一种基于小波优势频带的深层-超深层碳酸盐岩走滑断裂识别方法及应用

The method and application of minor strike-slip faults identification about deep and ultra-deep carbonate reservoir based on wavelet transform sensitive frequency

塔里木油田碳酸盐岩储层埋藏深,地震资料主频低,走滑断裂断距小,断层地震反射特征不清楚,识别解释难度大.本文基于连续小波变换,提出一种识别深层-超深层碳酸盐岩走滑断裂方法.通过井震标定和地震正演模拟确定走滑断裂敏感频段,利用连续小波变换方法对断裂敏感频率进行筛选加权,突出断层地震反射特征,提高地震资料对次序级走滑断裂的识别能力.ZG8井区实际资料应用表明:经过本文方法处理后的地震数据与常规数据相比,剖面上走滑断裂的断点特征更清楚,平面上提取的相干属性对次序级断裂的刻画更可靠清晰,有利于本区块走滑断裂的综合解释研究以及断溶体的识别刻画.

The carbonate reservoir in Tarim Oilfield is buried deeply and the dominant frequency of seismic data is lower than 20 Hz. Under this condition, the vertical resolution of seismic data is only about 80 m. However, the vertical distance of strike-slip faults of target layer ranges from tens to thousands of meters. The minor strike-slip faults that fault distance less than 80 m cannot be completely identified by current seismic data. Besides, the target layer is a set of carbonate rocks of high impedance which has strong shielding effect about seismic reflection energy. The internal seismic reflection of carbonate rocks are mostly blank or weak characteristics and the seismic reflection characteristics of minor faults are not clear. So that it is difficult to identify and interpret strike-slip faults. Based on the theory of continuous wavelet transform, this paper presents a method to identify deep and ultra-deep strike-slip faults in carbonate reservoir. First, analyzing the effective frequency components of target layer with well-seismic calibration and determining sensitive frequency to strike-slip faults by the seismic forward modeling. Then, picking the sensitive frequency based on continuous wavelet transform and combining the sensitivefrequency by the weighting algorithm. Finally highlighting the interior reflection of carbonate rocks and improving the recognition ability of seismic data for minor strike-slip faults. The application of ZG8 area shows that the processed seismic data characteristics of minor faults are easily distinguished. Compared with the conventional data, the extracted coherent attribute is more reliable and clear. The method can significantly increase the identified number and interpretation accuracy about strike slip faults in this area and is helpful to the comprehensive interpretation research about strike-slip faults and fault-karst in ZG8 area.