高分辨率小道距处理技术及属性分析在水合物识别中的应用

Application of high-resolution small group interval processing technology and attribute analysis for hydrate identification

  • 摘要: 天然气水合物资源在能源勘探中扮演着越来越重要的地位,浅表层天然气水合物的类型特征和成藏模式日益受到学者的广泛关注。浅表层天然气水合物一般赋存于近海底地层中,在勘探过程中要求有更高的分辨率,常规多道地震由于主频较低难以满足要求。海洋高分辨小道距地震探测技术具有分辨率高、作业方式灵活等优势,在浅表天然气水合物勘探中得到广泛应用。实际的高分辨小道距资料由于采集设备条件的影响,往往具有低信噪比的特点。本文针对高分辨小道距地震数据的特点开展精细化处理和属性分析。首先采用基于 f-x 域和曲波域的多域噪声压制方法、基于频率域自适应虚反射压制和基于相干函数控制的虚反射走时电缆等浮校正等关键技术方法,获得了波组特征更清晰的地震剖面。处理后的剖面具有信噪比较高、连续性好、地层结构清晰等特点,可以更好地揭示BSR特征、空白带、气通道等地震反射特征,为识别浅层天然气水合物赋存区地质信息奠定了基础;然后对精细处理后的数据进一步开展瞬时振幅属性、瞬时频率属性、烃类检测等地震属性分析,以此识别浅层天然气水合物的分布类型和成藏规律。

     

    Abstract: Natural gas hydrate resources are playing more and more important role in energy exploration, and the type characteristics and accumulation patterns of shallow layer natural gas hydrate have attracted more and more attention. Shallow layer gas hydrates generally occur in the near-seabed strata, and require higher resolution in the exploration process. Conventional multi-channel seismic are difficult to meet this requirement due to their low dominant frequency. With the advantages of high resolution and flexible operation mode, the marine high-resolution small group interval seismic exploration technology has been widely used in shallow gas hydrate exploration. Due to the influence of acquisition equipment conditions, the actual high-resolution small group interval data often has the characteristics of low signal-to-noise ratio. Therefore, fine processing and attribute analysis were carried out according to the characteristics of high-resolution small group interval seismic data. First, the key technical methods such as multi-domain noise suppression method based on the fx (f: frequency; x: the offset) domain and curvelet domain, adaptive ghost suppression based on frequency domain, and cable floating correction based on combination of gather coherence and ghost reflection traveltime were used to obtain seismic profiles with clearer wave group characteristics. The processed profile has the characteristics of high signal-to-noise ratio, good continuity, and clear stratigraphic configuration, which can better reveal the seismic reflection characteristics such as BSR characteristics, blank zone, and gas channel, and lay a foundation for identifying the geological information to locate the shallow gas hydrate occurrence area. Secondly, the seismic attributes such as instantaneous amplitude attribute, instantaneous frequency attribute, and hydrocarbon detection were further analyzed for the finely processed data for the identification of the distribution type and accumulation law of shallow gas hydrate.

     

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