摘要:
多次波压制是海洋地震资料处理的重要环节。在南黄海盆地崂山隆起区,印支期以来强烈的改造作用使得中生界遭受大面积整体剥蚀,部分区域新生界直接叠覆在古生界之上形成不整合屏蔽层。海面、海底及不整合屏蔽层这3个强反射系数界面的存在使得该区多次波异常发育,中—古生界有效反射湮没在多次波干扰中无法识别,有效地压制多次波已成为本区中—古生界成像的基础和关键。通过理论模拟及实际资料分析,总结了研究区多次波特征,认为自由表面多次波、长周期多次波、折射多次波及绕射多次波是主要的多次波类型。对各类型多次波采用了针对性方法进行压制,介绍了压制方法的基本原理,并对其适用性进行了评价。针对横跨本区的南北向测线的多次波压制及偏移成像结果表明,使用的组合压制策略能够较好地压制各类型多次波,最终提升该区中—古生界的地震成像质量。
Abstract:
Multiple suppression is an essential procedure in marine seismic data processing. On the Laoshan Uplift of the South Yellow Sea Basin, The Mesozoic was almost completely denudated since the strong Indo-China movement, and the Cenozoic directly covers the Paleozoic. There are three strong reflection coefficient interfaces, i.e. the sea surface, the sea bottom and the unconformity between the Cenozoic and the Paleozoic. They lead to the formation of various multiples, because of the interference of multiples. As the result, the primary reflection from the Meso-Paleozoic boundary is hard to be effectively identified. Therefore, multiple suppression is the key step to Meso-Paleozoic seismic imaging. Based on the theory of simulation and practical data analysis, we summarized the characteristics of multiples of the area. It is found that there are three main types of multiple in this sea area. They are the surface-related, long period and refraction multiples. These types of multiple are suppressed with appropriate methods described in this paper. The authors introduced the main principle first and then evaluated the applicability of these methods. The removal and migration results of multiples from the south-north survey line across the Laoshan Uplift show that the multiples are suppressed thoroughly with the integrated suppression methods described in this paper and the quality of Meso-Paleozoic seismic imaging is improved.
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