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    渤海湾盆地基岩潜山地震资料处理关键技术

    Key techniques of seismic data processing for bedrock buried hills in Bohai Bay Basin

    • 摘要: 渤海湾盆地基岩潜山顶部风化壳及内幕断裂带是一种新型的油气富集带。基岩潜山岩性为花岗岩和变质岩,地震反射结构杂乱,采用传统基于沉积岩的处理技术难以获得潜山内幕可靠成像,资料品质无法满足构造解释与储层预测需求。弱信号增强、速度建模和变质岩储层成像是资料处理的关键难题。研究和测试表明,采用高维滤波及五维数据规则化技术可有效增强变质岩内幕弱信号。针对古近系、新近系和太古宇地层的资料特征和速度分布规律,研究形成的分段式速度建模方法,建立了准确的基岩潜山速度场。反射角层析成像技术,有效提高速度建模精度。Q逆时偏移改善了顶部风化壳成像,散射波成像获得风化壳缝洞体和内幕断裂系统的清晰成像。实际资料处理结果表明,本文方法显著改善了潜山内幕成像质量,为同类地区潜山油气藏勘探提供了有效技术手段。

       

      Abstract: The weathering crust at the top of the bedrock buried hills and the internal fault zones in the Bohai Bay Basin represent a new type of hydrocarbon enrichment zone. The bedrock buried hills are lithologically composed of granites and metamorphic rocks. Owing to their chaotic seismic reflections, it is difficult to accurately image the internal structures of these buried hills, for reliable structure interpretation and reservoir prediction, by using conventional processing techniques for sedimentary rocks. Weak signal enhancement, velocity modeling, and metamorphic reservoir imaging are the key problems in data processing. Our study shows that weak signals within metamorphic buried hills can be effectively enhanced through high-dimensional filtering and five-dimensional data regularization. According to the data characteristics and velocity distribution patterns of Paleogene, Neogene, and Archean strata, a segmented velocity modeling method is developed to establish an accurate velocity field for the bedrock buried hills. Reflection angle tomography improves the accuracy of velocity modeling. Q reverse time migration improves the imaging of the top weathering crust, and scattered wave stacking clearly images the fracture-cavity units within the weathering crust and the internal fault system. Field data processing results show that the proposed methods significantly improve the imaging quality of buried hill interiors and thus provide effective technical means for the exploration of buried-hill reservoirs in similar areas.

       

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