【摘要】 波与非均匀介质的相互作用是多年来地球物理研究的理论问题之一.本文基于地震成像算子,定量分析了库车坳陷盐相关逆冲推覆构造的复杂性.首先,根据地震资料计算了大北构造、博孜构造、却勒构造、西秋10构造和西秋4构造的速度横向变化非均质谱和地层倾角变化非均质谱,这些量化表征高陡构造地质复杂性的地质非均质谱定量描述了速度横向变化和地层倾角变化分布.然后,通过地质非均质谱与地震成像算子角谱的点积运算,计算得到各个构造的地震成像效率和地震探测复杂系数,实现对库车坳陷复杂高陡构造地震探测复杂性的定量评估.结果表明,沿却勒至西秋一线构造带明显比大北至博孜构造带复杂,复杂系数沿却勒、西秋10至西秋4构造走向逐渐加大,主要表现为强速度扰动主分量所占比重增大,地质非均质谱带宽增大,非峰值岩性分量和倾角分量也相对较强,地震成像的难度逐渐加大,时间域成像易于形成严重的成像畸变和很强的偏移噪音,建议加强速度建模和叠前深度成像攻关研究.更多还原

【Abstract】 How a wave interacts with heterogeneous media has been pursued by many geophysicists.Based on seismic imaging operators,we conduct a quantitative assessment of the complexity of salt-related overthrust complex structures in Kuqa depression.We first use seismic data to compute the slowness spectrum and the dipping-angle spectrum for the Dabei,Bozi, Quele,Xiqiu 10,and Xiqiu 4 structures,respectively.These heterogeneity spectra express the geological complexity of subsurface structures as a spectrum to quantify lateral velocity variations and dipping-angle distributions.Through an interaction between the geological heterogeneity spectra and the migrator s angular spectra,we obtain imaging efficiencies and complexity coefficients for these complex structures in Kuqa depression,which quantitatively evaluate the geological complexity in terms of migrators.The results indicate that the Quele-Xiqiu structure zone is more complex than the Dabei-Bozi structure zone.Along Quele through Xiqiu 10 to Xiqiu 4,the complexity coefficient gradually increases because of stronger velocity contrasts,broader heterogeneity spectra,richer off-peak spectral contents in the slowness and dipping-angle spectra.These conclude that time migrations for complex Kuqa structures are prone to cause wrong imaging and migration noise.Depth migrations should be enhanced for Kuqa depression.更多还原