震源及电缆沉放深度对海上地震资料的影响

通过对南海某工区不同采集参数采集的地震数据的分析,就海上拖缆地震勘探中震源及电缆的沉放深度对采集数据质量影响进行讨论,得出如下结果:震源沉放越浅,子波频带变宽,高频效果越好;电缆沉放深度越浅,频带越宽,分辨率越高,但受风浪影响的噪声比较大。这为地震资料采集和后续的地震资料处理提供了良好的依据。     

Lessons from a joint interpretation of vibroseis wide-angle and near-vertical reflection data in the northeastern Yilgarn, Western Australia

A wide-angle reflection seismic experiment was carried out in the Eastern Goldfields granite–greenstone terrane of the Archaean Yilgarn Craton during 2001. This was the first time in Australia that wide-angle data were collected using a vibrator source and with a high density of observations. Unlike other wide-angle surveys carried out in other parts of the world, our survey used both a smaller number of sweeps, and shorter sweeps. We recorded three sweeps (each with its own frequency range) at each vibration point. The experiment demonstrated that the sum of three 12 s sweeps using 3 large vibrators provides enough energy to record signal at offsets up to up to 60–70 km. A comparison of individual shot gathers from near-vertical data and receiver gathers from wide-angle data demonstrated higher reflectivity in near-vertical data. This may be due to differences in the frequency bands of the recording equipment. The after stack section obtained from dense wide-angle data is different from that obtained from conventional near-vertical reflection data. The conventional reflection section provides higher quality image of the crust compared to the wide-angle section. This could be explained by the low-fold in wide-angle data and differences in the acquisition and processing methodology. The wide-angle survey, which was coincident with a regional vibroseis seismic reflection transect, was focused on the Leonora–Laverton region. The survey was designed to supplement the deep seismic reflection studies with velocity information. This also created an opportunity to compare velocity model derived from wide-angle reflection seismic data with a structural image obtained from the deep common mid-point seismic reflection data, and thus refine our geological understanding of the area. A high velocity body reaching a maximum thickness of 2 km was identified exclusively from the seismic velocity model derived from wide-angle study. This body is interpreted as mafic rocks within the Archaean Granite–Greenstone Belt. The joint interpretation also shows that structural boundaries do not always follow lithological boundaries in our study area. The combination of wide-angle reflection and near-vertical reflection data has facilitated a more complete geological interpretation of the seismic data.     

羌塘盆地石油地震反射新剖面及基底构造浅析

针对羌塘盆地地表地质条件复杂,地震资料信噪比低,取得高质量的地震剖面存在很大困难等问题,中国地质调查局在羌塘布设了总长约52km的试验剖面,初步摸索出一套适用于羌塘地区地震资料采集与处理的方法技术。处理后的地震叠加剖面上反射信息丰富,揭示出盆地基底以上各构造层的空间展布特征,为查明构造圈闭和构造界面,确定地层的组合等方面,提供了高质量数据。文中在对地震反射特征分析的基础上对两条剖面显示的盆地基底的埋深、形态等方面进行了初步研究。     

高分辨率地震野外参数的选取

野外地震资料采集的质量直接关系到地震勘探的成败。保证野外资料采集质量的关键是采集参数的选择。参数选择得当,就能有效地拓宽有效波频带范围,提高有效波的主频。以松辽盆地北部太平屯—宋芳屯高分辨率地震勘探区块的实际地质参数及相应的地震资料为基础,结合前人的工作经验,从地震波运动学的角度,确定了该地区高分辨率地震资料采集的参数,并分析了它对分辨率的影响程度。     

2.5D seismic velocity modelling in the south-eastern Romanian Carpathians Orogen and its foreland

