【摘要】：可控震源進(jìn)行地震勘探時(shí)，由于單震源激發(fā)能量較弱，可采用相控震源系統(tǒng)來(lái)提高激發(fā)信號(hào)能量。但相控震源系統(tǒng)存在搬運(yùn)困難、震源間的非一致性等問(wèn)題，可以利用接收端地震波束形成方法來(lái)提高單震源數(shù)據(jù)質(zhì)量。接收端地震波束形成方法是對(duì)地震數(shù)據(jù)進(jìn)行預(yù)處理的方法，對(duì)震源間的一致性和控制精度沒(méi)有嚴(yán)格的要求，因此相對(duì)相控震源系統(tǒng)應(yīng)用起來(lái)比較靈活、高效。 對(duì)于常規(guī)的接收端地震波束形成方法，如果地震勘探測(cè)區(qū)的噪聲很強(qiáng)，就需要增加疊加炮數(shù)N來(lái)提高合成后的地震數(shù)據(jù)中有效地震波的能量，，從而達(dá)到提高數(shù)據(jù)質(zhì)量的目的。由波束形成理論容易得出，波束的寬度將隨著疊加炮數(shù)N的增大而減小，若增大N后，使得有效地震波束寬度無(wú)法覆蓋全部檢波器排列，那么，常規(guī)的接收端地震波束形成方法合成的地震數(shù)據(jù)將難以滿(mǎn)足后續(xù)數(shù)據(jù)處理過(guò)程要求。 針對(duì)上述問(wèn)題，本文提出一種基于接收陣列的余弦振幅加權(quán)定向地震波束形成方法（Seismic directional beam-forming with the Cosine amplitude distribution，SDBCAD）。SDBCAD方法首先對(duì)各單炮記錄乘以相應(yīng)的余弦振幅因子值，然后進(jìn)行時(shí)間域的延時(shí)疊加生成定向地震記錄。使得合成后的有效波束范圍展寬，同相軸連續(xù)范圍延長(zhǎng)，進(jìn)一步改善合成單炮記錄的質(zhì)量，提高目的層橫向分辨率，為后續(xù)數(shù)據(jù)處理提供了更高質(zhì)量的數(shù)據(jù)。 首先，闡述了定向地震波束形成理論。推導(dǎo)了陣列地震波束的方向因子，根據(jù)方向因子得出了波束的主要特性，分析并研究了影響地震波束特性的主要參數(shù)。 其次，闡述了余弦加權(quán)定向地震波束形成原理與方法。推導(dǎo)了余弦加權(quán)波束的方向因子，分析了影響余弦加權(quán)地震波束特性的主要參數(shù)：震源（單炮記錄）數(shù)量、炮點(diǎn)間距、加權(quán)系數(shù)矩陣等，并研究了各參數(shù)對(duì)地震波束的影響。給出了余弦加權(quán)波束形成的參數(shù)選取方法和定向地震記錄合成方法。 再次，對(duì)余弦振幅加權(quán)方法進(jìn)行了初步的數(shù)值模擬。建立了一個(gè)水平層狀地質(zhì)模型，利用射線(xiàn)追蹤的方法合成了多個(gè)單震源地震記錄，并給出了單震源、均勻加權(quán)方法、余弦加權(quán)方法合成的單炮記錄。通過(guò)對(duì)比三種方式的單炮記錄，說(shuō)明了均勻加權(quán)方法能夠?qū)崿F(xiàn)地震波束定向，提高地震數(shù)據(jù)質(zhì)量；余弦加權(quán)方法增大了有效的地震波束范圍，使目標(biāo)地層同向軸更加連續(xù)，提高了地震記錄的整體質(zhì)量。 最后，在研究了方法理論結(jié)果與數(shù)值模擬結(jié)果差異的基礎(chǔ)上，對(duì)余弦加權(quán)波束形成方法參數(shù)進(jìn)行了優(yōu)化設(shè)計(jì)，并利用野外實(shí)驗(yàn)數(shù)據(jù)對(duì)比證明了方法的有效性。
[Abstract]:When vibroseis is used for seismic exploration, because the excitation energy of single source is weak, the phased vibroseis system can be used to improve the excitation signal energy. However, the phase vibroseis system has some problems, such as difficult transportation and inconsistency between sources. The seismic beamforming method at the receiving end can be used to improve the quality of single source data. The seismic beamforming method at the receiving end is a preprocessing method for seismic data, which has no strict requirements for the consistency and control accuracy between sources, so it is more flexible and efficient than the phased vibroseis system. For the conventional seismic beamforming method, if the noise in the seismic exploration survey area is very strong, it is necessary to increase the superposition number N to improve the energy of the effective seismic wave in the synthesized seismic data, so as to achieve the purpose of improving the data quality. It is easy to obtain from the beamforming theory that the width of the beam will decrease with the increase of the number of superimposed beams N. If the effective seismic beam width can not cover all geophone arrangement with the increase of N, The seismic data synthesized by conventional seismic beamforming methods at the receiving end will be difficult to meet the requirements of subsequent data processing. In order to solve the above problems, a cosine amplitude weighted directional seismic beamforming method based on receiving array (Seismic directional beam-forming with the Cosine amplitude distribution,SDBCAD) is proposed in this paper. SDBCAD method first times the corresponding cosine amplitude factor value for each single shot record. Then the time domain delay superposition is carried out to generate directional seismic records. The effective beam range after synthesis is widened and the continuous range of in-phase axis is extended, which further improves the quality of synthetic single gun record, improves the transverse resolution of the target layer, and provides higher quality data for subsequent data processing. Firstly, the theory of directional seismic beamforming is expounded. The direction factor of array seismic beam is derived. according to the direction factor, the main characteristics of the beam are obtained, and the main parameters affecting the seismic beam characteristics are analyzed and studied. Secondly, the principle and method of cosine weighted directional seismic beamforming are described. The direction factor of cosine weighted beam is derived, and the main parameters affecting the characteristics of cosine weighted seismic beam are analyzed, such as the number of sources (single shot record), the distance between shot points, the weighting coefficient matrix, etc., and the influence of each parameter on seismic beam is studied. The parameter selection method and directional seismic record synthesis method of cosine weighted beamforming are given. Thirdly, the cosine amplitude weighting method is simulated. In this paper, a horizontal layered geological model is established, and several single source seismic records are synthesized by ray tracing method, and the single gun records synthesized by single source, uniform weighting method and cosine weighting method are given. By comparing the single gun records of the three methods, it is shown that the uniform weighting method can realize seismic beam orientation and improve the quality of seismic data. The cosine weighting method increases the effective seismic beam range, makes the coaxial axis of the target strata more continuous, and improves the overall quality of seismic records. Finally, on the basis of studying the difference between the theoretical results of the method and the numerical simulation results, the parameters of the cosine weighted beamforming method are optimized, and the effectiveness of the method is proved by comparing the field experimental data.
【學(xué)位授予單位】：吉林大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：P631.4

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