反正切函数拟合下的地震数据体断裂刻画方法

利用界面的形状或者其不连续性是基于叠后地震数据刻画断裂的两种主要方法,根据实际地震资料的特点,两种方法各有其优劣性.对于同界面形状相关的断裂刻画方法,较常用的为地震曲率属性.受实际断裂模型的制约,在曲率属性的基础上,曲率变化率表现出对断裂更强的相关性及敏感性.本文发展了以反正切函数为准线的柱面拟合法来刻画断裂,主要包括两个步骤,分别为:一、柱面直母线的拟合;二、柱面准线拟合及曲率变化率的求取.实际地震资料计算结果表明,该方法对断裂刻画的精度高于传统方法,能够揭示更多的断裂细节,特别是对于地震剖面上不易识别的小断距断裂,亦能够清晰的刻画,同时具有较高的信噪比.     

Semi-automatic detection of faults in 3D seismic data

The semi‐automated detection of objects has been quite successful in detecting various types of seismic object, such as chimneys. The same technique can be applied successfully to detect faults in 3D seismic data. We show that several different attributes – among others, similarity, frequency and curvature, all of which potentially enhance the visibility of faults – can be combined successfully by an artificial neural network. This results in a fault ‘probability’ cube in which faults are more continuous and noise is suppressed compared with single‐attribute cubes. It is believed that the fault‐cube can be improved further by applying image‐processing techniques to enhance the fault prediction.     

基于地震多属性融合的断层识别与评价——以塔里木盆地SHB地区碳酸盐岩缝洞型储层为例

塔里木盆地SHB地区的深部碳酸盐岩缝洞型储层主要发育于断裂破碎带,大多表现为断裂破碎形成的裂缝和后期溶蚀形成相互连通的断溶体.因此,断层的识别与精细评价成为该区缝洞型储层识别评价的基础.考虑到研究区处于沙漠腹部,深部地层的地震反射能量相对较弱,用单一地震属性难以实现断裂带的识别.本文针对研究区地震资料的地质-地球物理特...     

Semi-automatic fault/fracture interpretation based on seismic geometry analysis

Fault and fracture interpretation is a fundamental but essential tool for subsurface structure mapping and modelling from 3D seismic data. The existing methods for semi-automatic/automatic fault picking are primarily based on seismic discontinuity analysis that evaluates the lateral changes in seismic waveform and/or amplitude, which is limited by its low resolution on subtle faults and fractures without apparent vertical displacements in seismic images. This study presents an innovative workflow for computer-aided fault/fracture interpretation based on seismic geometry analysis. First, the seismic curvature and flexure attributes are estimated for highlighting both the major faults and the subtle fractures in a seismic volume. Then, fault probability is estimated from the curvature and flexure volumes for differentiation between the potential faults and non-faulting features in the geometric attributes. Finally, the seeded fault picking is implemented for interpreting the target faults and fractures guided by the knowledge of interpreters to avoid misinterpretation and artefacts in the presence of faulting complexities as well as coherent seismic noises. Applications to two 3D seismic volumes from the Netherlands North Sea and the offshore New Zealand demonstrate the added values of the proposed method in imaging and picking the subtle faults and fractures that are often overlooked in the conventional seismic discontinuity analysis and the following fault-interpretation procedures.     

南天山及塔里木北缘构造带西段地震构造研究

南天山及塔里木北缘构造带位于帕米尔地区东北侧,地震活动强烈。文中通过地质构造剖面、深部探测资料和地震震源机制解资料,综合研究了该区的地震构造模型。结果认为,该区的构造活动主要表现为天山地块逆冲于塔里木地块之上。天山构造系统包括迈丹断裂及其前缘推覆构造;塔里木构造系统包括深部的塔里木北缘断裂、基底共轭断层和浅部的推覆构造。塔里木北缘断裂是发育于塔里木地壳内部的高角度断裂,其形成原因在于塔里木和天山构造变形方向的差异。塔里木北缘断裂为研究区大地震的主要发震构造,天山推覆构造和塔里木基底断裂系统均具有不同性质的中强地震发震能力     

