P-SV波在提取SS波零偏移距反射率中的应用

Calculation of zero-offset reflectivity of SS waves via P-SV waves

1. 吉林大学地球探测科学与技术学院,吉林长春 130026;2. 国土资源部应用地球物理综合解释理论开放实验室--波动理论与成像技术实验室,吉林长春 130026

College of Geoexploration Science and Technology Jilin University, Changchun 130026, China

利用Gardner's经验关系式对P-SV波反射系数近似公式进行了简化,给出了一个描述P-SV波反射系数和SS波零偏移距反射率之间关系的统一近似公式。4个不同的含油气砂岩模型的定量计算表明,该统一近似公式不受岩性弱反差条件的限制,入射角在30°以内能够准确地反映P-SV波反射系数和SS波零偏移距反射率之间的近似关系,而且能够适用于不同形式的P-SV波反射系数近似公式。因此,利用该关系式可以由P-SV波直接构建SS波零偏移距剖面,而且可以实现SS波阻抗的定量反演和多波AVO分析,还可以通过SS波资料提取P-SV波振幅随入射角变化的信息。

A uniform approximate relation between reflection coefficients of P-SV waves and SS waves is derived from simplifying the reflection coefficient formulae for P-SV waves using on Gardner's relation. The quantitative results from four gas sand models show that the new equation is free from the restriction of weak lithology contrast, and can not only describe the inherent relationship between the impedance of SS waves and reflection coefficients of P-SV waves within 30°, but also suitable for the different forms of reflection coefficient approximate formulae of P-SV waves. The new expression can be used to construct pure SS wave zero-offset section directly from P-SV converted waves, and also can used to carry out SS wave impedance inversion and multiwave AVO analysis. Furthermore, information of amplitude versus with incident angle of P-SV waves can be extracted from SS wave data.