The DACIA-PLAN (Danube and Carpathian Integrated Action on Processes in the Lithosphere and Neotectonics) deep seismic reflection survey was performed in August–September 2001, with the objective of obtaining new information on the deep structure of the external Carpathians nappe system and the architecture of the Tertiary/Quaternary basins developed within and adjacent to the Vrancea zone, including the rapidly subsiding Focsani Basin. The DACIA-PLAN profile is about 140 km long, having a roughly WNW–ESE direction, from near the southeast Transylvanian Basin, across the mountainous south-eastern Carpathians and their foreland to near the Danube River. A high resolution 2.5D velocity model of the upper crust along the seismic profile has been determined from a tomographic inversion of the DACIA-PLAN first arrival data. The results show that the data fairly accurately resolve the transition from sediment to crystalline basement beneath the Focsani Basin, where industry seismic data are available for correlation, at depths up to about 10 km. Beneath the external Carpathians nappes, apparent basement (material with velocities above 5.8 km/s) lies at depths as shallow as 3–4 km, which is less than previously surmised on the basis of geological observations. The first arrival travel-time data suggest that there is significant lateral structural heterogeneity on the apparent basement surface in this area, suggesting that the high velocity material may be involved in Carpathian thrusting.     

基于渤中A区块气云区目标体的采集参数优化设计

在气云区由于地震波能量被吸收造成地震资料品质极差,受影响地震剖面会出现弱振幅、弱连续性特征和杂乱反射的模糊带,严重影响构造的落实以及进一步的钻探评价。目标采集设计技术是以地质目的为导向,对目标体在地震和地质充分分析的基础上进行论证的综合方法,包括基于地球物理模型的观测系统参数分析设计技术和基于地下模型的正演模拟照明技术。这里以渤海A区块气云区为实例,通过目标体采集优化设计,得到的地震资料信噪比高、波组特征丰富、成像清晰,地震资料品质大幅提升。应用效果分析表明,目标采集技术可以较好地解决复杂气云区的成像问题。     

南海南部深水区低品质地震资料处理关键技术

中国南海南部深水区勘探前景广阔,但地震资料极其稀少且品质低。针对中国南海南部深水某区块原始地震资料采集于20世纪70年代、无导航文本、海底记录时间不确定、缺道严重及电缆短的品质限制,造成该区仅有的纸质成果剖面上多次波严重、信噪比低、地层构造形态模糊问题,探索出一套适合于工区地震资料处理的关键技术:采用导航重构技术解决无导航文本问题;采用自相关海底拾取技术解决海底记录不确定问题;采用限频F-K域插值技术解决缺道问题;采用组合法压制多次波技术解决因电缆短多次波难压制问题。最后处理效果表明关键技术的应用使该区地震资料处理取得了预期效果。这些技术成果不仅为我国南海南部深水的油气勘探提供较可靠的地震资料,同时为类似低品质地震资料的处理提供了可借鉴的思路和技术。     

海洋深部地震勘探技术

从国内外海洋油气资源的勘探开发来看 ,海洋 (中 )深部地震勘探技术是海洋探测和油气勘探的一种支柱技术 ,也是获取海洋环境、资源、能源、权益信息的重要技术手段。由于海洋地质构造的复杂性 ,海洋 (中 )深部地震勘探技术具有其自身的特殊性 ,主要表现在数据采集和数据处理两个方面。文中阐述了海上中深层单分量地震勘探数据采集和处理方面的若干关键技术。数据采集包含 :震源特性、电缆质量、高分辨率大动态范围的 2 4位数字地震仪、合理的观测系统、设计参数选择和仪器接收记录因素的选择。数据处理中有 :静校正、吸收补偿、压制多次波等干扰、多次折射波的消除和偏移等。文中列举的若干重点技术 ,特别是在采集处理方面的相关问题也是国际上研究的重点和难点。发展海上中深部地震勘探技术 ,可以提高我国海上油气资源勘探和地质调查的整体水平 ,增加国际上的竞争实力     

Hazardous geology zoning and influence factors in the near-shore shallow strata and seabed surface of the modern Yellow River Delta,China