基于加权一致性的蚁群算法在断层检测中的应用

突出地震数据振幅空间不连续性的断层增强属性体是断层自动解释的基础,而如何压制噪声、地层残余响应、角度不整合接触等伪断层的影响是断层自动检测的关键问题之一.在指纹图像边缘检测处理中,一致性是对指示局部方向场信息各向异性强度的一个度量,本文将其作为一种新的断层增强属性引入到地震数据处理中.为了更有效地压制噪声,本文通过对一致性进行加权处理,再结合蚁群算法,提出了新的断层自动检测方法——基于加权一致性的蚁群算法.理论地震模型和实际地震数据的处理结果表明,对于相同的断层检测过程,对比常规的基于方差属性的蚁群算法和基于C3相干属性的蚁群算法,本文所提方法不仅更有效地压制了噪声和地层残余响应产生的伪断层信息,而且更完整地展现了断层的延伸长度,同时具有更高的稳定性和计算效率.     

Steered migration in hard rock environments

Hard rock seismic exploration normally has to deal with rather complex geological environments. These types of environments are usually characterized by a large number of local heterogeneity (e.g., faults, fracture zones, and steeply dipping interfaces). The seismic data from such environments often have a poor signal‐to‐noise ratio because of the complexity of hard rock geology. To be able to obtain reliable images of subsurface structures in such geological conditions, processing algorithms that are capable of handling seismic data with a low signal‐to‐noise ratio are required for a reflection seismic exploration. In this paper, we describe a modification of the 3D Kirchhoff post‐stack migration algorithm that utilizes coherency attributes obtained by the diffraction imaging algorithm in 3D to steer the main Kirchhoff summation. The application to a 3D synthetic model shows the stability of the presented steered migration to the presence of high level of the random noise. A test on the 3D seismic volume, acquired on a mine site located in Western Australia, reveals the capability of the approach to image steep and sharp objects such as fracture and fault zones and lateral heterogeneity.     

Basement structural architecture and hydrocarbon conduit potential of polygonal faults in the Cooper‐Eromanga Basin,Australia

A thorough and complete understanding of the structural geology and evolution of the Cooper‐Eromanga Basin has been hampered by low‐resolution seismic data that becomes particularly difficult to interpret below the thick Permian coal measures. As a result, researchers are tentative to interpret the basement fault architecture within the basin, which is largely undefined. To provide a better understanding of the basement fault geometry, all available two‐dimensional seismic lines together with 12 three‐dimensional seismic surveys were structurally interpreted with assistance from seismic attribute analysis. The Upper Cretaceous Cadna‐owie Formation and top Permian reflectors were analysed using a common seismic attribute technique (incoherency) that was used to infer the presence of faults that may have otherwise been overlooked. Detailed basement fault maps for each seismic survey were constructed and used in conjunction with two‐dimensional seismic data interpretation to produce a regional basement fault map. Large north‐northeast–south‐southwest‐striking sinistral strike–slip faults were identified within the Patchawarra Trough appearing to splay from the main northeast–southwest‐striking ridge. These sinistral north‐northeast–south‐southwest‐striking faults, together with field‐scale southeast–northwest‐striking dextral strike–slip faults, are optimally oriented to have potentially developed as a conjugated fault set under a south‐southeast–north‐northwest‐oriented strike–slip stress regime. Geomechanical modelling for a regionally extensive system of Cretaceous polygonal faults was performed to calculate the Leakage Factor and Dilation Tendency of individual faults. Faults that extend into Lower Cretaceous oil‐rich reservoirs with strikes of between 060°N and 140°N and a high to near‐vertical dip angle were identified to most likely be acting as conduits for the tertiary migration of hydrocarbons from known Lower Cretaceous hydrocarbon reservoirs into shallow Cretaceous sediments. This research provides valuable information on the regional basement fault architecture and a more detailed exploration target for the Cooper‐Eromanga Basin, which were previously not available in literature.     

