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地震波在聚集了石油、天然气的储层中传播时存在能量的剧烈衰减,且频率越高能量衰减越快,所以通过地震波高频端能量衰减梯度可以灵敏地检测地层中是否存在烃类流体。通过传统的傅里叶变换求取地震波能量衰减梯度面临诸多问题,而伪Margenau-Hill(PMH)分布作为科恩类时频分布的一种则具有许多优良的特性:真边缘性、弱支撑性、好的时频聚集性等。为此,该文将PMH分布的时频分析方法引入到了地震波吸收衰减分析技术中,利用地震波高频端能量与其对应频率的拟线性关系来计算各时刻的地震波能量衰减梯度。实际资料应用表明,利用PMH分布来求取地震波能量衰减梯度在储层预测中具有重要意义。
When seismic waves propagate in oil and natural gas reservoirs, there is intense energy attenuation, and the higher the frequency is, the faster the energy decays. Therefore, the energy attenuation gradient at the high frequency end of seismic waves can sensitively detect the presence of hydrocarbon fluids in the formation. However, the pseudo-Margenau-Hill (PMH) distribution has many excellent characteristics as a Cohen type of time-frequency distribution: true edge, weak support, Good time-frequency aggregation and so on. Therefore, this paper introduces the time-frequency analysis method of PMH distribution into seismic absorption attenuation analysis, and uses the quasi-linear relationship between the energy of seismic wave and its corresponding frequency to calculate the seismic energy attenuation gradient at each moment. The application of actual data shows that the use of PMH distribution to obtain seismic energy attenuation gradient in reservoir prediction is of great significance.