大牛地气田煤系地层去煤影响储层预测技术

Research of Identification and Trimming of Coal-Bed Interference in Daniudi Gas Field

煤层造成的低频强反射对上覆下伏储层有效信号有着极强的干涉作用,如何从地震数据中剥离煤层干涉是煤系地层储层预测的难点所在。以大牛地气田低分辨率地震资料为例,利用Wigner-Ville分布时频分析技术对煤系地层造成的连续强反射同相轴进行高分辨率煤层定位,通过对比分析认为煤层具有典型的低频强能量中高频段急剧衰减特性。以此作为理论基础明确煤层反射优势频谱能量密度上限为26Hz,利用多子波分解与重构技术对大牛地气田三维地震资料开展分频段信号重组,即去煤干涉处理。在此基础上对煤系地层开展储层预测,并与实钻井勾绘砂体厚度图对比可知,储层有效信息得到充分展现。

Due to the powerful low frequency reflection from the coal bed,the effective signal from overlying or underlying reservoir is extremely distorted.How to identify and trim the interference of coal-bed from the seismic data is a key of coal-bed style reservoir prediction.In this paper,the Wigner-Ville distribution time-frequency analysis method is used to determine coal bed by the continuous events of high reflection energy.Results show that the behavior of coal bed is of high energy at low frequency while attenuated greatly at mid to high frequency.Therefore,the uplimit of dominant frequency is set to be 26 Hz.Furthermore,the goal aimed through multi-wavelets decompression and reconstruction technology,the interference from coal-bed trimmed effectively under the result of research,the signal of reservoir exposed extremely successful.