The Influence of a Local Fault Zone on High Energy Tremor Occurrence During Longwall Mining of a Coal Seam

Underground mining of coal seams in the Upper Silesian Coal Basin in Poland is accompanied by seismic activity of varying magnitude. The investigations which have been performed for several years distinguished high energy mine tremors connected directly with mining or coupled with geological structures, such as large faults. In mined seams, local fault zones occur. Faults in these zones are usually small, with throws comparable with coal seams thicknesses. Local fault zone may be responsible for the occurrence of high energy tremors as well as large faults, as presented in this article. An analysis of source mechanism of high energy tremors generated during longwall mining of the coal seam No. 510, with presence of a local fault zone, in one of the Polish hard coal mines in the Upper Silesian Coal Basin was performed. For this purpose, the seismic moment tensor inversion method was used. In most of foci, the process of shear predominated. Determined nodal plane parameters were correlated with parameters of faults forming the local fault zone. High energy tremors were generated mostly by dislocations on faults of the local fault zone. Weakening of roof rocks in the neighborhood of local fault zone takes an important role too, and was responsible for share of implosion in the focal mechanism.     

钻探揭示的黄河断裂北段活动性和滑动速率

黄河断裂是银川盆地内展布最长、切割最深的一条深大断裂,也是银川盆地的东边界。由于其北段呈隐伏状,因此,该段的活动性和滑动速率长期未知,影响了对盆地演化和地震危险性的认识。文中选择具有石油地震勘探基础的陶乐镇为研究场点,以人工浅层地震勘探结果为依据,在黄河断裂北段布设了一排钻孔联合剖面,并对标志层进行年代测试,获得了断裂的活动时代和滑动速率。结果表明,黄河断裂北段在晚更新世末期或全新世有过活动,在（28.16±0.12）ka BP 以来的累积位移为0.96m,晚第四纪以来的平均滑动速率为0.04mm/a,该值明显低于南段灵武断层（0.24mm/a）;尽管向下切割了莫霍面,黄河断裂晚第四纪活动强度和发震能力均要低于切割相对浅的贺兰山东麓断裂;黄河断裂可能在新生代之前已经强烈活动并深切莫霍面,新生代以来,银川盆地的构造活动迁移分解到以贺兰山东麓断裂为主的多条断裂之上,地壳双层伸展模型可解释银川盆地现今深浅部构造活动间的联系。     

Steerable Pyramid分解在储层断裂检测中的应用

在隐蔽油气藏勘探中,正确刻画储层断裂对于油气勘探和开发都有着至关重要的作用.储层断裂在地震数据中表现为边缘特征.但现今多尺度边缘检测的基本理论和方法都有其本身的局限性.本文详细阐述了Steerable Pyramid分解用于储层断裂检测的基本原理和方法.输入的三维地震切片经过Steerable Pyramid分解后,不仅可以分析不同尺度不同方向上断裂的特征及走向,还可以通过重构得到经S函数控制的断裂信息,该断裂信息不仅仅是断裂的边缘检测,而是增强的断裂本身.将该算法应用于实际地震切片的断裂检测,得到了清晰的断裂信息,完整细致地展现了这些地质类型的特征,为构造解释、地震相表征及储层预测提供了有用信息.     

Enhancement of Seismic Data Processing and Interpretation of Fracture Zones on the Upper Part of Granitic Basement in Cuu Long Basin,Vietnam

The fractured granite basement is the primary oil and gas reservoir in the Cuu Long Basin, Vietnam. Due to the complexity of this nonlayered unconventional target, combined with complicated fault and fracture systems, the seismic data quality near and within the basement section is very low. For this reason, it is important to apply improved seismic data processing workflows, filtering and migration techniques, as wells as attribute processing methods to enhance the imaging quality.Our studies show that applying different types of filters, including the f-k, Radon transform and Tau-P, improves signal to noise ratio, removing multiples, revealing basement’s top and its related fractured and fault zones. In addition, the application of multi-arrival-solution migration algorithms, such as Kirchhoff Migration and Controlled Beam Migration, provides improved imaging for identifying basement top and faults and fractures within the basement. Furthermore, the application of seismic attributes such as curvature, apparent dip, or energy gradient, is important in locating faults and fractures, whereas mapping of intensity and orientation of such structures assists the delineation of “sweet spots” and assists the planning of exploration.     

