本文選題：射線追蹤 + 旅行時線性插值法��； 參考：《長安大學》2017年碩士論文

【摘要】：簡單地表條件下的地震勘探已不能滿足人們?nèi)找嬖鲩L的需求,因此需要向具有復雜地表條件的地區(qū)或更深的區(qū)域進行,同時為了進一步開發(fā)我國西部地區(qū)油氣藏,那么研究地震波在起伏地表地質(zhì)模型中的傳播規(guī)律就顯得尤為重要。然而,在起伏地表地區(qū)利用地震勘探工作進行油氣藏的開發(fā)和利用會面臨各種各樣復雜難以處理的問題,例如:地震數(shù)據(jù)采集困難、采集到的地震數(shù)據(jù)質(zhì)量差不能用于研究、散射干擾嚴重、成像效果不好甚至不成像等。因此,本文在前人研究的LTI的基礎(chǔ)上,研究地震波在起伏地表地下介質(zhì)中的傳播情況。為了提高起伏地表和復雜構(gòu)造條件下LTI法對地表和速度界面的處理能力以及地震波旅行時的計算精度和效率。本文對完全矩形網(wǎng)格剖分的LTI方法進行了改進,提出用矩形網(wǎng)和不規(guī)則四邊形網(wǎng)相結(jié)合的方法離散速度模型,即采用不規(guī)則四邊形網(wǎng)剖分起伏地表和起伏界面附近的速度模型,而速度模型的其他部分則采用矩形網(wǎng)剖分,分別對矩形網(wǎng)和不規(guī)則四邊形網(wǎng)采用適用于矩形網(wǎng)和適用于不規(guī)則四邊形網(wǎng)的局部旅行時計算公式。通過全矩形網(wǎng)格剖分模型LTI法和混合網(wǎng)格剖分模型LTI法對同一均勻速度模型進行模型試算及誤差分析,其結(jié)果表明,本文提出的網(wǎng)格剖分方法計算效率和計算精度更高;通過使用混合網(wǎng)格LTI法追蹤Marmousi模型中地震波的傳播情況,由獲得的地震波的射線路徑說明此方法正確可靠。本文將分區(qū)多步思想應(yīng)用于起伏地表多類波傳播路徑的LTI射線追蹤中,用此方法計算多波的旅行時同時追蹤其射線路徑。通過模擬起伏地表層狀模型中的多次反射波和多次透射反射轉(zhuǎn)換波并進行誤差分析,驗證了分區(qū)多步LTI法在追蹤多類地震波時具有誤差收斂、數(shù)值穩(wěn)定等特點;同時模擬了人為劃定劇烈起伏地表的Marmousi模型中的一次反射波和多次反射波,從獲得的多次波的射線路徑和波前擴展過程圖可以看出起伏地表分區(qū)多步LTI法具有準確可靠的特點。
[Abstract]:Seismic exploration under simple surface conditions can no longer meet the increasing needs of people, so it is necessary to carry out seismic exploration in areas with complex surface conditions or deeper areas, and in order to further develop oil and gas reservoirs in the western part of China. So it is very important to study the propagation law of seismic wave in undulating surface geological model. However, the exploitation and utilization of oil and gas reservoirs by seismic exploration in undulating surface areas will face a variety of complex and difficult problems, such as the difficulty of seismic data acquisition, the poor quality of collected seismic data can not be used for research, The scattering interference is serious, the imaging effect is not good or even does not appear. Therefore, on the basis of LTI, the propagation of seismic waves in undulating surface and underground media is studied in this paper. In order to improve the processing ability of the LTI method to the surface and the velocity interface under the undulating surface and complex tectonic conditions, the calculation accuracy and efficiency of the seismic wave travel time are improved. In this paper, the LTI method of complete rectangular mesh generation is improved, and a discrete velocity model is proposed by combining rectangular mesh with irregular quadrilateral mesh, that is, the irregular quadrilateral mesh is used to divide the velocity model near the undulating surface and the undulating interface. The other parts of the velocity model are divided into rectangular mesh and irregular quadrilateral network respectively. The local travel time formulas suitable for rectangular network and irregular quadrilateral network are used respectively. By using LTI method and LTI method, the model of uniform velocity is calculated and the error is analyzed. The results show that the mesh generation method proposed in this paper is more efficient and accurate. The propagation of seismic waves in the Marmousi model is tracked by using the mixed grid LTI method. The ray paths of the obtained seismic waves show that this method is correct and reliable. In this paper, the idea of partition multistep is applied to the LTI ray tracing of multi-wave propagation paths on undulating surface. The method is used to calculate the travel time of multi-waves and track their ray paths simultaneously. By simulating and analyzing the multi-reflection and multi-transmission converted waves in the layered model of undulating surface, it is verified that the multi-step LTI method has the characteristics of error convergence and numerical stability in tracking multi-type seismic waves. At the same time, the primary and multiple reflection waves in the Marmousi model are simulated. From the ray paths and wavefront propagation process of the multiple waves obtained, it can be seen that the multistep LTI method has the characteristics of accuracy and reliability.
【學位授予單位】：長安大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：P631.4

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本文編號：2056571