基于曲波变换的琼东南盆地Y区潜山裂缝特征刻画及缝洞型储层预测技术

    Characterization of Buried Hills Fracture Features and Fracture-Cave Reservoir Prediction Technology in Y Gas Field of the Qiongdongnan Basin Based on Curvelet Transform

    • 摘要: 南海北部琼东南盆地中生界花岗岩潜山裂缝预测难度大,宽方位采集叠前地震数据缺失导致AVAz反演无法开展,潜山目的层地震信噪比低致使常规地震属性(相干、曲率)分析预测裂缝效果不佳。针对上述问题,本文聚焦琼东南盆地Y区,开展了花岗岩潜山岩石物理分析,揭示出潜山储层中强风化带和次风化带具有低横波阻抗特征,潜山内幕裂缝带具有高横波阻抗特征。依托道集优化后的叠加地震数据,开展了曲波变换处理、蚂蚁体属性及最大似然属性处理分析;开展了横波阻抗反演获得相对横波阻抗,并完成了潜山储层分析。研究证明,叠加地震曲波变换后蚂蚁体及最大似然属性能够刻画大、中尺度裂缝及内部细节变化,且优于叠加地震曲率属性的刻画效果,曲波变换横波阻抗能够比较可靠地刻画花岗岩潜山风化带储层。本文综合曲波变换后的蚂蚁体属性、最大似然属性和曲波变换横波阻抗成果,建立了研究区中生界花岗岩潜山发育模式。后续,潜山储层预测成果被钻井所证实,取得了较好的预测效果。上述方法不仅适用于花岗岩潜山裂缝和潜山风化带预测研究,并可为变质岩潜山储层预测提供借鉴,在类似地区具有较好的推广性。

       

      Abstract: The prediction of fractures in the Mesozoic granite buried hills in the Qiongdongnan Basin in the northern South China Sea is difficult, and the lack of wide azimuth pre-stack seismic data results in the inability to carry out AVAz inversion. The low seismic signal-to-noise ratio in the target layer of buried hills results in poor prediction of fractres using conventional seismic attributes (coherence, curvature) analysis. Rock physics analysis of the granite buried hill in the study area indicates that the heavily and moderately weathered zones of the buried hill reservoir exhibit low S-wave impedance characteristics, while the interior fracture zones of the buried hill demonstrate high S-wave impedance characteristics. Based on the stacked seismic data after gather optimization, curvelet transform processing, ant-tracking and maximum likelihood attribute analyses were conducted; shear-wave impedance inversion were performed which yield the relative shear-wave impedance results and the analysis of buried hill reservoir were completed. Research has shown that the ant-tracking attribute and maximum likelihood attribute after curvelet transform can characterize large and medium scale fractures and internal details, and the characterization effect is better than seismic curvature attribute. The shear wave impedance after curvelet transform can reliably characterize the weathered zone reservoir of granite buried hills. This article integrates the ant-tracking attribute, maximum likelihood attribute, and S-wave impedance results of the curvelet transform to establish the development model of Mesozoic granite buried hills in the study area. The prediction results of the buried hill reservoir have been confirmed by drilling, achieving good prediction results. The above method is not only applicable to the prediction of granite buried hill fractures and weathering zones, but also provides reference for the prediction of metamorphic rock buried hill reservoirs, and has good applicability in similar regions.

       

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