In this study, on the basis of 3,200 km shallow stratigraphic section and side-scan sonar data of the coastal area of the Yellow River Delta, we delineated and interpreted a total of seven types of typical hazardous geologies, including the hazardous geology in the shallow strata (buried ancient channel and strata disturbance) and hazardous geology in the seabed surface strata (pit, erosive residual body, sand patch, sand wave and scour channel). We selected eight parameters representing the development scale of the hazardous geology as the zoning indexes, including the number of hazardous geology types, pit depth, height of erosive residual body, length of scour channel, area of sand patch, length of sand wave, width of the buried ancient channel and depth of strata disturbance, and implemented the grid processing of the research area to calculate the arithmetic sum of the zoning indexes of each unit grid one by one. We then adopted the clustering analysis method to divide the near-shore waters of the Yellow River Delta into five hazardous geology areas, namely the serious erosion disaster area controlled by Diaokou lobe waves, hazardous geology area of multi-disasters under the combined action of the Shenxiangou lobe river wave flow, accumulation type hazardous geology area controlled by the current estuary river, hazardous geology area of single disaster in the deep water area and potential hazardous geology area of the Chengdao Oilfield. All four of the main factors affecting the development of hazardous geology, namely the diffusion and movement of sediment flux of the Yellow River water entering the sea, seabed stability, bottom sediment type and distribution, as well as the marine hydrodynamic characteristics, show significant regional differentiation characteristics and laws. These characteristics and laws are consistent with the above-mentioned zoning results, in which the distribution, scale and genetic mechanism of hazardous geology are considered comprehensively. This indicates that the hazardous geology zoning based on the cluster analysis is a new attempt in research regarding the hazardous geology zoning of the near-shore waters of the modern Yellow River Delta and that this type of zoning has a high level of reasonability.     

Lower lithospheric structure beneath the Trans-European Suture Zone from POLONAISE''97 seismic profiles

The large-scale POLONAISE'97 seismic experiment investigated the velocity structure of the lithosphere in the Trans-European Suture Zone (TESZ) region between the Precambrian East European Craton (EEC) and Palaeozoic Platform (PP). In the area of the Polish Basin, the P-wave velocity is very low (Vp <6.1 km/s) down to depths of 15–20 km, and the consolidated basement (Vp5.7–5.8 km/s) is 5–12 km deep. The thickness of the crust is 30 km beneath the Palaeozoic Platform, 40–45 km beneath the TESZ, and 40–50 km beneath the EEC. The compressional wave velocity of the sub-Moho mantle is >8.25 km/s in the Palaeozoic Platform and 8.1 km/s in the Precambrian Platform. Good quality record sections were obtained to the longest offsets of about 600 km from the shot points, with clear first arrivals and later phases of waves reflected/refracted in the lower lithosphere. Two-dimensional interpretation of the reversed system of travel times constrains a series of reflectors in the depth range of 50–90 km. A seismic reflector appears as a general feature at around 10 km depth below Moho in the area, independent of the actual depth to the Moho and sub-Moho seismic velocity. “Ringing reflections” are explained by relatively small-scale heterogeneities beneath the depth interval from 90 to 110 km. Qualitative interpretation of the observed wave field shows a differentiation of the reflectivity in the lower lithosphere. The seismic reflectivity of the uppermost mantle is stronger beneath the Palaeozoic Platform and TESZ than the East European Platform. The deepest interpreted seismic reflector with zone of high reflectivity may mark a change in upper mantle structure from an upper zone characterised by seismic scatterers of small vertical dimension to a lower zone with vertically larger seismic scatterers, possible caused by inclusions of partial melt.     

松辽盆地北部三分量地震勘探方法及效果

松辽盆地北部三分量地震勘探的主要任务是检测天然气的分布范围,预测岩性油气藏。三分量地震勘探的最大难点是采集上压制随机干扰,处理上去除转换波剖面上同相轴的人为的直立错断（由于通常处理软件不佳引起）。着重介绍了三分量地震勘探的采集原理和处理方法。本次试验取得了良好的三分量剖面。     

