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本文给出了北海中部地区关于地震叠前成像技术的一个简单应用实例。其中应用了两种深度成像方法——共炮检距和共角度叠前深度偏移。由于该研究区块构造不复杂,所以我们有理由相信研究结果能反映出地震资料中速度各向异性的影响。我们根据井约束建立了速度场,并证明主要标志层的双程旅行时能与井精确地闭合。还证明由叠前偏移得到的小角度(和小炮检距)深度成像也与速度场(由井导出的)相一致。然而,大角度(和大炮检距)深度偏移得到的资料比小角度的要浅。我们假定地层存在弱的速度各向异性(用Thomsen标记法),并证明椭圆深度偏移(ε=δ)和横向各向同性(TI)深度偏移(ε≠δ)方法在广阔的炮检距范围内能提供更精确的深度成像。我们认识到,在关键的各向异性参数估算中有很强的多解性。为此我们设计了一个方案,使其产生一个资料更能精确成像的模型估计,并有可能在一定程度上使人们深入理解速度、δ、ε等参数在弱的各向异性介质深度偏移中的相对重要性。
This paper presents a simple application example of seismic prestack imaging in the central North China Sea. Two types of depth imaging methods are used-common offsetting and common angle pre-stack depth migration. Due to the uncomplicated structure of the study block, we have reason to believe that the results of the study can reflect the effects of velocity anisotropy in seismic data. We set up a velocity field based on the well constraints and proved that the main marker layers were well closed to the well during the two-way trip. It has also been demonstrated that small-angle (and small-offset) depth imaging resulting from prestack migration is also consistent with the velocity field (derived from the well). However, the depth of the large-angle (and large offset) information obtained by the depth of shallow than shallow. We assume that there is a weak velocity anisotropy in the formation (using Thomsen’s notation) and demonstrate that elliptical depth migration (ε = δ) and transverse isotropy (TI) depth migration (ε ≠ δ) Within the range to provide more accurate depth imaging. We recognize that there is strong multi-solution in the estimation of key anisotropic parameters. To this end, we have devised a scheme to generate a more accurate model for the estimation of the data, and it is possible to gain some insight into the velocity, δ, ε and other parameters in weak anisotropic media depth migration The relative importance of.