天山地震带境内外主要断层滑动速率和地震矩亏损分布特征研究

本文搜集、整理1998—2013年境内外天山及周边地区(包括中国新疆、哈萨克斯坦、吉尔吉斯斯坦等)500余个GPS观测点数据,采用GAMIT/GLOBK软件对其进行解算和平差计算,并利用了弹性块体模型计算区域块体边界断层闭锁深度、块体运动参数和主要活动断层的滑动速率.研究结果表明,东、西昆仑地震带闭锁深度最大(19km),其次为南天山地区,闭锁深度达到17km,闭锁深度最小的为哈萨克斯坦(13km);各块体相对欧亚板块作顺(逆)时针旋转,旋转速率最大(-0.7208±0.0034°/Ma)为塔里木块体,其围绕欧拉极(38.295±0.019°N,95.078±0.077°E)顺时针方向转动,旋转速率最小为天山东段(0.108±0.1210°/Ma),而天山东、西两段无论是在旋转速率上还是在旋转方向上都有显著的区别.西昆仑断裂带的滑动速率(10.2±2.8mm·a-1)最大,南天山西段滑动速率为9.5±1.8mm·a-1,其东段为3.9±1.1mm·a-1;而北天山东段滑动速率(4.7±1.1mm·a-1)高于北天山西段(3.7±0.9mm·a-1);塔里木盆地南缘的阿尔金断裂带平均滑动速率为7.6±1.4mm·a-1,其结果与阿勒泰断裂带滑动速率(7.6±1.6mm·a-1)基本相当;天山断裂带运动方式主要以挤压为主,而阿尔金、昆仑、阿尔泰以及哈萨克斯坦断裂带均是以走滑运动方式为主,除阿勒泰断裂带走滑方式为右旋以外,其余几个断裂带均为左旋运动.最后,利用主要断裂带的滑动速率计算出各地震带的地震矩变化率以及1900年以来地震矩累计变化量,其结果与利用地震目录计算所得到的地震矩进行比较,判定出各地震带上地震矩均衡分布状态,研究结果显示阿尔金、西昆仑、东昆仑和北天山东段断裂带存在较大的地震矩亏损,均具有发生7级以上地震的可能性,南天山东段和哈萨克斯坦断裂带地震矩亏损相对较小,具有孕育6~7级地震的潜能,而天山西段、阿勒泰地震矩呈现出盈余状态,不具在1~3年内有发生强震的可能.     

Landslide distribution and size in response to Quaternary fault activity: the Peloritani Range,NE Sicily,Italy

Landslides contribute to dismantle active mountain ranges and faults control the location of landslides. Yet, evidence of the long‐term, regional dependency of landslides on active faults is limited. Previous studies focused on the transient effects of earthquakes on slope stability in compressive and transcurrent regimes. Here we show that in the Peloritani range, NE Sicily, Italy, one of the fastest uplifting areas in the Mediterranean, a clear geographical association exists between large bedrock landslides and active normal faults of the Messina Straits graben. By interpreting aerial photographs, we mapped 1590 landslides and sackungs and 626 fault elements and their facets in a 300 km² area in the eastern part of the range. We used the new landslide and fault information, in combination with prior geological and seismic information, to investigate the association between bedrock landslides and faults. We find that the distribution and abundance of landslides is related to the presence of large active normal faults, and matches the pattern of the local historical seismicity. Landslide material is more abundant along the East Peloritani Fault System where the long‐term activity of the faults, measured by the average yearly geological moment rate, is larger than in the West Peloritani Fault System where landslides are less abundant. Along the fault systems landslide material concentrates where the cumulated fault throws are largest. We conclude that large landslides and their cumulated volume are sensitive to local rates of tectonic deformation, and discriminate the deformation of the single fault segments that dissect the Peloritani range. Our findings are a direct test of landscape evolution models that predict higher rates of landslide activity near active faults. Our work opens up the possibility of exploiting accurate landslide and fault maps, in combination with geological and seismic information, to characterize the long‐term seismic history of poorly instrumented active regions. © 2015 The Authors Earth Surface Processes and Landforms Published by John Wiley & Sons Ltd     

