地震分频技术在扇三角洲演化过程研究中的应用

Application of seismic frequency-division technology in the study of fan-delta evolution

地震分频是应用离散傅立叶变换(DFT)或最大熵方法,将地震数据分解成不同频率域的调谐体技术,该项技术一般应用在薄层预测方面的研究。根据储层的厚度及分布特征,选择合适时窗参数,提取地震主频率。根据地震主频在平面上的变化,可以检测沉积体边界的变化,为沉积相演化过程提供准确依据。根据地震主频率与储层厚度的转换关系,可以进一步计算储层厚度。TLG油田J2井区九佛堂组—沙海组地层发育扇三角洲沉积,通过应用地震分频技术,重点分析了研究区九佛堂组—沙海组扇三角洲的平面分布及其纵向演化规律,判断了南部边界断裂处物源在不同时期的变化特征。实例应用显示,该方法在克服常规预测沉积相边界不确定性的同时,大大提高了常规地震相识别的精细程度。

Seismic frequency-division is to transform seismic data into different frequency domains via the Discrete Fourier Transform（DFY） or the Maximum Entropy Method（MEM）, and is generally used in the predication of thin reservoirs. Based on the thickness and distribution of reservoirs, seismic primary frequency can be extracted through selecting appropriate parameters of time window. Plane changes of seismic primary frequency can then be used to detect edges of sedimentary bodies, thus providing reliable evidences for the study of fan-delta evolutionary process. The relationship of seismic primary frequency and reservoir thickness can also be employed to calculate thicknesses of thin reservoirs. By applying the technology in the analysis of the Jiufetang-Shahai Formations in J2 wellblock of the TLG Oilfield,where deposits of fan-delta facies are developed,the horizontal distribution and vertical evolution pattern of the fan-delta in the research area is defined and the changing characteristics of the source near the southern boundary faults during different times are determined. This field application shows that the technology eliminates the uncertainty sedimentary facies and greatly enhances the accuracy of of conventional methods for predicting the boundary of seismic facies recognition.