In addition to rock porosity

pore structure (pore size and geometry) also affects velocity of seismic waves

lowering the accuracy of reservoir prediction of velocity-porosity model.This paper introduces the Sun Model named by Shell for advanced carbonate reservoir characterization

a new rock-physics-based parameter called frame flexibility factor

and the method of how to calculate this parameter.The frame flexibility factor can be used as a pore type indicator to quantify the effects of pore structure on velocity and permeability and establishes relations among porosity-sonic velocity-frame flexibility factor instead of porosity-sonic velocity.It also can be used to describe permeability heterogeneity

and establish relations among porosity-permeability-frame flexibility factor instead of porosity-permeability.Theoretical model has been built for porosity and permeability prediction and makes it possible to characterize reservoirs with porosity

permeability and pore structure on seismic.Good results have been achieved through the utilization of the model in the Puguang gas field.