The X Block in Peru is situated within the El Alto Uplift in the north-eastern T Basin of the South American fore-arc rift. It is a centurial oil field with a high degree of exploration. The deep Paleogene sandstone serves as the target oil reservoir for the field. The thin thickness and extensive lateral variability of the reservoir pose as a challenge for reservoir prediction. The present study focuses on medium-deep Paleogene sandstone reservoirs in the X Block. To achieve this, a combination of techniques is employed, including sandstone sedimentary facies analysis, dynamic cluster analysis of seismic waveforms, and the construction of Bayesian inversion frameworks for different seismic facies. The aim is to apply frequency fusion technology to perform facies controlled waveform indicator inversion. The inversion results demonstrate that the seismic waveform indicator inversion has enhanced the vertical and horizontal resolutions of the inversion results, and the identification accuracy of thin interbedded sandstone can be 5 m. The inversion results exhibit an 80% agreement with drilling results, elucidating the distribution pattern of sand bodies in the medium-deep layers of the Paleogene. The results show that the distribution of reservoirs is consistent with the regional sedimentary facies. The seismic waveform indicator inversion has yielded the anticipated outcomes in the prediction of Paleogene sandstone reservoirs, furnishing a reference point and guidance for the identification of thin interlayers in analogous aged oil fields.