method and compared with the field data. The feasibility of using mode converted waves （P to S and vice-versa at the top and bottom basalt interfaces） for sub-basalt imaging in Kutch region is discussed through a series of velocity-depth profiles. By comparing with the field data we demonstrate that the effects of multiple thin layering within the basalt can strongly deteriorate the image we seek to interpret and exploit. 相似文献
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《Journal of Applied Geophysics》2006,58(2):87-98
A geophysical campaign to characterize the subsurface of a contaminated site down to a depth of several tens of meters was carried out under the HYGEIA-CEE project. On this site, seismic techniques were combined to image the geological structures; i.e. seismic reflection, P-wave tomography and spectral analysis of surface waves. Because these techniques consider different wave components in the processing, they can be expected to provide complementary information concerning the site lithology. The special feature of this experiment is the fact that the same seismic acquisition device, consisting of a mobile central unit, a drop-weight seismic source, and a sensor line of gimbal mounted geophones, was used for each of the techniques. Two perpendicular seismic lines were set up in the field for testing two geophone spacings. Three processing procedures, one each for the seismic reflection, P-wave tomography and spectral analysis of surface waves, were developed for producing seismic images from the P-wave reflectivity, the first P-wave arrivals and the dispersion of Rayleigh waves, respectively. The images show good complementarity in terms of investigation depth. The results are also in good agreement with available borehole data: the sandy layers seem to be related to low velocities, since the high velocities are better explained by the presence of clayey and gravelly intervals. The contribution and the limits of this seismic multi-approach method is discussed. 相似文献
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深反射地震是了解深部地质结构的主要手段,获取高品质的数据是给出合理地质解释的基础.在结晶岩地区,由于地层成层性差、非均质性严重,地震散射效应明显,导致地震波场复杂,同时结晶岩为非理想弹性体,不利于地震波能量转换,有效反射能量弱,信噪比低.加之深反射地震的目标层较深且受环境噪声干扰严重,高频信号衰减快,地震资料主频较低.这些因素使得在结晶岩区难以获得高品质的地震资料,为探索提高该类地区深反射地震资料质量的方法和技术,本文依托长江中下游成矿带2009—2014年深反射地震数据采集工作,在精细设计、严格施工的基础上,从激发和接收入手,开展了"轴向不耦合激发"、"宽频接收"和"宽线观测"等技术方法试验研究.结果表明,这些方法技术措施提高了下传弹性波能量,展宽了接收地震信号的频带,提高了覆盖次数和信噪比,有效改善了地震原始资料的品质和成像效果.研究结果对今后结晶岩地区深地震反射数据采集工作具有重要的实用价值和参考意义. 相似文献
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近年来发展的新型地震观测系统--分布式光纤声波传感器(DAS,Distributed Acoustic Sensing)可以实现低成本高密度观测,有望提高浅层结构成像的精度以及分辨率.最近国内研发了一系列具有自主知识产权的DAS设备,为验证国产设备在浅层结构研究中的可行性以及应用效果,2018年7月我们开展了一次DAS观测实验.实验采集了50kg落锤震源激发的地震信号,并采用多道面波分析方法提取了8~20Hz频段的主动源Rayleigh波相速度频散曲线,得到了实验区浅层30m的S波速度结构.获得的主动源面波频散曲线与共址检波器的结果吻合,也与背景噪声提取的结果具有较好的一致性,表明国产设备的可靠性和DAS在浅层结构主动源面波成像研究中的可行性. 相似文献
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Seismic reflection data were acquired across volcanic hosted massive sulfides (VHMS) of Vihanti in order to improve the understanding of the regional geological setting. Commercially processed seismic data from Vihanti are of good quality, but reprocessing can be used to extract additional information about geological structures. Especially, careful velocity analysis influences the quality of seismic images. Differentiating reflections caused by fractures from those caused by lithological contacts is very important for exploration and geological modeling. Reflections from fracture zones known from drilling stack with lower velocity (~ 5100 m/s) compared to typical stacking velocities of the Vihanti area (> 5500 m/s). The reprocessing also indicated that fracture zones are better imaged with low frequencies due to the better overall continuity of the fault zones at scales of hundreds of meters rather than at shorter seismic wavelengths.In full stacks, long offset data can mask structure close to the surface. More detailed seismic images of the shallow subsurface emerged by preferentially stacking short offset data wherever acquisition and processing lines lay close together and were nearly straight. Long offset data remains valuable for imaging deeper structures as well as dipping reflectors. Cross-dip-analysis revealed a bright diffractor located near the base of the Vihanti volcanic basin at 1.5 km depth. The seismic data allow a geological interpretation in which the Vihanti structure has developed through significant thrust faulting and displacement of the lithological contacts. Gentle folds that were formed prior to faulting are visible as undulating reflectivity in seismic sections. The reprocessed seismic section indicates a potential deep extension of the ore-hosting altered volcanic and calc-silicate rocks previously unexplored. 相似文献
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我国南方碳酸盐岩广泛分布,具有巨大的油气资源潜力和勘探前景.全国油气资源战略选区调查与评价项目选择我国典型南方海相碳酸盐岩裸露区开展地震勘探技术攻关.针对该区地表灰岩普遍出露、激发弹性波能量转换少、散射噪音干扰严重等勘探难点,研究和应用了“宽线+折线”地震采集技术和与其配套的拟三维地震处理技术,能较好地压制噪音,提高剖面信噪比,在主要目的层得到了较好的成像效果,桂中1井钻探结果与地震勘探解释成果吻合较好,检验了该方法用于南方碳酸盐岩地区勘探的有效性. 相似文献
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We address the problem of increasing the signal-to-noise ratio during surface microseismic monitoring data processing. Interference from different seismic waves causes misleading results of microseismic event locations. Ground-roll suppression is particularly necessary. The standard noise suppression techniques assume regular and dense acquisition geometries. Many pre-processing noise suppression algorithms are designed for special types of noise or interference. To overcome these problems, we propose a novel general-purpose filtration method. The goal of this method is to amplify only the seismic waves that are excited in the selected target area and suppress all other signals. We construct a linear projector onto a frequency domain data subspace, which corresponds to the seismic emission of the target area. The novel filtration method can be considered an extension of the standard frequency–wavenumber flat wave filtration method for non-flat waves and arbitrary irregular receiver-position geometries. To reduce the effect of the uncertainty of the velocity model, we suggest using additional active shot data (typically the perforation shots), which provide static travel time corrections for the target area. The promising prospects of the proposed method are confirmed by synthetic and semi-synthetic data processing. 相似文献