摘要
为阐明地震低频阴影现象产生的机理,设计了2个等效地层模型,水平层状介质模型分析结果表明,在低频(如15 Hz)瞬时频谱剖面中,含油气层下部表现为强能量团;当频率为50 Hz以上时,储集层下方的能量比低频瞬时频谱剖面中对应位置的能量要弱得多,这就是典型的低频阴影现象。简化的碳酸盐岩溶蚀孔洞模型分析结果表明,溶洞含油时,溶洞下方最先存在波阻抗差异的界面附近会出现明显的低频阴影现象;而溶洞含水时,低频阴影现象不明显。该结论与实际地震解释结果相吻合,这为利用低频阴影现象识别油水层提供了理论依据。
The mechanism of the low-frequency shadows is explained from seismic wave attenuation with instantaneous spectral analysis method and two equivalent formation models are developed in this paper. The horizontal layered medium model analysis shows that in the instantaneous frequency spectrum profiles for the low frequency （such as 15 Hz）, the strong energy group occurs beneath the oil-gas bearing layer; when the frequency is above 50 Hz, the energy below the reservoir is much weaker than the energy of the corresponding position of it, which is a typical phenomenon of low-frequency shadows. The simplified caved carbonate reservoir model analysis result indicates that when hydrocarbon is contained in the karst caves, the obvious low-frequency shadows phenomenon may appear near the interface with the wave impedance difference at first beneath the caves, while water is contained in the caves, such a phenomenon is less clear. It is proved that this conclusion is relevant to the real seismic interpretation results, and can be as theoretical basis for identification of oil and water bearing layers by means of the low-frequency shadows.
出处
《新疆石油地质》
CAS
CSCD
北大核心
2014年第4期408-413,共6页
Xinjiang Petroleum Geology
基金
国家科技重大专项(2011ZX05004-003)
关键词
烃类检测
低频阴影
地震波衰减
黏弹性波动方程
频谱分解
溶蚀孔洞模型
hydrocarbon detection
low-frequency shadow
seismic attenuation
viscoelastic wave equation
spectral decomposition
cavedcarbonate reservoir model
