基于广义S变换的频移衰减估算方法及其在碳酸盐岩储层中的应用

传统频率域衰减Q值估算方法在碳酸盐岩储层地震预测中往往存在Q值精度不高和时频分辨率不足的问题，难以精细、有效地描述储层地震特征。本文利用改进的频移法Q值估算精度高、稳定性好的优势，引入广义S变换使其时频分辨率可调以满足实际需求，提出了一种完整的衰减方法研究流程，讨论了广义S变换双参数及振幅谱频段参数的选取方式，参考层识别与层剥离处理方法等问题，有效提升了衰减Q值方法在碳酸盐岩储层研究中的适用性。将该方法应用于安岳气田磨溪区块龙王庙组碳酸盐岩储层，提取了工区内一条二维地震测线的Q值剖面，对比实际资料进行分析，结果表明Q值结果较振幅、波阻抗属性更能反映储层含气特征，低Q分布区域与含气井位置基本吻合，衰减异常现象明显。将该方法应用于全工区地震资料，Q值结果反映了地层的吸收特征和储层特征差异，有效预测了优质储层分布的有利区。基于衰减Q值的估算方法在碳酸盐岩储层预测中具有明显效果。

Attenuation estimation method of frequency shift based on generalized S-transform and its application in carbonate reservoirs

Traditional attenuation Q factor estimation methods in the frequency domain faces the problem of the precision of extracted Q factors, and the time-frequency resolution is insufficient to support the seismic prediction of carbonate reservoirs. There is difficulty in effectively describing the carbonate reservoir characteristics with these methods. This paper took advantages of high accuracy and stability features of the improved frequency shift method, and the generalized S-transform was introduced to make the time-frequency resolution adjustable to meet the actual needs. A complete attenuation method of research flow was proposed to discuss on the selection of S-transform parameters and amplitude spectrum band parameters, the identification of reference layer and the layer-stripping methods. The applicability of the attenuation Q method was improved in the study of carbonate reservoirs. This method was applied to the carbonate reservoir of Longwangmiao Formation in the Moxi block of Anyue gas field. The Q factor profile of a 2D seismic survey line in the work area was extracted to be analyzed with actual data, and the results show that the Q factor results reflect the gas-bearing characteristics of the reservoirs better than the amplitude and wave impedance properties, The low-Q distribution area is basically consistent with the position of gas-bearing wells, and the attenuation anomaly is obvious. The method is then applied to seismic data in the whole work area. The Q factor results reflect the differences in the absorption characteristics and reservoir characteristics of the strata, and effectively predict the favorable areas for the distribution of high-quality reservoirs. The estimation method based on the attenuation Q factor has a significant effect in the prediction of carbonate reservoirs.