ABSTRACT In comparison to high‐frequency signals, low‐frequency seismic signals suffer less from scattering and intrinsic attenuation during wave propagation, penetrate deeper strata and thus can provide more energy information related to the hydrocarbon reservoirs. Based on the asymptotic representation for the frequency‐dependent reflections in the fluid‐saturated pore‐elastic media, we first derive a novel equation of the reservoir energy density and present an efficient workflow to calculate the reservoir energy density using low‐frequency seismic data. Then, within a low‐frequency range (from 1 to 30 Hz), we construct an objective function to determine the optimal frequency, using the energy densities calculated from the post‐stack seismic traces close to the wells. Next, we can calculate the reservoir energy density using the instantaneous spectra of optimal frequency at the low‐frequency end of the seismic spectrum. Tests on examples for synthetic and field data demonstrate that the proposed reservoir energy density can produce high‐quality images for the fluid‐saturated reservoirs, and it produces less background artefacts caused by elastic layers. This method provides a new way to detect the location of hydrocarbon reservoirs and characterize their spatial distribution.

中文翻译：

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一种基于地震低频信号的储层圈定能量密度计算新方法

摘要 与高频信号相比，低频地震信号在波传播过程中受到的散射和固有衰减较小，可以穿透更深的地层，因此可以提供更多与油气藏相关的能量信息。基于流体饱和孔隙弹性介质中频率相关反射的渐近表示，我们首先推导出了一个新的储层能量密度方程，并提出了一种使用低频地震数据计算储层能量密度的有效工作流程。然后，在低频范围内（从 1 到 30 Hz），我们构建了一个目标函数来确定最佳频率，使用从靠近井的叠后地震道计算的能量密度。下一个，我们可以利用地震谱低频端最优频率的瞬时谱计算储层能量密度。对合成和现场数据示例的测试表明，所提出的储层能量密度可以为流体饱和储层生成高质量的图像，并且产生较少的由弹性层引起的背景伪影。该方法为探测油气藏位置并表征其空间分布提供了一种新方法。