2014年2月12日M_w6.9于田地震震源破裂过程及对周围断层的应力影响

2014年2月12日,在新疆于田县发生了里氏7.3级地震.在该地震震中附近,前人研究证明发育了大量规模不同的活动断层(如康西瓦断裂与贡嘎错断裂等).根据地震触发理论,地震发生后因地壳同震变形会导致其周边不同性质断裂破裂应力发生变化,进而影响其地震的潜在危险性.本文利用地震远场波形记录,反演了该地震滑动模型.之后,根据弹性无限半空间位错理论,计算了该地震在近场范围内活动断裂上的同震应力变化.其目的在于讨论于田地震引起的附近断裂上的库仑应力变化以及这些活动断裂可能潜在的地震危险性.在地震发生后,从国际地震学联合会(IRIS)地震数据中心,下载了震中距离介于30°~90°的地震远场波形记录,为保证台站方位角分布均匀,从中挑选了27个不同方位角的高信噪比地震记录参与理论地震图的生成和波形反演过程.我们采用广义射线理论计算生成远场理论地震波形数据.每个子断层参数的反演则利用基于全局化反演的快速模拟退火反演方法.在有限断层反演过程中,我们采用了强调波形拟合的相关误差函数作为待反演的目标函数,拟合的断层参数使目标函数为最小.之后,根据弹性无限半空间位错理论,以库仑破裂准则为基础,结合反演得到的地震震源机制解和地震位错模型,计算该地震引起的近场断层面上库仑应力的变化.由远场波形计算结果可以看到,于田地震的震源深度为10km,地震断层的倾角约71.9°,破裂面上最大的同震位移达到210cm,以左旋走滑为主并具有正倾滑分量,地震能量主要在前15s内释放.由此得到该地震的地震矩为2.91×1019 N·m,地震震级为Mw6.9.于田地震引发的余震,大致分布在三个区域内:普鲁断裂北部、康西瓦断裂东部和贡嘎错断裂中部.弹性应力计算结果表明,于田地震导致阿尔金断裂西段、普鲁断裂中段、康西瓦断裂东段和贡嘎错断裂中段的静态库仑应力明显增加,其中以康西瓦断裂东段和贡嘎错断裂中段应力增量为最大,分别达到了0.05 MPa和0.04 MPa.大量研究证明,当地震所导致的库仑应力变化大于0.01 MPa时将具有明显的地震触发作用.根据本文结果,2014年于田Mw6.9地震使普鲁断裂、贡嘎错断裂和康西瓦断裂上的库仑应力增量均超过了触发阈值,具有被触发出地震的潜在危险.因此,在以后的地震学研究中,应加强对该三条断裂地震危险性的研究和监测.此外,近6年以来,研究区域发生了3次6级以上的地震.这些地震均沿着贡嘎错断裂,由南西向北东迁移,逐步靠近阿尔金断裂,并且逐渐由正倾滑型地震转变为走滑型地震.阿尔金断裂的走滑速率达到了9mm·a-1,所以,尽管本次地震导致的阿尔金断裂库仑应力增量小于0.01 MPa,阿尔金的地震危险性也应该加强监测.     

