摘要
黏滞—弥散波动方程理论能够将含油气储层的地震响应特征与频率紧密联系起来,而斑块饱和模型则常用来描述经典含气砂岩的岩石物理特征。根据Johnson理论,通过计算岩石动态体积模量可以得到等效纵波相速度和品质因子的频散关系,改变含气饱和度能够对砂岩中地震波速度的衰减产生十分显著的影响,在地震频段可高达数百米每秒。当地震频率较高时,含气饱和度越高地震波衰减越强;地震频率足够低时,含气饱和度越高地震波衰减越弱。根据Carcione衰减机制,结合叠前相移加插值黏滞—弥散波动方程正演,对三类经典含气砂岩的地震响应特征进行数值模拟,发现增大含气饱和度可使储层下界面反射产生明显"时间延迟",且地震波在欠压实和中等压实的砂岩储层中表现出一定的主频降低现象;渗透率的增大能够改变介质中流体的流动性,但对含气储层的地震响应影响相对较小。
Seismic responses of gas and oil reservoirs can be contacted with frequency through the diffusive-viscous equation simulation theory,while white periodical layout sphere patchy saturated model is usually used to describe rock physics characteristics of classic gas bearing sandstone.According to the Johnson theory,the dispersion relation between seismic phase velocity and quality factor can be obtained by calculating the dynamic bulk modulus.Great seismic velocity difference can be observed when gas saturation in sandstones changes,the difference can be sometimes as high as hundreds of meters per second.When gas saturation is higher,seismic energy at high frequency attenuates more,but when gas saturation is higher,seismic energy at low frequency attenuates less.With the Carcione attenuation mechanism,the prestack diffusive-viscous wave equation,and the phase shift interpolation,we simulate seismic responses of three classic sandstone reservoirs.Some phenomena has been found:a.Gas saturation increase can lead to reflection remarkable'time delay'at reservoir low interface,and the dominant frequency declines in unconsolidated and medium consolidated sandstone reservoirs;b.Permeability increase can improve the fluid fluidity,but it has much less impact on seismic response of gas saturated reservoirs.
出处
《石油地球物理勘探》
EI
CSCD
北大核心
2017年第4期752-759,共8页
Oil Geophysical Prospecting
基金
国家自然科学基金石油化工联合基金(U1562111)
国家科技重大专项(2016ZX05002-004-010)联合资助
关键词
黏滞—弥散
斑块饱和模型
含气砂岩
含气饱和度
渗透率
时间延迟
数值模拟
diffusive-viscous
patchy saturated model
gas bearing sandstone
gas saturation
permeability
time delay
numerical simulation
