Time-frequency analysis can be used to time-frequency decomposition of seismic waves,and thus to obtain absorption attenuation gradient of high-frequency for hydrocarbon detection. However, when there is strong high-frequency interference in seismic records,the absorption attenuation gradient of high frequency is not a very good response to the real absorption attenuation of layer. In this paper, we take the advantage of higher time-frequency resolution of the generalized S transform and use the time-frequency spectrum to obtain seismic absorption attenuation gradient of low-frequency, then compared with the absorption attenuation gradient of high-frequency to better direct hydrocar bon. Results of theoretical derivation, numerical simulation and field data application show that generalized S transform based on absorption attenuation gradient detection of low-frequency and high-frequency can mutually support, and better point the existence of hydrocarbon.%利用时频分析可以对地震波进行时频分解,进而获得地震波高频段吸收衰减梯度,用于油气检测.然而当地震记录中高频干扰较强时,高频段时频谱的吸收衰减梯度并不能很好反映真实的吸收衰减情况.本文提出利用目前时频分辨能力较高的广义S变换求取地震波低频段时频谱的衰减梯度,并与高频段的吸收衰减梯度进行对比,以期更好地指示油气.理论推导、数值模拟及实际应用结果表明:基于广义S变换的低频吸收衰减梯度可以与高频吸收衰减梯度相互佐证,更可靠地指示油气的存在.
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