基于海洋同步源高效混叠采集随机延迟时间序列定量设计与评价

    Study on the distribution principle of random time series in simultaneous source streamer seismic acquisition

    • 摘要: 随着海上中深层复杂地质构造及油气藏精细描述的需求提升,业界期望实现更高覆盖密度、更宽方位角、更高采集效率及更低作业成本的地震数据采集。海上高效混叠采集技术是提升采集效率的核心配套技术,由于相邻震源激发时间间隔小于采集记录长度,导致地震波记录范围内产生信号混叠,数据分离方法对混叠信号进行有效分离。在海上混叠采集技术中,时间延迟序列的编码方案是影响数据分离效果的关键因素之一,而高效采集过程中连续炮点间的时间间隔需具备一定随机性。目前,尚无可靠方法明确时间间隔 “随机性” 的合理阈值以确保分离效果。针对工业界普遍应用的均匀分布和正态分布两种随机编码方式,本文首先提出了编码方法及延迟时间设计流程;其次通过数值模拟手段,对比评价了两种随机时间序列的信号分离精度,进而构建出最优时间序列模型;并利用三维频率 - 波数域 - 波数域(FKK)反演方法进行数据分离,从理论层面验证了不同编码方式的有效性。最后,通过海上靶区实际数据的采集与分离处理,进一步验证了该方法的可靠性。

       

      Abstract: With the increasing demand for the fine description of complex middle-deep geological structures and oil/gas reservoirs in offshore areas, the industry expects to achieve seismic data acquisition with higher coverage density, wider azimuth, higher acquisition efficiency, and lower operational costs. Offshore high-efficiency aliased acquisition technology is a core supporting technique for improving acquisition efficiency. As the excitation time interval between adjacent sources is shorter than the acquisition record length, signal aliasing occurs within the seismic wave recording range, and data separation methods are used to effectively separate the aliased signals. In offshore aliased acquisition technology, the coding scheme of the time delay sequence is one of the key factors affecting data separation performance, and the time intervals between consecutive shot points during high-efficiency acquisition need to have a certain degree of randomness. Currently, there is still no reliable method to determine the reasonable threshold of "randomness" for time intervals to ensure separation performance.Aiming at the two random coding schemes widely used in the industry (uniform distribution and normal distribution), this paper first proposes the coding methods and delay time design procedures. Secondly, through numerical simulation methods, the signal separation accuracy of the two random time sequences is compared and evaluated, and an optimal time sequence model is constructed. The three-dimensional frequency-wavenumber-wavenumber (FKK) inversion method is used for data separation to theoretically verify the effectiveness of different coding schemes. Finally, the reliability of the method is further validated through actual data acquisition and separation processing in offshore target areas.

       

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