【摘要】：隨著勘探過程中采集條件的限制以及后續(xù)工作處理中對廢道廢炮的剔除,不可避免的使地震波場數(shù)據(jù)存在不完整性,對地震資料的后續(xù)處理產(chǎn)生一定的影響,因此有必要對地震波場數(shù)據(jù)進行重建。但是,受奈奎斯特(Nyqusit)采樣定理的限制,傳統(tǒng)的地震信號重建方法對采樣率有較高的要求。壓縮感知(Compressive/Compressed sensing,CS)理論主要包括信號的稀疏化處理、測量矩陣的構(gòu)造以及重建算法三個部分。重建算法是CS理論的核心內(nèi)容,即通過低維的稀疏信號精確的恢復出原始信號。本文基于CS理論對其重建算法進行了深入研究。選取正交匹配追蹤算法(Orthogonal Matching Pursuit,OMP)作為重建算法,并對OMP的實現(xiàn)原理、算法結(jié)構(gòu)等進行具體的研究同時做出信號仿真。針對OMP算法的重構(gòu)速度比較慢和迭代次數(shù)需要給定的問題,發(fā)展了一種改進方案,將最優(yōu)匹配追蹤算法(Optimized OMP,OOMP)的約束最優(yōu)匹配原子選擇策略和自適應變步長梯度投影(Adaptive Variance Step Gradient Projection method,AVSGP)算法的后向投影思想與其進行結(jié)合。仿真實驗證明,在稀疏條件同等的情況下,改進的OMP算法在重構(gòu)時間及效果方面明顯優(yōu)于傳統(tǒng)OMP算法。針對重建地震波場數(shù)據(jù)中混有隨機噪聲的情況,本文選取曲波閾值法進行去噪,對于處理大規(guī)模數(shù)據(jù)的情況引入分塊思想及二次曲波變換對曲波閾值進行改進。同時與CS理論相結(jié)合,可以重構(gòu)出去噪后的地震信號。通過仿真實驗證明,在稀疏條件同等的條件下,改進的曲波閾值法與原始曲波閾值法相比在去噪方面有明顯提高。最后,對本文的研究工作進行總結(jié),通過對仿真模型的建立驗證出方法的有效及實用性。
[Abstract]:With the limitation of acquisition conditions in the process of exploration and the elimination of abandoned road guns in the subsequent work, the seismic wave field data will inevitably be incomplete, which will have a certain impact on the subsequent processing of seismic data. Therefore, it is necessary to reconstruct seismic wave field data. However, due to the limitation of Nyquist (Nyqusit) sampling theorem, the traditional seismic signal reconstruction method requires high sampling rate. The theory of Compressive/Compressed sensing CS mainly includes three parts: signal sparse processing, measurement matrix construction and reconstruction algorithm. The reconstruction algorithm is the core of CS theory, that is to say, the original signal can be recovered accurately by low dimensional sparse signal. In this paper, the reconstruction algorithm based on CS theory is studied. The orthogonal matching tracking algorithm (Orthogonal Matching pursuit OMP) is selected as the reconstruction algorithm, and the realization principle and algorithm structure of OMP are studied in detail and the signal simulation is made at the same time. Aiming at the problem that the reconstruction speed of OMP algorithm is slow and the number of iterations need to be given, an improved scheme is developed. The constrained optimal matching atomic selection strategy of the optimal matching tracking algorithm (Optimized OMP) and the backward projection idea of the adaptive variable step size gradient projection (Adaptive Variance Step Gradient Projection method AVSGP algorithm are combined. Simulation results show that the improved OMP algorithm is superior to the traditional OMP algorithm in reconstruction time and effect under the same sparse condition. In order to solve the problem of mixed random noise in reconstructed seismic wave field data, this paper selects Qu Bo threshold method for denoising, and introduces the block idea and the quadratic Qu Bo transform to improve the Qu Bo threshold when dealing with large scale data. At the same time, combined with CS theory, the seismic signal after noise can be reconstructed. The simulation results show that the improved Qu Bo threshold method is better than the original Qu Bo threshold method in denoising under the same sparse condition. Finally, the research work of this paper is summarized, and the effectiveness and practicability of the method are verified by the establishment of simulation model.
【學位授予單位】：東北石油大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：P631.4

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本文編號：2181318