本文選題：VTI介質(zhì) + 轉(zhuǎn)換波�。� 參考：《長安大學(xué)》2015年博士論文

【摘要】：在地震資料處理中,地震成像作為一個工具正發(fā)揮著越來越重要的作用。在具有一定周期的復(fù)雜數(shù)據(jù)處理流程中,偏移成像是最后一個環(huán)節(jié),它的目的是為地球科學(xué)家提供適合于解釋的地球內(nèi)部清晰圖像。近年來轉(zhuǎn)換波地震.勘探技術(shù)有了.迅猛發(fā)展,轉(zhuǎn)換波偏移成像.方法技術(shù)成為研究.的重點課題。在地球介質(zhì)中普遍存在各向異性,同時各向異性介質(zhì)中的地震波偏移成像比在各向同性介質(zhì)中更加復(fù)雜,因此研究復(fù)雜介質(zhì)的轉(zhuǎn)換波偏移成像方法顯得尤為必要,疊前時間成像.實現(xiàn)的是真正共反射點道.集的疊加,偏移后數(shù)據(jù).的信噪比有較大提高,同時還可以.實現(xiàn)保持振幅偏移,偏移成像.效果突出,所以疊前時間.偏移倍受關(guān)注。本文在VTI介質(zhì)中研究了虛擬偏移距(POM-Pseudo-Offset Migration)的轉(zhuǎn)換波疊前時間保幅成像方法。針對VTI介質(zhì),論文從偏移的基本概念和各向異性介質(zhì)的基本原理出發(fā),在前人研究的基礎(chǔ)上,研究并實現(xiàn)了各向同性介質(zhì)中兩種求取轉(zhuǎn)換波虛擬偏移距(POM)的方法以及它們的成像效果,在VTI介質(zhì)中分別用二分法和弦截法求解虛擬偏移距,并將這兩種偏移方法的成像結(jié)果進行對比分析。論文重點研究了VTI介質(zhì)轉(zhuǎn)換波POM疊前時間保幅偏移,給出了疊前時間偏移中保幅權(quán)函數(shù)的不同形式和轉(zhuǎn)換波保幅偏移在時間域的共炮檢距權(quán)函數(shù)的具體表達(dá)式,在抽取共轉(zhuǎn)換散射點道集(CCSP)映射時將振幅用權(quán)函數(shù)來補償以直接實現(xiàn)保幅,避免了相同時間點的累加現(xiàn)象,提高了運算效率。論文取得的主要研究成果有:(1)在各向同性介質(zhì)中,分別用迭代法和極限法求解虛擬偏移距來抽取共轉(zhuǎn)換散射點道集和保幅偏移成像,用傾斜模型驗證了各向同性介質(zhì)中使用這兩種方法進行POM轉(zhuǎn)換波疊前時間保幅偏移的正確性,并對比了它們的耗時,發(fā)現(xiàn)極限法的運算效率高于一般的迭代法,所以論文在各向同性介質(zhì)中用極限方法抽取CCSP道集。對Marmousi模型試算的結(jié)果也表明了在各向同性介質(zhì)中POM方法進行疊前時間保幅成像的有效性。(2)在VTI介質(zhì)中,由于轉(zhuǎn)換波時距曲線方程的復(fù)雜性,較難推導(dǎo)出如各向同性介質(zhì)中求虛擬偏移距的公式,所以針對VTI介質(zhì)轉(zhuǎn)換波的時距曲線方程,推導(dǎo)了VTI介質(zhì)中求射線參數(shù)的數(shù)學(xué)迭代表達(dá)式,論文分別用二分法和弦截法求解射線參數(shù),進而求解虛擬偏移距,因為這兩種迭代算法避免求導(dǎo)數(shù),簡化了求虛擬偏移距的步驟。(3)在VTI介質(zhì)中,通過單一的散射點模型對比分析了各向同性介質(zhì)和VTI介質(zhì)中的CCSP道集,結(jié)果表明散射點模型的旅行時按照雙曲線分布,符合共轉(zhuǎn)換散射點道集的映射規(guī)律,收斂性好。對傾斜模型分別使用弦截法和二分法求解虛擬偏移距,對比了這兩種方法的計算耗時,結(jié)果表明弦截法比二分法收斂速度快,可提高計算效率,最終的成像效果也說明了用這兩種方法抽取CCSP道集的正確性。用兩平層模型驗證了各向異性參數(shù)會影響CCSP道集的結(jié)果以及最終的成像效果,所以各向異性參數(shù)在實際計算中是不容忽視的。通過用傾斜模型驗證虛擬偏移距間隔和偏移孔徑對成像效果的影響,表明在進行疊前時間偏移時,選取合適的虛擬偏移距間隔和偏移孔徑是至關(guān)重要的。使用單層VTI介質(zhì)模型,發(fā)現(xiàn)構(gòu)建準(zhǔn)確的速度函數(shù)相當(dāng)關(guān)鍵。(4)在VTI介質(zhì)中,對單層的凹陷模型、凸起模型、斷層模型和多層組合模型等進行偏移成像,驗證了POM的方法的準(zhǔn)確性,并且對比分析了在各向同性介質(zhì)和VTI介質(zhì)中的成像效果,最后將該方法運用到實際資料中,取得了較好的偏移成像效果。說明在VTI介質(zhì)中使用POM轉(zhuǎn)換波保幅疊前時間偏移方法有一定優(yōu)越性。
[Abstract]:In seismic data processing, seismic imaging is playing a more and more important role as a tool. In a complex data processing process with a certain period, migration imaging is the last link. Its purpose is to provide the earth scientists with a clear image of the interior of the earth. In recent years, the converted wave earthquake and exploration technology have been used. There is a rapid development, converted wave migration imaging. Method technology has become the focus of research. Anisotropy exists in the earth medium, and seismic wave migration imaging in anisotropic media is more complex than in isotropic medium. Therefore, it is necessary to study the transfer wave migration imaging method of complex medium. It realizes the real common reflection point channel. The superposition of the set, the offset data and the signal to noise ratio are greatly improved. At the same time, it is possible to maintain the amplitude offset and offset imaging. The effect is outstanding, so the prestack time. The offset is paid attention. In this paper, the conversion wave of the virtual offset distance (POM-Pseudo-Offset Migration) is studied in the VTI medium. Based on the basic concepts of migration and the basic principle of anisotropic media, based on the basic concepts of the VTI medium and the basic principle of anisotropic media, two methods for obtaining the virtual offset (POM) of converted waves in isotropic media and their imaging results are studied and implemented in the isotropic medium. The binary and chord in VTI medium are used respectively. The section method solves the virtual offset and compares the imaging results of the two migration methods. The paper focuses on the POM prestack time shift shift of VTI medium converted wave, and gives the different forms of the amplitude preserving