【作者】 李学聪；

【导师】 段云卿；

【作者基本信息】 中国地质大学（北京） ， 地球探测与信息技术， 2006， 硕士

【摘要】 目前,常规的地震资料处理一般采用叠后时间偏移,但它只能解决反射层归位和绕射波收敛,而不能解决倾斜界面的非共反射点叠加问题。叠前偏移技术是解决精细速度分析和复杂构造成像的有效手段之一,也是近年来国内外地震资料成像的发展趋势。叠前深度偏移更是解决速度横向变化剧烈的复杂地区的地震资料成像的关键技术。本文首先介绍了偏移的基本概念,以及其发展历史。根据偏移的这几个发展阶段,然后分别介绍了其基本原理和实现方法。然后重点以酒泉盆地窟窿山逆掩推覆构造的一个三维工区为例,通过 GeoDepth 叠前深度偏移软件给出了三维叠前偏移的原理、实现步骤与成像效果。本次处理的任务要求查明窟窿山逆掩推覆带断层特征,要求断点清晰,目的层反射可靠,可对比追踪。根据资料特点,我们将处理过程分为时间域和深度域两个部分。本次资料时域处理的难点是:规则干扰的压制及随机干扰的衰减;叠前能量和频率的补偿;速度分析;静校正量的求取;正确的叠加成像,准确的偏移归位。根据原始资料的特点及处理的难点,以及地质任务处理要求和要解决的重点问题分析,本次处理采取了相应的技术措施。深度域处理的关键步骤是:(1)时间域构造模型的建立;(2)初始速度模型的建立;(3)速度模型的优化。通过时间剖面与深度偏移后剖面对比分析可以看出,深度偏移后的剖面较时间偏移剖面有一些改善,具体表现在以下几个方面:(1)深度偏移剖面构造形态相对完整,反射的信噪比有所提高;(2)经叠前深度偏移后,地层的接触关系清楚,(3)深浅层的成像都有一些的改进,波组特征较好,频带较宽,分辨率有一定的提高,振幅的保真度较高。不足之处一是由于叠前深度偏移的目标层较深,信噪比很低,成像效果不甚理想。二是偏移画弧现象在个别地方压制不够。更多还原

【Abstract】 Normal seismic data processing usually uses post-stack migration ,however, it just canmake reflecting layers return its own position and make coiling wave converge and can’t dealwith uncommon reflecting points stacking of inclining interfaces .The pre-stack migrationtechnique is one of the effective methods in solving fine velocity analysis and complexstructures imaging, at the same time it is also the development tendence of seismic dataimaging in our country or overseas in recent years. Pre-stack migration is also the keytechnique in solving seismic data imaging in complex areas where the velocity vary rapidly .The paper firstly introduce the basic conception of migration and its developmenthistory .According to these development phases of migration ,it introduce the basic principleand achieving methods of migration.The paper places the emphasis in the sample of a 3D prospect in Jiuquan basinKulongshan contradictory covering and overturning structure , through GeoDepth pre-stackmigration software introducing 3D pre-stack migration principle ,its achievement steps and itsimaging effect .The task require us to find out fault character of Kulongshan contradictorarycovering and overturning zoster and make broken points clearer and make objective layersmore reliable to be easily traced. According to data character ,we divide the process into timefield and depth field .The difficulty of data time process is : suppressing regular disturbanceand attenuating random disturbance;compensating pre-stack energy and frequency;velocityanalysis;calculating static correlations;right stacking and imaging ,accurate migration andreturn its position. According to the character of original data and the difficulty of theprocessing and the processing requirement of the geological task and the key things to bedealed with ,we adopt corresponding technique measurement. The key steps in depth field is :the first one is founding the structure model in time field;the second one is founding originalvelocity model;the third one is optimizing the velocity model. Comparing and analyzing thetime section with post-depth migration section, we can realize that there are someimprovement in depth migration section than time section and representing in these aspects:the first one is that the structure shape of depth migration is relatively integral and reflectingS/N improves;the second is that stratum contact relation is more clearer after pre-stack depthmigration;The third one is that there are also some improvement in imaging in deep andshallow stratum and that wave group character is preferable and that its frequency straps arewider and that the resolution improves and that swing fidelity is higher. The shortcoming isthat the imaging effect isn’t perfect because the objective layer of pre-stack depth migration isvery deep and its S/N is very low. At the same time migration drawing arc phenomena can’tbe suppressed enough in some places.更多还原