Modeling of seismic response of a thin bed In this paper we analyze and compared two techniques that allowed to model the variations of the seismic response depending on the incident angle, of a thin geologic layer representative of a typical reservoir. The two analyzed techniques assume an incident plane compressional wave and take into a account the energy partitioning on the interface caused by the conversion to shear and compressional waves reflected and transmitted. The first technique, that we call "approximate", is more efficient in computational terms, and it is based on the reflections coefficients calculation and transmission through Aki Richard's approximation. The second, that we call "complete", which provides more precise and realistic solutions, is based on the calculation of scalar and vector potentials associated with different waves propagating in several media involves. This technique includes, besides the incident energy partition, the creation of several reflections on the layer, due to the compressional and shear waves. Aditionally, we conclude about the approximates techniques precisions based on reflections and transmission conventional coefficients for the modelling, and their possible influence in the inversion for the estimation of the parameters of interest.