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构造深度偏移的目标是为了提供地下反射界面的精确聚焦和空间位置。为了达到这个目的,必须建立速度模型,该模型必须包含与精确描述波在地下传播的运动学有关的全部信息。这可能是一项艰难的任务,但综合各种资料和了解当地的地质情况,便能极大地帮助该任务的完成。现在介绍两个实例,以说明如何使用深度偏移精确预测地质目标深度。在第一个实例中,为了获得可靠地认识目标所能接受的聚焦,叠前偏移是必要的。在第二个实例中,速度模型必须是各向异性的,以便满意地描述地下波传播的运动学特征,而使用叠前偏移是为了使一系列倾角能够成像。
The goal of constructing a depth offset is to provide a precise focus and spatial location of the subsurface reflection interface. To do this, a speed model must be established that must contain all the information that relates the kinematics that accurately describe the wave propagation in the ground. This can be a difficult task, but the combination of various sources and knowledge of the local geology can greatly assist in the task. We now present two examples that illustrate how to accurately predict the depth of a geological target using depth migration. In the first instance, a prestack offset is necessary in order to obtain a focus that can be reliably recognized by the target. In the second example, the velocity model must be anisotropic in order to satisfactorily describe the kinematic characteristics of the propagation of the ground wave, whereas the prestack migration is used to image a series of dip angles.