基于吸收和速度频散的孔隙弹性介质流体识别研究

Study on Pore-elastic Medium Fluid Detection Based on Attenuation and Velocity Dispersion

为了研究利用自激自收地震资料进行储层中流体识别的可行性,根据储层和上覆介质波阻抗的差异特性,将油气勘探中遇到的砂岩储层分为3类,设计了3个模型,利用模型分析了3类储层反射系数振幅和相位角随频率变化的特征。模型分析结果表明,储层中岩石的渗透率、流体的饱和度对与低频相关的吸收和相速度影响较大,且证实在某种程度上,利用吸收和速度频散引起的反射系数和相位角表现出的低频异常特征可以作为储层流体识别的一个标志,并根据其特征建立了识别不同类型储层流体的准则和步骤。通过实例分析证实了经过适当处理的自激自收地震资料中存在吸收和速度频散产生的低频异常特征,以及利用其特征进行储层流体识别的有效性。

To study the feasibility for detecting reservoir fluid based on self-excited and self-received seismic data,three reservoir models were selected by classifying sandstone reservoirs encountered in oil-gas exploration into 3 types according to the difference of wave impedance of overlaying medium.The models were used to analyze the characteristics of magnitude and phase angle of the normal-incident reflection coefficient as a function of frequency at an interface between non-dispersive medium and patchy-saturated dispersive medium for 3 types of reservoirs.Results indicate that permeability of rock and fluid saturation in reservoir have stronger effects on both attenuation and phase velocity related to low-frequency,and also show that low-frequency seismic anomalies associated with hydrocarbon reservoirs that cause by attenuation and velocity dispersion can be an indicator of reservoir fluid detection.According to the characteristics,a criterion and procedure are established for fluid detection.Finally,the proposed methods are applied to real data.The result demonstrates that it is effective to self-excited and self-received seismic data to detect reservoir fluid.