Conventional shot-gather migration uses a cross-correlation imaging condition proposed by Clarebout （1971）, which cannot preserve imaging amplitudes. The deconvolution imaging condition can improve the imaging ampli...Conventional shot-gather migration uses a cross-correlation imaging condition proposed by Clarebout （1971）, which cannot preserve imaging amplitudes. The deconvolution imaging condition can improve the imaging amplitude and compensate for illumination. However, the deconvolution imaging condition introduces instability issues. The least-squares imaging condition first computes the sum of the cross-correlation of the forward and backward wavefields over all frequencies and sources, and then divides the result by the total energy of the forward wavefield. Therefore, the least-squares imaging condition is more stable than the classic imaging condition. However, the least-squares imaging condition cannot provide accurate results in areas where the illumination is very poor and unbalanced. To stabilize the least-squares imaging condition and balance the imaging amplitude, we propose a novel imaging condition with structure constraints that is based on the least-squares imaging condition. Our novel imaging condition uses a plane wave construction that constrains the imaging result to be smooth along geological structure boundaries in the inversion frame. The proposed imaging condition improves the stability of the imaging condition and balances the imaging amplitude. The proposed condition is applied to two examples, the horizontal layered model and the Sigsbee 2A model. These tests show that, in comparison to the damped least-squares imaging condition, the stabilized least-squares imaging condition with structure constraints improves illumination stability and balance, makes events more consecutive, adjusts the amplitude of the depth layers where the illumination is poor and unbalanced, suppresses imaging artifacts, and is conducive to amplitude preserving imaging of deep layers.展开更多
O431 99021399二维剪切波面重建的有限元模型=Finite elementmodel for the reconstruction of two—dimensionalshearing wavefront[刊,中]/白剑,杨国光(浙江大学现代光学仪器国家重点实验室.浙江,杭州(310027))∥光学学报.—1998,18(...O431 99021399二维剪切波面重建的有限元模型=Finite elementmodel for the reconstruction of two—dimensionalshearing wavefront[刊,中]/白剑,杨国光(浙江大学现代光学仪器国家重点实验室.浙江,杭州(310027))∥光学学报.—1998,18(6).—726-731提出了解析二维剪切波面的有限元方法,建立了二维剪切波面重建的有限元模型。计算机模拟结果表明,有限元法解析二维剪切波面精度高,对剪切波面具有平均作用,对测量误差不敏感,可适用于实时测量。图9表2参10(严寒)展开更多
According to the Collins’ formula and its inverse diffraction computation,this paper presents an algorithm for reconstructing the object wavefront of a numerical holograph.To improve the quality of wavefront reconstr...According to the Collins’ formula and its inverse diffraction computation,this paper presents an algorithm for reconstructing the object wavefront of a numerical holograph.To improve the quality of wavefront reconstruction,a technique of eliminating the zero-order diffraction light is introduced,which is achieved by subtraction of two intensities of the interference patterns.The computer simulation and image processing show that the method of eliminating the zero-order diffraction beam can be applied to the wavefront reconstruction of inverse diffraction computation.展开更多
基金financially supported by Important National Science and Technology Specific Projects of China(Grant No. 2011ZX05023-005-005)
文摘Conventional shot-gather migration uses a cross-correlation imaging condition proposed by Clarebout （1971）, which cannot preserve imaging amplitudes. The deconvolution imaging condition can improve the imaging amplitude and compensate for illumination. However, the deconvolution imaging condition introduces instability issues. The least-squares imaging condition first computes the sum of the cross-correlation of the forward and backward wavefields over all frequencies and sources, and then divides the result by the total energy of the forward wavefield. Therefore, the least-squares imaging condition is more stable than the classic imaging condition. However, the least-squares imaging condition cannot provide accurate results in areas where the illumination is very poor and unbalanced. To stabilize the least-squares imaging condition and balance the imaging amplitude, we propose a novel imaging condition with structure constraints that is based on the least-squares imaging condition. Our novel imaging condition uses a plane wave construction that constrains the imaging result to be smooth along geological structure boundaries in the inversion frame. The proposed imaging condition improves the stability of the imaging condition and balances the imaging amplitude. The proposed condition is applied to two examples, the horizontal layered model and the Sigsbee 2A model. These tests show that, in comparison to the damped least-squares imaging condition, the stabilized least-squares imaging condition with structure constraints improves illumination stability and balance, makes events more consecutive, adjusts the amplitude of the depth layers where the illumination is poor and unbalanced, suppresses imaging artifacts, and is conducive to amplitude preserving imaging of deep layers.
文摘O431 99021399二维剪切波面重建的有限元模型=Finite elementmodel for the reconstruction of two—dimensionalshearing wavefront[刊,中]/白剑,杨国光(浙江大学现代光学仪器国家重点实验室.浙江,杭州(310027))∥光学学报.—1998,18(6).—726-731提出了解析二维剪切波面的有限元方法,建立了二维剪切波面重建的有限元模型。计算机模拟结果表明,有限元法解析二维剪切波面精度高,对剪切波面具有平均作用,对测量误差不敏感,可适用于实时测量。图9表2参10(严寒)
基金Supported bythe Natural Science Foundation of Yunnan Province(2004F0025 M)
文摘According to the Collins’ formula and its inverse diffraction computation,this paper presents an algorithm for reconstructing the object wavefront of a numerical holograph.To improve the quality of wavefront reconstruction,a technique of eliminating the zero-order diffraction light is introduced,which is achieved by subtraction of two intensities of the interference patterns.The computer simulation and image processing show that the method of eliminating the zero-order diffraction beam can be applied to the wavefront reconstruction of inverse diffraction computation.
