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上行波与下行波的分离是垂直地震剖面(VSP)处理中的关键步骤。对这个问题已经有许多理论上的探讨,但到目前为止,所有发表的文章都是根据时—深(t-z)、频率—波数(w-k)或截距时间—射线参数(τ-p)域中两种波列之间的差异进行分离的。在倾角很陡的情况下,例如,当探井邻近盐丘壁或存在高阻抗差的垂直断面时,反射上行波的入射角可能十分接近于下行波的入射角,以至于在处理过程中,两种波都可能被目前所用的速度滤波器同时滤掉。本文介绍一种实用的方法,它可解决上述情况下使用速度滤波器的这一缺点。这种方法是波场减法技术(在其他 VSP 文献中已有描述)的延伸。文中并用一个最近的典型勘探实例作了说明。然而,要实现本方法,就必须只借助于 VSP,从地质上了解模型的特点。因此,这就需要加强解释人员与处理人员之间的最佳协作。
The separation of upstream and downstream waves is a key step in vertical seismic profiling (VSP). There have been many theoretical discussions of this issue, but so far all published articles are based on the time-depth (tz), frequency-wavenumber (wk) or intercept time-ray parameter The difference between the two wavelets is separated. For example, when the exploration well is adjacent to the salt dome or there is a vertical section with high impedance difference, the incident angle of the reflected upstream wave may be very close to the incident angle of the descending wave, so that during processing, two The kind of wave can be filtered by the speed filter used at the same time. This article describes a practical method that addresses the disadvantage of using a speed filter in the above situations. This method is an extension of the wavefield subtraction technique (described in other VSP documents). A recent example of a typical exploration is illustrated in the paper. However, to implement this method, the characteristics of the model must be geologically understood using only the VSP. Therefore, there is a need to strengthen the best collaboration between the interpreter and the handler.