【作者】 沈鸿雁；

【导师】 李庆春；

【作者基本信息】 长安大学 ， 地球探测与信息技术， 2010， 博士

【摘要】 随着亟待解决地质问题的复杂化程度和解决问题精细程度的进一步提高,多次覆盖反射地震勘探技术暴露出的弊端和问题越来越多,虽然能较好地提高地震资料的信噪比,但在复杂构造情况下,尤其是在山前断裂带、盆地边缘破碎带、岩浆侵入型的勘探问题以及近地表不均匀性突出地带的探测问题,难以取得精确的成像结果,究其原因是传统反射地震勘探技术的理论基础限定了其不可能完全逾越对地质信息完整、准确地提取的能力。另外,传统方法只应用单一类型地震波场(如反射波、面波、折射波等)进行成像,成像效果和地质信息提取能力都受到一定的限制,尤其是地质情况复杂地带效果更差。其实,地震波所携带的地质信息是非常丰富的,单一类型地震波(如反射波)仅体现地质属性信息的一部份或者是某一方面,限定了其精细提取地质信息的能力。本文较系统地开展了地震散射波成像方法与技术研究,即应用更为广泛意义上的地震散射波场进行成像。在已有地震散射波理论的基础上,针对地震散射波传播的特性,建立了点散射地震-地质模型,在此基础上,完善了地震散射波几何运动学,总结了地震散射波的时距规律,并将散射波的时距特征和规律与传统的反射波时距特征和规律进行了深入的分析与对比,与此同时,提出了“视反射波”的概念。借助典型地质模型的地震波场数值模拟,深入分析了地震散射波的传播特征。研究表明,传统意义上的地震反射波不是真正意义上的反射波,而是地震散射波相互干涉的最终结果,地震散射波是孤立地质体表现出的基本特征,由于干涉效应,连续介质已经模糊了部分地震散射波的基本传播属性,尤其是连续水平弹性界面情况下,再加上背景噪音的影响,散射波性质就更不容易被发现。但是,当界面不规整、不均匀性突出的情况下,地震散射波的传播性质和规律就被凸显出来了,特别是存在尖灭点、断面等异常地质现象时,地震记录上就会出现传统意义上的异常波(如绕射波、断面波等),此时,地震散射波的传播规律和性质就体现出来了。通过散射波时距规律分析得出,散射波的时距曲线特征只与上行波有关系,其规律满足双曲线特征,而下行波仅与旅行时长短有关。针对转换波来说,由于上行波与下行波的传播速度是彼此孤立的,当然其时距规律也满足双曲线特征,这为地震转换波处理与信息获取提供了新的思路和理论支持。基于地震散射波的传播规律,研究了地震散射波成像速度分析方法与技术,深入分析了该技术与传统速度分析技术和基于等效偏移距地震散射波速度分析技术的异同点和优劣性。采集数据时,在传统覆盖次数固定的前提下,由于充分利用上了所有采集到的地震信息,在散射波速度分析时,使得叠加次数得以大大提高,这样不但使有效散射波能量聚焦能力更强,而且能有效提高信噪比,同时利用上了绕射波、断面波等传统意义上的异常波信息进行速度分析,因此,与传统速度分析技术相比较,该技术能更精确地获取成像速度,尤其对构造复杂地区和低信噪比地区的地震资料,能有效避免传统技术中异常波的伪能量团影响的弊端,同时可减小多次波的影响。在地震散射波速度分析技术的基础上,研究了地震散射波时间域成像方法与技术。基于点散射地质模型,无须进行道集选排,而是基于散射波时距双曲线规律,通过单点寻优成像。在传统覆盖次数一定的情况下,该技术比传统水平叠加成像技术的叠加次数大大提高了；另外,由于获取了精确的成像速度,同时利用上了传统意义上的绕射波、断面波等异常波信息进行成像。因此,该技术不但有效提高了信噪比,而且能大大提高成像精度；同时,因成像位置和区域可以根据实际情况来定义,对采集数据所覆盖的区域均可进行成像,所以比传统成像技术扩大了成像区域,所获取的地质信息更加丰富。在速度分析和成像技术的基础上,编制了相关软件,并建立了数套典型地质模型(水平层模型、断层模型、薄互层模型、角度不整合面模型、凹陷模型)进行成像处理与效果分析,取得了预期的效果。针对实际资料,建立了合理的地震散射波处理流程,从处理工艺上分析了该技术的优越性,并与传统的标准成像处理流程(包括叠后偏移成像、叠前偏移成像、基于等效偏移距的地震散射波成像等)进行了对比与分析,得出速度获取的精确成度直接影响到成像质量的好坏,本文方法与技术获取的速度精确度高,而且处理流程直观明了、简单。在此基础上,从实际亟待解决的实际地质问题出发,针对近地表工程与环境探测、城市活断层探测、煤田和油气地震勘探与开发问题,处理了数套实际资料(包括单分量、多分量),并与传统速度分析和叠后偏移技术处理的结果进行了对比与分析,取得了非常丰富的认识。更多还原

