用切变模量近似P-SV波反射系数及在多波AVO反演中的意义

本文从精确的P－SV反射系数公式出发,推导出了作为射线参数函数的近似公式。该式说明,在非法线入射时,P－SV波反射系数主要取决于两个弹性参数：①反射界面两侧介质体密度之差与平均体密度之比△ρ／ρ；②反射界面两侧切变模量差与平均体密度之比△μ／ρ。文中还给出了数值实例,以说明该式的计算精度,同时分析了其适用范围,并与Aki和Richards（1980）的近似式的数值结果作了比较。本文采用阻尼最小平方反演理论计算出的反演参数的结果表明,在AVO资料线性反演中,估算△μ／ρ比估算泊松比差△σ精度高。

P-SV reflection coefficient approximation using shear modulus and its significance in multiwave AVO inversion

Approximate expression as the function of ray parameters can be derived from the accurate P-SV reflection coefficient formula. The approximate expression shows that when in non-normal incidence,P-SV reflection coefficient mainly depends on two elastic parameters:1)p/p,the ratio of bulk density difference to average bulk density from bath sides of an interface;and 2) a Jp ,the ratio of shear modulus difference to average bufk density. Numerical example result is given to show computation accuracy of the approximate expression,and compared with the numerical recults of Aki and Richards'(1980)approximate formula. The applicability of our approximate expression is analysed here. The inversion parameters computed by using damped least-squares inversion theory demonstrate that in AVO data linear inverlion,estimation is mare accurate than△.(Poisson ratio difference)estimation.