水淹层功率谱熵识别方法

The Power Spectral Entropy Identification Method for Water Flooded Zone

储集层的孔隙度和电阻率曲线间微差形态波形的复杂程度隐含着储集层含油气性的信息。功率谱密度不论水淹程度如何,整体为一随频率增大其能量按指数递减连续频谱;随水淹程度逐渐减弱,递减减小,整体能量逐渐降低,某些频率成分被吸收削弱,由光滑状逐渐演变成锯齿起伏状,其功率谱熵逐渐增大。信号的功率谱熵取决其复杂程度而与其绝对值的大小无关,基于测井信息的功率谱熵特征识别水淹层的方法,对利用传统测井解释理论判别比较困难的“低阻油层和高阻水淹层(水层)”有较强的识别能力。

The information of petroliferous reservoir is hided in the level of differential waveform complexity between the resistivity and porosity log curves of reservoirs. The density of power spectral entropy, on the whole, is an exponential decline curve with frequency augmentation without reference to water flooded extent. Along with water flooded extent reducing gradually, the declining rate of power spectral is reducing and some frequency components are absorbed, the whole of which energy gradually falls. The curve changes gradually from slick to dentate form, and the power spectral entropy increases gradually. The signal power spectral entropy depends on the level of signal complexity and is independent of signal absolute value. It is indicated that the low resistivity oil layer and the high resistivity swept layer and water layer can be much better identified by the identification method of swept layer based on the power spectral entropy characteristic of log signal than by the conventional well log explanation theory.