本文關(guān)鍵詞： 全波形反演 隨機(jī)相位編碼技術(shù) L-BFGS算法 Huber函數(shù)　出處：《吉林大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：油氣資源目前是世界上最重要的一次能源之一。隨著社會的發(fā)展，油氣勘探逐漸由淺層向深層轉(zhuǎn)移，傳統(tǒng)的地震勘探方法的反演深度比較淺，對地下深層反演結(jié)果不能滿足精度要求。不同于旅行時層析成像和偏移速度分析，全波形反演能夠充分利用地震記錄中的所有信息，是一種高分辨率的反演方法，具有揭示復(fù)雜地質(zhì)背景下構(gòu)造與巖性細(xì)節(jié)的潛力。 全波形反演的目標(biāo)是利用野外采集所得地震記錄的振幅、相位等信息恢復(fù)得到地下介質(zhì)的物性參數(shù)模型。全波形反演理論的實現(xiàn)是利用一種非線性優(yōu)化算法將波場殘差（實際采集的觀測波場與對初始模型正演得到的理論波場之差）對應(yīng)的目標(biāo)函數(shù)極小化，不斷地優(yōu)化初始模型，最終得到地下介質(zhì)的速度分布。 本論文基于二維聲波介質(zhì)，針對全波形反演計算量大，對內(nèi)存要求高，，以及實際應(yīng)用中受噪聲影響大的問題做了研究，并提出了一系列的方案加以解決。 全波形反演中為了保證反演結(jié)果的精度，往往要進(jìn)行很多次迭代，每次迭代中，需要對參與反演的所有炮集所對應(yīng)的震源激發(fā)位置做波場傳播正演模擬，從而導(dǎo)致很大的計算量和內(nèi)存需求。多炮正演模擬中引入隨機(jī)相位編碼技術(shù)，通過將不同位置的多個震源組合成超級炮，大大減少了正演模擬所需要的時間。并且有效的壓制了串?dāng)_噪聲的影響。 全波形反演局部優(yōu)化算法采用L-BFGS算法。L-BFGS局部優(yōu)化算法對計算機(jī)內(nèi)存的占用少，不需要存儲Hessian矩陣，只需要保存少量向量對Hessian矩陣進(jìn)行更新，并且收斂速度快，計算精度高。 實際數(shù)據(jù)中往往存在噪聲，對反演結(jié)果影響很大，目標(biāo)函數(shù)基于Huber函數(shù)形式的全波形反演同時結(jié)合了L1范數(shù)抗噪性和L2范數(shù)穩(wěn)定性的優(yōu)點(diǎn)，在觀測地震記錄存在噪聲的情況下也能得到很好的反演結(jié)果。
[Abstract]:Oil and gas resources are currently one of the most important primary energy sources in the world. With the development of society, oil and gas exploration is gradually transferred from shallow to deep layer, and the inversion depth of traditional seismic exploration method is relatively shallow. Different from travel time tomography and migration velocity analysis, full waveform inversion can make full use of all the information in seismic records, so it is a high resolution inversion method. It has the potential to reveal the details of structure and lithology in complex geological background. The goal of full waveform inversion is to use the amplitude of seismic records obtained from field acquisition. The whole wave inversion theory is to use a nonlinear optimization algorithm to calculate the residual error of the wave field (the observed wave field and the theory of forward modeling for the initial model). On the minimization of the objective function corresponding to the difference of wave field, The initial model is continuously optimized and the velocity distribution of underground media is finally obtained. Based on the two-dimensional acoustic medium, this paper studies the problems of large computation amount of full waveform inversion, high memory requirement, and the influence of noise in practical application, and puts forward a series of schemes to solve the problem. In order to ensure the accuracy of the inversion results, many iterations are often carried out in the whole waveform inversion. In each iteration, it is necessary to do forward simulation of the wave field propagation at the source excitation positions corresponding to all the gun sets involved in the inversion. The random phase coding technique is introduced in the forward modeling of multiple guns, and by combining multiple seismic sources in different positions into super guns, It greatly reduces the time required for forward modeling and effectively suppresses the influence of crosstalk noise. The whole waveform inversion local optimization algorithm uses L-BFGS algorithm. L-BFGS local optimization algorithm occupies less memory, does not need to store Hessian matrix, only needs to save a small number of vectors to update the Hessian matrix, and the convergence speed is fast and the calculation accuracy is high. There is always noise in the actual data, which has a great influence on the inversion results. The full waveform inversion of the objective function based on Huber function combines the advantages of L1 norm anti-noise and L2 norm stability at the same time. Good inversion results can also be obtained in the presence of noise in observed seismic records.
【學(xué)位授予單位】：吉林大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：P631.4

【共引文獻(xiàn)】

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本文編號：1503350