【摘要】：海洋拖纜采集中,檢波器接收到的記錄包括來自地下反射界面的一次反射波和一次反射波到經過海水表面反射到達檢波器的虛反射(鬼波)。鬼波緊隨一次波后,與一次波相互干涉,改變了一次反射波的波形特征,甚至產生虛假的同相軸。此外,鬼波的陷頻特性,使得地震資料頻帶變窄,降低了地震資料的分辨率,給地震資料反演、解釋帶來了困難。高分辨率的寬頻帶地震資料是實現(xiàn)對地下復雜地質體精確成像的先決條件,為了得到高分辨率的寬頻帶地震資料,地震資料處理過程中需要對鬼波進行壓制。鬼波壓制過程中,起伏海面是不可忽略的一個影響因素。然而,目前針對單分量拖纜鬼波壓制的方法都是基于平坦海表面的假設,導致對鬼波算子參數(shù)(海表面反射系數(shù)、鬼波延遲時間)估計不準確,使得鬼波壓制不完全,去鬼波結果中引入不必要的竄擾噪音,陷波點能量得不到較好的恢復。針對以上問題,本文首先對鬼波的產生機理進行了研究。然后介紹了頻率-時間域、頻率-波數(shù)域、拉東域常規(guī)鬼波壓制方法的原理和適用條件,并分析了起伏海表面對鬼波壓制效果的影響。最后提出了起伏海面背景下的頻率域自適應鬼波壓制方法和拉東域鬼波壓制方法,實現(xiàn)對鬼波的精準壓制,為海上地震資料的鬼波壓制提供了技術支持�；谛盘柷投茸畲蠡念l率域自適應鬼波壓制方法,通過定義峭度系數(shù)來評價去鬼波結果的質量,通過設定搜索范圍,對鬼波延遲時間進行搜索,能自適應準確估計最優(yōu)反射系數(shù)和鬼波延遲時間,達到自適應壓制鬼波的目的。該方法無論是在平坦海表面背景或者起伏海表面背景下,都能有效地壓制鬼波,使得陷波點處的能量得到恢復,地震剖面的頻帶寬度得到拓寬�；诤１砻娉上竦睦瓥|域鬼波壓制方法,通過求解最小線性拉東方程得到海表面處上行波場,正向和反向延拓海表面處上行波場至檢波器處,利用最小二乘反演精確求解獲得海表面處上行波場,采用最小平方成像條件成像海表面,進而校正檢波器實際沉放深度來消除起伏海面的影響,實現(xiàn)了起伏海面背景下鬼波的壓制。方法通過考慮起伏海表面對鬼波的影響,改善基于平坦海表面假設下鬼波壓制不完全的情況。數(shù)值模擬數(shù)據和海上實際拖纜數(shù)據測試結果表明,該方法能更好地壓制鬼波,最大程度拓寬地震記錄頻帶。
[Abstract]:In the acquisition of ocean towing cables, the records received by the geophone include one reflection from the underground reflection interface and one reflection wave to the virtual reflection (ghost wave) which is reflected through the sea water surface to the geophone. After the first wave, the ghost wave interacts with the first wave, which changes the waveform characteristics of the first reflection wave, and even produces a false cophase axis. In addition, the notch frequency characteristic of ghost wave makes the frequency band of seismic data narrow, reduces the resolution of seismic data, and brings difficulties to inversion and interpretation of seismic data. Broadband seismic data with high resolution is a prerequisite for accurate imaging of underground complex geological bodies. In order to obtain broadband seismic data with high resolution, ghost waves need to be suppressed in the process of seismic data processing. In the process of ghost wave suppression, undulating sea surface is a factor that can not be ignored. However, the current methods for suppressing ghost waves by single component towing cable are based on the assumption of flat sea surface, which leads to inaccurate estimation of the parameters of ghost wave operator (reflection coefficient of sea surface, delay time of ghost wave), which makes the suppression of ghost waves incomplete. When unnecessary noise is introduced into the deconvolution result, the energy of the notch point can not be recovered well. In order to solve the above problems, the mechanism of ghost wave is studied in this paper. Then the principle and applicable conditions of conventional ghost wave suppression methods in frequency-time domain, frequency-wavenumber domain and Radon domain are introduced, and the influence of the surface of undulating sea on the suppression effect of ghost waves is analyzed. Finally, the adaptive suppression method in frequency domain and the ghost wave suppression method in Radon region in the background of undulating sea surface are proposed to achieve the accurate suppression of ghost wave, which provides technical support for the suppression of ghost wave in seismic data on the sea. Based on the frequency domain adaptive ghost suppression method based on the maximum kurtosis of signal, the kurtosis coefficient is defined to evaluate the quality of the deghost result, and the delay time of the ghost wave is searched by setting the search range. The optimal reflection coefficient and ghost delay time can be estimated adaptively and accurately, and the purpose of adaptive suppression of ghost wave can be achieved. This method can suppress ghost wave effectively in the background of flat sea surface or undulating sea surface, so that the energy at the notch point can be restored and the band width of seismic section can be widened. On the basis of sea surface imaging, the ghost wave suppression method in Lato domain is used to obtain the upward wave field at the sea surface by solving the minimum linear eastward path, and the upstream wave field from the forward and reverse extending sea surface to the geophone. The up-going wave field at the sea surface is obtained by using the least square inversion, and the least square imaging condition is used to image the sea surface, and then the actual sinking depth of the geophone is corrected to eliminate the influence of the undulating sea surface. The suppression of ghost waves under the background of undulating sea surface is realized. Methods the influence of undulating sea surface on ghost wave was considered to improve the incomplete suppression of ghost wave on the assumption of flat sea surface. The numerical simulation data and the actual towed cable data at sea show that the method can suppress ghost waves better and widen the seismic record frequency band to the greatest extent.
【學位授予單位】：吉林大學
【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：2265020