Seismic Quality Factors Estimation From Spectral Correlation

Abstract

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> This letter describes a method for estimating seismic quality <formula formulatype="inline"><tex Notation="TeX">$(Q)$</tex> </formula> factors from spectral correlation (SC). For a linear frequency attenuation model, the SC coefficient is examined between the amplitude spectrum of a reference pulse multiplied by an absorption filter and that of a target pulse, and then, the <formula formulatype="inline"><tex Notation="TeX">$Q$</tex></formula> factor can be determined from the absorption filter which yields the maximum SC coefficient. In this way, <formula formulatype="inline"><tex Notation="TeX">$Q$</tex></formula> -factor estimation is converted into an optimization problem which can be quickly implemented by the Newton iteration scheme. Synthetic tests with different source signatures show that the SC method is free of the type of source wavelet. Noisy tests indicate that the SC method has higher noise resistance than the logarithm spectral ratio and the centroid frequency shifting methods. Field test indicates that the depth range of lower <formula formulatype="inline"><tex Notation="TeX">$Q$</tex></formula> values estimated by the SC method well corresponds to the distribution of gas reservoirs. With better <formula formulatype="inline"><tex Notation="TeX">$Q$</tex></formula>-factor evaluation, the SC method may become a more practical tool for gas reservoir characterization than before. </para>