江陵凹陷北部高速玄武岩下二维广角地震初探

江汉油田江陵凹陷北部高速玄武岩发育,利用常规地震资料很难得到高速玄武岩下的地震反射。分析研究表明,广角地震有利于玄武岩下的地震成像。通过综合正演和实际地震数据完成了广角地震资料的处理,获得了江陵凹陷北部高速玄武岩下的反射地震信息。在开展广角地震波场的识别和利用研究过程中,从正演模型出发,探讨了在不同地质条件下高速层对地震波场的影响,并针对靶区资料讨论了如何识别广角地震信息。在上述基础上,通过对实际地震资料做精细的分析和处理,最终完成了高速玄武岩下地震资料的成像。     

3D structure of the Earth's crust beneath the northern part of the Bohemian Massif

The SUDETES 2003 wide-angle refraction/reflection experiment covered the area of the south-western Poland and the northern Bohemian Massif. The good quality data that were gathered combined with the data from previous experiments (POLONAISE'97, CELEBRATION 2000) allowed us to prepare a 3D seismic model of the crust and uppermost mantle for this area. We inverted travel times of both refracted and reflected P waves using the JIVE3D package. This allowed us to obtain a model of P-wave velocity distribution as well as the shape of major boundaries in the crust. We also present a detailed uncertainty analysis for both the boundary depths and the velocity field. In doing the uncertainty analysis we found an interesting, strong dependence between uncertainty and inversion scheme (order of used phases). We also compared the model with surface geology and found good correlation between velocity inhomogeneities in the uppermost crust (down to 2 km) and major geological units. The higher velocity lower crust (6.9–7.2 km/s) could result from remelting of the lower crust or magmatic underplating.     

湖区三维地震勘探应用与效果

微山湖某采区面积约4.07km2,区内长年积水,个别区域水深达5～6m,地震勘探施工条件复杂。针对该区资料采集的技术难点,其深水区使用专用检波器,并系重物固定到位;激发井位10～12m,采用船载人工钻成孔;观测系统为8线8炮36道中间激发,24次覆盖。资料处理采用折射静校正及分频处理等方法,其资料处理效果满足地质解释的要求。通过属性识别及相干分析等技术手段本区共解释断层49条,陷落柱2个,目前已验证断层2条,两者高度吻合。     

南方复杂山地碳酸盐岩出露区地震采集技术分析

在受山地和碳酸盐岩裸露双重复杂条件影响的南方地区开展地震勘探工作,采集的地震数据质量很难达到理想效果。基于对南方复杂地形山区的地震地质特征及勘探技术难点深入分析的基础上,对地震数据采集技术与方法进行了一系列的技术攻关和对比分析：(1)综合应用多种表层调查技术进行精细表层结构调查,建立相对准确的近地表结构模型和速度模型,求准静校正量,指导井位优选和井深设计。(2)采用动态观测系统,高陡构造成像方面采用长排列大炮检距,灰岩区采用加密炮观测系统,溶洞裂隙发育地区采用宽线观测系统;(3)针对复杂多变出露多地层岩性,改善激发接收条件,根据岩性变化优选炮点点位,尽量避开溶洞和厚层纯灰岩区。灰岩区采用双深井组合激发,每道至少要两串以上检波器面积大组合接收,检波器井下接收比地面接收效果好。采用以上技术方法,对采集的地震资料进行处理和分析,地震剖面和单炮记录品质有所改善,地震反射波能量及信噪比均有所提高。     

A Geotransect in the Central Indian Shield,across the Narmada-Son Lineament and the Central Indian Suture

This paper reports on a geotransect in the central Indian shield along a 100 km wide NW-SE corridor between Hirapur and Rajnandgaon. This corridor has been selected based on two seismic profiles—a 235 km long seismic-refraction/wide-angle-reflection profile between Hirapur and Mandla and a 130 km long coincident deep-reflection/refraction profile between Seoni and Kalimati. Since the geologic, gravity, magnetic, and heat-flow data are available up to Rajnandgaon, the second part of the corridor has been extended by another 80 km in the absence of seismic data. From northwest to southeast, the transect corridor covers different tectonic units of the Late Archean to Mesoproterozoic Bundelkhand craton, the Paleoproterozoic to Mesoproterozoic Satpura mobile belt, the Middle Archean to Mesoproterozoic Kotri-Dongargarh mobile belt, and the Neoproterozoic Bastar craton.

