基于衰减补偿的高斯束偏移方法研究

发布时间：2018-09-08 13:11

【摘要】：高斯束偏移是近年来发展的一种较好的偏移算法,它不仅具有接近于波动方程偏移的成像精度,而且保留了Kirchhoff积分方法高效灵活的优点,能够有效解决多值走时问题。由于实际地下介质的黏滞性引起地震波传播过程中的振幅衰减和相位畸变,降低了地震勘探的分辨率,影响了偏移成像的质量。本文以补偿地震波在黏弹性介质中的衰减,增强深层反射能量,提高偏移成像质量为目标,以高斯束偏移理论为基础,研究基于衰减补偿的高斯束偏移方法。为了用高斯束法模拟黏弹性介质中波的传播,本文基于已有的弹性高斯束理论,引入与品质因子Q有关的复速度和精确的黏弹性Zoeppritz方程,合成黏弹性地震记录。为了对衰减的地震记录进行补偿,本文首先基于共炮域高斯束偏移原理,推导补偿吸收衰减的表达式,校正品质因子Q引起的振幅衰减和相位畸变,实现基于吸收衰减补偿的高斯束偏移。数值试验和实际资料表明,该方法有效补偿了深层反射能量,提高了偏移成像质量。然后,本文利用格林函数合成正传和反传波场,基于互相关成像条件实现共炮域高斯束逆时偏移,并在此基础上引入与Q有关的吸收(补偿)算子,对比高斯束波场格林函数与频率域波动方程正演格林函数的精度,给出补偿原理和流程,实现基于吸收衰减补偿的高斯束逆时偏移。基于衰减补偿的高斯束逆时偏移同时补偿正传和反传波场,校正波传播中的旅行时,可以得到与波动方程逆时偏移补偿相当的效果。多分量地震勘探能得到PP波和PS波数据,与仅有P波相比,这些波携带了目标区不同的信息,他们能够提供更多的地球物理参数,有效地提高了地震勘探的精度。因此,为了充分利用多分量信息,本文在黏声波高斯束偏移和黏声波高斯束逆时偏移方法的基础上提出了基于吸收衰减补偿的多分量高斯束偏移和基于吸收衰减补偿的多分量高斯束逆时偏移。首先把波场分解为PP波和PS波,然后分别基于声波方程的标量方法做偏移,目的是提供一个新的有效的多分量数据成像技术,同时补偿多分量地震记录的衰减效应。数值试验结果表明,以上两种基于衰减补偿的多分量高斯束偏移方法均有效地改进了多分量地震记录的成像精度,提高了偏移成像分辨率,尤其是在强吸收区域。
[Abstract]:Gao Si beam migration is a better migration algorithm developed in recent years. It not only has the imaging accuracy close to wave equation migration, but also retains the advantages of Kirchhoff integration method, which can effectively solve the multi-value travel time problem. The amplitude attenuation and phase distortion in the process of seismic wave propagation are caused by the viscous property of the actual underground medium, which reduces the resolution of seismic exploration and affects the quality of migration imaging. In order to compensate the attenuation of seismic waves in viscoelastic media, enhance the deep reflection energy and improve the imaging quality of migration, based on Gao Si's beam migration theory, this paper studies a new method of Gao Si beam migration based on attenuation compensation. In order to simulate the propagation of waves in viscoelastic media by using Gao Si beam method, the viscoelastic seismic records are synthesized by introducing complex velocities and accurate viscoelastic Zoeppritz equations related to the quality factor Q based on the existing theory of elastic Gao Si beams. In order to compensate for the attenuation of seismic records, based on the principle of Gao Si beam migration in common gun domain, the expression of compensation for absorption attenuation is derived, and the amplitude attenuation and phase distortion caused by quality factor Q are corrected. Gao Si beam offset based on absorption attenuation compensation is realized. Numerical experiments and practical data show that the method can effectively compensate the deep reflection energy and improve the migration imaging quality. Then, the forward and backward wave fields are synthesized by Green's function, and the inverse time migration of Gao Si beam in common gun domain is realized on the basis of cross-correlation imaging condition. On this basis, the absorption (compensation) operator related to Q is introduced. Comparing the accuracy of Green's function of Gao Si beam wave field with that of forward Green's function of wave equation in frequency domain, the principle and flow of compensation are given, and then the inverse time migration of Gao Si beam based on absorption attenuation compensation is realized. Based on attenuation compensation, Gao Si beam inverse time migration compensates both forward and back wave fields, and the travel time in wave propagation can be corrected, which is equivalent to the compensation of wave equation inverse time migration. PP wave and PS wave data can be obtained by multi-component seismic exploration. Compared with only P wave, these waves carry different information of target area, they can provide more geophysical parameters and effectively improve the accuracy of seismic exploration. Therefore, in order to make full use of multi-component information, In this paper, based on the methods of Gao Si beam migration of viscoacoustic wave and the inverse time migration method of Gao Si beam, we propose a new method, which is based on absorption attenuation compensation, and a new method based on absorption attenuation compensation, which is based on the inverse time migration of Gao Si beam, which is based on absorption attenuation compensation. First, the wave field is decomposed into PP wave and PS wave, and then the scalar method based on acoustic wave equation is used to offset the wave field. The aim is to provide a new and effective multi-component data imaging technique and compensate for the attenuation effect of multi-component seismic records. The numerical results show that the above two methods based on attenuation compensation can effectively improve the imaging accuracy of multi-component seismic records and improve the resolution of migration imaging, especially in the strong absorption region.
【学位授予单位】：中国石油大学(北京)
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P631.4

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