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倾斜页岩的地震各向异性会使下伏构造的成像和归位出现问题我们开发了一种适合于横向各向同性介质的P波地震资料的各向异性深度偏移方法,这种横向各向同性介质具有垂直于地层的倾斜对称轴。我们在深度成像速度模型中加入了各向异性及倾角参数,并使用叠前深度偏移成像道集以一种诊断方式来修改各向异性速度模型。用各向异性偏移和各向同性偏移得到的倾斜各向异性介质下面的构造的视位置差别很大。用修改后的2-D叠前基尔霍夫深度偏移的射线追踪算法来计算具有倾斜对称轴的横向各向同性介质的旅行时。并将得到的各向异性深度偏移结果应用于物理模型的地震救据和从加拿大落基山冲断层和褶皱带采集的野外地震数据。与用各向同性算法计算的结果相比,各向共性深度偏移能给出归位和反射层连续性得到明显改善的结果。
Seismic Anisotropy of Tilting Shales Causes Imaging and Homing Problems in Underlying Structures We have developed an anisotropic depth migration method for P-wave seismic data suitable for transversely isotropic media The isotropic medium has a tilt axis of symmetry perpendicular to the formation. We added anisotropy and dip parameters to the depth imaging velocity model and modified the anisotropic velocity model using a diagnostic approach using prestack depth migration imaging gathers. The apparent positions of the structures under the slant anisotropy medium obtained with anisotropic and isotropic deviations are greatly different. A modified 2-D pre-stack Kirchhoff depth-shift ray tracing algorithm was used to calculate the travel time of a transversely isotropic medium with a tilted axis of symmetry. The obtained anisotropic depth migration results are applied to the physical model of seismic rescue and field seismic data collected from the Canadian Rocky Mountain thrust and fold belt. Compared with the results calculated with the isotropic algorithm, the isotropic generalized depth offset can give a significant improvement in the homing and reflective layer continuity.