The seismic results in the Bundelkhand craton show lower crustal velocity values at a very shallow depth; these data have now been interpreted as a lower-crustal intrusive body that is present throughout the Bundelkhand craton in the lower crust at depths of 23 to 25 km. Combined interpretation of seismic travel times with the gravity data indicate the presence of a local magmatic body at mid-crustal depth in the Satpura mobile belt. The crust-mantle boundary is at depths varying between 40 and 44 km.

The seismic-reflection data set identifies the presence of a suture at the Satpura mobile belt/ Kotri-Dongargarh mobile belt boundary. A well-defined Moho offset and a pattern of adjacent fabrics, each characterized by dips toward each other, mark tectonically imbricated crust on opposite sides of the suture.     

四扣地区高精度目标地震采集技术研究

在四扣地区，由于地下地质构造非常复杂，老观测系统炮检距分布不均，方位角较窄，覆盖次数较低，使义东大断裂系统及潜山构造的资料信噪比较低，无法进行精细的构造解释和油藏描述。为了得到该目标区域的资料，作者在文中提供了一种解决思路，即针对复杂地质构造进行精细的目标地震采集设计，并在野外实际生产中运用了一系列的高精度采集技术手段和措施，使目标区域内的资料整体水平比以往有了较大幅度的提高，最终可获得用于精细构造解释的地震剖面。从本次采集在该地区成功应用的实例表明，目标地震采集技术对于解决复杂地质构造区域资料较差的问题是一种很好的方法，对以后类似工区的采集具有参考价值。     

海洋区域地质调查中的高分辨率单道地震资料关键处理技术

在海洋区域地质调查中,为了揭示浅地层结构、断裂、岩浆活动以及各种潜在地质灾害,高分辨率单道地震勘探是不可缺少的重要手段之一,但由于受到各种噪声干扰,原始地震资料质量不佳,信噪比较低,影响了后续的解释工作。笔者阐述了采用关键单道地震处理技术,极大地提高了资料的信噪比和分辨率,为海域区域地质研究提供了良好的基础资料。     

Gold and Silver Prospection Using Magnetic,Radiometry and Microgravity Methods in the Kışladağ Province of Western Turkey

The study area lies in the K??lada? province of western Turkey. The site has an approximate dimension of 1.5 to 2 km north‐south length and 3 km east‐west width. Combined methods from the fields of geology, geochemistry and geophysics were applied to elucidate the regional geologic framework and identify favorable environs for mineralization. There are a few volcanic hills in the center of the K??lada? caldera, which is actually a field of interest. Magnetics (M), Magnetic Total Field Gradient (Mg), Radiometry (Ra), Microgravity (MG) and Microgravity Gradient (MGG) methods were used to prospect the terrains and boundaries of gold and silver deposition in the area. The observed mineralized zones are characterized by low magnetization, low radiation, and high density contrast. Such zones appear to exist outside and beneath a magnetized cap rock. The locations of proposed drill holes were determined with varying depths. Following completion of geophysical and geochemical exploration, an open cut mine with a yearly production rate of about 5 to 6 tons of gold minerals at depths varying between 50 to 225 m has been operational.     

高精度层序地层学和储层预测

当前层序地层学的研究不断从盆地规模的层序地层和体系域分析向储层规模的高精度层序地层学的方向深化。层序地层学的概念和方法可应用于从盆地到储层的各种规模的沉积充填分析。高精度层序地层学是以露头、岩芯、测井和高分辨地震等密集控制的资料分析为基础的。精细的测井分析、高分辨三维地震剖面和各种参数处理和切片技术、计算机模拟及可视化技术等是开展高精度层序地层学研究和应用于地下沉积地质分析的重要支持。高精度层序地层学的概念和方法为盆地沉积充填的精细研究、储集体分布和储层不均一性预测以及开发地质等研究提供了重要的方法和手段