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.