天山构造带及邻区地壳各向异性

天山构造带位于中国大陆西北部,是典型的岩石圈陆内缩短造山带.本文利用新疆区域数字地震台网2009年1月至2014年12月的近场小地震波形资料,采用剪切波分裂分析对天山构造带及邻区的地壳各向异性特征进行研究,获得了研究区域内39个台站的快剪切波偏振方向和慢剪切波时间延迟.剪切波分裂参数的空间特征显示,研究区上地壳各向异性具有分区性,各向异性特征与局部构造、地壳介质变形和应力分布有关.天山构造带的快剪切波偏振呈现出两个优势方向的特点,第一优势方向大致平行于台站附近断裂和天山构造带的走向,与断裂构造和应力的综合影响有关,另一个优势方向反映了主压应力的直接作用.北天山山前断裂带东段的断裂弯折部位和南天山局部地区的剪切波分裂参数与东、西两侧不同,与准噶尔盆地、塔里木盆地的南北向挤压作用密切相关.快剪切波偏振优势方向的剧烈变化揭示,在准噶尔盆地和塔里木盆地双向挤压隆起的过程中,天山构造带产生了强烈的局部不均匀变形.塔里木盆地西侧快剪切波偏振具有两个优势方向,一个为NNE方向,与帕米尔高原受到印度一欧亚板块碰撞产生的北向挤压作用有关,另一个为NW方向,指出了塔里木盆地区域主压应力方向.准噶尔盆地北部也存在NE和NW两个快波偏振优势方向,主要与断裂的影响有关.天山构造带区域内的慢剪切波时间延迟总体上低于塔里木盆地西侧和准噶尔盆地北部,同时慢剪切波时间延迟的结果也进一步证实了天山构造带的局部强烈变形.     

Seismotectonic Study on the West Part of the Interaction Zone Between Southern Tianshan and Northern Tarim

The interaction zone between southern Tianshan and northern Tarim is located at the northeast side of Pamir. It is a region with high seismicity. We constructed a seismotectonic model for the west part of this zone from geological profiles, deep crust seismic detection and earthquake focal mechanisms data. Based on the synthesized geological features, deep crust structure, and earthquake focal mechanisms, we think that the main regional tectonic feature is that the Tianshan tecto-lithostratigraphic unit overthrusts on the Tarim block. The Tianshan tectonic system includes the Maidan fault and thrust sheets in front of the fault; The Tarim tectonic system includes the underground northern Tarim margin fault, conjugate faults in basement and overthrust fault in shallow. The northern Tarim margin fault is a high angle fault deep in the Tarim crust, adjusting different trending deformation between Tianshan and Tarim. It is a major active fault that can generate large earthquakes. The other faults, such as the Tianshan overthrust system and the Tarim basement faults in this area may generate moderately strong earthquakes with different styles.     

基于局部直方图规定化的相干体增强

Coherence analysis is a powerful tool in seismic interpretation for imaging geological discontinuities such as faults and fractures. However, subtle faults or fractures of one stratum are difficult to be distinguished on coherence sections (time slices or profiles) due to interferences from adjacent strata, especially these with strong reflectivity. In this paper, we propose a coherence enhancement method which applies local histogram specification (LHS) techniques to enhance subtle faults or fractures in the coherence cubes. Unlike the traditional histogram specification (HS) algorithm, our method processes 3D coherence data without discretization. This method partitions a coherence cube into many sub-blocks and self-adaptively specifies the target distribution in each block based on the whole distribution of the coherence cube. Furthermore, the neighboring blocks are partially overlapped to reduce the edge effect. Applications to real datasets show that the new method enhances the details of subtle faults and fractures noticeably.     

新疆地区环境噪声层析成像研究

本文利用北京大学宽频带流动地震台阵和新疆地震监测台网12个月连续地震记录数据,采用环境噪声层析成像方法获得了新疆地区的周期从10～35 s范围内的瑞利面波相速度异常分布图像.研究结果与地表地质构造相一致,新疆地区的天山、两盆大地构造与瑞利面波相速度异常有较好的对应关系.短周期10～20 s的图像显示两个盆地内都呈现低速...     

2003年2月24日新疆巴楚-伽师6.8级地震发震构造

2003年2月24日发生在新疆塔里木盆地的巴楚-伽师6.8级地震可能是1997—1998年伽师强震群的继续,但其震源机制解、破裂过程与1997—1998年的强震群有一定的差别。从地震重新定位的结果看,巴楚-伽师6.8级地震与塔西南坳陷东侧麦盖提斜坡带上发育的一组NWW向隐伏逆断层有关,地震宏观考察①所发现的与构造变形有关的地裂缝也与这一隐伏断层带的位置相吻合,等震线形态与隐伏断层带的走向一致,极震区的形态与断层的破裂方向基本一致。这些均表明这次地震是盆地内一条近EW向北倾逆断层自NW向SE由深至浅破裂的结果