function in the prestack time migration and the specific expression of the total offset weight function of the conversion wave preserving amplitude offset in the time domain. The weight function is used to compensate the amplitude by extracting the amplitude of the common conversions scatter point channel set (CCSP), avoiding the accumulation of the same time points and improving the operation efficiency. The main research results obtained in this paper are as follows: (1) in isotropic media, the common conversion scattering is extracted by iterative method and limit method, respectively. Point set and amplitude preserving migration imaging are used to verify the correctness of the two methods in isotropic media using these two methods to protect the amplitude shift of the pre stack time in the isotropic medium, and compare their time consuming. It is found that the operation efficiency of the limit method is higher than that of the ordinary iterative method. So the paper uses the limit method to extract the CCSP channel in the isotropic medium. The results of the trial calculation of the Marmousi model also show the validity of the pre stack time preserving imaging of the POM method in the isotropic medium. (2) in the VTI medium, because of the complexity of the time distance curve equation of the converted wave, it is difficult to deduce the formula for finding the virtual offset in the isotropic medium, so the time distance curve of the converted wave of the VTI medium is so used. Linear equation, the mathematical iterative expressions for ray parameters in VTI medium are derived. The paper uses dichotomy and chord method to solve the ray parameters, and then solves the virtual offset, because these two iterative algorithms avoid the derivative and simplify the steps to find the virtual offset. (3) in the VTI medium, a single scattering point model is compared and analyzed. The results of CCSP channel set in isotropic medium and VTI medium show that the scattering point model is distributed according to the hyperbolic distribution and conforms to the mapping law of the converged scatter point channel set, and its convergence is good. The calculation time of the two methods is compared with the use of the string section method and the dichotomous method for the tilted model, and the results show the chord method. The rate of convergence is faster than the dichotomy, and the computational efficiency can be improved. The final imaging results also show the correctness of using these two methods to extract the CCSP set. The two flat layer model proves that the anisotropic parameters will affect the results of the CCSP set and the final imaging effect, so the anisotropic parameters can not be ignored in the actual calculation. The influence of the virtual offset interval and the offset aperture on the imaging effect is verified by the tilt model. It is shown that it is very important to select the appropriate virtual offset interval and the offset aperture in the prestack time migration. Using the single layer VTI medium model, it is found that the construction of accurate velocity function is the key. (4) in the VTI medium, the single layer is concave. The subsidence model, the convex model, the fault model and the multi-layer combination model are used for migration imaging. The accuracy of the POM method is verified, and the imaging results in the isotropic medium and the VTI medium are compared and analyzed. Finally, the method is applied to the actual data, and the better migration imaging results are obtained. It shows that the POM rotation is used in the VTI medium. The method of wave amplitude preserved prestack time migration has certain advantages.

【學(xué)位授予單位】：長安大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：P631.44

【參考文獻】

相關(guān)期刊論文 前1條

1 張中杰;地震各向異性研究進展[J];地球物理學(xué)進展;2002年02期

，

本文編號：1858708