西部沙漠区中深层地震数据近地表Q补偿应用研究

2021年 60卷 第No. 6期
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Application of near-surface Q compensation for seismic data from a mid-depth layer in the western desert in China
(中国石油勘探开发研究院西北分院,甘肃兰州730020)
(Northwest Branch of Research Institute of Petroleum Exploration & Development,Petrochina,Lanzhou 730020,China)

中国西部沙漠地区采集的地震数据分辨率低,且频带较窄,这主要是由近地表低降速带对地震波的吸收衰减作用所致。因此,降低近地表低降速带对地震波的吸收衰减作用和提高地震数据的分辨率对沙漠工区地震数据的处理具有重要意义。首先概述了谱比法和峰值频移法的方法原理;然后将这两种方法应用于西部某沙漠工区地震勘探资料的Q值估计,并分析其适用条件与补偿效果,用于指导选择适合工区的Q值估计方法;通过对比相位补偿、振幅补偿和相位振幅同时补偿方法的不同效果,形成一套适用于研究工区的近地表Q值求取与补偿的处理流程。数值试验结果表明:相较于谱比法,峰值频移法对近地表低速层的Q值估计更适合本工区;且相位振幅组合补偿方法对地震波的吸收衰减补偿作用效果显著。中深层地震数据的补偿结果表明,将利用峰值频移法估算得到的Q值与相位振幅组合补偿方法相结合,既可保持地震数据低频成分,又有效提高了地震数据的高频成分,进而有效拓宽了地震数据的频带,提高了地震数据的分辨率和信噪比,使得复杂构造区域的成像更加清晰准确。

Seismic data acquired from desert regions in western China exhibit low resolutions and narrow frequency bands,which are mainly caused by the absorption and attenuation of seismic waves in the near-surface low-velocity (NSLV) layer.Reducing these phenomena and improving the resolution of seismic data is therefore of great significance to seismic data processing and imaging.In this work,the spectral ratio and peak frequency shift methods were implemented to estimate the Q-value of seismic data from the western desert area.The conditions for applying these methods and the effects of compensation were analyzed to identify the most suitable method for estimating the Q-value in the area.By comparing the effects of phase compensation,amplitude compensation,and phase-amplitude combined compensation (PACC) methods,a procedure was developed to calculate and compensate for the Q-value of the NSLV layer.Numerical test results showed that the peak frequency shift method is more suitable for estimating the Q-value of the NSLV layer than the spectral ratio method.The PACC method has a significant effect on seismic wave absorption and attenuation compensation.With respect to the compensation of seismic data from the mid-depth layer,it was shown that by combining the Q-value estimations by the peak frequency shift method and PACC methods,the low-frequency component of the seismic data could be retained,and the high-frequency component could be improved,thereby effectively broadening the frequency band and improving the resolution and signal-to-noise ratio of the seismic data,thus achieving clearer and more accurate imaging of complex structures.

地层品质因子; Q补偿; 谱比法; 峰值频移法; 近地表吸收衰减; 提高分辨率; 西部沙漠区; 中深层;
formation quality factor;; Q compensation;; spectral ratio method;; peak-frequency shift method;; near-surface absorption;; resolution enhancement;; western desert;; mid-deep layer;

国家油气重大专项(2016ZX05004003)资助。

10.3969/j.issn.1000-1441.2021.06.008