... Aki-Richards approximation, which is in error by as much as 25% in the same angle range. nonlinear avo avo approximation relative change upstream oil & gas boundary angle range order error correction amplitude nonlinearity reservoir characterization procedure innanen equation...

... Summary New approximations are developed for R PP and R PS that are optimal in the sense that they preserve as much accuracy as possible with as much simplicity as possible. In particular, they are expressed in a form that is pseudo-linear after the form of the Aki-Richards approximation...