频率与多尺度吸收属性应用研究——以川西坳陷深层气藏预测为例

Application of frequency and multi-scale absorption attribute of deep formation in Western Sichuan Depression

川西坳陷深层须家河组气藏为超致密超高压非常规近源气藏。勘探区地震地质条件复杂,地震资料的有效频带窄,主频较低,不能很好地对储层进行描述。针对上述特点,开展了频率与多尺度吸收属性研究。利用小波函数具有局部化特征这一性质,基于Aki和Richards振幅公式,推导出地震主频和多尺度吸收属性计算公式,并通过研究和开发形成了分析技术。正演模拟结果表明,利用该技术可以在不同尺度范围分析地震波的传播时间和主频与吸收属性之间的关系,刻画能量、频率、吸收衰减和波形等属性的含油气响应特征。将该方法应用于新场地区须家河组气藏描述,所得结果与钻井结果吻合。

The gas reservoir at Xujiahe formation in deep Western Sichuan Depression has the characteristics of near-source,ultra tight and ultrahigh pressure.The seismic-geologic conditions in exploration area are complex,the effective frequency band of seismic data is narrow and the dominant frequency is relatively low,which cannot well describe reservoirs.Aiming at the above characteristics,frequency and multi-scale absorption attributes were studied.By adopting the property that wavelet function has localized characteristic, based on Aki and Richards amplitude formula,the computation formula for seismic dominant frequency and multi-scale absorption attribute was deduced,and a interpretation technique was formed. Forward modeling result shows that the technique can be used to simulate the relationship between travel time,dominant frequency and absorption of seismic wave in different scale range,and to describe gas/oil-bearing response characteristics of energy,frequency, absorption attenuation and wave pattern,etc.the method was applied to the description of gas reservoir at Xujiahe formation of Xinchang area,the obtained result coincided with drilling result.