【Abstract】 Along with urgently awaits to be solved the complication degree of geological question and to solve the question fine degree further enhancement, the malpractice and the question that the multifold reflected wave exploration technical has exposed are getting more and more. Although it can enhance the signal-to-noise ratio of seismic data well, in the complex structure situation, particularly the fault zone of mountain front, the crushed zone of basin edge, exploration question of magmatic intrusion as well as the survey question of nonuniformity prominent region in near surface, it is difficulty to obtain the precise imaging result. The reason is that the theory of the tradition reflected exploration technical has defined it is impossible to overstep the ability that withdraws geological feature accurately and geological information completely. Moreover, the traditional methods only apply the sole type seismic wave field (for example reflected wave, surface wave, refracted wave and so on) to carry on imaging, the imaging effect and the ability of geology information extracting is limited certainly, particularly the effect is worse in geological situation complex region. Actually the seismic wave which carries the geological information is very rich. And the sole type seismic wave (for example reflected wave) only manifests one part or one hand of the geological attributes information, has defined the ability of extracting geology information well. This article has developed the seismic scattered wave imaging method and technical research systematically, namely applying the seismic scattering wave field which is more widespread significance for seismic wave field to carry on imaging.In the existing seismic scattering wave theory foundation, in view of the characteristic of seismic scattering wave propagating, this paper has established the point scattering seismic geological model, based on this, consummated the seismic scattering wave geometry kinematics, summarized the seismic scattering wave time-distance curve rule, and has carried on analyzing and contrasting the time-distance curve characteristic and rule for scattering wave with traditional reflected wave, at the same time, proposed the concept of apparent reflected wave.With the wave field numerical simulation of the typical geological model, this paper analyzed the seismic scattering wave propagation characteristic thoroughly. The research has indicated that the seismic reflected wave in the traditional significance is not reflected wave in fact, but is the final outcome which the seismic scattering wave interfered mutually. The seismic scattering wave is the basic feature which the isolated geological body appeared. As a result of the interference effect, the continuous medium already blurred the partial seismic scattering wave basic propagation attribute, particularly in the elastic contact surface situation with horizontal and continues. In addition with the influence of background noise, the scattering wave nature has not been discovered easily. But, when contact surface not neat and nonuniform prominent, the propagation nature and the rule of the seismic scattering wave are highlighted, especially unusual geological phenomenon, such as thin out point, fault and so on. There will be the extraordinary wave with traditional significance in seismic record (for example diffracted wave, fault section wave and so on), and the seismic scattering wave propagation rule and the nature has been manifested at this time.Through analyzing scattering wave time-distance rule, this paper obtained that the relation of the scattering wave time-distance curve characteristic only relating with the upgoing wave, and the rule following hyperbolic curve characteristic. But the downgoing wave only relates with the length of the travel time. As for the converted wave, the propagation velocities of downgoing and upgoing wave are each other isolated, certainly the time-distance curve rule also following hyperbolic curve characteristic. This provides one new mentality and theory to support for seismic converted wave processing and information acquisition.Based on the propagation rule of seismic scattering wave, this paper studied on seismic scattering wave imaging velocity analysis method and technical, and analyzed the similarities and differences thoroughly as well as superiority-inferiority of the technical with the tradition velocity analysis technical and the technical of basing on equivalent off-setting seismic scattering wave velocity analysis. When data acquiring, under the premise of tradition fold number fixed, the scattering velocity analysis technical not only made the focusing ability of effective scattering wave energy to be stronger, but also could enhance the signal-to-noise ratio effectively, simultaneously used on the information with the traditional extraordinary wave of diffracted wave and fault section wave etc to carry on velocity analysis. Because the technical used on the seismic information which fully all gathered, simultaneous the times of stacking number is able to enhance greatly. Therefore, compared with the tradition velocity analysis technical, the technical could gain the imaging velocity precisely, especially to the seismic data of constructed complex region and low signal-to-noise ratio area, which could avoid the malpractice of the extraordinary wave false energy group affected in the traditional technical effectively, simultaneously may reduce influence of multiple wave.In the foundation of seismic scattering wave velocity analysis technical, this paper studied on the seismic scattering wave imaging method and technical in time domain. With the point scattering geological model, the technical does not need gathers collection, but bases on the scattering wave time-distance curve hyperbolic rule, adopts single point optimization imaging. Comparing with the traditional horizontal stacking imaging technical under the premise of tradition fold number fixed, the stacking number of the imaging technical is enhance greatly. Moreover, because gained the precise imaging velocity, simultaneously used on the information with the traditional extraordinary wave of diffracted wave and fault section wave etc carry on imaging, therefore, the technical not only enhanced the signal-to-noise ratio effectively, but also could increase the imaging precision greatly; At the same time, because the imaging position and the region may act according to the actual situation to define, so long as the region of the gathering data covered may carry on the imaging. Therefore compared with the traditional imaging technical, the imaging technical can extend imaging region. And the gained geological information is richer.In the foundation of the velocity analysis and imaging technical, compiled the related software, and established several sets of typical geological models (horizontal level model, fault model, thin interbed model, angle plane of unconformity model, hollow model) to carry on imaging processing and analysis with the effect, this paper has made a good progress.In view of the actual data, this paper has established standard seismic scattering wave processing flow, analyzed this technical congenital superiority from the processing craft, and carry on contrasting and analyzing with traditional standard imaging processing flow (post-stack imaging, pre-stack imaging, based on equivalent offset seismic scattering wave imaging and so on), which obtained the precise of the gained velocity becoming immediate influence to the imaging quality. The gained velocity precision of the technical in this article is high, moreover processing flow direct-viewing perspicuity and simple.Based on this, urgently awaits the actual geological question which from the reality is solved to embark, in view of the near surface engineering and environment survey, the urban active fault survey, the coal field and oil gas seismic exploration and the development question, this paper has processed several sets of actual data (including single component, multi-components), and carry on contrasting and analyzing with the result of the tradition velocity analysis and post-stack migration technical, has obtained a very rich understanding.更多还原