本文選題：交錯網(wǎng)格　切入點：有限差分　出處：《成都理工大學》2015年碩士論文　論文類型：學位論文

【摘要】：為了更好地研究復雜構(gòu)造和速度分布條件下地震資料的精確成像方法,本文首先介紹了偏移原理、傳統(tǒng)偏移方法及逆時偏移的概念。針對逆時偏移波場遞推計算和成像過程中的具體問題進行了探討,推導了適合于交錯網(wǎng)格有限差分法的速度-應力方程,建立了高階交錯網(wǎng)格有限差分格式,形成了波場計算遞推計算方程。就逆時偏移中涉及的邊界條件、成像條件、逆時偏移中假象的消除等問題進行了分析。衰減吸收邊界條件使得位于邊界的干擾反射得到了有效的消除,減少了對計算區(qū)域正常波場的影響。逆時偏移有效突破了地層傾角的限制,對橫縱向速度變化劇烈的復雜模型成像效果顯著提高,對處理陡傾構(gòu)造和多斷層等復雜地質(zhì)情況的偏移問題具有良好的實用價值。缺點是逆時偏移計算量和存儲量都比較大。討論了逆時疊前偏移的成像條件,并選擇互相關(guān)成像條件為該方法偏移處理的成像條件。在逆時偏移處理過程中,互相關(guān)成像條件能消除假象干擾,使成像噪音得到較好的壓制。用對點脈沖、雙曲線反射波記錄進行了疊后偏移脈沖響應試驗,試驗結(jié)果驗證了理論;將Marmousi模型作為疊后偏移的處理對象進行了試算;四川某工區(qū)的實際地震資料進行了偏移處理;隨后進行了疊前偏移脈沖響應試驗,以及理論模型的單炮道集錄和多炮道集疊前逆時偏移試算,均取得了很好的成像效果,證明所用的方法具有較好的偏移效果和很強的可靠性。
[Abstract]:In order to better study the accurate imaging method of seismic data under complex structure and velocity distribution, the migration principle is introduced in this paper. The traditional migration method and the concept of inverse time migration are discussed, and the velocity stress equation suitable for the staggered grid finite difference method is derived. In this paper, a high order staggered grid finite difference scheme is established, and a recursive computing equation for wave field calculation is formed. For the boundary conditions involved in inverse time migration, the imaging conditions are obtained. Some problems such as the elimination of false image in inverse time migration are analyzed. The attenuation absorbing boundary condition can effectively eliminate the interference reflection at the boundary. The effect of inverse time migration on the normal wave field in the calculated area is reduced. The inversion migration effectively breaks through the limitation of the dip angle of the formation and improves the imaging effect of the complex model whose velocity varies dramatically in the horizontal and vertical direction. It has good practical value in dealing with the migration problem of steep dip structure and multi-fault, etc. The disadvantage is that the computation and storage amount of inverse time migration are relatively large. The imaging conditions of inverse time prestack migration are discussed. The cross-correlation imaging condition is chosen as the imaging condition for the migration processing of this method. In the inverse time migration processing, the cross-correlation imaging condition can eliminate the false image interference and suppress the imaging noise. The hyperbolic reflection wave record is tested by post-stack migration pulse response test, the experimental results verify the theory, the Marmousi model is used as the processing object of post-stack migration, and the actual seismic data in a work area in Sichuan are processed by migration. Then the pulse response test of prestack migration and the theoretical model of single shot gather record and multi shot gather prestack inverse time migration are carried out, and good imaging results are obtained. It is proved that the proposed method has good migration effect and strong reliability.
【學位授予單位】：成都理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：P631.44

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